HK1062658A - Buckling arm robot - Google Patents

Description

The invention relates to a flex-arm robot according to claim 1.

Mobile robots are now taking up an increasingly large space, but their practical usefulness is usually lacking manipulators (e.g. [1]: Moeller et al., 1998) or these are only useful for specific applications ([2]: Topping and Smith, 2000). The combination of industrial robot arms and mobile platforms is also hardly possible, as the requirements for attachment, power supply, computer performance and space use are different.[3]: Onori et al. (2000) describe a hyperflexible automatic assembly system.It is proposed to build the respective automation system from different standardized components, but this principle has not been able to be implemented until now due to standardization procedures. The first two are the following: (1) the use of the computer vision and mobile robotics workshop, CVMR'98, 37-45, FORTH, Heraklion, Greece, 1998.[2] Mike Topping, Jane Smith (2000): Hand 1 - A Rehabilitation Robotic System for the Severely Disabled. Proceedings of the 31st International Symposium on Robotics, May 14-17, 2000, Montreal, Canada; pp. 254-257.[3] Onori, M., Alsterman, H., Bergdahl, A., Johansson, R. (2000): Hyper Flexible Automatic Assembly, Needs and Possibilities with Standards Assembly Solutions.The first is the use of the term "technology" to describe the use of technology in the production of robots.

US Patent No. 4,641,251 describes a mechanism for protection against unforeseen obstructions using a secondary control system that detects arm sensors and movements that deviate from the programmed movements or expected sensor signals.

EP0616874 is a flexible robot arm designed for a portable robot with up/down movements and two horizontal directions perpendicular to each other. This arm is designed for a mobile platform. This robot is designed for large loads of a specific industrial sector.

According to US Patent No. 4,986,723, an anthropomorphic robotic arm is known, with hand, wrist and arm. The hand contains a base plate, several flexible fingers with several joints each, an opposite thumb that can rotate in one direction. Actuators within the arm drive each degree of freedom independently, so that the same movements as with a human arm are possible.

Further, US Patent No. 4,737,697 describes a teaching method for industrial robots. A position encoder generates a signal that indicates the current position of the arm, while a manually controlled positioning system stores the assumed positions. A servo control system responds to the signals so that the current position of the arm approaches the desired position during playback.

CN1,225,523 is a miniature robot known for medical applications, showing the great progress in miniaturizing robots and how they can be built in a way that minimises the potential damage caused by the robot.

According to US Patent No. 4,990,839, a modular robot system is known in which several robot arms, with active and passive elements, are controlled by a central processor. Each active part of each arm contains an integrated microprocessor connected to the central processor. The individual displacements of the active parts result in the desired position of the end effector (generally the gripper tool).

DE 195 21 833 A describes a handhold for used motor vehicles to be dismantled. A tilting bearing has a swiveling receiver at its free end. The bearing is formed as a jointed arm with at least two back-to-back bearings, the inner of which is articulated to the pillar and the outer of which carries the receiver. The inner bearing is telescopic and has at least two telescopic sheets.

U.S.A.-5-219,264 defines a multi-axis robotic arm as a mobile system with a camera-integrated gripper that locates the target object or area by means of two light-emitting diodes at a known distance and orientation from the target object or area.

Rainer Bischoff describes the design and construction of an anthropomorphic robot (13th issue Autonomous Mobile Systems, pages 1-12, AMS, Stuttgart, October 1997): an autonomously moving robot system that, thanks to its human-like structure, sensors (including camera) and actuators, and its action-related intelligence, is capable of handling tasks required by many areas of service robotics.

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The German Aerospace Center (DLR) has developed a robotic arm with an optimized self-weight/usable load ratio. Each axis contains integrated electronics that communicate with the main controller via fiber optics. Each joint contains torque sensors that allow the arm to be moved by hand and to compensate for the vibrations caused by the reduced stiffness (Report on Hannover Fair 20-25 March 2000, http://trueforce.com/News/Hannover2000_Report.htm).

The disadvantages of these systems are that: (a) the interaction between man and robot to perform a job is still very poor, for mutual safety reasons; (b) the flex-arm robots performing industrial handling tasks are too heavy to be mounted on medium to small mobile systems; (c) the power electronics are housed in a separate case, which even by its large dimensions and weight limits the mobile use of the robot; (d) the robots perform the calculation power on a central unit and thereby there is no 'local intelligent' actuator and sensor performance, which requires unnecessarily long sales loads, and limits the possibilities of the robots' loaders; (e) the flex-arm robot is not available for different tasks, both because of its large dimensions and weight; (e) the robots cannot be used in situations where the maximum load and the maximum load are not available; (e) the sensors cannot be used for simple and high-quality work; and (f) the maximum load and the maximum load requirements are not available for different types of industrial tasks.

The present invention is intended to propose a flexible arm robot which has means of protecting man and machine from excessive force.

According to the invention, this task is solved by a flex-arm robot according to the wording of claim 1.

The following illustration shows the details of the invention: Figure 1Basic structure of a flexural arm robot in schematic representationFigure 2Construction and arrangement of the drive mechanismFigure 3A-3BGriggers arm with rotating passive joint

Fig. 1 shows the basic structure of a flexural robot in schematic representation. A base element 1 has a mounting element 2 on its bottom side, over which it is attached to a base plate 3. The top side of the base element has a horizontal surface 4 on which a joint block 5 is mounted horizontally and rotatable around an axis 6. The joint block 5 and the base element define a first degree of freedom for movement around the axis 6 with a rotation angle α (((1) (not shown) of about 360°. The axis runs essentially in the centre of base element 1 and joint block 5. At the top of joint block 5 there is a second axis 7 perpendicular to axis 6.The second axis 7 is surrounded by a joint 8 surrounded and firmly connected by a cylindrical support tube 9 also called 'upper arm'.The support tube 9 and the joint block 5 define a second degree of freedom for a movement of about 150° around the axis 7, which is indicated by the angle of rotation α(2).At the other end of the support tube 9 is a second joint block 11 through the centre of which a third axis 12 runs parallel to the second axis 7. A joint 13 is moved about this third axis 12 and is surrounded by and firmly connected to a cylindrical support tube 16, also called the 'forward arm'.The support tube 16 and the second joint block 11 define a third degree of freedom for a movement of about 240° about the 12th axis, which is indicated by the angle of rotation α (). The support tube 16 has a flange-shaped termination 18 perpendicular to the support tube axis, situated near the second joint block 11, through the centre of which a fourth axis 19 parallel to the support tube axis passes. The side opposite to joint 13 of the end of the fixture 18 has a flat surface 21 on which a 16' part of the support tube 16 is fixed and rotatable around the fourth axis 19.The angle of rotation is α (not shown). At the other end of the 16' support tube, a flange 22 is fitted through the centre of which a fifth axis 23 parallel to the fourth axis 19 passes.

The side of flange 22 opposite the support tube 16' has a flat surface 25 on which workpieces 30 or more degrees of freedom 5 to 7 are suspended in a loop with their workpieces and are rotatably arranged around the fifth axis 23. Base elements, support tubes, spindle blocks and workpieces are manufactured as milling and turning parts and are therefore easily disassembled, interchangeable and adaptable to the application. The basic element 1 has an external interface 26 for the serial data transmission including power supply, from which a connection cable 27 leads to power supply 28 and a second connection cable 31 to external computing power 32.

The work tools 30 are grippers and other tools necessary for problem solving. The form and the additional number of degrees of freedom depend on the task to be solved. The presence of several sensors at critical positions allows the centralization of the objects to be manipulated, their detection and categorization.

The use of IR sensors, local force sensors, conductivity sensors, stretch sensors, ultrasonic sensors, lasers and a miniature camera is used as sensors.

The power supply 28 is provided by a 12 V power supply or a 12 V battery, which can also be used as a mobile robot.

As a means of external computing power 32 is provided a PC, a laptop or a processor of another robot, all of which have a high computing power. This allows several complex algorithms from the fields of artificial intelligence (learning by neural networks, genetic algorithms, tabu search), kinematics, etc. to run in parallel and online change the values in the processors of the microcontrollers.

Fig. 2 shows the structure and arrangement of the drives. Mechanical drives include five motor gear units 101, 102, 103, 104 and 105, of which the first is located in base unit 1, the second in joint block 5, the third in joint block 11, the fourth and the fifth in carrier tube 16'. The motor gear units are equipped with an incremental encoder designed for position detection. The advantage is the necessary wiring, which can be placed together by motor and encoder, i.e. only one connection per motor is required.

The motor drive units are controlled by electric drives consisting of five microcontrollers (also called motor controllers) 201, 202, 203, 204 and 205, each of which is assigned to the motor drive units 101, 102, 103, 104 and 105. The microcontrollers are connected to each motor drive unit (not shown) and serve to drive and control them. Also in the mounting element 2 is the mainboard on which the microcontroller connections are connected and on which the external interface is managed. All power electronics are on the mainboard and are fully integrated into the robot,And that's been a particularly beneficial thing. A digital bus system connects the electric drives and work equipment 30 to the external interface 26. This eliminates sensitive analog signals, such as those to magnetic fields, over long distances. This results in trouble-free operation and thus greater precision of movements. The electric drives may have in-circuit programmable flash memory, which allows firmware updates without the need for mechanical intervention or component replacement. The engine gear units 102 and 103 are located in the respective joints, so that the entire drive is axially located in the joint axis, i.e. on the second axis 7.This eliminates the need for transmission of play through other joints and simplifies installation and maintenance. The joints are held by ball or slide bearings, which allow precise guidance at low friction, especially for the suspension of the fourth degree of freedom (rotation of the 'front arm' or 16' support tube) to ensure optimal pressure balance in the event of asymmetrical load distribution. The arrangement of the power electronics inside the bending arm robot reduces the need for external devices and cables. The microcontrollers are placed as close as possible to the motor drives, which is particularly advantageous for short cable lengths.The main features of this system are the ability to use the same number of bits and the same number of bits, the longest of which can only be used to pass through a single joint. Since each motor transmission unit is assigned a microcontroller for drive and control, this approach differs from conventional robots, where all the movements are often carried out by an external common controller.The advantages of this solution are the independence of the software of different motor axes, which provides greater reliability, the lower computing power required per chip or per microcontroller and fewer peripheral connections.This results in so-called 'low-cost microcontrollers'. Since the position adjustment per axis is done locally,The control parameters can be changed online by superior control units (mainboard, external computer).

The design of the mechanical components, particularly the joint blocks 5 and 11, but also the base element 1 and the workpieces 30 with rounded edges, ensure a low risk of injury.

A flexible robot with only four motor drives and microcontrollers is also possible, depending on the application.

The flex-arm robot operates at lowest voltage and has a very low energy consumption. The maximum power consumption is 30 watts. Due to the limited forces involved, no special safety regulations need to be observed. Any type of protective grating, as is common with common industrial robots, can be dispensed with. This makes it possible to use it in a much smaller space where people have direct access.

In the case of a sudden force on the support tubes or workpieces, e.g. a gripper, a defined part of the structure must be able to yield, as is the case with a fault point. This part is located during the transition to the aluminium structure.

Figures 3A and 3B show a grip arm with a rotating passive joint attached to it as a workpiece. On the flange 22 of the 16' support tube, the workpieces 30 are mounted, consisting of a grip arm 33 and a passive joint 34. The passive joint, formed as a grip back, is rotated at the 35 position and is used to hold a lifting object 40, e.g. a metal object, always vertical using gravity. This results in reduced computational effort and a simplified design compared to a solution with an active joint or a parallelogram guide.

The invention of the flex-arm robot allows for work in a confined space because of its small size and compact design. It has a maximum mass of 10.5 cm x 33 cm x 33 cm at rest with an operating radius of about 0.5 m. This design gives a net weight of less than 5,0 kg, preferably less than 3,0 kg. The net weight does not take into account the power supply and the external computing power. Despite its small size, the ratio of the net weight to the payload has been shown to be about 5,0, which is very advantageous at a net weight of 2,5 kg and a payload of 0,5 kg. This ratio is much less favourable for all known bending robots. It is ideally suited for interactive work with human labour and allows for so-called 'hand-in-hand' work. The modular design allows, for example, the work area to be easily extended by a telescopic piece instead of the 16' support tube, while maintaining the compact design.

The workpiece corresponds to a two-fingered gripper with rotating passive joints attached to it, as shown in Fig. 3A-3B. Maxon DC motors and planetary gearboxes are used as drive elements, i.e. motor-gear units, for all joints. e.g. for the first motor gear unit: Maxon RE 15 DC 1.6 Watt type, external diameter 15 mm, torque 0.5 Nm, planetary gear 455 : 1. The local processors for master and slave boards are PICs (Microchip Embedded Control Solutions Company). The connection between the boards or sensors and actuators is partly by flat-band cables and partly by flexprints. The flexor arm robot is preferably operated on a stationary base.

Claims (6)

1. Buckling arm robot, comprising a base element (1), at least two articulated blocks (5, 11), at least three supporting tubes (9, 16, 16'), working means (30), mechanical and electrical drive means and power supply means (28), the mechanical drive means consisting of at least four motor/gearbox units (101, 102, 103, 104, 105) which are located in the base element (1), in the articulated blocks (5, 11) and in the support tubes (16, 16'), the electrical drive means consisting of at least four microcontrollers (201, 202, 203, 204, 205) located in the base element (1) and in the support tube (9), each motor/gearbox unit being allocated a microcontroller for its drive and control and connected with and arranged near said unit, a digital bus system (150) connecting the electrical drive means and the working means (30) with an external interface (26) which is located in the base element (1), the interface (26) being connected with the power supply means (28) via a connecting cable (27) and with the external processor capacity means (32) via a second connecting cable (31), the mechanical drive means having been designed to provide the movements of the articulated blocks (5, 11), the supporting tubes (9, 16, 16') and the working means (30), and the entire power electronics having been integrated, wherein by virtue of the arrangement of the microcontrollers (201, 202, 203, 204, 205) an internal processor capacity is available which is present distributed locally in the mechanical drive means and the working means (30) thereby forming a local intelligence, wherein an external intelligence in the external processor capacity means (32) is available, and wherein on the transition from the motor axle of the electrical drive means to the aluminum construction by means of fastening screws there is a protection point per rotational axle which affords protection against the attack of excessive force.
2. Buckling arm robot as claimed in claim 1, wherein the fastening screws yield to a high pressure and after an excessive attack of force are quickly replaceable from outside.
3. Buckling arm robot as claimed in of claims 1 or 2, wherein said robot has a maximum power input of 30 watts and wherein on the basis of the forces which occur in a limited magnitude can be used in a space to which persons have direct access.
4. Buckling arm robot as claimed in any one of claims 1 - 3, wherein the working means (30) are furnished with IR sensors, local force sensors, conductivity sensors, expansion sensors, ultrasonic sensors and/or lasers.
5. Buckling arm robot as claimed in claim 4, wherein sensors of various modalities are installed which form a sensor redundancy that increase the learning ability.
6. Buckling arm robot as claimed in any one of claims 1 - 5, wherein for the movement of the articulated blocks (5, 11) the support tubes (9, 16, 16') and the working means (30) adaptive controls and pilot control parameters are available, for the operation or the calculation of which the external processor capability means (32) are available and by means of algorithms of artifical intelligence the learning ability is given.