HK40030308A - An industrial robot arm - Google Patents

Description

Industrial robot arm

Technical Field

The present disclosure pertains to the technical field of industrial robot arms and in particular to a lightweight robot arm for fast handling objects, for extremely fast moving objects and for high security robot devices.

Background

For example, direct cooperation between humans and robots and when the use of a fencing-free robotic device is advantageous, a high security device is required. In view of the prior art, there are parallel kinematics robots (such as the Delta robot described in WO1987003528a 1) which all have actuators mounted on a fixed mount and which therefore can achieve a lightweight structure. However, these parallel kinematics robots have the following disadvantages: the arm system takes up a lot of space and the working space is small in relation to the space needed for the arm system. Therefore, these robots can only be used for applications that leave a large space for the arm system, and for applications that are sufficient to have a very limited working space, in particular in the vertical direction. Thus, Delta robots are primarily used for pick and place operations above a plane, such as a conveyor belt, which has ample space for the robot arm structure.

In patent application WO2014187486 elongated (slim) parallel structures are proposed, enabling a larger working space with respect to the space required by the arm system compared to for example Delta robots. In this robot structure, a first actuator drives the first arm about a first axis, a first kinematic chain is configured to transmit rotation of the first arm to movement of the end effector, and the first kinematic chain has a first rod and a first joint between the first arm and the first rod. The first joint has at least two degrees of freedom (DOF) and the second joint is mounted between the first rod and the end effector. To operate without losing the six DOF limits for the end effector, the design according to WO2014187486 relies on the torsional stiffness of the first rod. However, this means that both the first joint and the second joint of the first rod must have two degrees of freedom and not more, which in turn means that it is not possible to obtain a constant tilt angle of the end effector more than at the middle of the working space. Thus, even in a simple pick and place operation on a horizontal surface, the elongated robot concept according to WO2014187486 requires a two DOF wrist. However, this wrist adds considerable weight and the robot does not have a light arm system such as a Delta robot. Again, wiring would be required to transmit power and control the actuators of the wrist.

In patent application WO2015188843, a parallel kinematics robot comprises a base and an end effector movable relative to the base. The first actuator is attached to the base and is connected to the end effector via a first kinematic chain that includes a first arm, a first rod, a first joint between the first arm and the first rod, and a second joint between the first rod and the end effector. A second actuator is attached to the base and is connected to the end effector via a second kinematic chain that includes a second arm, a second rod, a third joint between the second arm and the second rod, and a fourth joint between the second rod and the end effector. A third actuator is attached to the base or to the first arm and is connected to the end effector via a third kinematic chain comprising a first gear and a second gear, the first and second gears being bearing-supported to the (jounaled) end effector and being in mesh with each other. At least one element of the third kinematic chain constitutes a kinematic pair with at least one element of the first kinematic chain. The kinematic chain responsible for the translational movement of the end effector therefore acts as a support structure for the kinematic chain responsible for the rotational movement of the end effector.

WO2015188843 describes a robot structure where the arm system requires a lot of space compared to the elongated structure in WO 2014187486. The robot structure contains three separate kinematic chains that directly connect the three actuators with the end effector platform to be moved and therefore requires considerable space for the three arms to swing in three different directions. Furthermore, the working space of the robot structure in WO2015188843 is much smaller than in the present invention.

WO2015188843 includes an arrangement for turning a tool mounted on an end effector platform. The arrangement in figure 1 of WO2015188843 consists of tandem working links and gears. These linkages are mounted on two separate kinematic chains of three separate kinematic chains connecting the actuator and the end effector platform and limit the already limited positioning capabilities. These limits depend on the fact that the links are mounted on two separate kinematic chains, on how the connection of the working links in series is obtained, and on the fact that the working range of the links considerably decreases when the arms are rotated away from their zero position. In figure 1 of WO2015188843 rotation of the tool about the first axis will simultaneously rotate the tool about the second axis and compensate for this, the range of rotation for the second axis will be lost. Moreover, the ability to rotate is severely reduced and large excursions are obtained, further moving the end effector platform away from the center of the workspace. However, the arrangement in fig. 2 of WO2015188843 would give a large range of rotation but would reduce even more of the limited workspace than the concept described in fig. 1 of WO 2015188843. One reason for this is the need for a universal joint in the linkage between the arm and the end effector platform. Furthermore, several gear stages connected in series are required in a kinematic chain for rotating a tool. This will increase the weight of the arm and end effector platform, increase backlash and friction, and increase maintenance requirements.

SUMMARY

It is therefore an object of the present disclosure to mitigate at least some of the disadvantages of the prior art. It is another object of the present disclosure to provide a lightweight robotic arm suitable for fast handling, extremely fast movement and/or high safety robotic devices of objects. These objects and others are at least partly achieved by a robot arm according to the independent claims and by embodiments according to the dependent claims.

According to a first aspect, the present disclosure relates to a robot arm for end effector motion. The robotic arm includes a first actuator configured to rotate the inner arm assembly about a first axis of rotation. The inner arm assembly is connected to an outer arm linkage pivotally disposed about a second axis of rotation, and the outer arm linkage is connected to the end effector platform, thereby forming a first kinematic chain from the first actuator to the end effector platform that imparts a first degree of freedom for positioning the end effector platform. The robotic arm includes a second actuator configured to rotate the outer arm linkage about a second rotational axis, thereby forming a second kinematic chain from the second actuator to the end effector platform that imparts a second degree of freedom for positioning the end effector platform. The robotic arm further includes a third actuator configured to rotate the shaft about a third rotational axis such that the outer arm linkage rotates via the joint, thereby forming a third kinematic chain from the third actuator to the end effector platform that imparts a third degree of freedom for positioning the end effector platform. The robotic arm also includes a fourth actuator and a fourth kinematic chain configured to transmit motion of the fourth actuator to a corresponding directional axis of the end effector. The fourth kinematic chain includes an orientation linkage mounted to the inner arm assembly via at least one bearing, and an orientation actuator (orientation transmission) mounted to the end effector platform. The orientation linkage includes end effector rotation links and joints that provide at least two degrees of freedom for each end joint of the end effector rotation links.

Thus, the disclosed robotic arm is industrially applicable because it has the ability to maintain a constant tilt angle of the end effector, control the angle of rotation and the constant tilt angle of the end effector, and control both the tilt angle and the rotation of the end effector, all without including any actuator in the arm structure. Such a design allows the robot to simultaneously achieve the important features of a slim structure and a large working space.

According to some embodiments, the orientation actuator includes a linkage device connected to the end effector, the linkage device imparting at least four degrees of freedom to the end effector motion. Thus, the end effector may move in at least four degrees of freedom without any actuators in the arm structure.

According to some embodiments, the orientation drive comprises at least one external gear mechanism arranged to rotate the end effector within an angular range determined by a gear ratio (gear ratio) of the external gear mechanism. Such that the end effector can be controlled to achieve a programmed rotational angle when the inner arm assembly is arranged to rotate about a vertical axis or a programmed tilt angle when the inner arm assembly is arranged to rotate about a horizontal axis.

According to some embodiments, the directional linkage includes at least one internal gear mechanism arranged to rotate the end effector within an angular range determined by a gear ratio of the internal gear mechanism, independent of rotation of the outer arm linkage. Thus, reorientation of a large end effector may be provided for all large workspaces.

According to some embodiments, the orientation linkage and the orientation driver are arranged to rotate the end effector about the orientation axis without rotational angle limitations. So that the end effector can always be turned so that the shortest possible path (and thus the smallest cycle time) can be selected.

According to some embodiments, the second kinematic chain comprises an inner arm linkage comprising at least one link connected to the outer arm linkage via a connecting bearing, and wherein the second actuator is configured to move the at least one link via at least one inner connecting joint connected to the at least one link. The second actuator may thus be located at the robot stand without moving with the arm structure.

According to some embodiments, the outer arm linkage includes an outer parallel link pair connected to the end effector platform. The inner arm linkage includes an inner parallel link pair connected to an outer parallel link pair of the outer arm linkage. Also, the second kinematic chain is configured to transmit the rotation of the lever to a corresponding movement of the end effector platform. Because the outer parallel link pair prevents unwanted rotation of the end effector platform, no additional wrist action (actuators and actuators that add cost and weight) is required, for example, in an industrially important scenario of four degrees of freedom for pick and place operations.

According to some embodiments, the outer parallel link pair and the inner parallel link pair are connected with one connecting bearing for each link connection of the respective link, and wherein the rotational axis of the connecting bearings is at right angles to the axial centre line of each respective link of the outer parallel link pair. The outer arm linkage is thus precisely controlled by the inner arm linkage without any uncertainty with respect to the movement of the connection point between the links of the inner and outer arm linkages. The outer arm linkage is connected to the inner arm assembly via two joints such that a rotation line through the centers of the two joints remains vertical (or horizontal, depending on the arm orientation) during positioning.

According to some embodiments, the robot arm comprises a rigid beam mechanically connecting the connection bearings to each other. In this way a more accurate mechanical solution is obtained to transmit the direction of the axis of rotation of the inner arm assembly to the axis of rotation of the end effector via the inner and outer arm linkages connected in series. In an alternative embodiment, the bearings of the second pair of bearings are connected to each other with a beam parallel to the end effector beam.

According to some embodiments, the inner parallel link pair is mounted to the rigid beam via a ball joint on the offset beam. This further increases the accuracy of transmitting the direction of the axis of rotation of the inner arm assembly to the axis of rotation of the end effector via the inner and outer arm linkages connected in series, since the geometry of the ball-and-socket joint can be easily manufactured with great accuracy.

According to some embodiments, the third kinematic chain comprises an inner driver connected between the third actuator and the actuating link of the outer parallel link pair. Thus, the inner and largest load bearing parts of the robot arm can be made strong but elongated, the inner parts of the third kinematic chain being well protected.

According to some embodiments, the robotic arm includes a link bearing mounted along the actuating link of the outer parallel link pair. The rotation axis of the link bearing coincides with the center of the actuating link of the outer parallel link pair. The link bearing is used in order to avoid any unwanted tilt angle errors of the end effector caused by rotation of the inner drive. In this manner, the link bearing enables the inner link pair to always swing in both directions at a constant end effector tilt angle.

According to some embodiments, the robotic arm includes an end effector bearing connecting the outer parallel link pair and the end effector platform, wherein an axis of rotation of the end effector bearing is perpendicular to a center of the outer parallel link pair. This allows the elongated robotic arm structure to have a lightweight end effector platform. Because of the end effector bearings, the outer arm linkage will constrain all six degrees of freedom of the end effector platform and no links are required between other parts of the robot structure and the end effector platform.

According to some embodiments, the rotational axis of the end effector bearing is parallel to the rotational axis of the connection bearing. Thereby obtaining precise control of the rotating tool shaft.

According to some embodiments, the robot arm comprises a connecting bearing connecting the links of the outer parallel link pair and the links of the inner parallel link pair, wherein the rotational axis of each connecting bearing coincides with the centre of the corresponding link of the outer parallel link pair. The joint connection between the outer arm linkage and the inner arm linkage thus results in a lower degree of freedom and thus in a lower manufacturing cost.

According to some embodiments, the links of the inner parallel link pair comprise pairs of parallel links, and the parallel links of the pairs are mounted on each side of the links of the outer parallel link pair by ball joints. This will enable more increased accuracy in the connection between the outer arm linkage and the inner arm linkage. Also, simpler connecting rod and joint solutions may be used with pairs of sockets.

According to some embodiments, the inner arm assembly includes a hollow arm link and a shaft axially mounted within the hollow arm link with a bearing. The shaft is arranged to be rotated by means of a third actuator. Thereby obtaining an extremely compact inner arm solution with an internal inner drive engaging the outer arm linkage. Furthermore, the inner drive comprising two bearings will be fully protected from the environment. In some embodiments, to rotate the rotational line or axis of a bearing pair about an axis perpendicular to the rotational line or axis of the bearing pair, the bearing pair may be mounted on a shaft that rotates within a hollow arm link and is actuated by a rotational actuator via a 90 degree gear.

According to some embodiments, the robotic arm comprises a plurality of directional linkages, each directional linkage comprising a directional transmission. The plurality of orientation linkages are configured such that the corresponding plurality of concentric output shafts can actuate a number of end effector orientations for one or a number of end effectors disposed onto the end effector platform. More than one end effector orientation, such as actuated by the fourth and sixth kinematic chains, may thus actuate a large orientation.

According to some embodiments, the robotic arm includes a plurality of orientation linkages, each orientation linkage having connected orientation actuators configured such that each corresponding end effector orientation is accomplished for one or several end effectors disposed onto the end effector platform. Thus, the typical existing robot wrist of a conventional articulated robot (with a turning shaft usually from a motor at the robot's elbow) can then be used where such a heavy design is suitable for the application.

According to some embodiments, the robotic arm comprises at least two directional actuators mounted to the end effector platform and wherein the external gear mechanism of one of the at least two directional actuators is arranged to rotate at least another one of the at least two directional actuators. In this manner, a second wrist motion may be added in a separate and modular manner.

According to some embodiments, the robotic arm comprises a fifth actuator and a fifth kinematic chain configured to transmit movements of the fifth actuator to corresponding movements of an end effector disposed on the end effector platform via at least one further orientation actuator. In this way, tool rotation and tilting can be obtained simultaneously in the entire working space of the robot arm. The fifth kinematic chain will always effectively transmit the required motion of the linkage actuator to achieve a particular end effector rotation or tilt.

According to some embodiments, the robotic arm comprises at least one further actuator and at least one further kinematic chain configured to transmit movement of the at least one further actuator to corresponding movement of an end effector arranged on the end effector platform, which gives the end effector motion at least six degrees of freedom.

According to some embodiments, the external gear mechanism comprises a first gear arranged to rotate the tool in one degree of freedom.

According to some embodiments, the first gear is mounted to the end effector platform in such a way that the rotational axis of the first gear is parallel to the first rotational axis. Thus, the end effector will always be perpendicular to the horizontal plane in the workspace in the case where the inner arm assembly is arranged to rotate about a vertical axis, and the end effector will always tilt about a horizontal axis when the inner arm assembly rotates about a horizontal axis. These features make robotic arms very useful in pick, place, pack applications and palletize applications.

According to some embodiments, the external gear mechanism comprises a second gear, and the first gear is engaged by the second gear, which second gear is arranged to be rotated by the gear link via a lever connected to the second gear. Because the gears, levers and gear links can all be made of reinforced carbon fiber composite (carbon reinforced epoxy) or composite materials, a lightweight arrangement is available for rotating the tool. The transmission solution also enables a defined rotation range or tilt range of the tool to be obtained by selecting a suitable ratio between the radius of the second gear and the radius of the first gear, the ratio being typically selected to be greater than 1. To control the rotation of the tool when the end effector beam of the end effector platform is vertical and to control an angle of inclination of the tool when the end effector beam is horizontal, an external gear mechanism such as a gear drive is used, which may include any one of a rotary gear drive or a linear gear drive. The gear drive is mounted on the end effector platform and now includes a first end effector beam and an optional structure, with the other end effector beam being parallel to the first end effector beam. In both cases, the first rotary gear is mounted on the other end effector beam via one or more bearings whose axes of rotation coincide with the center of the other end effector beam. The first rotary gear is mechanically connected to the tool via a shaft. In an exemplary embodiment, the gear linkage is implemented with a joint of at least two degrees of freedom in each end to connect the gear transmission to the actuator via a kinematic chain. In the case of a rotary gear drive, a second rotary gear having an axis of rotation parallel to or coincident with the center of the end effector beam is connected to the gear link via a lever, such that movement of the gear link will be translated into rotation of the second rotary gear of the rotary gear drive. The first rotary gear is forced to turn by the second rotary gear and the diameter of the first rotary gear may be smaller than the diameter of the second rotary gear.

According to some embodiments, the first gear is engaged by a rack arranged to be moved by a gear link connected to the rack. In this way, a more space-saving gear transmission is obtained compared to the use of a transmission with two gears. This is because there is no need for a lever mounted on the second gear and because the linear rack can be made thinner than the circular gear. In the case of a linear gear drive, a linear gear (e.g. a rack, with a gear ratio determined by the size of the pinion) is connected to a gear link via a joint having at least two degrees of freedom, so that a movement of the gear actuation link will be converted into a rotation of a first rotary gear of the linear gear drive. This first rotary gear (acting as a pinion) is forced to turn by the linear movement of the rack and advantageously, the circumference of the first rotary gear is smaller than the length of the linear gear.

According to some embodiments, the robotic arm comprises at least two gear drives mounted to the end effector platform and wherein a first gear of the first gear drive is arranged to rotate at least one second gear drive. In this manner, the tilt and rotation angles of the end effector will be controlled, which is important in many applications.

According to some embodiments, the at least one second gear drive is in the form of a rack and pinion drive, and wherein the rack is connected to a rack bearing, the axis of rotation of which is parallel to the direction of movement of the rack. In this way, the control of the first gear transmission will be independent of the control of the second gear transmission, meaning that if the tilt angle of the end effector is changed with the first gear transmission, the angle of rotation will not change and vice versa. To control the rotation of the end effector with two degrees of freedom, a first rack and pinion driver is mounted on the first rotary gear. A linear gear (e.g., a rack) is connected to the second gear link via a rack bearing and lever arrangement.

According to some embodiments, the at least one pinion of the at least one second gear drive is connected to the end effector for tool rotation. Such that tilting of the tool is performed independently of the first gear drive, the end effector may be rotated by the second gear drive, and vice versa. In other words, the pinion of the first rack and pinion driver is connected such that the end effector can be tilted or rotated.

According to some embodiments, the at least one rack bearing has a rotational axis that coincides with the rotational axis of the first gear. A rack bearing is here necessary in order to make the rotation control of the end effector independent of the tilt control and by mounting the rotation axis of the rack bearing coincident with the rotation axis of the first gear, a more precise mechanical transmission to the second gear transmission is obtained. In other words, the center of rotation of the rack bearing coincides with the center of rotation of the rotary gear carrying the first rack and pinion driver.

According to some embodiments, the robot arm comprises one pinion of the at least one second gear transmission, which pinion is connected to the end effector via a right angle gear. Thus, control of two tilt angles and one rotation angle of the end effector will be available. In this way a six axis robot arm is obtained without any actuators in the arm structure and all mounted actuators being fixed to the robot support.

According to some embodiments, the robot arm comprises one pinion of the at least one second gear drive, the pinion being connected to an end effector shaft, the end effector being mounted on the shaft via a bearing, the axis of rotation of the bearing coinciding with the axis of rotation of the end effector shaft. In order to obtain the angle of rotation and at the same time the angle of inclination via the right-angle gear, the end effector shaft is mounted on a bearing connected to the pinion of the second gear drive. Rotating the pinion of the second gear drive, on which the end effector shaft is mounted, will tilt the bearing in this way.

According to some embodiments, the robot arm comprises one rack and pinion drive comprising two racks connected via a common pinion and wherein the two racks are arranged to move at right angles to each other. The two tilt angles and one rotation angle can thus be actuated independently of each other, which means that actuating any tilt angle or rotation angle will not change the other angles. This means that the limited angular working range of tilt and swivel angles can be used completely anywhere in the working space of the robot arm and is independent of the actual tilt and swivel angles of the end effector.

According to some embodiments, the robot arm comprises two racks connected to each other via a rack shaft and a rack bearing. Such that the third rack is rotatable by the second rack pinion when the third rack is coupled to the first rack, which allows the end effector to be rotated through an angle independent of one of the tilt angles of the end effector.

According to some embodiments, the rack shaft is arranged to move freely in an axial through hole of a pinion belonging to the other rack and pinion drive. Such that the third rack is rotatable by the second rack pinion when the third rack is coupled to the first rack, which allows the end effector to be rotated at an angle independent of one of the end effector tilt angles.

According to some embodiments, the robotic arm includes at least one rack bearing connected to the fifth actuator via a fixed rack and pinion drive mounted on the end effector platform. A simpler link structure is thus obtained for the fifth kinematic chain.

According to some embodiments, the rack bearing is connected to a fixed rack and a rack of the pinion driver. In this way, the use of a fixed rack and pinion in order to simplify the fifth kinematic chain will still enable independent control of the inclination angle and the rotation angle to be performed.

According to some embodiments, the pinion of the fixed rack and pinion transmission comprises a lever on which the gear link is mounted via a joint of at least two degrees of freedom. An efficient transmission is obtained for the fifth kinematic chain, in which the working range of the end effector rotation or rotation angle can be defined by the diameter of the pinion of the fixed rack and pinion drive.

According to some embodiments, the actuation link of the outer arm linkage is connected to the third actuator via a pair of bearings, the common axis of rotation of which is rotatable about an axis parallel to the central axis of the inner arm assembly. Thus, the robot arm will be particularly suitable for applications where a high stiffness transmission is required for the motion of the end effector in the direction of the rotational axis of the first axis. In another embodiment, the gear link is connected at one end to a lever mounted on a bearing whose axis of rotation is parallel to the end effector beam. The lever is connected to the rotary actuator via two more levers and a link. In order to rotate the rotation line or axis of the bearing pair about an axis perpendicular to the rotation line or axis of the bearing pair, the bearing pair is mounted on a bearing in a design with the rotation axis of the bearing parallel to the central axis of the hollow link of the inner arm linkage, and the lever is used to rotate the bearing pair about the rotation axis of the bearing mounted on the rotation axis. The lever is connected to the actuator via a link having a joint at each end.

According to some embodiments, the link driver comprises a turning shaft with a lever in one end and wherein the lever is connected to the gear link via a joint of at least two degrees of freedom. This embodiment is particularly useful in applications requiring an elongate inner arm assembly, meaning that the robotic arm needs to work in a confined environment. Moreover, this solution will have the highest transmission efficiency to control the angle of rotation or any tilt angle of the end effector. In an exemplary embodiment, the gear drive is connected to the actuator via a kinematic chain and one end of the gear link is connected to a lever mounted on a second rotating shaft having an axis of rotation parallel to the hollow link of the inner arm assembly.

According to a second aspect, the present disclosure relates to a robot arm for positioning an end effector with three degrees of freedom, the end effector having a constant tilt angle. The robotic arm includes an end effector platform arranged to receive an end effector. The robotic arm includes a first actuator configured to rotate the inner arm assembly about a first axis of rotation. The inner arm assembly is connected to an outer arm linkage that is pivotally disposed about a second pivot axis. The outer arm linkage includes an outer parallel link pair connecting the end effector platform via the end effector bearing, thereby forming a first kinematic chain from the first actuator to the end effector platform. The robotic arm includes a second actuator configured to rotate the outer arm linkage about a second axis of rotation. The outer arm linkage connects the inner arm linkage comprising an inner parallel linkage pair via a universal joint comprising a connecting bearing, thereby forming a second kinematic chain from the second actuator to the end effector platform. The robotic arm also includes a third actuator configured to rotate the shaft about a third axis of rotation such that the outer arm linkage rotates about the third axis of rotation via the elbow joint, thereby forming a third kinematic chain from the third actuator to the end effector platform.

Brief Description of Drawings

Fig. 1 shows a robotic arm structure that may have an end effector actuated to rotate about an axis perpendicular to a horizontal plane, according to some embodiments.

Fig. 2A shows a robot arm structure according to some other embodiments.

Fig. 2B shows a detail of a type of universal joint mounted on the rotating shaft of the inner transmission in fig. 2A.

Fig. 3A shows an industrial robot arm according to a first embodiment, which enables the end effector to be actuated for rotation about an axis perpendicular to the horizontal plane.

Fig. 3B shows an industrial robot arm according to a second embodiment, which comprises an alternative gear drive for turning the end effector.

Fig. 3C shows a directional linkage according to some embodiments.

FIG. 3D shows a universal joint according to some embodiments.

Fig. 4A shows an industrial robot arm according to a third embodiment, wherein the main structure is arranged with a horizontal common turning axis of the rotary actuator.

Fig. 4B shows an industrial robot arm according to a variant of the third embodiment.

Fig. 4C shows an industrial robot arm according to another variant of the third embodiment.

Fig. 4D shows an alternative embodiment with a belt drive.

Fig. 5A shows an industrial robot arm according to a fourth embodiment, wherein the end effector can be controlled to turn and tilt.

Fig. 5B shows an alternative embodiment of a rack for tilting an end effector having two degrees of freedom.

Fig. 6A and 6B show an industrial robot arm according to a fifth embodiment comprising a combination of the rack and pinion concept of fig. 5A and 5B and a transmission comprising right angle gears and universal joints to obtain a six degree of freedom robot arm with all actuators fixed to the robot support.

Fig. 7 shows an embodiment with two rack and pinion arrangements that are rotated by a gear to obtain six degrees of freedom with only one right angle gear and no universal joint.

Fig. 8 shows an embodiment with a three rack and pinion arrangement that is rotated by gears to avoid right angle gears and universal joints in a six degree of freedom robot arm.

Fig. 9A shows an industrial robot arm according to a sixth embodiment with a transmission instead of the rack and pinion arrangement in fig. 5.

Fig. 9B shows an alternative orientation linkage according to some embodiments.

Fig. 10A, 10B show an industrial robot arm with a horizontal common axis of rotation of a rotary actuator according to a seventh and eighth embodiment.

Fig. 11 shows an embodiment in which the rotary actuators are arranged to obtain a common rotating shaft without the use of a hollow shaft motor as shown in fig. 1-6.

Fig. 12A shows an alternative main structure of the industrial robot arm of fig. 2A.

Fig. 12B shows how a linear actuator can be used, in this case without a lever in the linkage as presented in fig. 12A.

Fig. 13 shows an alternative actuator.

Fig. 14A shows a variation of joint type, allowed joint offset and a back hoe mechanism (back mechanism) as part of the second kinematic chain.

FIG. 14B shows an alternative backhoe configuration that fundamentally increases the workspace of the robotic arm.

Detailed Description

In order to obtain a lightweight robot structure for an industrial robot, the invention uses a new combination of parallel robot structures and actuators. The actuators of the robot arm may be mounted on a fixed robot support and the large weight of the actuators then does not need to be moved around by the arm structure. The arm structure of the robot can then be implemented using only lightweight components such as carbon tubes, carbon gears and carbon bearings. This allows the design of the robot with minimal inertia for high speed, acceleration and acceleration derivatives. Furthermore, when no or fewer actuators are placed on the arm structure itself, it may be easier to build robots that can work in environments with explosion risks, such as on oil and gas platforms, and in industries handling explosives. Robots that can operate in harsh environments such as outdoor processing equipment, tunnel inspection, and vehicle cleaning systems can also be more easily constructed.

The disclosed industrial robot arm solves the following problems: how to obtain a constant tilt angle of the end effector of an industrial robot arm and at the same time a slim structural design of the robot arm. This makes it possible for the robotic arm to perform pick and place operations with limited space requirements in a horizontal plane without any added wrist for compensating end effector tilt errors. Furthermore, a robot arm according to the invention may comprise up to six degrees of freedom (DOF) and all actuators are fixed to the support. The end effector may also be referred to as a tool.

For clarity of explanation below, we refer to the normal and preferred arrangement of positioning in the x, y and z directions relative to a robotic support (not shown) of the end effector platform, which provides the basis for tool orientation in one or several degrees of freedom. Tool orientation includes tool rotation actuated by some tool driver, about a tool attachment shaft at the end effector platform or about some axis perpendicular to the tool attachment shaft, or about both for five degrees of freedom. For six degrees of freedom, tilting tool rotation may be added, or the desired tool tilt may form one of the axes 4 or 5. In any event, it is highly desirable to position the end effector platform without (in this case undesirable) tilting motion, thereby decoupling the tool positioning from the tool orientation. In principle, but omitted for clarity, several end effectors and tool orientation mechanisms/actuators may be attached to the end effector platform, e.g. pointing in different directions and mounting different types of tools, carrying different tools for different purposes and avoiding the need to use tool exchangers. As will be apparent from the following description, different actuators for tool orientation may be combined so that all actuators can still be fixed to the robot support. As such, more than 6 degrees of freedom are possible, but for the sake of simplicity, are not explained in detail.

The industrial robot arm disclosed herein comprises a four or five axis solution, which in some embodiments are always parallel to each other. The structure may be mounted in such a way that all axes are vertical or horizontal (or any other angle), including one or more of the following:

in an exemplary embodiment, where the axes are vertical, the resulting movement of the end effector is such that the end effector is always perpendicular to a horizontal plane throughout the workspace.

In an exemplary embodiment, where the axes are vertical, the rotation of the end effector about the vertical axis may be controlled via the addition of linkage drives and gears, whereby the actuators for controlling the rotation of the end effector may be fixed to the robot support.

In an exemplary embodiment, where the axes plus the fifth axis are horizontal, the configuration includes the addition of linkage actuators plus gears to maintain the end effector perpendicular to a horizontal plane throughout the workspace.

In an exemplary embodiment, where the axes plus the fifth axis are horizontal, the addition of the linkage driver plus gears may be used to control a tilt angle of the end effector throughout the workspace. An actuator for controlling the tilt angle of the end effector may be fixed to the robot support.

In an exemplary embodiment, where the axes plus the fifth axis are horizontal, a second additional linkage driver plus a rack and pinion may be used to control the rotation of the end effector while controlling the tilt of the end effector. Actuators controlling the tilt and rotation angles of the end effector may be affixed to the robotic frame. Also, with the third link, the end effector can be controlled to rotate with three degrees of freedom.

Also, because only two parallel links are required in the linkage structure connecting the end effector platform and the inner arm assembly, a robot arm according to embodiments of the present disclosure may be made slimmer than robot designs according to WO2014187486 and WO 2015188843.

In the present disclosure, a robot is defined to include a robot arm and a robot controller. The robotic arm includes an actuator for completing movement of the end effector. The robot controller or a computer connected to the robot controller may include a program with instructions for moving the end effector according to the program. The robot controller and/or computer includes a memory and a processor, with programs stored in the memory. The robot arm is thus a programmable robot. However, the robot may be of various types, such as an industrial robot or a service robot.

Fig. 1 shows a basic embodiment of a robotic arm 500 that includes structures according to some embodiments to obtain tool rotation, but does not include tool tilting.

The robot arm comprises a first actuator 4, which first actuator 4 is configured to rotate the inner arm assembly 1 about a first rotational axis 29. The inner arm assembly 1 is connected to the outer arm linkage, which here includes an actuating link 18. The outer arm linkage is pivotably arranged about a second axis of rotation 40. The outer arm linkage is connected to the end effector platform 41, forming a first kinematic chain from the first actuator to the end effector platform. This gives a first degree of freedom for positioning the end effector platform and thus also for the end effector action.

The robotic arm 500 in fig. 1 also has a second actuator 5, the second actuator 5 being configured to rotate the outer arm linkage about a second rotational axis 40, thereby forming a second kinematic chain from the second actuator to the end effector platform. This provides a second degree of freedom for positioning the end effector platform. The second kinematic chain may be designed in a different way. One possibility is a second kinematic chain with links between the second actuator 5 and the actuating link 18. This possibility is illustrated in fig. 1, where the actuating link is connected to the inner arm assembly 1 by a pair of bearings (rotating about a second axis of rotation 40) as part of the joint 16, and the lever 2 is mounted on the output shaft of the second actuator 5 to rotate about a first axis of rotation 29. The lever 2 is connected to the actuating link using an inner arm linkage comprising links 12 with joints 10, 14 at each end.

The joints 10, 14 are depicted as ball joints having at least two degrees of freedom, but of course, other kinematically equivalent embodiments are possible, as explained below for the end effector rotation links (and fig. 3C).

In other words, the second kinematic chain comprises an inner arm linkage comprising lever 2 and link 12 connected to an outer arm linkage comprising actuating link 18 here (in fig. 1) firmly connected to end effector platform 41 and beam 41A. As such, the second kinematic chain includes an inner arm linkage that includes at least one link 12 connected to an outer arm linkage via a connecting bearing 14. The second actuator is configured to move the at least one link 12 via the at least one inner connection joint 10 connected to the at least one link 12. Another alternative to actuating the second degree of freedom is to have the second actuator mounted at the end of the inner arm assembly 1 and the second actuator's rotational shaft parallel to the second rotational axis 40. Because it is not a preferred embodiment, this alternative arrangement of the second actuator, referred to as 5b, is shown in phantom because the actuator moves with the arm structure, but it does not require an inner arm linkage, thereby providing a more compact inner arm design. In this alternative, the second kinematic chain comprises a mechanical connection with an optional transmission between the rotating second actuator 5b and the actuating link 18. In this way, the second actuator 5, 5b moves the end effector platform 41 in one direction, which in combination with the first kinematic chain gives a second degree of freedom for positioning the end effector platform and thus also for the end effector action.

The robot arm 500 in fig. 1 also comprises a third actuator 6, which third actuator 6 is configured to rotate the shaft 3 around a third axis of rotation 33. The third actuator 6 is arranged to rotate the shaft 3 around a third rotation axis such that the outer arm linkage is rotated via joint 161, thereby forming a third kinematic chain from the third actuator to the end effector platform. This gives a third degree of freedom for positioning the end effector platform.

The third kinematic chain can be designed in different ways. According to an exemplary embodiment, a 90 degree angle gear (not shown in fig. 1 but the same concept as shown at 51 for actuating the fourth degree of freedom below) is between the output shaft of the third actuator 6 and the turning shaft 3 within the inner arm assembly 1. The shaft 3 will then rotate the actuator linkage 18 up and down about the axis of rotation 33 and thus the end effector platform 41 will move up and down. Another alternative is to use a third actuator (6 b in this case, fixed to the robot support, shown hatched because it is not a preferred alternative) to rotate the other actuator (mounted on the housing 6c, the second actuator 5b instead being at the end of the inner arm assembly 1) about a rotation axis 99 perpendicular to the first rotation axis 29, allowing two different arrangements according to the rotation axis 99 defined perpendicular to the rotation axis 29, possibly with the dual actuators 6b arranged to rotate about the x-axis and the y-axis respectively (assuming that the axis 29 points in the z-direction), which can be used to maintain the maneuverability of the end effector when the outer arm linkage is extended all the way in or all the way out (close to or single, not allowed in the preferred embodiment). In any case, the third kinematic chain includes inner arm assembly 1 and an outer arm linkage consisting only of actuation links 18 attached to end effector beam 41A. In general, the embodiment depicted in fig. 1 will enable the design of the largest thin arm, but it will exhibit undesirable tilt in most workspaces, and thus further embodiments (fig. 2 and others) are needed for industrial applications.

The robot arm 500 in fig. 1 also comprises a fourth actuator 50 and a fourth kinematic chain. The fourth kinematic chain is configured to transmit movement of the fourth actuator to a corresponding directional axis of the end effector 28. The orientation axis is defined by shaft 65. The fourth kinematic chain comprises a directional linkage 52, 57, 59 mounted to the inner arm assembly via at least one bearing 53. The fourth kinematic chain also includes orientation actuators 64B, 64A mounted to the end effector platform. The orientation linkage includes an end effector rotation link 59 and joints 58, 60 that provide at least two degrees of freedom for each end joint of the end effector rotation link. In one embodiment, end effector rotation link 59 is connected to joints 58, 60 at each end of end effector rotation link 59, respectively. Of course, the joints 58, 60 may be accomplished with at least two degrees of freedom in a number of kinematically equivalent ways to the at least two degrees of freedom, as depicted, for example, in fig. 3C.

The directional linkage may be implemented using different linkage configurations. In fig. 1, the fourth actuator 50 is connected to a 90 degree angle gear 51 that drives a shaft 52, on which shaft 52 a lever 57 is mounted.

The orientation drive may also be implemented in different ways, for example by a rack and pinion or by a backhoe linkage. In fig. 1, the orientation drive is implemented using an orientation drive that includes gears 64A, 64B mounted to the end effector platform 41. With the implementation of the orientation linkage and orientation drive shown in fig. 1, the orientation linkage is mounted to the joint 58 by the lever arm 57 and the orientation drive is mounted to the joint 60 via the lever arm 61 mounted on the gear 64B. As such, fourth actuator 50 will be able to rotate gear 64A because of the second kinematic chain. This would be possible even when the first, second and third actuators move the end effector platform in three different directions, x, y and z. Gear 64A is connected to shaft 65 which rotates in bearing 67. The orientation drive includes a connection device, referred to in this embodiment as a shaft 65, to the end effector 28 that provides at least four degrees of freedom for the end effector action.

Fig. 2A shows a configuration of a robotic arm 500 included in some embodiments of the present disclosure that includes a desired constant tool tilt angle, but does not include a fourth kinematic chain for tool rotation. In other words, this configuration makes it possible to move the tool 28 in the x, y and z directions while maintaining a constant tilt angle. The three actuators 4, 5 and 6 have a common vertical axis of rotation, which axis coincides here with the first axis of rotation 29. The three actuators are arranged to move the tool 28 such that the end effector beam 41A of the end effector platform 41 will always be parallel to the common axis of rotation of the actuators. In more detail, the robot arm 500 comprises a first actuator 4 configured to rotate the inner arm assembly 1 about a first rotation axis 29. The first kinematic chain is here configured to transmit the rotation of the inner arm assembly 1 to a corresponding movement of the end effector platform 41, the end effector platform 41 comprising only the end effector beam 41A in fig. 2A. Thus, according to the present invention, an end effector platform comprising only beams rather than more complex end effector platforms may be made much simpler than in the referenced prior art.

The first kinematic chain comprises an outer arm linkage comprising an outer parallel link pair 17, 18, each link 17, 18 being connected at one end to an end effector platform 41. The first link 17 of the outer parallel link pair 17, 18 is connected at its other end to the inner arm assembly 1. The inner arm assembly 1 is here designed to swing in a horizontal plane, actuated by a first actuator 4 aligned with a vertical first axis of rotation 29. The inner arm assembly 1 carries two parallel links 17 and 18. The two parallel links 17, 18 are connected at their outer ends to a vertical end effector beam 41A of an end effector platform 41, which beam 41A in turn carries a tool 28 (shown as a vacuum gripper in the figure) via a shaft 27 projecting from the end effector platform 41 (here the end effector beam 41A). The first link 17 of the outer link pair is connected to the inner arm assembly 1 via the attachment portions 7A and 7B with a ball joint 15. The attachment portions 7A, 7B are rigid mechanical portions, such as carbon rods that rigidly connect the balls of the joint 15 with the inner arm assembly 1. The joint 15 may also be embodied as a universal joint having three degrees of freedom. In some embodiments, one, several or all of the joints 9, 10, 13, 14 and 15 are ball joints or universal joints. In some embodiments, the joint 16 is a universal joint. In some embodiments, one or both of the joints 19, 20 is a hinge joint.

The robot arm 500 in fig. 2A also comprises a second actuator 5 configured to rotate the lever 2 about the first rotation axis 29. The second kinematic chain is configured to transmit the rotation of the lever 2 to a corresponding movement of the end effector platform 41. The second kinematic chain comprises an inner arm linkage comprising an inner parallel link pair 11, 12 connected to the outer arm linkage so as to be connected to the outer parallel link pair 17, 18, for example between the ends of the outer parallel link pair 17, 18. In other words, the second kinematic chain comprises an inner arm linkage comprising the inner parallel link pair 11, 12 and the lever 2. The inner parallel link pair is connected to the lever and to an outer arm linkage comprising an outer parallel link pair 17, 18. The second actuator 5 is arranged to rotate the lever about a first rotational axis 29. Also, in some embodiments, the outer arm linkage includes outer parallel link pairs 17, 18 connected to the end effector platform 41. The second kinematic chain is configured to transmit the rotation of the lever 2 to a corresponding movement of the end effector platform.

The robot arm 500 further comprises a third actuator 6. The third kinematic chain is configured to transmit the movement of the third actuator 6 to a corresponding movement of the end effector platform 41. The third kinematic chain comprises the inner transmission 3, 16(161, fig. 1) between the third actuator 6 and the other end of the actuating link 18 of the outer arm linkage. In other words, the third kinematic chain comprises an inner transmission connected between the third actuator and the actuating link of the outer parallel link pair. The actuating link 18 of the outer arm linkage is here connected to the rotating shaft 3 of the inner transmission with a type of universal joint 16. The swivel shaft 3 is arranged to rotate within the hollow link 1A of the inner arm assembly 1, where it is supported by one bearing (not shown in the figures) at each end. The rotating shaft 3 is connected to a third actuator 6 with a 90 degree angle gear (not shown in the figures) at the inner end of the hollow link 1A. The output shaft from the third actuator 6 is assembled through the hollow shaft of the second actuator 5 to achieve a 90 degree gear. In other words, the robot arm 500 comprises an inner arm assembly comprising one hollow link 1A, and the inner transmission of the third kinematic chain comprises a shaft 3 mounted axially with bearings in the hollow link 1A. The shaft 3 is arranged to be rotated by means of a third actuator 6. By turning the turning shaft 3, the parallel links 17 and 18 are swung up and down to obtain a vertical movement of the tool 28. To swing the outer arm linkage in the horizontal plane, the lever 2 is connected to the outer arm linkage via the inner arm linkage. The lever 2 is arranged to be actuated by a second actuator 5 and is connected to links 11 and 12 via a beam 8 and ball joints 9 and 10. The joints 9, 10 are also referred to as inner connection joints. The inner arm linkage is connected to the outer arm linkage using joints 13 and 14, beams 23 and 24, and connecting bearings 21 and 22. In an exemplary embodiment, the inner parallel link pair 11, 12 is mounted to the rigid beam 25 via ball joints 13, 14 on offset beams 23, 24. Between bearings 21 and 22, beam 25 is connected to bearings 21, 22, which bearings 21, 22 constrain the end effector beam 41A of end effector platform 41 to always be vertical. At the same time, the beam 25 can be used to get a pre-stress on the connection means to the links 17 and 18 of the outer arm linkage, meaning that backlash in the bearings 19, 20, 21, 22 and joints 15 and 16 is reduced. I.e. the bearings are connected at the ends of the links 17, 18 of the outer arm linkage. As such, in an exemplary embodiment, robotic arm 500 includes a rigid beam 25 that mechanically connects connection bearings 21, 22 to one another.

The outer arm linkage is connected to end effector beam 41A with end effector bearings 19 and 20. Furthermore, end effector bearings 19, 20 connect the outer parallel link pairs 17, 18 and the end effector platform 41, wherein the rotational axes 36, 37 of the end effector bearings 19, 20 are perpendicular to the centers of the outer parallel link pairs 17, 18.

To ensure that the end effector beam 41A of the end effector platform 41 will have a constant tilt angle so that the tool 28, e.g., a vacuum gripper, will always be able to pick and place items at a perpendicular angle relative to a horizontal plane, the design of the robotic arm 500 may include one or more of the following:

the common first axis of rotation 29 of the first actuator 4, the second actuator 5 and the third actuator 6 is vertical.

The mounting of the beam 8 and the joints 9 and 10 is assembled so that the axis 30 through the centre of the joints 9 and 10 is always parallel to the first axis of rotation 29.

The links 11 and 12 have the same length, meaning that the distance between the joints 9 and 13 is the same as the distance between the joints 10 and 14.

The distance between the joints 13 and 14 is the same as the distance between the joints 9 and 10.

The distance between the centres of the joints 15 and 16 is the same as the distance between the centre of rotation 36 of the bearing 19 and the centre of rotation 37 of the bearing 20.

The distance between the centres of rotation 34 and 35 of the bearings 21 and 22 is the same as the distance between the centres of rotation 36 and 37 of the bearings 19 and 20.

The distance between the centres of rotation 34 and 35 of the bearings 21 and 22 is the same as the distance between the centres of rotation of the joints 15 and 16.

The length of the link 17 is the same as the length of the link 18, meaning that the distance between the centre of rotation of the joint 15 and the centre of rotation 36 of the bearing 19 should be the same as the distance between the centre of rotation 33 of the rotating shaft 3 and the centre of rotation 37 of the bearing 20.

The distance between the centre of rotation 36 of the bearing 19 and the centre of rotation 37 of the bearing 21 is the same as the distance between the centre of rotation 37 of the bearing 20 and the centre of rotation 35 of the bearing 22.

Bearings 19, 20, 21 and 22 are mounted so that their axes of rotation 36, 37, 34 and 35 are parallel and at right angles to axes 31 and 32 which are parallel to axes 29, 30 and 40. In this manner, the rotational axes 36, 37 of the end effector bearings 19, 20 are parallel to the rotational axes 34, 35 of the connecting bearings 21, 22.

The shaft 40 runs through the centre of the joints 15 and 16. The shaft 40 is also defined by the centers of the bearings 16A and 16B when the link 18 is horizontal. The axles 34 and 35 are also perpendicular to the links 17, 18 of the outer arm linkage. In other words, the outer arm linkage (outer parallel link pair 17, 18) and the inner arm linkage (inner parallel link pair 11, 12) are connected with one connecting bearing 21, 22 for each link connection of the respective links 11, 12, 17, 18, and wherein the rotational axes 34, 35 of the connecting bearings 21, 22 are at right angles to the axial centre line of each respective link 17, 18 of the outer arm linkage.

Fig. 2B shows a detail of a universal joint 16 of this type mounted on the rotating shaft 3 of the first transmission. This joint 16 connects the rotating shaft 3 to the actuating link 18 of the outer arm linkage and vertically moves the end effector beam 41A of the end effector platform 41. The bearings 16A and 16B are mounted symmetrically with pins 16D and 16E on the rotating shaft 3. Because the rotational axis 40 is defined by the common rotational axis of the bearings 16A and 16B, the actuating link 18 rotates about the axis 33, and the rotational axis 40 will also rotate about the axis 33. In more detail, the actuation link 18 of the outer arm linkage is connected to the third actuator 6 via a pair of bearings 16A, 16B, wherein the common axis of rotation 32 is rotatable about an axis parallel to the central axis of the hollow links of the inner arm assembly 1. The rotating outer portions of bearings 16A and 16B are connected to beam 16H with attachments 16F and 16G. The attachments 16F, 16G are rigid mechanical structures such as rods. The attachments 16F, 16G and the beam 16H may be implemented as a strong fork made of reinforced carbon fiber composite material. The actuating link 18 is connected to the beam 16H via a bearing 16C, which bearing 16C allows the actuating link 18 to rotate about its own axis. The bearing 16C is referred to herein as a connecting rod bearing 16C. This will keep the shafts 31 and 32 vertical throughout the working space of the tool 28, since the link bearing 16C allows the actuating link 18 to rotate about its own axis. The link bearing 16C can be placed in any position between the joint 16 and the mounting location of the bearing 22 to the actuating link 18 of the outer arm linkage. In this way, in other words, the robot arm comprises a link bearing 16C mounted along the actuating link 18 of the outer parallel link pair 17, 18, wherein the rotational axis of the link bearing 16C coincides with the centre of the actuating link 18 of the outer parallel link pair. The connecting rod bearing 16C is a differentiated feature with respect to WO 2014187486. As such, in an exemplary embodiment, the robotic arm 500 may comprise a link bearing 16C mounted to the actuation link 18 of the outer arm linkage between the connection bearing 22 and the connection of the actuation link 18 with the inner transmission 3, and wherein the rotational axis of the link bearing 16C coincides with the center of the actuation link 18 of the outer arm linkage. Another feature is the mounting of links 17 and 18 on end effector beam 41A of end effector platform 41 using bearings 19 and 20. This allows a much more slender robot to be built than described in WO2014187486, since only two links 17 and 18 are required between the inner arm assembly 1 and the end effector platform 41. The end effector platform 41 here comprises an end effector beam 41A. The end effector platform may be used with a robotic arm having five or six degrees of freedom. The robot described in WO2014187486 requires three links between its first arm and the end effector. Another difference with respect to WO2014187486 is the use of a beam 25 to obtain a pre-stress on the rods 17 and 18. This will also make it possible to use ball joints between the outer link pairs 17, 18 and the inner link pairs 11, 12. Also, the proposal in fig. 4 of WO2014187486 requires two arms (linkages) instead of only one arm, as in the inner arm assembly 1 in the present disclosure. That is, the robot according to WO2014187486 requires much more space for the arm system. The robot structure of the present invention does not have these drawbacks of WO2014187486 because it works with three degrees of freedom in the joint connecting one (only one) inner arm assembly (hollow rod 1A) corresponding to the first arm in WO2014187486 to the outer arm rod corresponding to the first rod in WO 2014187486. This solution is not possible in the elongated structure of WO2014187486 because the end effector will lose one constraint and cannot be controlled with the added degree of freedom between the first arm and the first rod. In fig. 4 of WO2014187486 there is a structure that is not elongated and requires a large space for the arm system, but the structure may have a joint that may have three degrees of freedom between the first arm and the first rod. However, it is not possible to obtain an elongated compact robot structure with the solution suggested in fig. 4 of WO2014187486, because in this case the vertical motion can only be performed by independent kinematics chains directly connected to the end effector platform as in the case of delta robots, and thus much space is required for the arm structure. Thus, the robot structure according to WO2014187486 can only control three degrees of freedom with actuators fixed to the support.

It should be mentioned that the bearings 19, 20, 21 and 22 of fig. 2A may be replaced by an assembled bearing pair according to the bearings 16A and 16B in fig. 2B. Vice versa, the pair of bearings 16A and 16B may be replaced by a single bearing. The use of a bearing pair will give higher stiffness or make it possible to use a lighter weight bearing. Instead of ball bearings, sliding bearings, such as carbon bearings, can also be used.

With the design as described above and when the angle between the inner arm assembly 1 and the actuation link 18 is 90 degrees, an infinite rotation of the output shaft of the first actuator 4 will move the tool 28 to one side in the horizontal plane and an infinite rotation of the output shaft of the second actuator 5 will move the tool 28 in or out in the horizontal plane. An infinite rotation of the output shaft of the third actuator 6 will move the tool 28 up or down. Moreover, all movement in the entire workspace will be with the shaft 32 vertical, and the tool 28 will have a constant tilt angle. As such, the robot arm 500 will have the same movement characteristics as the three main axes of a so-called SCARA robot. But in contrast to a SCARA robot all actuators 4, 5, 6 can be fixed to a robot support (not shown) and can therefore implement a very light weight robot arm. The robot support is a rigid mechanical structure on which the actuators are rigidly mounted. In which case the robot support can be manufactured as a fork having one part holding the first actuator 4 and another part holding the second and third actuators 5 and 6. The robot support can be rigidly mounted on the floor, on a wall, or in the ceiling or on another robot arm.

Accordingly, the present disclosure includes a robotic arm 500 for positioning end effector 28 with three degrees of freedom and a constant tilt angle. A second aspect of the disclosure is disclosed in at least fig. 2A, 2B, 3A, 4B, 10A, 10B, 12A, 12B, 14A, and 14B and in illustrations that describe these figures or at least some aspects of these figures. The robotic arm comprises an end effector platform 41 arranged to receive an end effector. The robotic arm comprises a first actuator 4 configured to rotate the inner arm assembly 1 about a first axis of rotation 29, 29A. The inner arm assembly 1 is connected to the outer arm linkages 17, 18 which are pivotally arranged about a second axis of rotation 40. The outer arm linkage includes outer parallel link pairs 17, 18 connected to an end effector platform 41 via end effector bearings 19, 20, forming a first kinematic chain from the first actuator to the end effector platform. The robot arm 500 also comprises a second actuator 5 configured to rotate the outer arm linkage 17, 18 around a second rotation axis 40, the outer arm linkage 17, 18 being connected to the inner parallel link pair 11, 12 via a universal joint comprising connection bearings 21, 22; 811. 812(811, 812 see fig. 12B), thereby forming a second kinematic chain from the second actuator to the end effector platform. The robotic arm 500 also includes a third actuator 6 configured to rotate the shaft 3 about a third axis of rotation 33 such that the outer arm linkage 17, 18 rotates about the third axis of rotation via the elbow joint 161, thereby forming a third kinematic chain from the third actuator to the end effector platform.

According to some embodiments of the second aspect, the end effector bearings 19, 20 are hinge joints having rotational axes 36, 37 that are parallel to each other.

According to some embodiments of the second aspect, elbow joint 161 comprises a hinge joint having an elbow axis of rotation that intersects the second axis of rotation and the third axis of rotation.

According to some embodiments of the second aspect, the toggle joint 161 is connected to an actuating link 18, the actuating link 18 being one of the links of the outer parallel link pair 17, 18 connected to the toggle joint 161.

According to some embodiments of the second aspect, the actuating link 18 is equipped with at least one link bearing 16C mounted along the actuating link for accepting rotation of the actuating link ends relative to each other.

According to some embodiments of the second aspect, the axis of rotation of the link bearing 16C coincides with the centerline of rotation of the actuation link 18.

According to some embodiments of the second aspect, the second actuator 5 is configured to move the inner parallel link pair 11, 12 via an inner connecting joint 9, 10 connected to the inner parallel link pair 11, 12.

According to some embodiments of the second aspect, the second kinematic chain is configured to transmit the rotation of the lever 2 to a corresponding movement of the end effector platform 41.

According to some embodiments of the second aspect, the outer parallel link pair 17, 18 and the inner parallel link pair 11, 12 utilize a common connection for the respective links 11, 17; 12. 18 are connected by one connecting bearing 21, 22 of each connecting rod connection. For each respective link of the outer parallel link pair 17, 18, a rotation shaft 34, 35 connecting the bearings 21, 22; 31 are at right angles to the centre line of rotation along the connecting rod.

According to some embodiments of the second aspect, the robot arm 500 comprises a rigid beam 25 mechanically connecting the connection bearings 21, 22 to each other.

According to some embodiments of the second aspect, the inner parallel link pair 11, 12 is mounted to the rigid beam 25 via ball joints 13, 14 on the offset beams 23, 24.

According to some embodiments of the second aspect, the shaft 3 is connected between the third actuator 6 and the actuating link 18 of the outer parallel link pair 17, 18 via an elbow joint 161.

According to some embodiments of the second aspect, the robot arm comprises end effector bearings 19, 20 connecting the outer parallel link pairs 17, 18 and the end effector platform 41. The rotational axes 36, 37 of the end effector bearings are perpendicular to the center line of rotation of each link of the outer parallel link pair.

According to some embodiments of the second aspect, the rotational axes 36, 37 of the end effector bearings 19, 20 are parallel to the rotational axes 34, 35 of the connecting bearings 21, 22.

According to some embodiments of the second aspect, the robot arm comprises connection bearings 21A, 22A (21A in fig. 3D, corresponding to 21A but 22A in connection bearing 22) connecting the links of the outer parallel link pair 17, 18 and the links of the inner parallel link pair 11, 12. The axis of rotation of each connecting bearing 21A, 22A coincides with the centre line of rotation of the corresponding link of the outer parallel link pair 17, 18.

According to some embodiments of the second aspect, the inner arm linkage comprises a backhoe mechanism 803, 10B, 802, 8, 9C/10C, 805/806 which rotates the outer arm linkage 804, 17, 18 about the second axis of rotation 40, wherein the backhoe mechanism is connected to the outer parallel link pair 17, 18 via a connecting bearing 21, 21 which allows rotation about an axis 31 parallel to the second axis of rotation 40. See fig. 14A, 14B for 803, 10B, 802, 8, 9C/10C, 805/806. By suitable dimensioning, which can be found by a person skilled in the art from fig. 14B, the rotary shaft 31 can be placed such that it does not intersect with either of the rotary shafts of the two links of the outer parallel link pair. The backhoe mechanism can be configured (see fig. 14A and 14B) to essentially increase the operating range of the second kinematic chain, even by more than 180 degrees; this may provide a larger workspace without any singularities.

According to some embodiments of the second aspect, the links of the inner parallel link pair 11, 12 comprise a parallel link pair 11A, 11B; 12A, 12B. These parallel link pairs 11A, 11B; 12A, 12B are mounted on each side of the links of the outer parallel link pair 17, 18 by ball joints.

According to some embodiments of the second aspect, inner arm assembly 1 comprises a hollow arm link 1A and a shaft 3 axially mounted within hollow arm link 1A by bearings. The shaft 3 is arranged to be rotated by means of a third actuator 6.

Fig. 3A shows a first embodiment of a robotic arm 500 capable of actuating rotation of tool 28 about an axis perpendicular to a horizontal plane. The reference numerals of common features in different embodiments are the same and thus reference is made to other figures, e.g. fig. 1, fig. 2A and fig. 2B, for explaining them. In this first embodiment, rotary gear drives 64A, 64B having a gear factor greater than 1 are summarized to obtain the target tool rotation. It is also shown how the rotary gear transmission is actuated via a mechanical transmission from the rotary fourth actuator 50 to the lever 61 on the largest gear 64B of the rotary gear transmission. The robotic arm 500 in fig. 3A thus includes the fourth actuator 50. The fourth kinematic chain is configured to transmit the movement of the fourth actuator 50 to a corresponding movement of the tool 28 mounted to the end effector platform 41 (here comprising components 41A, 68, 69, 70). The fourth kinematic chain comprises a directional linkage 52, 57 mounted to the inner arm assembly 1 via at least one bearing 53, 55. The orientation actuators 64A, 64B are mounted to the end effector platform 41 and the orientation linkage is connected to the orientation actuators 64A, 64B via end effector pivot links 59 having joints 58, 60 of at least two degrees of freedom at each end. Fig. 3A shows an option to also obtain the axes 4 of a SCARA robot with all actuators fixedly mounted on the robot support. The four actuators 4, 5, 6 and 50 have coinciding turning axles along a vertical first turning axis 29. The output shaft of the fourth actuator 50 passes through the hollow shaft actuator 50 and is connected to the inner arm assembly 1, in the same way the output shaft of the third actuator 6 passes through the second actuator 5 and controls the rotation of the shaft 3 via a 90 degree angle gear (not shown in the figure). The second actuator 5 controls the lever 2 and the fourth actuator 50 for rotating the tool 28 about the vertical axis 71, engaging the shaft 52 with a 90-degree gear 51 (of the same type as for the 90-degree gear between the third actuator 6 and the shaft 3). With respect to fig. 2A, there are the following new features in the implementation of a robotic arm, some with reference also to the embodiment in fig. 1:

the links 17 and 18 of the outer arm linkage are directly connected to the links 11 and 12 of the inner arm linkage using a universal joint, such as connecting bearings 21, 22. These linkers are identical and appear in detail in fig. 3D. With respect to the universal joint shown in fig. 3D and designated 21, the bearing 21 is mounted around the first link 17 with its axis of rotation coincident with the center of the link. Bearings 21B and 21C having coincident rotational axes perpendicular to the rotational axis of the bearing 21A are mounted on the outer ring of the bearing 21A with shafts 21D and 21E. In other words, the outer arm linkage and the inner arm linkage are connected with one connection bearing 21, 22, here a universal joint, for each link connection of the respective links 11, 12, 17, 18. The axes of rotation 34, 35 of these connecting bearings 21, 22 are at right angles to the respective links 17, 18 of the outer arm linkage.

The outer rings of bearings 21B and 21C are mounted on beam 21H using rods 21F and 21G. The lever 21H is mounted on the first link 11. It is also possible, but not necessary, to add a bearing between the beam 21H and the first link 11, the centre of rotation of which coincides with the central axis of the first link 11. With respect to the universal joint, indicated at 22, the bearing 21A is mounted around the actuating link 18 so that its axis of rotation coincides with the center of the link. In other words, the connecting bearings 21A, 22A connect the links 17, 18 of the outer arm linkage and the links 11, 12 of the inner arm linkage, wherein the rotational axis of each connecting bearing 21A, 22A coincides with the center of the respective link 17, 18 of the outer arm linkage.

The rod 21H is then mounted on the second connecting rod 12. A link bearing may also be added between the beam 21H and the link 12 with the center of rotation coinciding with the central axis of the second link 12, but this is not essential. The joints 21 and 22 should be mounted on the links 17 and 18 such that the distance between the centers of the joints 15 and 21 is the same as the distance between the centers of the joints 16 and 22. Connecting the inner pair of rods 11, 12 to the outer pair of rods 17, 18 has advantages compared to the solution in fig. 1: the mechanical system will not be redundant, making assembly easier. However, when a large-sized link is used while the bearing 21A takes a large size, it is more difficult to replace the bearing 21A in the event of a failure. Then, of course, the prestressing of the links 17 and 18 will not take place. Of course, the connection of beam 25 and bearings 21 and 22 can also be used in the 4-axis robot arm in fig. 3A.

Because of the bearing arrangement in the joint 22, the actuating link 18 is now also allowed to rotate about its central axis to the right of the joint 22, and the link bearing 16C can be placed anywhere along an actuating axis centerline along the actuating link 18, for example at the end of the actuating link 18 on the joint 20 as depicted in detail in fig. 3A. More generally, it is theoretically possible to deviate from the actuating link 18 if the actuating shaft centerline is parallel to the centerline of the bearing 22A (i.e., such as the bearing 21A but for the joint 22, see fig. 3D), but in practice, considering the power, it should also intersect the rotating shaft 33. That is, the actuation shaft centerline need not intersect the rotational shaft 40, although it is in FIG. 3A.

To turn the tool 28 about the shaft 71, which shaft 71 is the vertical axis of the tool 28, the lever arm 57 is mounted on the axle 52 to swing in a vertical plane. In this way, end effector rotation link 59 will rotate gear 64B using lever 61. Gear 64B will in turn rotate gear 64A (i.e., gear wheel or teeth wheel) with a gear ratio greater than, for example, 3, the tool can be rotated 360 degrees and more. As such, the gear transmission 64A, 64B may include a first gear 64A arranged to rotate the tool 28 with one degree of freedom. Shaft 52 is mounted by bearings 53 and 55, which bearings 53 and 55 are in turn mounted to inner arm assembly 1 by means of rods 54 and 56. Lever arm 57 is advantageously mounted at right angles to shaft 52 and end effector rotation link 59 is mounted to arm 57 with ball joint 58. At its other end, end effector pivot link 59 is also mounted on lever 61 by means of ball joint 60. In other words, the robot arm 500 comprises a directional transmission 64A, 64B, 100, 270, 271 comprising a second gear 64B, and the first gear 64A is engaged by the second gear 64B, which second gear 64B is arranged to be rotated by the end effector rotation link 59 via the lever 61 connected to the second gear 64B. Of course, all of the ball joints in the drawings can be replaced with two or three degree of freedom universal joints, even though this implementation often requires more space and weight. The second gear 64B is mounted on the outer ring of a bearing 63, which bearing 63 is in turn mounted by its inner ring on a vertical shaft 62, which vertical shaft 62 is mounted on the end effector beam 41A. The second gear 64B engages a smaller first gear 64A mounted on a vertical shaft 65, which vertical shaft 65 is arranged axially through a hollow beam 68. The shaft 65 is thus rotatably arranged within the hollow beam 68. As such, in other words, the first gear 64A is mounted to the end effector platform 41 such that the rotational axis 71 of the first gear 64A is parallel to the first rotational axis 29. The shaft 65 is supported by bearings 66 and 67 which in turn are mounted on a beam 68. Beam 68 is mounted to end effector beam 41A using rods 69 and 70. The tool 28 is mounted at the end of the rotating shaft 65, either manually screwed to the end flange (end flange on shaft 65, not shown) or with a tool exchanger on the end flange, so that tool change can be automated.

The same kinematic requirements as in fig. 1-2B are valid when applicable in fig. 3A. For example, all of the axes 29, 30, 31, 32 and 40 should be parallel and vertical, and this is also required for fig. 3A at the axis 71, which axis 71 is defined by the center of rotation of the shaft 65. The links 17 and 18 of the outer link pair should be parallel and of the same length and the same applies to the links 11 and 12 of the inner link pair. Note that joint 9 (fig. 2A) and part of first link 11 are hidden behind inner arm assembly 1 in fig. 3A. No solution for tool rotation is obtained in WO 201418748. Figure 1 in WO2015188843 includes an arrangement for turning a tool mounted on an end effector platform of a robot having three arms. The robotic arm system requires a large space and a fourth axis is implemented to tilt the tool. Tool rotation is here performed with a separate rotary actuator mounted on the wrist. Moreover, the working space of the robot is small and further reduced due to the transmission to the wrist axis. In the solution of fig. 1 and 3A of the present disclosure, the turning shaft 3 with the lever arm 57 connected to the lever arm 61 via the end effector turning link 59 enables a complete working area with a fourth axis in the whole positioning working space of the robot arm. This is not possible with the fourth shaft type of gearing in WO2015188843, since the offset of the transmission working range becomes larger as the wrist moves further away from the centre of the working space. Another problem with the gearing solution in fig. 1 of WO2015188843 is that the gears required in the wrist will be close to the motor of the sixth axis and hence to the tool, providing an awkward end effector platform, implying accessibility issues. As can be seen from fig. 1 and 3, the bearings are far from the tool due to the design of the robot arm with the beam 68 always vertical and the gear side is separated from the tool side.

Thus, in the present disclosure by mounting two tandem work actuators for tool rotation, whereby the orientation linkage and orientation actuator are on only one kinematic chain, and by using a fourth actuator 50 connected to a gear actuator 64A, 64B on the end effector platform 41 via a second rotation shaft 52 with a lever arm 57, the lever arm 57 being connected to the gear actuator via an end effector rotation link 59 having a joint of at least 2 degrees of freedom, e.g. in each end, the limitations of WO2015188843 are avoided, resulting in an optimal transmission efficiency between the fourth actuator 50 and the orientation actuators 64A, 64B. Also, two versions of the directional driver are cited, one with gears and one with rack and pinion, both of which can achieve +/-180 degrees of tool rotation capability.

Fig. 3B shows a robot arm 500 according to a second embodiment, which comprises an alternative directional drive to rotate the tool 28 compared to the drive in fig. 1 and 3A. In this embodiment a rack and pinion driver 100, 64A is used, wherein a pinion shaped gear 64A turns the tool 28. The rack 100 of the driver 100, 64A is moved by the end effector turning link 59 which is connected to the fourth actuator 50 via a mechanical driver, in other words, the first gear 64A engages the rack 100 which is arranged to be moved by the end effector turning link 59 connected to the rack 100. The basic three degree of freedom robot structure with beam 25 and bearings 21 and 22 is the same as in fig. 1 and the transmission for tool rotation with shaft 52, lever arm 57 and end effector rotation link 59 is the same as in fig. 1 and 3A. The new part in this implementation is that the transfer gear 64B in fig. 1 and 3A has been replaced by a linear gear, rack 100 to obtain a rack and pinion drive. The linear gear is moved by end effector rotation link 59 via ball joint 60. The rack drive moves in linear bearings, outlined by reference numerals 101 and 102, which are mounted on the rod 69 via a rod 103. As in fig. 1 and 3A, rods 69 and 70 are used to mount beam 68 to end effector beam 41A of end effector platform 41. Also, as in fig. 1 and 3A, a pinion gear 64A is mounted on a rotating shaft 65 to rotate the tool 28.

An advantage of the solution using the rack and pinion of fig. 3B over the gear solution of fig. 1 and 3A is that the end effector rotating link 59 can be kept closer to the vertical plane defined by the parallel links 17, 18 of the outer link pair in the workspace. This will further increase the transmission efficiency between the rotation of the shaft 52 and the shaft 65. Moreover, this solution would provide a somewhat elongated end effector platform arrangement.

Fig. 3C shows a directional linkage according to some embodiments. The directional linkage shows that the degrees of freedom of joints 58 and 60 can be distributed among lever 57, link 59, and lever 61. In this way, the bearing 58A is mounted in the lever 57 with a rotation shaft coinciding with the central axis of the lever 57, the bearing 58B is mounted with its rotation shaft perpendicular to the rotation shaft of the bearing 58A and the bearing 58C is mounted with its rotation shaft coinciding with the central axis of the link 59. The bearing 60A is perpendicular to the central axis of the link 59 and the bearing 60B coincides with the central axis of the lever 57.

Fig. 1 to 3D show how the robot arm 500 is designed to get the same motion characteristics as a SCARA robot, but with lower inertia of the arm structure, since all actuators are fixed to the robot support.

Fig. 4A shows a third embodiment of a robot arm 500, which shows that the robot arm can also be implemented as an articulated robot arm for reaching objects from above. This means that the structure of the robot arm does not swing in a horizontal plane but in a vertical plane. This means that all axes in fig. 1 to 3 that have to be vertical will now have to be horizontal. However, most of the design features from fig. 1-3 can still be used. Thus, referring to FIG. 4A, the only new design principle that can be illustrated is for transmission to gear 64B, except that it works using horizontal axes instead of vertical axes 29, 30, 31, 32, 40 and 71. Of course, the same transmission principle as in fig. 1 and 3A can also be used in this case and the transmission principle of fig. 4A can also be used in fig. 1 and 3A.

Looking at the actuator, the hollow shaft actuator of fig. 4A, i.e. the second actuator 5, is arranged to swing the lever 2 in and out of the pair of outer links 17 and 18. A third actuator 6, the output shaft of which passes through the second actuator 5, is arranged to turn the shaft 3 via a 90-degree gear to swing the pair of outer links 17 and 18 sideways. The first actuator 4, whose output shaft passes through the fourth actuator 150, is arranged to swing the inner arm assembly 1 and thus the outer link pair 17 and 18 up and down. The new feature of this embodiment of the robotic arm 500 in fig. 4A is the alternative fourth actuator 150, the hollow shaft actuator arranged to swing the first lever 200. The first lever 200 is connected to the rotation gear 64B by two links 202, 209 included in the directional linkage. One link 202 is mounted at one end to the lever 200 by a bearing 201 and to a second lever 204 by another bearing 203. The second lever 204 is mounted on an outer ring of a bearing 206, the inner ring of the bearing 206 in turn being mounted on the inner arm assembly 1 via a projection 205. A third lever 207 is also mounted on the outer ring of the bearing 206 such that the tip (tip) of the third lever 207 moves in the vertical direction when the tip of the second lever 204 moves in the horizontal direction. The rotational axis of bearing 206 coincides with axis 40, which provides simpler kinematics for gear 64B transmission. The tip of the third lever 207 is connected to another link 209 via a ball joint 208 and the other end of the other link 209 is connected to a fourth lever 211 via a ball joint 210. It should be noted that the bearings 201 and 203 may be replaced by ball joints. Now, when the first lever 200 is swung, the fourth lever 211 will swing up and down (vertically) and the gears 64A, 64B will rotate back and forth about their rotational axes with the swing of the fourth lever 211. In this figure the second gear 64B is mounted on the end effector beam 41A via a shaft 213 and a bearing 214. To maintain a constant tilt angle of tool 28 or to control the tilt angle of tool 28 to a target angle, rotary gear drives 64A, 64B on end effector platform 41 are used herein as in fig. 1 and 3A. However, the gears of the transmission are here arranged vertically, rather than horizontally as in fig. 1 and 3A. In this manner, the rotary gear transmissions 64A, 64B are controlled by the rotary fourth actuator 150 via the arrangement of the links 202, 209 and the levers 200, 204, 207. As in fig. 1 and 3A, rotating the second gear 64B will rotate the first gear 64A at gear magnification. The first gear 64A is mounted on a beam 68 via a shaft 65 and a bearing 66. Rotating the first gear wheel 64A means that the shaft 216 holding the gear wheel 64A is rotated and the tool 27, 28 arranged on the shaft 216 will change its tilt angle (the shaft 216 is here the connecting means to the end effector). This may be useful, for example, when picking and placing objects at different inclinations. For example when picking up objects from a conveyor, will also be used to maintain a constant tilt angle throughout the working space.

Fig. 4B shows a robot arm according to a variation of the third embodiment. With this variant, the working range of the actuator between the levers 200 and 211 can be increased compared to the embodiment shown in fig. 4A. With the solution in fig. 4B, the gear ratio of the gear transmission 64B-64A can be reduced and the ability of the gear 64B to rotate in the inner and outer parts of the working space of the robot arm will be increased. Here, an internal gear mechanism comprising a backhoe linkage has been cited, including an additional lever 501 longer than the lever 204. Levers 501 and 204 are connected by a link 505 having bearings 503 and 203 at its ends. When the actuator 150 swings the lever 200, the link 202, having bearings 201 and 506 at its ends, will swing the lever 501 about the bearing 502 mounted on the beam 504. Using the backhoe principle, the angular rotation of lever 204 will be greater than the angular rotation of lever 501 and gear 64B will take a greater rotation than the direct drive in fig. 4A. As such, in other words, the internal gear mechanism is arranged according to the backhoe principle to rotate the end effector 28 within an angular range determined by the gear ratio of the internal gear mechanism without being constrained by the outer arm linkage. That is, without the backhoe mechanism, the large angular range of the second degree of freedom tends to result in an undesirable limitation of the working range of the fourth degree of freedom of large orientation about axis 40. This is avoided with a backhoe mechanism, which is a well known mechanism for excavators and various cranes. Thus, the standard backhoe principle can be applied to virtually any lever and rod linkage within the present invention, and for the sake of brevity is not further reviewed or described. The bearing 206 in fig. 4B has an offset from the shaft 40 compared to fig. 4A, which is of course not necessary, but may make the mechanical design more efficient in terms of force and/or working space.

In fig. 4B there are thus two steps with different principles to increase the amplification of the rotation ratio between the actuator 150 and the gear 64A. Of course, a directional transmission having lever 211 and gears 64A and 64B could also be used with the backhoe mechanism implemented in FIG. 4B and vice versa. The same concept can be used for the transmission between the actuator 150 and the gear 64A in fig. 5A and the transmission between the lever 351 and the lever 362 in fig. 10B (with the symbol as in fig. 3D).

Fig. 4C shows a robot arm according to another variation of the third embodiment. According to this further variant, the actuators 4, 5, 6 and 150 are mounted on a carriage 510, the carriage 510 being rotatable by an actuator 512 connected to the carriage 510 by a shaft 511. The centerline of shaft 511 is at right angles to the centerlines of actuators 4, 5, 6 and 150. With the actuator 511 the agility of the robot arm will be improved and since the actuators 4, 5, 6 and 150 for controlling the robot arm are all located close to each other, the mass inertia to be rotated by the actuator 512 will be small. As such, the torque and power required for the actuators 512 will be much lower than that required for known tandem robots having actuators distributed in the robot arm. It should also be mentioned that according to an embodiment, the carriage 510 may be mounted on a linear actuator to increase the working space. Fig. 4C also shows the option of using an actuator 514 for the rotary tool 28. When the robotic arm handles small objects with small mass inertia, the actuator 514 may be lightweight and this solution may be advantageous because the mechanical complexity for the rotation of the tool is lower than the solution in fig. 8.

Fig. 4D shows an alternative solution with a belt drive for transmitting motion to the tool 28, where the gear 64B of fig. 4C has been replaced by a pulley 64C, and the gear 64A has been replaced by another smaller pulley 64E. A belt 64D connects the two pulleys. The belt drive may also replace the backhoe mechanism. Instead of a belt, a wire may be used between the two wheels.

Generally, a connecting rod is used to transmit force, and a lever is used to transmit torque.

A rack and pinion solution as in fig. 3B can of course be used instead of the gear drives 64A, 64B. The direction in which the racks are mounted may be as in fig. 3B or at right angles to the plane formed by the outer link pairs 17, 18.

In WO201418748 no solution is available for an articulated robot that reaches the object from above and no solution is shown for a fourth axis to be able to tilt the tool or to keep the tool tilt angle constant.

In some applications, it is desirable to tilt and rotate the tool 28. One possibility is to mount a small actuator on a shaft 27 connected to a tool 28, for example in fig. 4A, to rotate the tool 28. This will add inertia to the arm structure and an electrical line, and to avoid this, a gearing solution with a rack and pinion as shown in fig. 5A is used. Shaft 27 is the connection means to the end effector. Fig. 5A shows a robot arm 500 according to a fourth embodiment, wherein the tool 28 is controlled to both rotate and tilt or to tilt in two degrees of freedom. In fig. 5A, in order to effectively rotate the tool in two degrees of freedom, a rack and pinion arrangement 270, 271 is mounted to the rotating first gear 64A and the rack 271 is connected to the gearing arrangement 264, 266 via a bearing 267, the centre of rotation of the bearing 267 coinciding with the centre of rotation of the first gear 64A carrying the rack and pinion arrangement 270, 271. Implementing these features enables the tool to be rotated +/-180 degrees about two axes that are 90 degrees from each other. This is not possible with the arrangement described in figure 1 of WO 2015188843. In more detail, a rack and pinion 270 is connected to the tool 28 and arranged to be turned by the rotary gear transmission 64A, 64B, and a rack 271 of the rack and pinion is moved via a bearing 267 and an arrangement of links 258, 264, 266 and levers 256, 260, 262.

The first gear 64A is actuated in the same manner as described in fig. 4A but the first gear 64A now rotates the linear bearing assemblies 270, 271 with the rack 271 sliding parallel to the axis of rotation of the gear 64A. As such, the robotic arm 500 includes at least two directional actuators 64A, 64B mounted to the end effector platform 41; 270. 271; 293. 294; 315. 316; 311. 312, 313 (see also other figures), the end effector platform 41 includes components 41A, 68, 69, 70 and similarly depending on the orientation embodiment. The first gear 64A of the orientation transmission is arranged to rotate at least one other orientation transmission 270, 271; 293. 294; 315. 316; 311. 312, 313 (see also other figures). As in fig. 3B, the rack rotates a pinion, here indicated at 270, to rotate the tool 28 via shaft 65A (corresponding to 65 of fig. 3B). In other words, at least one other orientation drive 270, 271; 293. 294; 315. 316; 311. 312, 313 is connected to the tool 28 for tool rotation. In some embodiments, the robotic arm includes at least two orientation actuators 64A, 64B mounted to the end effector platform 41; 270. 271; 293. 294; 315. 316; 311. 312, 313 and wherein the external gear mechanism 64B, 64A of one of the at least two orientation drives; 64C, 64D, 64E; 100. 64A; 271. 270 are arranged to rotate at least two directional transmitters 270, 271; 293. 294; 315. 316; 311. 312, 313.

The sliding movement of the rack 271 is achieved by the curved rod 266 via the bearing 267. The bearing 267 preferably has its axis of rotation coincident with the axis of rotation of gear 64A. The linear bearing assemblies 270, 271 can then be rotated by the gear 64A without any rotation or translation of the curved rod 266. In other words, the rotational axis 71 of the at least one rack bearing 267 coincides with the rotational axis 71 of the first gear 64A.

The curved rod 266 is moved by the link 264 via the ball joint 265. The link 264 is mounted to the lever 262 via a bearing 263. The inner ring of bearing 261 is mounted on a beam 269 which beam 269 in turn is mounted on shaft 62 which exits the inner ring of bearing 63 of gear 64B. The shaft 62 is mounted on the end effector beam 41. The lever 260 is mounted on the outer ring of the bearing 261, as is the case with the lever 262. Comparing this arrangement to the previously described levers 204 and 207, the tip of lever 263 moves horizontally as the tip of lever 260 moves vertically. Vertical movement of the tip of the lever 260 results from vertical movement of the tip of the lever 256 via the gear link 258. A gear link 258 is mounted on the tips of the levers 256 and 260 using ball joints 257 and 259. In contrast to the arrangement of the lever 57 in fig. 1 and 3B, the lever 256 is mounted on the turning shaft 261 at an angle of approximately 90 degrees. In this manner, the turning shaft 251 will swing the lever 256 up and down and move the rack 271 back and forth via the gear link 258, the two levers 260 and 262, the link 264, the rod 266, and the bearing 267, providing rotation of the tool 28 in a tilting direction determined by the turning angle of the gear 64A. In other words, the robot arm 500 comprises a directional linkage 251, 256, 264, the directional linkage 251, 256, 264 comprising a rotational shaft 251 having a lever 256 at one end, and wherein the lever 256 is connected to the gear link 258 via a joint 257 of at least two degrees of freedom. Shaft 251 is mounted on bearings 253A and 253B. Bearing 253A is mounted on inner arm assembly 1 via beam 255 and bearing 253B is mounted on the inner arm assembly via shaft 269 of bearing 206. A shaft 269 for bearing 253B is mounted on inner arm assembly 1 via projection 205. In the figure, the shaft 251 is arranged to be rotated by the fifth actuator 250. As such, the robotic arm 500 includes a fifth kinematic chain configured to transmit motion of the fifth actuator 250 to corresponding movement of the tool 28, the tool 28 being mounted to the end effector platform 41 via an external gear mechanism, here including the first gear 64A. The fifth kinematic chain includes at least one rack bearing 267, 297 connected to the fifth actuator 250 via a directional linkage 251, 258, 264. However, a fifth actuator whose axis of rotation coincides with the first axis of rotation 29 may be used, the shaft 251 being connected to the fifth actuator via a 90-degree angle gear as shown in fig. 1 and 3B. Of course, a drive chain arrangement for rotating gear 64B via fourth actuator 150 may also be used to move lever 260 up and down. The link chain arrangement for the rotary tool 28 could of course also be placed on the other side of the inner arm assembly 1, and then the linear bearing arrangements 270, 271 would instead be mounted on the shaft 65 on the left side of the bearing 66, making it possible to design a more compact solution. Also, the entire rack and pinion arrangement may be located to the left of the gear 64A, but this more compact solution is not shown for clarity of the drawing. The gear drives 64A, 64B may also be replaced with a rack and pinion arrangement as in fig. 3B.

The transmission from actuator 150 to the lever mounted on gear 64B is different from the transmission from actuator 250 to lever 260, however, the same transmission concept can be used for both cases. When the transmission concept for the actuator 150 and the lever mounted on gear 64B is used, a backhoe linkage may be included. The same gearing concept as used between the actuator 250 and the lever 260 in fig. 5A is also used in fig. 6A, 9 and 10A as will be shown below. Of course, these transmissions may be replaced by the type of transmission used in FIG. 5A from actuator 150 to the lever mounted on gear 64B and they may include the backhoe linkage depicted in FIG. 4B.

In fig. 5B, an alternative embodiment of the rack 271 is shown, the rack 271 having been rotated 90 degrees so that the teeth point downwards. The connected pinion 270 now has a horizontal axis of rotation and the shaft 65 is horizontal. The tool 28 is mounted to the shaft 65A at a right angle. As in fig. 5A, a linear bearing assembly 273 for the rack 270 is mounted on the pinion 64A and a bearing 267 between the rack 271 and the transmission portion 266 has a center of rotation that coincides with the center of rotation of the pinion 64A. The mounting of the rack and pinion creates the possibility of controlling both angles of inclination of the tool 28.

Solutions have been shown so far to control five-axis robots with all actuators fixed to the robot carriage. To obtain 6 degrees of freedom, one solution uses a transmission with a rotating shaft, a universal joint and a 90 degree gear as shown in fig. 6A and 6B.

Fig. 6A and 6B show a robot arm 500 according to a fifth embodiment, comprising a combination of rack and pinion concepts according to fig. 5A and 5B, wherein a transmission comprising right angle gears and universal joints 282, 280 is used to implement a further kinematic chain. That is, the other kinematic chain is configured to transmit movement from the actuator 285 to corresponding movement of an end effector disposed on the end effector platform, which provides at least six degrees of freedom for end effector motion, all actuators still being fixed to the robotic stand.

The robot arm 500 has been split here into two figures to enable a more detailed display. Fig. 6A shows the transmission from rotary actuator 285 to horizontal rotary shaft 275 on end effector platform 41 through its right angle gear transmission 299. To make this possible, the output from right angle gear drive 299 rotates a shaft 284, which shaft 284 is mounted on inner arm assembly 1 (mounting not shown). The shaft 284 engages a right angle gear 283, the output of the right angle gear 283 being connected via a link 286 to a first universal joint 282 mounted with its center on line 40. The output of universal joint 282 rotates a shaft 281, the other end of shaft 281 being connected to a second universal joint 280 via a link 279, the second universal joint 280 being centered on shaft 32. The output of the second universal joint 280 drives the right angle gear 278, which in turn rotates the shaft 275 with the right angle gear 278. The shaft 275 is bearing mounted in the beam 68 and is free to rotate in the bearing 66, which bearing 66 supports the first gear 64A via the hollow shaft 65. The shaft 275 is also arranged to rotate freely within the shaft 65 and the first gear 64A. As such, the directional linkage comprising 284 and 286 and the directional driver comprising 281, 279 and 275 are arranged to rotate the end effector about the directional axis 71, since there is no stop in free rotation within the shaft 65 and elsewhere, there will be no rotational angle limitation.

Fig. 6B shows the shaft 275 connected to a right angle gear 277, the right angle gear 277 rotating on its output a shaft 65B, the shaft 65B being free to rotate within the bearings of the pinion gear 290. The shaft 65B is connected to a final right angle gear 288, which gear 288 is connected at its output to the shaft 65C of the rotary tool 28. As such, the connection means of the end effector here comprises a shaft 65C. Furthermore, a pinion 270 of the at least one second gear transmission 270/271 is connected to the tool 28 via a right angle gear 288. The shaft 65C is connected to the pinion gear 270 via a bearing 291 and a beam 290. As in fig. 5A and 5B, the rack and pinion 270, 271 is arranged to be rotated by the first gear 64A. The center of rotation of the output gear of the right angle gear 278, the center of rotation of the shaft 275, and the center of rotation of the input gear of the right angle gear 277 are on the common shaft 71. The rack 271 is moved by the link 264, and the link 264 is connected to the rack 271 via the beam 266, the rack bearing 267, and the rack attachment 287. As in fig. 5A, the link 264 is connected to the link arrangement via a lever 262.

As can be seen from fig. 6A, five right angle gears and two universal joints are required to get the rotation of the tool 28 from the actuator 285 fixed to the robot stand. This solution has the advantage of allowing infinite tool rotation angles and the disadvantage of losing the positioning workspace due to the limited working range of gimbals 280 and 282.

By observing that the shaft 275 in fig. 6A is a straight shaft (with some form of bearing 66) that is open at both ends, one skilled in the art will note similarities to the external robot arm segments of robots according to many existing products. This directly indicates that the shaft 275 is made hollow, that the other bearing 66 and the other shaft 275 are inside, etc., for a plurality of concentric shafts. It is common practice in the art to have three such concentric shafts. Such a plurality of concentric shafts 275 making up the exemplary wrist mechanism shown in fig. 6B may then be used to extend/modify the mechanism (in various ways, not considered here) or to install an existing standard robot wrist into a location of a new end effector platform according to the present disclosure. Considering the other end of the concentric shaft 275, the inner shaft protrudes further outward (to the left along the centerline 71 in fig. 6B), and adding another right angle gear 278 for each shaft, the rest of the sixth kinematic chain (from the right angle gear 278 up to the actuator 285) can be duplicated, and therefore, multiple kinematic chains can be added. The robotic arm then includes a plurality of directional linkages 284, 286, each directional linkage 284, 286 including a directional actuator 281, 279, 275.

Still further, as another variation that one of ordinary skill in the art would find, the plurality of orientation linkages may be configured such that a corresponding plurality of concentric output shafts 275 may actuate a number of end effector orientations, not only for one end effector, but also for a number of end effectors arranged onto the end effector platform, e.g., in different directions or adjacent to one another. As mentioned above, since many standard articulated robots have wrist motors arranged behind their outer arm links with axles running parallel or concentrically through the outer arm links to a wrist with 2 or 3 degrees of freedom, the present invention has the option to combine SCARA-like motions according to the 3 degrees of freedom of fig. 2A with a standard 3-degree-of-freedom robot wrist (not the mechanism shown in fig. 6B, but using existing components/interfaces) that is actuated by multiple axles 275 driven by multiple motors 285, all motors 285 fixed to the robot gantry. Arranging the shaft 275 on a standard SCARA robot requires an expensive and heavy telescopic shaft to handle the vertical placement of the wrist (and no useful 6 degrees of freedom SCARA exists), which is in contrast to the present invention where the nature of the third kinematic chain enables a more efficient solution.

Fig. 7 shows an alternative exemplary embodiment of the rack and pinion arrangement shown in fig. 6B, providing the possibility of obtaining six degrees of freedom without using a universal joint. Here, a second or additional rack and pinion arrangement 293, 294 is introduced, wherein the pinion 294 is used to turn the tool 28 via a right angle gear 288. Also, a pinion gear 294 of the at least one second orientation driver 293/294 is connected to the tool 28 via a right angle gear 288. The same principle as for the rack and pinion arrangement 270 and 271 can be used to slide the rack 293, but now the connection of the transmission to the actuator on the robot stand (not shown in the figure) is obtained through the first gear 64A. As such, the linkage is connected to the beam 297, which beam 297 will move by translating the shaft 275 back and forth via the bearing 296. Shaft 275 will move freely within bearing 66, shaft 65 and first gear 64A and is connected to rack 293 via beam 295. The two rack and pinion arrangement would be mounted on the first gear 64A and the shaft 65C mounted to the pinion 270 via the bearing 291 and beam 290 as in fig. 6B. For clarity, the linear bearings of the racks 271 and 293 are not shown, but are mounted on a platform (not shown) to be rotated by the first gear 64A. The pinions 270 and 294 are bearing mounted on the same platform and the shaft 65 is free to rotate within the bearings that support the pinion 270. A right angle gear assembly 288 is mounted (not shown) on the pinion gear 270. In this manner, turning gear 64A will turn the tool (and the entire rack and pinion drive) about axis 71, transfer beam 266 will turn tool 28 about the center of shaft 65, beam 266 is at right angles to axis 71, and transfer beam 297 will turn tool 28 about the center of rotation of shaft 65C.

One disadvantage of the arrangement in fig. 7 is that because of the functionality of the right angle gear 288, turning the tool 28 about the center of the shaft 65 will simultaneously turn the tool 28 about the center of the shaft 65C. To avoid this, a third rack and pinion arrangement may be introduced according to fig. 8.

Fig. 8 shows an embodiment of a three rack and pinion arrangement to be rotated by gear 64A, completely avoiding the addition of right angle gears and universal joints to a six degree of freedom robot. One of the rack and pinion arrangements comprises two racks with a common pinion, wherein the racks are mounted at right angles to each other. Here, the right angle gear 288 of fig. 7 has been replaced by a rack and pinion arrangement 315, 316. The pinion 316 turns the tool via the shaft 65C and the rack 315 is connected to the rack 313 via the shaft 65 and the bearing 314. The rack 313 shares a pinion 312 with a rack 311, the rack 311 being connected to the shaft 275 via a beam 310. As such, the travel beam 297 will move the shaft 275 and then the rack 311 via the bearing 296. Moving the rack 311 will move the rack 313, which is at right angles to the movement of the rack 311, via the pinion 312. In other words, one rack and pinion gear 311, 312, 313 here comprises two racks 311, 313 connected via a common pinion 312 and the two racks 311, 313 are arranged to move at right angles to one another. Then, the rack 315 will be moved by the freely moving shaft 65 via the rack bearing 314. In other words, the rack shaft 65 is arranged to move freely in the axial through hole of the pinion 270 belonging to the other rack and pinion driver 270, 271. The rack 271 moves via the rack attachment 287 and the rack bearing 267 in the same manner as in fig. 6B. The two racks 313, 315 may be connected to each other via the rack shaft 65 and the rack bearing 314. As such, this solution enables to obtain a six degree of freedom movement of all actuators on the robot arm 500 on the robot stand without any coupling between the rotational axes of the tools. In other words, the robotic arm comprises at least one further actuator and at least one further kinematic chain configured to transmit movement of the at least one further actuator to corresponding movement of an end effector disposed on the end effector platform, which provides at least six degrees of freedom for end effector motions. As can be seen in the figures, the shaft 65C of the rotary tool 28 is mounted on the underside of the pinion 316. However, it may equally be mounted on the upper side of the pinion 316 and it is also possible to have a tool mounted by a shaft on the upper side of the pinion 316 and at the same time another tool mounted on the lower side of the pinion 316. The arrangement of figure 8 of three parallel link drives and actuators mounted on the main structure of the axes 1-3 and having the orientation drives 64A, 64B and having the axes 4-6 can be further developed into a 7 degree of freedom robot using the rotary base actuators and the axes 1-6 actuators. If only rotary seals are used, it is easier to protect the components of the wrist shafts 4, 5 and 6 in hygienic applications or in dirty environment applications. To seal an arrangement such as in fig. 5, a seal for linear movement is required for the rod 266. Fig. 9A, which shows a robot arm 500 according to a sixth embodiment, shows a solution to this problem, since here only the rotary seal is needed. A way to achieve this feature is to implement a second rack and pinion arrangement where the racks are connected and where the pinions have different dimensions providing a gear factor greater than 1. With the same driver design as fig. 5, from the fifth actuator 250 to the vertical movement of the link 258, the pinion 302 is turned via a shaft 301 by a lever 300, the tip of which lever 300 is mounted on the link 258 via a ball joint 259. As such, the pinion 302 of the fixed rack and pinion driver 302, 307 comprises a lever 300, on which lever 300 a gear link 258 is mounted via a joint 259 of at least two degrees of freedom.

Pinion 302 is mounted on shaft 301 and shaft 301 is mounted in the inner ring of bearing 303. The outer ring of bearing 303 is mounted by beam 304 on linear bearing assembly portion 305, which linear bearing assembly portion 305 is in turn mounted on shaft 63 and thus stably secured to end effector beam 41. As such, at least one rack bearing 267, 297 is connected to the fifth actuator 250 via a fixed rack and pinion drive 302, 307 mounted on the end effector platform 41. As such, at least one rack bearing 267, 297 is connected to the fifth actuator 250 via a fixed rack and pinion drive 302, 307 mounted on the end effector platform 41. When the pinion 302 rotates, the rack will move horizontally and because of the rigid coupling obtained by the beam 308, the rack 271 will also move horizontally. The beam 308 is connected to the rack 271 via a shaft 309 and a bearing 267. Furthermore, rack bearings 267, 297 are connected to the rack 307 of the fixed rack and pinion gear drives 302, 307. Shaft 309 is mounted in the inner ring of bearing 267 and the outer ring of bearing 267 is mounted on rack 271. In one embodiment, the diameter of the pinion 302 is about three times the diameter of the pinion 270 to obtain at least 360 degrees of rotation of the tool 28. As such, fig. 9A shows an alternative actuator to the link and lever arrangement 260, 262, 264 of fig. 5. Here, the second rack and pinion is connected in series with the rack and pinion shown in fig. 5. In this way a simpler arrangement of links and levers may be used with only one link 258 and two levers 256 and 300. As such, the robotic arm 500 includes the fifth actuator 250 and a fifth kinematic chain configured to transmit the motion of the fifth actuator 250 to corresponding movement of a tool mounted to the end effector platform 41 via the first gear 64A. The fifth kinematic chain here comprises at least one rack bearing 267, 297 connected to the fifth actuator 250 via a link transmission 251, 258, 264.

Fig. 9B shows an alternative orientation linkage according to some embodiments. The orientation linkage gives the option to use the 90 degree gear 256A to rotate the shaft 256B and lever 256 about an axis perpendicular to the central axis of the inner arm assembly 1. This will increase the transmission working range between the lever 256 and the gear transmission.

As can be appreciated from the present disclosure, in some embodiments, the robotic arm includes a plurality of directional linkages 52, 57, 59; 202. 204, 207, 209; 251. 256, 258. Each directional linkage has a connected directional actuator 64B, 64A, 216, respectively; 64C, 64D, 64E; 100. 64A; 260. 262, 264, 266, 271, 270. The plurality of orientation linkages are configured such that each corresponding end effector orientation is accomplished for one or more end effectors disposed onto the end effector platform.

Fig. 10A, 10B show a robot arm 500 according to a seventh embodiment with a horizontal common first rotation axis 29 of the rotation actuators. The robot arm 500 is divided into fig. 10A and 10B to more easily understand the movement structure. As such, fig. 10A shows a complete robot structure with a kinematic chain to control the tilt angle of tool 28. In this case the tool 28 is rotated by a lightweight rotary actuator 390, which rotary actuator 390 is mounted on a horizontal shaft 65 connected to the gear 61B. Gear 61B is engaged by gear 64B mounted on shaft 213, which shaft 213 is connected to end effector beam 41A via bearing 214. In this case the end effector beam 41A is part of the end effector platform 41, the end effector platform 41 comprising elements 366 and a hollow beam 68, the shaft 65 being mounted in each end of the hollow beam 68 by one bearing. End effector platform 41, including element 366, forms a rigid frame with the rods mounted together to support joints 367, 368, and 369, bearing 214, and shaft 65. The shaft 213 is rotated by a lever 61, which lever 61 is connected to the end effector rotation link 59 by a ball joint 60. The end effector rotation link 59 is arranged to move up and down by a lever 257, which lever 257 is connected to the end effector rotation link 59 via a ball joint 58. The lever 257 is arranged to be pivoted up and down by the axle 52, the axle 52 being mounted on bearings 53 and 55, the bearings 53 and 55 in turn being mounted on the inner arm assembly 1 by means of beams 53 and 56. The shaft 52 is arranged to be rotated by the rotary actuator 50 via a 90 degree angle gear 51.

In the design shown in fig. 10A, 10B, the constraint on the tilt freedom about the axial center of end effector beam 41A is obtained by a third link 365, which third link 365 is connected to end effector platform 41 with ball joint 367A and to inner arm assembly 1 with ball joint 367B. First link 17 is connected to end effector platform 41 with joint 368 and to inner arm assembly 1 with joint 15 and link 18 is connected to end effector platform 41 with joint 369. As can be seen in fig. 7B, in which the drive controlling the tilt angle has been removed for clarity, the upper ends of the actuating links 18 of the outer link pair are connected to the bearing pair 16A and 16B via bearings 16C. The center of rotation of the bearing 16C coincides with the axial center of the actuating link 18. Bearings 16A and 16B are mounted on bearing 364 such that the axes of rotation of bearings 16A and 16B coincide and are at right angles to the angle of rotation of bearing 363. The bearing 363 is mounted on a shaft 363, which in turn is mounted on the inner arm assembly 1 via a beam 364. The lever 362, now in the center of the bearing 16A and connected to the outer ring of the bearing 363, serves to swing the bearing pair 16A, 16B about the bearing 363 and thus the actuating link 18 will swing about the lever 362, which lever 362 is parallel to the center of the hollow link of the inner arm assembly 1. The shaft 363 is oscillated up and down actuated by a link 360, the link 360 having ball joints 359 and 361 in each end. The joint 359 is connected to a lever 358 mounted on the outer ring of the bearing 356. The inner ring of the bearing 356 is mounted on a beam 357, which beam 357 is in turn mounted on the inner arm assembly 1. Another lever 355 is mounted on the outer ring of bearing 356 at an angle of about 90 degrees relative to lever 358. The lever 355 is connected to the link 353 via a bearing 354, the bearing 354 also being a ball joint in nature. The other end of the link 353 is connected to the lever 351 via a bearing 352. The bearing 352 may also be replaced by a ball joint. The lever 351 is forced to swing by the rotary actuator 350. The transmission of this swing link 18 is in some applications better than using the first turning axle lever 3 as in the previous figures. For example, stiffness in link 353 is easier to achieve when inner arm assembly 1 is very long and uses only axial force rather than axle 3 with rotational torque.

Another novel feature introduced in these figures is the use of link pairs 11A, 11B and 12A, 12B instead of single links 11 and 12 as in the previous figures. This enables the use of a simple pair of ball joints held together by a spring between the links of the pair. As such, where the linkage system includes a third link 365, the inner arm linkage includes a pair of parallel links 11A, 11B and 12A, 12B and actuation of the tilt angle of tool 28 is now achieved by link 353 which uses only axial force. In other words, the links of the inner arm linkage (inner parallel link pair 11, 12) include parallel link pair 11A, 11B; 12A, 12B, and these parallel link pairs 11A, 11B; 12A, 12B are mounted on each side of the links of the outer arm linkage by ball joints.

In the preceding figures, the hollow shaft actuator has been outlined to make the figures more readily apparent. Figure 11 shows how actuation can alternatively be achieved with a standard motor without a hollow shaft. Fig. 11 is a sectional view of two actuators driving the hollow link 1A and the rotating shaft 3. Both the hollow connecting rod 1A and the shaft 3 are tubes made of, for example, a reinforced carbon fiber composite material. The hollow link 1A is mounted on the outside of a ring 424, and the ring 424 is assembled with the housing 417. The housing is mounted on a shaft 416, which shaft 416 is rotated by a motor 412 via a shaft 413 and gears 414 and 415. Gear 415 is mounted directly on the outer surface of shaft 416 and gear 414 is mounted at the end of shaft 413. The shaft 413 is provided with a pair of bearings 428 between the gear housing 430 and the shaft 413. In the same manner, the shaft 416 is equipped with a bearing pair 426 between the gear housing 430 and the shaft 416.

The shaft 3 is mounted between an inner short shaft 422 and an outer ring 423 which in turn is mounted in the housing 417 via bearings 425 to support rotation of the shaft 3. In the other end the shaft 3 will be mounted inside the hollow link 1A of the inner arm assembly 1 by corresponding bearings. The 90-degree gear 421 is mounted on the stub shaft 422. Gear 421 is driven by a 90 degree gear 420 mounted on a shaft 419, which shaft 419 is driven by a motor 418. Shaft 419 is supported by bearing pair 427 between shafts 416 and 419. The first axis of rotation 29 (compare previous figures) is defined by the centre of rotation of the bearing 425 and the corresponding centre of rotation of the bearing in the other end of the shaft 3. The first rotation axis 29 (also shown in the previous figures) is defined by the center of rotation of the shaft 419. As such, fig. 11 shows an embodiment in which the rotary actuators are arranged to obtain a common rotational axis without the use of a hollow shaft motor as shown in fig. 1-6. The motors 412, 418 are mounted alongside one another and a hollow shaft 416, gears 414, 415 are used.

Fig. 12A shows an alternative version of fig. 1, in which the first axis of rotation 29 of the actuator has been split into two different parallel axes of rotation 29A and 29B. In this way no hollow shaft actuator is required. The second actuator 5 is here moved with its own axis of rotation 29B and, as previously mentioned, it is arranged to swing the lever 2 in order to move the parallel links 11 and 12. The first actuator 4 and the third actuator 6 have a common rotation shaft 29A. The first actuator 4 is mounted directly on the inner arm assembly 1 and the third actuator 6 is connected to a right angle gear, not shown in the figures, to rotate the shaft 3. With the advantage that the actuator arrangement will be simpler, there will be at the same time the disadvantage that the working space will be somewhat reduced and the transmission of the forces in the links 11 and 12 will depend on the angle of rotation of the inner arm assembly 1. In the figures with more than three actuators it will of course be possible to have parallel rotation axes between the different actuators. Further description of fig. 12A refers to the description of fig. 1.

Fig. 12B shows that instead of an actuator consisting of a rotary motor (here actuator 5), a gearbox can be provided on the output motor shaft, and the required motion of the transport as in fig. 12A to actuate the lever of each respective kinematic chain (here lever 2), the desired motion of the link ends can be done directly by a linear actuator. The function of the two links 11 and 12 in fig. 12A (moving the joints 13 and 14) is performed by two ball screws 811 and 812 terminating at the joints 13 and 14, respectively, thereby providing the function of the links 11 and 12. The other ends of the ball screws 811 and 812 are here connected to the beam 8 via universal joints 809 and 810, which universal joints 809 and 810 have the same function as the joints 9 and 10, but are not allowed to rotate around each respective link 811 and 812 for optimal function of the ball screws. Each ball screw includes a ball nut portion 811A, 812A that is rotationally fixed at 809, 810 to its base end and that is also rotationally fixed as needed relative to a screw portion 811B, 812B to effect linear movement from the screw 811B, 812B extending from the ball screw portion 811A, 812A, thereby making the links 811 and 812 shorter or longer. Here, the actuator 5 is duplicated and built into or attached to both 811A and 812A so that the screws 811B, 812B rotate. Here the actuator 5 (fig. 12A) is integral with 811A and 812A and is therefore not visible in the figure. In fig. 12A single actuator 5 and lever 2 move beam 8, but in fig. 12B two ball screws each have one actuator, and therefore they must move synchronously (with the mentioned control system) to keep shafts 30 and 33 parallel. An alternative embodiment is to rotate the lever 2 about the axis 29B without the actuator 5, but with a ball bearing acting on the beam 8 from a position near the centre line 29A. This approach requires only one ball screw. The ball screw may also act from a location (not shown) on the hollow link 1A and then not transmit forces to the robot support.

In general, another way of using linear actuators is that they are used with levers to produce a limited range of rotation. In particular, it applies to all the rotations represented by all the actuators in all the figures, except for fig. 6A, 6B and 12B, the action of which is generated by a rotary actuator, which according to the known robot implementations generally has an infinite rotation capacity. However, for the disclosed robot arm, it is not necessary to have a large range of actuators, other than the multiple wrist motions in fig. 6A and 6B. Instead, according to the invention, each actuator may be linear, provided with a suitable lever. Thus, in addition to a ball screw, the actuator may also be pneumatic or hydraulic, respectively for very low robot costs or for very high end effector forces.

The driver as used herein may be a gear driver, such as a conventional pinion-pinion or rack-pinion with actual gears, but may be replaced by another driver based on a wire or belt of the same function as the pinion-pinion or rack-pinion driver. As used herein, the term "transmission" means any transmission that functions similarly to the type of gear transmission described above.

Fig. 13 shows the components of a drive for rotation of the end effector of fig. 1 and 3A, but here gears 64A and 64B have been replaced by pulleys 64C and 64D connected to belt 64E. For further description of the components in fig. 13, reference is made to the illustrations of fig. 1, 3-3D. The belt drive is sometimes manufactured with a simpler mechanism than the gear drive. Moreover, if the transmission is made of a plastic material, an inexpensive belt transmission can have a longer life than a gear made of plastic.

Fig. 14A and 14B illustrate the use of a backhoe mechanism (see fig. 4B) of the second kinematic chain, according to some embodiments. Fig. 14A first shows a backhoe mechanism in which the connecting bearings are still placed around the rotational center line of the two links of the outer parallel link pair 17, 18. The base bearing 803 of the backhoe mechanism is placed on portion 1A of the inner arm assembly 1, which means that the backhoe mechanism operates via the two links 805, 806 and the universal joints 21, 22 as in FIG. 3A. Placing the bearing 803 on the shaft 3 to create a more preferred force direction on the connecting bearing would require another way of keeping the rotating shafts 31 and 32 parallel to the shaft 33, for example by introducing an additional joint between 8 and 802 and an additional connecting rod between 8 and 7C (this is not shown in the figures). The motivation for the backhoe is to increase the working range of the second kinematic chain and thereby increase the working space of the robotic arm 500. In particular, most SCARA robots have a second degree of freedom with a working range of more than 180 degrees. On the other hand, the robot design according to WO2014187486 is limited by the parallelogram based on the inner and outer arm linkages and cannot operate within the desired 180 degree range. A backhoe (introduced in figure 4B) can solve this problem, creating a differential feature with respect to WO 2014187486.

The backhoe applied as in fig. 14A shows the basic principle where the beam 8 is now closer to the elbow, now by pivoting the lever 802 about the bearing 803 so that the actuation force on the joints 9C and 10C is better guided when the arm is extended at an increased angle about the second axis of rotation 40 intersecting the elbow joint 161. This provides some working space increase, at least considering the end effector force capability in the direction of axis 33, but it does not reach a competitive working range, as the extended arms will reach a singularity where the outer parallel link pairs are flipped around their rotational axes, as allowed by bearings 15C and 16C. Note that the bearings 15A, 15B, 15C are added together to be equivalent to the joint 15 in the previous figures. That is, the link portion 804 is not a problem with flipping; as shown in fig. 14B, the joint 15 is divided into a single degree-of-freedom joint as an illustrative preparation of the solution.

In fig. 14B the backhoe is configured to act on the outer parallel linkage pair via the linkage bearings 21, 22 disposed on the offset portion of the outer arm linkage. That is, the common rotating shaft 31 connecting the bearings no longer intersects with the rotating shafts of the outer parallel link pairs 17, 18. Instead, the connecting bearings are each placed such that their inner bearings (as in bearing 21A in fig. 3D) rotate about an axis that intersects the second axis of rotation 40. As will be readily determined by those skilled in the art (it is found that the offset, i.e. the distance between shaft 40 along axis 33 until it intersects the axis of rotation of actuating link 18, should be at least the length of the actuating link multiplied by the sine of the maximum angle of the outer arm linkage relative to a plane parallel to shaft 40 in the normal direction), the design has the appropriate size of said offset as compared to the length of the link. With a suitable offset (e.g. the length of the actuating link 18 multiplied by sin (x), where x is the maximum allowed rotation of the outer arm linkage relative to the normal direction parallel to the plane of the shaft 40), the singularity will be outside the working space (the range allowed in the z-direction coincides with the maximum allowed x configured in the control system) and the second kinematic chain may operate past the outermost extended position of the outer arm linkage.

The present disclosure is not limited to the above-described embodiments. Various alternatives, modifications, and equivalents may be used. Of course, the principles shown in the different figures can be combined not only for the specifically shown kinematics chains or embodiments, but also for other parts of the arm structure that are applicable and obvious to the skilled person. Accordingly, the above-described embodiments should not be taken as limiting the scope of the invention, which is defined by the appended claims.

Claims (22)

1. A robotic arm (500) for end effector action, the robotic arm comprising:

a first actuator (4) configured to rotate an inner arm assembly (1) about a first axis of rotation (29, 29A), the inner arm assembly being connected to an outer arm linkage (17, 18; 18) pivotably arranged about a second axis of rotation (40), the outer arm linkage being connected to an end effector platform (41) forming a first kinematic chain from the first actuator to the end effector platform, the first kinematic chain providing a first degree of freedom for positioning the end effector platform;

a second actuator (5; 5b) configured to rotate the outer arm linkage (17, 18; 18) about the second rotational axis (40) to form a second kinematic chain from the second actuator to the end effector platform, the second kinematic chain providing a second degree of freedom for positioning the end effector platform;

a third actuator (6; 6b, 512) configured to rotate the shaft (3) about a third rotational axis (33; 99) such that the outer arm linkage (17, 18; 18) is rotated via a joint (16; 161) forming a third kinematic chain from the third actuator (6; 6b) to the end effector platform, the third kinematic chain providing a third degree of freedom for positioning the end effector platform;

a fourth actuator (50; 150) and a fourth kinematic chain configured to transmit movement of the fourth actuator to a corresponding orientation shaft (65) of an end effector (28), the fourth kinematic chain comprising:

an orientation linkage (52, 57, 59; 202, 204, 207, 209; 284, 286; 251, 256, 258) mounted to the inner arm assembly via at least one bearing (53, 55; 206), and

an orientation actuator (64B, 64A, 216; 64C, 64D, 64E; 100, 64A; 281, 279, 275; 260, 262, 264, 266, 271, 270) mounted to the end effector platform,

wherein the orientation linkage includes an end effector rotation link (59; 209; 258; 281) and a joint (58, 60; 208, 210; 257, 259; 282, 280) that provides at least two degrees of freedom to each end joint of the end effector rotation link.

2. A robot arm as claimed in claim 1, wherein the orientation actuator comprises a connection means (65; 65, 216, 27; 216, 514, 27; 65A; 65C; 65B, 65C; 65, 390) to the end effector, the connection means providing at least four degrees of freedom to the end effector action.

3. A robot arm as claimed in claim 1 or 2, wherein the orientation transmission (64B, 64A, 216; 64C, 64D, 64E; 100, 64A; 260, 262, 264, 266, 271, 270) comprises at least one external gear mechanism (64B, 64A; 64C, 64D, 64E; 100, 64A; 271, 270) arranged to rotate the end effector (28) within an angular range determined by the gear ratio of the external gear mechanism.

4. A robot arm as claimed in any preceding claim, wherein the directional linkage (52, 57, 59; 202, 204, 207, 209; 251, 256, 258) comprises at least one internal gear mechanism (501, 502, 503, 504, 505) arranged to rotate the end effector (28) within an angular range determined by the gear ratio of the internal gear mechanism without being restricted by rotation of the outer arm linkage (17, 18; 18).

5. A robot arm as claimed in claim 1, wherein the orientation linkage (284, 286) and the orientation driver (281, 279, 275) are arranged to rotate the end effector about an orientation axis (71) without rotational angle limitation.

6. A robot arm according to any of the preceding claims, wherein the second kinematic chain comprises the inner arm linkage comprising at least one link (11, 12; 12), which at least one link (11, 12; 12) is connected to the outer arm linkage (17, 18; 18) via a connecting bearing (14; 21, 22), and wherein the second actuator (5) is configured to move the at least one link (11, 12; 12) via at least one inner connecting joint (10; 9, 10) connected to the at least one link (11, 12; 12).

7. The robot arm as claimed in claim 6, wherein the outer arm linkage comprises an outer parallel link pair (17, 18) connected to the end effector platform (41), the inner arm linkage comprises an inner parallel link pair (11, 12) connected to the outer parallel link pair (17, 18) of the outer arm linkage, and wherein the second kinematic chain is configured to transmit rotation of a lever (2) to corresponding movement of the end effector platform.

8. A robot arm according to claim 7, wherein the outer parallel link pair (17, 18) and the inner parallel link pair (11, 12) are connected by means of one connection bearing (21, 22) for each link connection of the respective link (11, 17; 12, 18), and wherein the rotational axis (34, 35; 31) of the connection bearing (21, 22) is at right angles to the axial centre line of each respective link of the outer parallel link pair (17, 18).

9. A robot arm as claimed in claim 8, comprising a rigid beam (25), the rigid beam (25) mechanically connecting the connection bearings (21, 22) to each other.

10. A robot arm as claimed in claim 9, wherein the inner parallel link pair (11, 12) is mounted to the rigid beam (25) via a ball joint (13, 14) on an offset beam (23, 24).

11. A robot arm as claimed in any of claims 7 to 10, wherein the third kinematic chain comprises an inner transmission (3; 362, 360, 353), the inner transmission (3; 362, 360, 353) being connected between the third actuator (6) and an actuating link (18) of the outer parallel link pair (17, 18).

12. A robot arm as claimed in any of claims 7 to 11, comprising a link bearing (16C) mounted along an actuating link (18) of the outer parallel link pair (17, 18), wherein the axis of rotation of the link bearing (16C) coincides with the centre of the actuating link (18) of the outer parallel link pair.

13. A robot arm as claimed in any of claims 7 to 12, comprising an end effector bearing (19, 20) connecting the outer parallel link pair (17, 18) and the end effector platform (41), wherein the axis of rotation (36, 37) of the end effector bearing is perpendicular to the centre of the outer parallel link pair.

14. A robot arm as claimed in claim 13, wherein the rotational axes (36, 37) of the end effector bearings (19, 20) are parallel to the rotational axes (34, 35) of the connecting bearings (21, 22).

15. A robot arm as claimed in any of claims 7 to 14, comprising a connecting bearing (21A, 22A) connecting the links of the outer parallel link pair (17, 18) and the links of the inner parallel link pair (11, 12), wherein the axis of rotation of each connecting bearing (21A, 22A) coincides with the centre of the respective link of the outer parallel link pair (17, 18).

16. A robot arm as claimed in any of claims 7 to 15, wherein the links of the inner pair of parallel links (11, 12) comprise a pair of parallel links (11A, 11B; 12A, 12B) and these pairs of parallel links (11A, 11B; 12A, 12B) are mounted on each side of the links of the outer pair of parallel links (17, 18) by means of ball joints.

17. A robot arm as claimed in any preceding claim, wherein the inner arm assembly (1) comprises a hollow arm link (1a) and the shaft (3) is axially mounted within the hollow arm link (1a) by a bearing, the shaft (3) being arranged to be rotated by the third actuator (6).

18. The robot arm as claimed in any of claims 5 to 16, comprising a plurality of directional linkages (284, 286) each comprising a directional driver (281, 279, 275), wherein the plurality of directional linkages are configured such that a corresponding plurality of concentric output shafts (275) are capable of actuating a number of end effector orientations for one or a number of end effectors arranged onto the end effector platform.

19. A robot arm as claimed in any of claims 3, 4 and 6 to 17, comprising a plurality of orientation linkages (52, 57, 59; 202, 204, 207, 209; 251, 256, 258), each orientation linkage having an orientation actuator (64B, 64A, 216; 64C, 64D, 64E; 100, 64A; 260, 262, 264, 266, 271, 270) connected thereto being configured such that each corresponding end effector orientation is accomplished for one or several end effectors arranged to the end effector platform.

20. A robot arm as claimed in any preceding claim, comprising at least two orientation drives (64A, 64B; 270, 271; 293, 294; 315, 316; 311, 312, 313) mounted to the end effector platform (41), and wherein the external gear mechanism (64B, 64A; 64C, 64D, 64E; 100, 64A; 271, 270) of one of the at least two orientation drives is arranged to rotate at least one other of the at least two orientation drives (270, 271; 293, 294; 315, 316; 311, 312, 313).

21. A robot arm as claimed in any of claims 2 to 20, comprising a fifth actuator (250) and a fifth kinematic chain configured to transmit movements of the fifth actuator (250) to corresponding movements of an end effector (18) arranged on the end effector platform via at least one further directional driver.

22. A robot arm as claimed in any of claims 2 to 21, comprising at least one further actuator (50; 150; 250; 285) and at least one further kinematic chain configured to transmit movement of the at least one further actuator to corresponding movement of an end effector arranged on the end effector platform, providing at least six degrees of freedom to the end effector action.