JP2019038077A - Hand mechanism and cover - Google Patents

Abstract

To inhibit deterioration of detection accuracy of pressure-sensitive sensors and improve holding power of a hand mechanism in the hand mechanism which includes multiple finger parts and the pressure-sensitive sensors attached to outer wall surfaces of the finger parts and is used to hold an object with the finger parts.SOLUTION: A hand mechanism according to the invention includes multiple finger parts and holds an object with the finger parts. This hand mechanism includes: pressure-sensitive sensors disposed at predetermined portions including tip parts of the finger parts; and a cover for covering the finger parts. The cover is formed so that a friction coefficient of each finger tip cover part that is a portion covering the predetermined portion is larger than that of an outer wall surface of the finger part and each finger tip cover part adheres to the predetermined portion in a state that the cover is attached to the finger parts.SELECTED DRAWING: Figure 11

Description

  The present invention relates to a hand mechanism for gripping an object by a plurality of finger parts, and a cover for covering the finger parts of the hand mechanism.

  A hand mechanism attached to a robot arm or the like and gripping an object with a plurality of fingers has been developed. In such a hand mechanism, in order to prevent dust from adhering to the finger part, or dust or oils on the finger part from adhering to the object, a cover for covering the finger part is attached. (For example, refer to Patent Document 1).

JP 2009-56558 A

  Here, considering the durability and wear resistance of the finger part in the hand mechanism, it is necessary to manufacture the finger part from a member such as metal or hard resin, and to form the outer wall surface of the finger part with a relatively smooth surface. is there. Therefore, the coefficient of friction of the outer wall surface of the finger portion is likely to be small, and accordingly, the gripping force of the hand mechanism is likely to be small. On the other hand, when grasping the object by the hand mechanism, a method of increasing the force for pressing the finger part against the object is conceivable, but reinforcement of each part of the hand mechanism, enlargement of the driving device, addition of a deceleration mechanism, etc. May be necessary, or the object may be deformed.

  In addition, when the object is gripped by the hand mechanism, it is also important to accurately detect the contact state between the finger part and the object. In response to such a request, a method of attaching a pressure-sensitive sensor to the outer wall surface of the finger portion can be considered. However, when the above-described cover is attached to the hand mechanism including the pressure sensor, the sensitivity of the pressure sensor decreases, and it becomes difficult to accurately detect the contact state between the finger and the object. there is a possibility.

  The present invention has been made in view of various circumstances as described above, and an object thereof is to include a plurality of finger portions and a pressure-sensitive sensor attached to an outer wall surface of the finger portions, and the finger portions. In the hand mechanism for gripping an object by the above, the gripping force of the hand mechanism is increased while suppressing a decrease in detection accuracy of the pressure sensor.

  The hand mechanism according to the present invention is a hand mechanism that includes a plurality of finger portions and grips an object with the finger portions. The hand mechanism includes a pressure-sensitive sensor disposed on an outer wall surface of a predetermined portion including a tip portion of the finger portion, and a cover for covering the finger portion. In the state in which the cover has a coefficient of friction of a fingertip covering portion that is a portion for covering the predetermined portion larger than an outer wall surface of the finger portion, and the cover is attached to the finger portion, The covering portion is formed so as to be in close contact with the predetermined portion. Note that the “predetermined part” here is a part that can come into contact with the object at the finger portion when the hand mechanism grips the object.

According to the present invention, in a hand mechanism that includes a plurality of fingers and a pressure-sensitive sensor that is attached to an outer wall surface of the fingers, the detection accuracy of the pressure-sensitive sensor in the hand mechanism for gripping an object by the fingers. It is possible to increase the gripping force of the hand mechanism while suppressing the lowering of the movement.

It is a figure which shows schematic structure of the robot arm which concerns on an Example. It is a perspective view of the hand mechanism which concerns on an Example. It is a top view of the hand mechanism which concerns on an Example. It is a side view of the finger | toe part of the hand mechanism which concerns on an Example. It is the figure which looked at the front-end | tip part side of the finger | toe part of the hand mechanism which concerns on an Example from the direction of the arrow A of FIG. It is a figure which shows the movable range of the 2nd joint part in the finger | toe part of the hand mechanism which concerns on an Example. It is a figure which shows the movable range of the 1st joint part in the finger | toe part of the hand mechanism which concerns on an Example. It is a 1st figure which shows arrangement | positioning of the pressure sensor in the 1st link part of the finger | toe part of the hand mechanism which concerns on an Example. It is a 2nd figure which shows arrangement | positioning of the pressure sensor in the 1st link part of the finger | toe part of the hand mechanism which concerns on an Example. It is a perspective view which shows schematic structure of the cover (glove) concerning a present Example. It is a figure which shows the positional relationship of the finger | toe part and a glove in the state which mounted | wore the hand mechanism with the glove. It is a figure which shows the other method for enlarging the friction coefficient in the fingertip coating | coated part of a glove. (A) is a figure which shows a mode that a pressure-sensitive sensor is covered with a fingertip coating | coated part, (B) is a figure which shows a mode that a pressure-sensitive sensor is covered with a sensor cover and a fingertip coating | coated part. It is a block diagram which shows each function part contained in the arm control apparatus and hand control apparatus which concern on an Example. It is a figure which shows an example of the shape of the target object hold | gripped by a hand mechanism. It is a figure showing the state where a plurality of objects were arranged and arranged. It is a 1st figure which shows the operation | movement at the time of changing the attitude | position of a target object with the 1st finger | toe part of the hand mechanism which concerns on an Example. It is a 2nd figure which shows the operation | movement at the time of changing the attitude | position of a target object with the 1st finger | toe part of the hand mechanism which concerns on an Example. It is a 1st figure which shows the state which hold | gripped the target object with the 2nd finger part, the 3rd finger part, and the 4th finger part of the hand mechanism which concerns on an Example. It is a 2nd figure which shows the state which hold | gripped the target object with the 2nd finger part, the 3rd finger part, and the 4th finger part of the hand mechanism which concerns on an Example. It is a figure which shows schematic structure of the cover concerning another Example.

A hand mechanism according to the present invention includes a plurality of finger portions and a pressure-sensitive sensor disposed on an outer wall surface of a predetermined portion including a tip portion of the finger portions, and grips an object with the plurality of finger portions. is there. Here, the finger part of the hand mechanism is formed of a highly rigid material such as metal or hard resin in order to ensure durability and wear resistance, and the outer wall surface of the finger part is as smooth as possible. It is formed. In the hand mechanism having such a structure, the friction coefficient on the outer wall surface of the finger portion is likely to be small, and accordingly, the gripping force when gripping an object with the hand mechanism is likely to be small. Therefore, when gripping the object by the hand mechanism, it is necessary to secure the gripping force of the hand mechanism by increasing the force with which the finger is pressed against the object. On the other hand, by attaching a cover having a coefficient of friction larger than the outer wall surface of the finger part to the hand mechanism, the gripping force of the finger part against the object is reduced while holding the object by the hand mechanism, and the hand A method for increasing the gripping force of the mechanism is conceivable. However, if the cover as described above is attached to the hand mechanism, the detection accuracy of the pressure sensor may be reduced.

  Therefore, the hand mechanism according to the present invention is a cover for covering a plurality of finger parts, and has a friction coefficient of a part covering a predetermined part of the finger parts (hereinafter also referred to as “fingertip covering part”). A cover that is larger than the outer wall surface of the finger portion and is formed so that the fingertip covering portion is in close contact with the predetermined portion in a state where the cover is attached to the finger portion. When the object is gripped by the hand mechanism configured as described above, the fingertip covering part comes into contact with the object, so that the frictional force acting between the finger part and the object can be increased. The gripping force of the hand mechanism can be increased while minimizing the force pressing the part against the object. Further, in a state where the cover is attached to the finger portion, the fingertip covering portion of the cover and the predetermined portion are in close contact with each other, so that a decrease in detection accuracy of the pressure sensor can be suppressed.

<Example>
Specific embodiments of the present invention will be described below with reference to the drawings. The dimensions, materials, shapes, relative arrangements, and the like of the components described in the present embodiment are not intended to limit the technical scope of the invention to those unless otherwise specified.

  Here, a case where the hand mechanism and the gripping system according to the present invention are applied to a robot arm will be described. FIG. 1 is a diagram illustrating a schematic configuration of a robot arm according to the present embodiment. The robot arm 1 includes a hand mechanism 2, an arm mechanism 3, and a pedestal portion 4. A hand mechanism 2 is attached to one end of the arm mechanism 3. The other end of the arm mechanism 3 is attached to the pedestal portion 4. The hand mechanism 2 includes a base unit 20 connected to the arm mechanism 3, a plurality of finger units 21 (four fingers 21 in the example shown in FIG. 1) supported movably by the base unit 20, It has. The detailed configuration of the hand mechanism 2 will be described later.

<Arm mechanism>
The arm mechanism 3 includes a first arm link portion 31, a second arm link portion 32, a third arm link portion 33, a fourth arm link portion 34, a fifth arm link portion 35, and a connection member 36. The base portion 20 of the hand mechanism 2 is connected to a first joint portion 30 a formed on one end side of the first arm link portion 31 of the arm mechanism 3. The first joint portion 30 a is provided with a motor (not shown) for rotating the hand mechanism 2 around the axis of the first arm link portion 31 with respect to the first arm link portion 31. The other end side of the first arm link portion 31 is connected to one end side of the second arm link portion 32 at the second joint portion 30b. The first arm link part 31 and the second arm link part 32 are connected so that their central axes intersect perpendicularly. A motor for rotating the first arm link part 31 around the axis of the second arm link part 32 around the other end side with respect to the second arm link part 32 is provided in the second joint part 30b. (Not shown) is provided. Further, the other end side of the second arm link portion 32 is connected to one end side of the third arm link portion 33 at the third joint portion 30c. The third joint part 30 c is provided with a motor (not shown) for rotating the second arm link part 32 relative to the third arm link part 33.

Similarly, the other end side of the third arm link portion 33 is connected to one end side of the fourth arm link portion 34 at the fourth joint portion 30d. Further, the other end side of the fourth arm link portion 34 is connected to the fifth arm link portion 35 by a fifth joint portion 30e. The fourth joint portion 30d is provided with a motor (not shown) for rotating the third arm link portion 33 relative to the fourth arm link portion 34. Further, the fifth joint portion 30e is provided with a motor (not shown) for rotating the fourth arm link portion 34 relative to the fifth arm link portion 35. Further, the fifth arm link portion 35 is connected to a connection member 36 disposed vertically from the pedestal portion 4 by a sixth joint portion 30f. 5th arm link part 35 and connecting member 36
Are connected so that their central axes are coaxial. The sixth joint portion 30f is provided with a motor (not shown) for rotating the fifth arm link portion 35 around the axes of the fifth arm link portion 35 and the connection member 36. With the arm mechanism 3 having such a configuration, for example, the arm mechanism 3 can be a mechanism having six degrees of freedom.

<Hand mechanism>
Next, the configuration of the hand mechanism 2 will be described with reference to FIGS. FIG. 2 is a perspective view of the hand mechanism 2. FIG. 3 is a top view of the hand mechanism 2. In FIG. 3, the arrows indicate the rotation movable ranges of the finger portions 21. As shown in FIGS. 2 and 3, in the hand mechanism 2, the four fingers 21 on the base 20 are centered on the axis in the longitudinal direction of the hand mechanism 2 (direction perpendicular to the paper surface in FIG. 3). On the circumference, they are arranged at equiangular intervals (ie, 90 deg intervals). The four finger portions 21 all have the same structure and the same length. However, the operation of each finger 21 is controlled independently.

  4 to 9 are diagrams for explaining the configuration of the finger portion 21 of the hand mechanism 2. FIG. 4 is a side view of the finger part 21. In FIG. 4, the base portion 20 is shown in a transparent state. FIG. 5 is a view of the distal end side of the finger portion 21 as viewed from the direction of arrow A in FIG. 4 and 5, a part of a second finger link part 212 of the finger part 21 to be described later is shown in a transparent state, and the internal structure of the second finger link part 212 is also shown. Yes.

  As shown in FIGS. 2 and 4, each finger portion 21 has a first finger link portion 211, a second finger link portion 212, and a proximal end portion 213. In addition, a first joint portion 22 formed so as to be able to bend and extend is provided between the first finger link portion 211 and the second finger link portion 212. Furthermore, between the 2nd finger link part 212 and the base end part 213, the 2nd joint part 23 formed so that bending and extension is possible is provided. The base end portion 213 of the finger portion 21 is connected to the base portion 20. At this time, the base end portion 213 is connected to the base portion 20 so as to be rotatable about the longitudinal axis of the finger portion 21 (direction perpendicular to the paper surface in FIG. 3) with respect to the base portion 20, as indicated by an arrow in FIG. Yes.

  Further, as shown in FIG. 4, the base unit 20 incorporates a second motor 52 and a third motor 53. As shown in FIG. 6, the second motor 52 is a motor for bending and extending the second joint portion 23. On the other hand, the third motor 53 is a motor for rotationally driving the entire finger portion 21 within a range indicated by an arrow in FIG. Next, as shown in FIG. 5, the first motor 51 is built in the second finger link portion 212. As shown in FIG. 7, the first motor 51 is a motor for bending and extending the first joint portion 22.

In addition, as shown in FIGS. 2, 4, and 5, in this embodiment, a pressure-sensitive sensor 70 is attached to the distal end side of the first finger link portion 211 of the finger portion 21. Specifically, as shown in FIGS. 8 and 9, a wall surface on the bending direction side of the first joint portion 22 in the first finger link portion 211 (hereinafter also referred to as a “bending side wall surface”) 215. The four pressure-sensitive sensors 700, 701, 702, and 703 (hereinafter, collectively referred to as “pressure-sensitive sensor 70”) from the wall surface to the wall in the extension direction (hereinafter also referred to as “extension side wall surface”) 216. Are arranged in series along the longitudinal direction of the first finger link portion 211. In the example shown in FIGS. 8 and 9, one pressure-sensitive sensor 700 is disposed on the extended side wall surface 216, and the remaining three pressure-sensitive sensors 701, 702, 703 are moved from the distal end side to the proximal end side of the bent side wall surface 215. It is arranged in the longitudinal direction. In addition, the arrangement method of the pressure-sensitive sensor 70 is not limited to the method of arranging the pressure-sensitive sensor 70 in series along the longitudinal direction of the first finger link portion 211, and is arranged in series along the short direction of the first finger link portion 211. Alternatively, the first finger link portion 211 may be disposed along an oblique direction with respect to the longitudinal direction or the short direction. In the example shown in FIGS. 8 and 9, four pressure-sensitive sensors 70 are used.
0, 701, 702, and 703 are arranged in a row, but four or more pressure sensors may be arranged in two or more rows, or four or more pressure sensors may be arranged in a staggered manner. Good. Further, the number of pressure sensitive sensors arranged on the extended side wall surface 216 is not limited to one, and two or more pressure sensitive sensors may be arranged on the extended side wall surface 216. Similarly, the number of pressure sensitive sensors arranged on the bent side wall surface 215 is not limited to three, and may be two, or four or more. In short, the number and position of the pressure-sensitive sensors arranged in the first finger link part may be determined as appropriate according to the size and shape of the object. The pressure sensor 70 is a sensor that detects an external force (pressure) acting on the first finger link portion 211. As such a pressure-sensitive sensor 70, any known pressure-sensitive sensor such as a piezoelectric pressure-sensitive sensor, a strain gauge-type pressure-sensitive sensor, or a capacitance-type pressure-sensitive sensor may be used. Good. The four pressure sensitive sensors 700, 701, 702, and 703 described above may be covered with a flexible sensor cover formed of polyolefin or the like. Further, in the example shown in FIGS. 8 and 9, the pressure-sensitive sensor 70 is formed in a rectangular shape, but is not limited to a rectangular shape, and is appropriately changed depending on the shape of the first finger link portion 211 and the like. Just do it.

<Cover>
In the present embodiment, when the object is gripped by the hand mechanism 2 configured as described above, a cover is attached to the hand mechanism 2. The cover of the present embodiment is a glove-like cover (hereinafter sometimes referred to as “glove”) formed so as to cover the finger part 21 and the base part 20 of the hand mechanism 2. Below, the structure of the glove in a present Example is demonstrated based on FIGS. 10-12. FIG. 10 is a perspective view showing a schematic configuration of the globe in the present embodiment. FIG. 11 is a diagram illustrating a positional relationship between the finger part 21 and the globe 900 in a state where the globe 900 is attached to the hand mechanism 2. As shown in FIGS. 10 and 11, the globe 900 is formed so as to cover the four finger parts 21 independently of each other and to cover the base part 20. Specifically, the glove 900 includes a fingertip covering portion 901 for covering a predetermined portion including the distal end portion of the first finger link portion 211 of each finger portion 21, and a portion closer to the proximal end than the predetermined portion of each finger portion 21. A joint covering portion 902 for covering the base portion 20 and a base covering portion 903 for covering the base portion 20 are integrally formed. Here, the “predetermined part” is a part where the object can come into contact with the first finger link unit 211 when the hand mechanism 2 grips the object. For example, the above-described four pressure-sensitive sensors 700 and 701 are used. , 702, and 703 are portions.

  Here, as shown in FIG. 11, the fingertip covering portion 901 is formed so that the fingertip covering portion 901 is in close contact with a predetermined portion of the first finger link portion 211 in a state where the glove 900 is attached to the hand mechanism 2. Is done. Further, the fingertip covering portion 901 is formed so that the friction coefficient of the fingertip covering portion 901 is larger than the outer wall surface of the first finger link portion 211. As a method for increasing the friction coefficient of the fingertip covering portion 901, the entire glove 900 including the fingertip covering portion 901 is made of a substance having a larger friction coefficient than the outer wall surface of the first finger link portion 211 (for example, rubber is the main component. A method of forming the fingertip covering portion 901 with a material having a coefficient of friction larger than that of the outer wall surface of the first finger link portion 211, and covering the joint covering portion 902 with the fingertip A method in which the portion 901 is formed of a material different from that of the portion 901 (for example, a flexible material such as polyethylene, polypropylene, polyester, vinyl chloride, or cloth), or as shown in FIG. In addition, the entire globe 900 is made of a flexible material and is made of a material having a larger coefficient of friction than the outer wall surface of the first finger link portion 211. 901a it is possible to use a method such as that formed on the outer surface of the fingertip covering portion 901.

Further, as shown in FIG. 11, the joint covering portion 902 has a portion (FIG. 11) where the joint covering portion 902 is proximal to the predetermined portion of the finger portion 21 in a state where the glove 900 is attached to the hand mechanism 2. In the example shown, the first joint portion 22, the second finger link portion 212, and the second joint portion 23) are formed so as not to be in close contact with each other. That is, the joint covering portion 902 is formed such that a gap is formed between the inner side surface of the joint covering portion 902 and the outer wall surface of the finger portion 21 at the base end side of the predetermined portion. Specifically, the joint covering portion 902 is formed of a flexible material having an inner diameter larger than the outer diameters of the first joint portion 22, the second finger link portion 212, and the second joint portion 23.

  In addition, as shown in FIG. 11, the base covering portion 903 is fixed in position when the base covering portion 903 comes into close contact with the base portion 20 in a state where the globe 900 is attached to the hand mechanism 2. It is formed so that. For example, the base covering portion 903 is formed of a stretchable material having an inner diameter equal to or smaller than the outer diameter of the base portion 20.

  When the glove 900 configured as described above is attached to the hand mechanism 2, it occurs between the first finger link unit 211 and the object when the hand mechanism 2 grips the object, compared to when the glove 900 is not attached. Therefore, the gripping force of the hand mechanism 2 is increased accordingly. As a result, the object can be gripped without excessively increasing the force pressing the first finger link portion 211 against the object. Further, when the glove 900 is attached to the hand mechanism 2, the pressure-sensitive sensor 70 (the sensor cover when the pressure-sensitive sensor is covered with a sensor cover) and the object do not directly contact each other. It is also possible to suppress wear of the (or sensor cover). Further, since the globe 900 is detachable from the hand mechanism 2, when the globe 900 is worn, it may be replaced with a new one.

  Further, according to the glove 900 in the present embodiment, when the glove 900 is attached to the hand mechanism 2, as shown in FIG. 13A, the fingertip covering portion 901 of the glove 900 is a pressure-sensitive sensor. 70 comes into close contact. When the pressure sensor 70 is covered with a sensor cover, the fingertip covering portion 901 of the globe 900 comes into close contact with the sensor cover 800 as shown in FIG. Therefore, when the part covering the pressure sensor 70 in the fingertip cover 901 comes into contact with the object, the pressure acting on the fingertip cover 901 from the object is more reliably transmitted to the pressure sensor 70. As a result, a decrease in sensitivity of the pressure sensor 70 due to the wearing of the globe 900 is suppressed.

  By the way, when the glove is attached to the finger part of the hand mechanism, if the joint part of the finger part and the glove are in close contact, the joint part bends and extends, or the finger part rotates with respect to the base part. When doing so, the amount of bending and twisting of the cover tends to increase, and the restoring force of the cover against such bending and twisting also tends to increase. As a result, when the joint part bends and extends, or when the finger part rotates with respect to the base part, the force repelling those actions becomes large. There is a possibility that the load of will become excessively large. In addition, when the glove is attached to the finger part of the hand mechanism, if the joint part of the finger part and the glove are in close contact, the joint part bends and extends, or the finger part rotates relative to the base part. In such a case, the cover may be sandwiched between joints or the like, and the finger part may malfunction.

On the other hand, according to the cover (glove 900) of the present embodiment, the first joint part 22, the second finger link part 212, and the second joint part 23 in a state where the glove 900 is attached to the hand mechanism 2. Since a gap is formed between the outer wall surface of the joint and the inner side surface of the joint covering portion 902, when the finger portion 21 is bent and extended by the first joint portion 22 or the second joint portion 23, the finger portion 21 is The amount of bending and twisting of the globe 900 when rotating around the rotation axis of the end portion 213 is smaller than that of the globe formed so as to be in close contact with the joint portion of the finger portion. Therefore, when the finger 21 is bent and extended by the first joint 22 or the second joint 23, or when the finger 21 rotates around the rotation axis of the base end 213, the restoring force of the globe 900 is also It is smaller than a glove formed so as to be in close contact with the joint of the finger. As a result, when the finger portion 21 is bent and extended by the first joint portion 22 or the second joint portion 23, or when the finger portion 21 is in the proximal end portion 213.
When rotating around the rotation axis of the motor, it is possible to prevent such operations from being performed smoothly and the load on the motors 51, 52, 53 from becoming excessively large. Furthermore, according to the glove 900 of the present embodiment, when the finger portion 21 is bent and extended by the first joint portion 22 or the second joint portion 23, the finger portion 21 rotates around the rotation axis of the base end portion 213. Occasionally, the glove 900 is also prevented from being sandwiched between the first joint part 22 and the second joint part 23, so that the hand mechanism 2 is also prevented from malfunctioning due to the wearing of the glove 900. You can also Further, the glove 900 according to the present embodiment includes the outer wall surface and the joint covering portion of the first joint portion 22, the second finger link portion 212, and the second joint portion 23 in a state where the glove 900 is attached to the hand mechanism 2. Since the gap is formed between the inner surface of 902 and the glove formed so as to be in close contact with the joint portion of the finger portion, attachment / detachment to / from the hand mechanism 2 is facilitated.

<Pedestal part>
Next, configurations of the arm control device 42 and the hand control device 43 built in the pedestal portion 4 will be described with reference to FIG. The arm control device 42 is a control device for controlling the arm mechanism 3 of the robot arm 1. The hand control device 43 is a control device for controlling the hand mechanism 2 of the robot arm 1. FIG. 14 is a block diagram illustrating each functional unit included in the arm control device 42 and the hand control device 43.

  The arm control device 42 includes a plurality of drivers that generate drive signals for driving the motors provided at the joints of the arm mechanism 3 so that the drive signals from the drivers are supplied to the corresponding motors. Configured. The arm control device 42 includes a computer having an arithmetic processing device and a memory. The arm control device 42 includes an arm control unit 420 and a motor state quantity acquisition unit 421 as functional units. These functional units are formed by executing a predetermined control program in a computer included in the arm control device 42.

  The arm control unit 420 supplies each driver of the arm mechanism 3 by supplying a drive signal from each driver based on target information acquired by a target information acquisition unit 430 described later, which is a functional unit of the hand control device 43. The motors provided in the joint portions 30a, 30b, 30c, 30d, 30e, and 30f are controlled. The arm controller 420 moves the arm mechanism 3 by controlling each motor, thereby moving the hand mechanism 2 to a predetermined grippable position suitable for gripping the object. In addition, the motors provided in the joint portions 30a, 30b, 30c, 30d, 30e, and 30f of the arm mechanism 3 detect state quantities (such as the rotational position and rotational speed of the rotation shaft of the motor) regarding the respective rotational states. An encoder (not shown) is provided. Then, the state quantity of each motor detected by the encoder of each motor is input to the motor state quantity acquisition unit 421 of the arm control device 42. Then, the arm control unit 420 servo-controls each motor so that, for example, the hand mechanism 2 moves to a predetermined grippable position based on the motor state quantity input to the motor state quantity acquisition unit 421.

  The hand control device 43 includes a plurality of drivers that generate drive signals for driving the motors provided in the hand mechanism 2 so that the drive signals from the drivers are supplied to the corresponding motors. Composed. The hand control device 43 includes a computer having an arithmetic processing device and a memory. And the hand control apparatus 43 has the target object information acquisition part 430, the hand control part 431, the motor state quantity acquisition part 432, and the sensor information acquisition part 433 as a function part. These functional units are formed by executing a predetermined control program in a computer included in the hand control device 43.

The object information acquisition unit 430 acquires object information that is information regarding an object to be gripped by the hand mechanism 2. Here, the object information includes information on the shape, dimensions, and position of the object, and environmental information around the object (information on objects other than the object existing around the object, for example, , Information on the shape of the container in which the object is stored and the arrangement of the objects in the container). The object information acquisition unit 430 may acquire object information input by the user. When a visual sensor that captures an image including an object is provided, the object information acquisition unit 430 may acquire object information from an image captured by the visual sensor.

  In addition, the hand control unit 431 supplies the driving signal from each driver based on the object information acquired by the object information acquiring unit 430, thereby driving each finger unit 21 of the hand mechanism 2. 51, each 2nd motor 52, and each 3rd motor 53 are controlled. For example, the hand control unit 431 controls each of the first mechanisms of the hand mechanism 2 in order to grip the object by the hand mechanism 2 that has been moved to a predetermined grippable position by controlling the arm mechanism 3 by the arm control unit 420. The motor 51, each second motor 52, and each third motor 53 are controlled. In addition, the first motor 51, the second motor 52, and the third motor 53 of the hand mechanism 2 detect state quantities (such as the rotational position and rotational speed of the rotation shaft of the motor) related to the respective rotational states. An encoder (not shown) is provided. Then, the state quantities of the motors 51, 52, 53 detected by the encoders of the motors 51, 52, 53 are input to the motor state quantity acquisition unit 432 of the hand control device 43. Then, based on the state quantities of the motors 51, 52, 53 input to the motor state quantity acquisition unit 432, the hand control unit 431, for example, moves each finger so as to hold the object with the plurality of finger parts 21. Servo-control each motor 51,52,53 in the part 21. FIG.

  Further, the hand control device 43 has a sensor information acquisition unit 433. The sensor information acquisition unit 433 receives detection values of a plurality of pressure sensitive sensors 70 provided in the first finger link unit 211 of each finger unit 21 of the hand mechanism 2. And the hand control part 431 can detect the contact with each finger | toe part 21 and a target based on the detection value of each pressure sensor 70 acquired by the sensor information acquisition part 433, and each based on the detection signal. Each motor 51, 52, 53 in the finger part 21 can also be controlled.

<Finger functions>
Next, the function of each finger part 21 when the object is gripped by the hand mechanism 2 will be described. Here, FIG. 15 is a diagram illustrating an example of the shape of the target object 10 held by the hand mechanism 2. FIG. 16 is a diagram showing a state in which a plurality of objects 10 (10 ′) are arranged and arranged. As shown in FIGS. 15 and 16, the object 10 is a rectangular parallelepiped having six surfaces (S1 to S6). However, the shape of the object 10 shown in FIG. 15 is merely an example, and the shape of the object gripped by the hand mechanism 2 is not limited to a rectangular parallelepiped.

  Here, when the object 10 is gripped by the hand mechanism 2, at least two of the six surfaces of the object 10 are defined as predetermined gripping surfaces, and each of the predetermined gripping surfaces has the hand mechanism 2. It is necessary to bring any object 10 into contact with any one of the finger portions 21 by the finger portions 21. In the following, a case will be described in which the object 10 is gripped using the two surfaces S5 and S6 having the largest area among the six surfaces of the object 10 as predetermined gripping surfaces.

When the object 10 is to be gripped by the hand mechanism 2 using the surfaces S5 and S6 of the object 10 as predetermined gripping surfaces, both of the surfaces S5 and S6 are connected to any of the finger portions 21 of the hand mechanism 2. It must be exposed so that it can be touched. However, as shown in FIG. 16, in a state where a plurality of objects 10 (10 ′) to be grasped sequentially by the hand mechanism 2 are arranged in contact with each other, a predetermined grasping of the object 10 is performed. The surface may be placed in contact with the adjacent object 10 '. When the target object 10 (10 ′) is arranged as shown in FIG. 16, one of the two predetermined gripping surfaces S5 and S6 of the target object 10 is adjacent to the target object 10 ′. Is in contact with. In such a case, the gripping surface S6 of the object 10 is not exposed. Therefore, if the target object 10 remains in the state shown in FIG. 16, the finger part 21 of the hand mechanism 2 cannot be brought into contact with the gripping surface S6 of the target object 10, so that the target object 10 is gripped by the hand mechanism 2. Can not do it.

  Thus, in this embodiment, when the hand mechanism 2 grips the target object 10 in the above-described situation, first, it functions as a state changing finger portion of the four finger portions 21 in the hand mechanism 2. The posture of the object 10 is changed by one finger part. After that, among the four finger portions 21 in the hand mechanism 2, the three finger portions other than the finger portions functioning as state changing finger portions and the finger portions functioning as gripping finger portions are targeted. Hold the object 10.

  Hereinafter, in the present embodiment, details of a procedure for gripping the object 10 placed in the state shown in FIG. 16 by the hand mechanism 2 will be described based on FIGS. 17 to 20. Here, each finger part 21 of the hand mechanism 2 is referred to as a first finger part 21A, a second finger part 21B, a third finger part 21C, and a fourth finger part 21D, respectively. In the following description, the case where the finger functioning as the state change finger is the first finger 21A and the finger functioning as the gripping finger is the second to fourth fingers 21B, 21C, 21C will be described. To do. FIGS. 17 and 18 are diagrams illustrating an operation when the posture of the object 10 is changed by the first finger portion 21 </ b> A of the hand mechanism 2. 19 and 20 are diagrams illustrating a state in which the object 10 is held by the second finger portion 21B, the third finger portion 21C, and the fourth finger portion 21D of the hand mechanism 2. The procedure of gripping the object 10 by the hand mechanism 2 as described below is performed after the hand mechanism 2 is moved to a predetermined grippable position by the arm mechanism 3 being controlled by the arm control device 42. This is realized by controlling the hand mechanism 2 by the control device 43.

  As shown in FIG. 16, even when the object 10 is placed in a state in which the object 10 is in contact with an adjacent object 10 ′ using one gripping surface S <b> 6 as a contact surface, the upper surface S <b> 4 is exposed. . Therefore, the finger part 21 of the hand mechanism 2 can be brought into contact with the upper surface S4 of the object 10. Therefore, in this embodiment, as shown in FIG. 17, first, the first finger link portion 211 </ b> A of the first finger portion 21 </ b> A that functions as a state changing finger portion in the current gripping of the target object 10 is used as the upper surface of the target object 10. Contact S4. In the stage where the first finger part 21A is brought into contact with the upper surface S4 of the object 10, the other finger parts 21B, 21C, and 21D in the hand mechanism 2 are not brought into contact with the object 10.

  Here, as shown in FIGS. 13A and 13B, the fingertip covering portion 901 of the globe 900 is in close contact with the pressure sensor 70 or the sensor cover 800. Therefore, as shown in FIG. In addition, the contact between the first finger link portion 211 </ b> A and the object 10 is more reliably detected by the pressure-sensitive sensor 70. When the contact between the first finger link unit 211 and the object 10 is detected in this way, the detection signal is input to the sensor information acquisition unit 433 of the hand control device 43, so that the hand control device 43 has the first information. It is possible to accurately grasp the contact state between the finger link portion 211A and the object 10.

Next, as shown in FIG. 18, the first finger 21 </ b> A tilts the object 10 toward the front in a state where the first finger link part 211 </ b> A is in contact with the upper surface S <b> 4 of the object 10. That is, the object 10 is tilted in a direction in which the gripping surface S6 of the object 10 is separated from the adjacent object 10 ′. At this time, since the friction coefficient of the fingertip covering portion 901 is larger than the outer wall surface of the first finger link portion 211, the target is pressed without excessively increasing the force pressing the first finger link portion 211A against the upper surface S4 of the target object 10. The object 10 can be tilted. In addition, the joint covering portion 902 of the globe 900 is formed between the inner surface of the joint covering portion 902 and the outer wall surface of the first joint portion 22 and between the inner surface of the joint covering portion 902 and the outer wall surface of the second joint portion 23. Therefore, when the finger portion 21 is operated as shown in FIGS. 17 and 18, the bending amount and the twisting amount of the globe 900 are relatively small. As a result, it is possible to suppress the smooth movement of the finger 21 as shown in FIGS. 17 and 18 and the excessive load on the motors 51, 52, and 53. In addition, there are gaps between the inner side surface of the joint covering portion 902 and the outer wall surface of the first joint portion 22 and between the inner side surface of the joint covering portion 902 and the outer wall surface of the second joint portion 23. Thus, when the finger portion 21 is operated as shown in FIGS. 17 and 18, the globe 900 is also prevented from being sandwiched between the first joint portion 22 and the second joint portion 23. Thus, by changing the posture of the object 10 by the first finger part 21A functioning as the state changing finger part, the interval between the object 10 and the adjacent object 10 ′ can be increased. . Thereby, the gripping surface S6 of the object 10 can be exposed. As a result, not only the other gripping surface S5 of the object 10 but also the one gripping surface S6 can be brought into contact with fingers other than the first finger 21A in the hand mechanism 2. In this way, the state of the object 10 in which the finger portion 21 of the hand mechanism 2 can be brought into contact with both of the predetermined gripping surfaces S5 and S6 of the object 10 in the following is referred to as “predetermined This is referred to as a “gripable state”.

  Then, as shown in FIGS. 19 and 20, the object 10 is tilted by the first finger 21 </ b> A so that the posture of the object 10 becomes a predetermined graspable state, and the object 10 is gripped this time. The object 10 is gripped by the second finger portion 21B, the third finger portion 21C, and the fourth finger portion 21D that function as gripping finger portions. At this time, in FIG. 19 and FIG. 20, the first finger link portion 211 </ b> B and the fourth finger portion 21 </ b> B of the second finger portion 21 </ b> B are formed on one gripping surface S <b> 6 of the target object 10 exposed by changing the posture of the target object 10. The first finger link portion 211D of the finger portion 21D is brought into contact. On the other hand, the first finger link portion 211C of the third finger portion 21C is brought into contact with the other gripping surface S5 of the object 10. However, it is not always necessary to bring two fingers into contact with one gripping surface S6 of the object 10. That is, one finger part is brought into contact with one gripping surface S6 of the object 10, and the two objects are brought into contact with the other gripping surface S5 of the object 10, It may be gripped. In addition, one finger part is brought into contact with one gripping surface S6 of the object 10, and the other gripping surface S5 of the object 10 is also brought into contact with one finger part. It may be gripped. In other words, in a hand mechanism including three fingers, one finger functions as a state change finger, and the remaining two fingers function as a gripping finger. It may be gripped. When the object 10 is gripped by the various methods described above, the fingertip covering part 901 having a friction coefficient larger than that of the outer wall surface of the first finger link part 211 comes into contact with the object. The object 10 can be gripped without excessively increasing the pressing force against the object 10. In addition, the joint covering portion 902 of the globe 900 is formed between the inner surface of the joint covering portion 902 and the outer wall surface of the first joint portion 22 and between the inner surface of the joint covering portion 902 and the outer wall surface of the second joint portion 23. 19 and 20, when the finger portion 21 is operated as shown in FIG. 19 and FIG. 20, the operation cannot be performed smoothly or the load on the motors 51, 52, 53 Is suppressed from becoming excessively large. Further, there are gaps between the inner side surface of the joint covering portion 902 and the outer wall surface of the first joint portion 22 and between the inner side surface of the joint covering portion 902 and the outer wall surface of the second joint portion 23. Thus, when the finger portion 21 is operated as shown in FIGS. 19 and 20, the globe 900 is also prevented from being sandwiched between the first joint portion 22 and the second joint portion 23.

Here, the pressure sensitivity attached to each of the first finger link part 211B of the second finger part 21B, the first finger link part 211C of the third finger part 21C, and the first finger link part 211D of the fourth finger part 21D. Since the sensor 70 or the sensor cover 800 is in close contact with the fingertip covering portion 901 of the glove 900, the contact of each of the three first finger link portions 211B, 211C, and 211D with the target object 10 is the first finger link. It is reliably detected by the pressure sensor 70 of the parts 211B, 211C, 211D. In this way, the three first finger link portions 211B, 211C, 21
When contact between each 1D and the object 10 is detected, the detection signal is input to the sensor information acquisition unit 433 of the hand control device 43, so that the hand control device 43 receives the first finger link units 211B and 211C. , 211D and the object 10 can be accurately grasped.

  As described above, according to the hand mechanism 2 according to the present embodiment, since the friction coefficient of the fingertip covering portion 901 is larger than the outer wall surface of the first finger link portion 211, the force pressing the finger portion 21 against the object is minimized. It is possible to change the posture of the object and hold it while limiting to the limit. Therefore, it is not necessary to increase the rigidity of the finger portion 21 excessively, and it is not necessary to reinforce the hand mechanism 2, increase the size of the drive motor, and add a speed reduction mechanism. Furthermore, it is also possible to suppress deformation or the like of the object when the finger unit 21 is brought into contact with the object so that the hand mechanism 2 can change the posture or hold the object. Further, according to the hand mechanism 2 according to the present embodiment, since the fingertip covering portion 901 of the globe 900 is in close contact with the pressure sensor 70 (or sensor cover 800), it is possible to suppress a decrease in detection accuracy of the pressure sensor 70. You can also.

<Other embodiments>
In the above-described embodiment, as an example of a cover according to the present invention, a glove-like cover (glove) that covers the finger portion 21 and the base portion 20 is illustrated, but only the finger portion 21 is covered as shown in FIG. It can also be set as the cover 900 'formed in what is called a finger sack shape. In that case,
A fingertip covering portion 901 ′ that is a portion for covering a predetermined portion of the first finger link portion 211 in the cover 900 ′ is formed so that the friction coefficient is larger than the outer wall surface of the first finger link portion 211. Further, the joint covering portion 902 ′, which is a portion for covering the base portion of the cover 900 ′ with respect to the predetermined portion of the finger portion 21, has the joint 900 ′ in the state where the cover 900 ′ is attached to the finger portion 21. A gap is formed between the inner side surface of the covering portion 902 ′ and the outer wall surface of the finger portion 21 on the base end side of the predetermined portion. According to the cover 900 ′ configured as described above, the same effect as that of the globe 900 according to the above-described embodiment can be obtained.

  In the embodiment described above, in the cover, in addition to the portion covering the first joint portion 22 and the portion covering the second joint portion 23, the inner diameter of the portion covering the second finger link portion 212 is also larger than the outer diameter of the finger portion 21. Although the example formed so as to be described has been described, the inner diameter of the portion covering the first joint portion 22 and the portion covering the second joint portion 23 is made larger than the outer diameter of the finger portion 21, while the second finger link portion 212 is You may form a cover so that the site | part to cover may contact | adhere with the 2nd finger link part 212 closely. According to such a configuration, the positional relationship between the cover and the finger portion 21 is difficult to shift during the operation of the hand mechanism 2. Therefore, it is possible to suppress the detection accuracy of the pressure-sensitive sensor 70 from being lowered or the gripping force of the hand mechanism 2 from being changed due to the positional relationship between the cover and the finger part 21 being shifted.

  In the above-described embodiment, the example in which only the portion covering the first finger link portion 211 among the portions covering the finger portion 21 in the cover is formed in close contact with the finger portion 21 has been described. From the viewpoint of improving the gripping force of the hand mechanism while suppressing a decrease in accuracy, the entire portion covering the finger portion 21 may be formed so as to be in close contact with the finger portion 21.

DESCRIPTION OF SYMBOLS 1 ... Robot arm, 2 ... Hand mechanism, 20 ... Base part, 21 ... Finger part, 22 ... 1st joint part, 23 ... 2nd joint part, 211 ... 1st finger link part, 212 ... 2nd finger link part, 213 ... Base end part, 3 ... Arm mechanism, 30a ... 1st joint part, 30b ... 2nd joint part, 30c ... 3rd joint part, 30d ... 4th joint part, 30e ... 5th joint part, 30f ... 6th joint part, 31 ... 1st arm link part, 32 ... 1st 2 arm link part, 33 ... 3rd arm link part, 34 ... 4th arm link part, 35 ... 5th arm link part, 36 ... connecting member, 4 ... pedestal part, 42 ...
Arm control device, 420 ... arm control unit, 421 ... motor state quantity acquisition unit, 43 ... hand control device, 430 ... object information acquisition unit, 431 ... hand control unit, 432 ..Motor state quantity acquisition unit, 433 ... sensor information acquisition unit, 51 ... first motor, 52 ... second motor, 53 ... third motor, 70 ... pressure sensor, 800 ... Sensor cover, 900 ... Glove (cover), 901 ... Fingertip cover, 902 ... Joint cover, 903 ... Base cover

Claims (7)

A hand mechanism comprising a plurality of fingers and gripping an object by the fingers,
A pressure-sensitive sensor disposed on an outer wall surface of a predetermined portion including a tip portion of the finger portion;
A cover for covering the finger part;
With
In the state in which the cover has a coefficient of friction of a fingertip covering portion that is a portion for covering the predetermined portion larger than an outer wall surface of the finger portion, and the cover is attached to the finger portion, the fingertip covering portion Is formed so as to be in close contact with the predetermined portion,
Hand mechanism. The finger part is provided on the proximal side from the predetermined part in the finger part, and has a joint part that can be bent and extended,
The cover has a flexible portion covering a portion of the finger portion that is proximal to the predetermined portion, and further covers the joint portion when the cover is attached to the finger portion. It is formed so that a gap is generated between the inner side surface of the joint covering portion that is a part and the outer wall surface of the joint portion.
The hand mechanism according to claim 1. A base portion supporting the plurality of finger portions;
The cover is formed in a glove shape that covers the plurality of fingers and the base.
The hand mechanism according to claim 1 or 2. The hand mechanism includes three or more fingers,
When gripping an object, a state changing finger that changes the posture and / or position of the object after at least one of the three or more fingers touches the object. And at least two of the finger parts other than the finger parts functioning as the state changing finger parts are in a state in which the posture and / or position has been changed by the state changing finger parts. Functions as a gripping finger to grip the object,
The hand mechanism according to claim 1 or 2. A cover for covering the finger part in a hand mechanism comprising a plurality of finger parts and a pressure-sensitive sensor disposed on an outer wall surface of a predetermined part including a tip part of the finger part,
In the state where the coefficient of friction of the fingertip covering portion which is a portion for covering the predetermined portion is larger than the outer wall surface of the finger portion, and the cover is attached to the finger portion, the fingertip covering portion is the predetermined portion. Formed to adhere to
cover. The finger part of the hand mechanism has a joint part that is provided on the proximal side from the predetermined part of the finger part and can be bent and extended,
In the cover, a portion of the finger portion that covers a portion closer to the base end side than the predetermined portion has flexibility, and the cover is configured to cover the joint portion when the cover is attached to the finger portion. It is formed so that a gap is generated between the inner side surface of the joint covering portion that is a part and the outer wall surface of the joint portion.
The cover according to claim 5. The hand mechanism further includes a base portion that supports the plurality of finger portions,
The cover is formed in a glove shape that covers the plurality of fingers and the base.
The cover according to claim 5 or 6.

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