Robot hand and robot system

Abstract

This robot hand (20) includes a pair of finger parts (21) for sandwiching and holding each of the plurality of workpieces, a winding part (22), and a holding part (23). The winding part (22) is disposed at distal end parts of the pair of finger parts (21), and winds up each of the plurality of workpieces by rotational driving. The holding part (23) is disposed closer to base end parts of the pair of finger parts (21) than the winding part (22), and collectively holds the plurality of workpieces wound up by the winding part (22) by pressing.

Description

Robotic Hands and Robotic Systems

[0001] This disclosure relates to a robotic hand and a robotic system.

[0002] Conventionally, robot systems have been disclosed. JP 2014-24143 A discloses a robot system that holds bulk-stacked workpieces one by one. This robot system uses a hand with two fingers to pick up the bulk-stacked workpieces one by one and transport them to a predetermined location.

[0003] JP 2014-24143 A

[0004] However, when transporting multiple workpieces using a robot hand that holds each workpiece one by one, as in the robot system described in JP 2014-24143 A, a series of transport operations, including an operation of holding the workpiece, an operation of moving the held workpiece, and an operation of placing the held workpiece after movement, are performed sequentially for each of the multiple workpieces. Therefore, transporting multiple workpieces one by one increases the work time required to transport the multiple workpieces. Therefore, it is desirable to suppress the increase in work time when transporting multiple workpieces.

[0005] This disclosure has been made to solve the above-mentioned problems, and one purpose of this disclosure is to provide a robot hand and a robot system that can prevent an increase in work time when transporting multiple workpieces.

[0006] A robot hand according to a first aspect of this disclosure includes a pair of fingers that clamp and hold each of a plurality of workpieces, a hoisting section that is disposed at the tip end of the pair of fingers and that winds up each of the plurality of workpieces by rotational drive, and a holding section that is disposed closer to the base end of the pair of fingers than the hoisting section and that holds the plurality of workpieces wound up by the hoisting section together by pressing them.

[0007] As described above, the robot hand according to the first aspect of this disclosure includes a holding unit that is positioned closer to the base ends of the pair of fingers than the hoisting unit and that presses and holds multiple workpieces wound up by the hoisting unit. This allows the holding unit to hold multiple workpieces together, enabling the robot hand to hold multiple workpieces together. Therefore, the work time required to transport multiple workpieces can be reduced compared to when the robot hand holds the workpieces one by one. As a result, the increase in work time when transporting multiple workpieces can be suppressed.

[0008] A robot system according to a second aspect of this disclosure comprises a robot hand including a pair of fingers that clamp and hold each of a plurality of workpieces, a hoisting section that is arranged at the tip of the pair of fingers and that winds up each of the plurality of workpieces by rotational drive, and a holding section that is arranged closer to the base end of the pair of fingers than the hoisting section and that holds the plurality of workpieces wound up by the hoisting section together by pressing them, a robot arm section to which the robot hand is attached, and a control section that controls the operation of the robot hand and the robot arm section.

[0009] As described above, a robot system according to a second aspect of this disclosure includes a robot hand including a holding unit that is positioned closer to the base ends of the pair of fingers than the hoisting unit and that presses and holds multiple workpieces wound up by the hoisting unit. This allows the holding unit to hold multiple workpieces together, allowing the robot hand to hold multiple workpieces together. Therefore, the work time required to transport multiple workpieces can be reduced compared to when the robot hand holds the workpieces one by one. As a result, a robot system can be provided that can prevent an increase in work time when transporting multiple workpieces.

[0010] The robot hand and robot system disclosed herein can prevent an increase in work time when transporting multiple workpieces.

[0011] 1 is a diagram illustrating a robot system according to an embodiment of the present disclosure; FIG. 2 is a block diagram illustrating a configuration of a robot system according to an embodiment; FIG. 3 is a front view illustrating a configuration of a robot hand; FIG. 4 is a side view illustrating a configuration of a robot hand; FIG. 5 is a schematic view illustrating a configuration of a holder in the robot hand; FIG. 6 is a schematic view illustrating a configuration of a drive unit in the robot hand; FIG. 7 is a flowchart illustrating a control process of a workpiece transport method for a robot system according to an embodiment of the present disclosure; FIG. 8 is a diagram illustrating detection of a workpiece based on a captured image; FIG. 9 is a diagram illustrating winding up of a workpiece by a belt member; FIG. 10 is a diagram illustrating adjustment of the inclination of a workpiece by a belt member; FIG. 11 is a diagram showing an example of detection of a workpiece by a sensor unit; FIG. 12 is a diagram illustrating adjustment of the positions of multiple workpieces held by a holder; FIG. 13 is a diagram illustrating discharge of a workpiece by a robot hand.

[0012] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.

[0013] (Configuration of Robot System) The configurations of a robot system 100 and a robot hand 20 according to the present disclosure will be described with reference to FIGS. 1 to 6 . As shown in FIG. 1 , the robot system 100 includes a robot arm unit 10, a robot hand 20, an imaging unit 40, and a control unit 90. That is, the robot system 100 includes an industrial robot including the robot arm unit 10 and the robot hand 20. The robot system 100 operates the robot arm unit 10 and the robot hand 20 to perform a transfer operation in which multiple workpieces 101 arranged in a container 102 are held and transferred to another container 103. The workpieces 101 are, for example, fastening members such as bolts. The multiple workpieces 101 are arranged in a bulk pile in the container 102. The term "bulk pile" as used herein refers to a state in which the orientations and positions of the multiple workpieces 101 are irregularly arranged in the container 102. The robot system 100 performs a kitting operation in which the workpieces 101 are removed from the bulk pile in the container 102 and transferred to predetermined positions in the container 103.

[0014] The robot arm unit 10 has a base end attached to a base 12 and a robot hand 20 attached to its tip. The base 12 is installed, for example, on the floor. The robot arm unit 10 is, for example, a six-axis vertical articulated robot arm. The robot arm unit 10 has a plurality of links that rotate relative to one another. The robot arm unit 10 has, at each joint connecting the plurality of links, a drive unit 11 (shown in FIG. 2 ) that serves as a drive source for the plurality of joints. In addition, a support unit 13 is attached to the tip of the robot arm unit 10. The robot hand 20 and an imaging unit 40 are arranged on the support unit 13. The support unit 13 is, for example, a plate-shaped metal member.

[0015] The robot hand 20 is an end effector disposed at the tip of the robot arm unit 10. The robot hand 20 holds a plurality of workpieces 101 together. In this embodiment, the robot hand 20 includes a pair of fingers 21. The pair of fingers 21 holds each of the plurality of workpieces 101 by pinching it between them. As shown in FIG. 2 , the robot hand 20 includes a drive unit 30. The drive unit 30 has, for example, three motors, 31, 32, and 33, which serve as drive sources for the operation of each part of the robot hand 20. Details of the robot hand 20 and the drive unit 30 will be described later.

[0016] As shown in FIG. 1 , the imaging unit 40 is attached to the robot arm 10 via the support 13 together with the robot hand 20. The imaging unit 40 captures an image of the workpiece 101 placed in a container 102 before being held by the pair of fingers 21. The imaging unit 40 includes an image sensor such as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). As shown in FIG. 2 , the imaging unit 40 captures a captured image 40 a, which is a two-dimensional image of the workpiece 101, and transmits the captured two-dimensional image 40 a to the control unit 90.

[0017] As shown in FIG. 2 , the control unit 90 is a robot controller including a main control unit 91, a servo control unit 92, a drive circuit unit 93, and an image processing unit 94. The control unit 90 has a calculation unit that performs calculation processing and a storage device that stores parameters, programs, and the like. The control unit 90 controls the operations of the robot arm unit 10 and the robot hand 20 by the calculation unit executing the programs stored in the storage device. For example, the main control unit 91 and the servo control unit 92 include a CPU (Central Processing Unit) as the calculation unit. The main control unit 91 controls the drive unit 11 of the robot arm unit 10 and the drive unit 30 of the robot hand 20. The servo control unit 92 controls the power supplied to the drive unit 11 of the robot arm unit 10 and the drive unit 30 of the robot hand 20 based on commands from the main control unit 91. The drive circuit unit 93 supplies drive power to the drive unit 11 of the robot arm unit 10 and the drive unit 30 of the robot hand 20. The drive circuit unit 93 is arranged for each of the drive units 11 for each of the six joints of the robot arm unit 10 and for each of the motors 31, 32, and 33 of the drive unit 30 of the robot hand 20. Each of the drive units 11 and 30 includes a servo motor, an encoder, and a reducer. Note that the drive unit 30 does not necessarily have to include an encoder and a reducer. That is, each of the motors 31, 32, and 33 of the drive unit 30 is a servo motor. The image processing unit 94 also performs image processing on the captured image 40a captured by the imaging unit 40. The image processing unit 94 includes, for example, a GPU (Graphics Processing Unit). The control unit 90 detects the position and orientation of multiple workpieces 101 placed in the container 102 based on the captured image 40a using the image processing unit 94, and controls the operation of the robot arm unit 10 and the robot hand 20 based on the detection results from the captured image 40a, thereby controlling the transport operation of the workpieces 101.

[0018] (Details of Robot Hand) As shown in Fig. 3, the robot hand 20 includes a hoisting unit 22, a holding unit 23, a rod unit 24, and a sensor unit 25. The robot hand 20 also includes a main body 20a. In this embodiment, in the pair of fingers 21, the hoisting unit 22 hoists each of the multiple workpieces 101 by rotational drive. The holding unit 23 collectively holds the multiple workpieces 101 hoisted by the hoisting unit 22. The rod unit 24 presses the multiple workpieces 101 held by the holding unit 23 from the base end 21b toward the tip end 21a of the pair of fingers 21. The rod unit 24 is an example of a pressing unit.

[0019] The main body 20a is disposed on the Z1 side, which is the base end side of the robot hand 20, and is connected to the tip of the robot arm 10 via the support 13. A pair of fingers 21 are disposed on the Z2 side of the main body 20a so as to extend along the Z direction. Inside the main body 20a, motors 31, 32, and 33 of the drive unit 30 are disposed. For example, the motor 31 is a drive source for the opening and closing operation of the pair of fingers 21. The motor 32 is a drive source for the rotational drive of the hoisting unit 22. The motor 33 is a drive source for the extension and retraction operation of the rod 24.

[0020] The pair of fingers 21 are arranged to extend in the Z direction toward the tip of the robot hand 20. The hoisting unit 22 is arranged at the tip 21a of each of the pair of fingers 21 on the Z2 direction side. The holding unit 23 is arranged closer to the base end 21b of the pair of fingers 21 on the Z1 direction side than the hoisting unit 22. The tip 21a of the pair of fingers 21 is an end opposite to the connection between the robot hand 20 and the robot arm unit 10, and is an end arranged on the Z2 direction side away from the robot arm unit 10. The base end 21b of the pair of fingers 21 is an end on the Z1 direction side that is connected to the main body unit 20a on the opposite side to the tip 21a.

[0021] The pair of fingers 21 are arranged side by side along the X direction and are driven by the motor 31 to open and close in an opening direction in which they move away from each other and in a closing direction in which they face each other. Specifically, each of the pair of fingers 21 is arranged one on the X1 direction side, which is one side of the X direction, and one on the X2 direction side, which is the other side. For the finger 21 arranged on the X1 direction side, the X1 direction is the opening direction and the X2 direction is the closing direction. Conversely, for the finger 21 arranged on the X2 direction side, the X2 direction is the opening direction and the X1 direction is the closing direction. The pair of fingers 21 have a common structure and are arranged in a mirror image relationship along the X direction.

[0022] <Winding Unit> As shown in FIG. 4 , the winding unit 22 has a pair of belt members 22a. The pair of belt members 22a are circular endless belts wound around the tip ends 21a of the finger portions 21. The pair of belt members 22a are rotationally driven by the motor 32 of the drive unit 30. A pair of belt members 22a is disposed on each of the pair of fingers 21. That is, a pair of belt members 22a is disposed on the finger portion 21 on the X1 direction side, and a similar pair of belt members 22a is disposed on the finger portion 21 on the X2 direction side. Therefore, four belt members 22a are disposed on one robot hand 20. On one finger portion 21, the pair of belt members 22a are disposed spaced apart from each other in the Y direction. The pair of belt members 22a wind up each of the multiple workpieces 101 toward the base ends 21b of the finger portions 21 along directions parallel to each other. For example, in each pair of fingers 21, a pair of belt members 22a are rotationally driven by the driving force of the common motor 32. That is, all four belt members 22a arranged in the robot hand 20 are rotationally driven by the driving force of the common motor 32. In Fig. 3, the pair of belt members 22a arranged in the finger 21 arranged on the X1 direction side rotates clockwise when viewed from the Y2 direction side, and the pair of belt members 22a arranged in the finger 21 arranged on the X2 direction side rotates counterclockwise when viewed from the Y2 direction side.

[0023] Specifically, as shown in Fig. 3, the pair of belt members 22a of the hoisting unit 22 are wound around pulleys 32a, 32b, and 32c that rotate about a rotation axis extending in the Y direction. The pulley 32a is a drive pulley that is rotated by the motor 32 of the drive unit 30. The pulleys 32b and 32c are driven pulleys that rotate following the rotational drive of the belt member 22a. Each of the pulleys 32a, 32b, and 32c is a toothed pulley. The annular belt member 22a is, for example, a toothed belt having teeth on its inner periphery that engage with the pulleys 32a, 32b, and 32c. 4, in one finger 21, the pulleys 32a, 32b, and 32c around which one belt member 22a is wound and the pulleys 32a, 32b, and 32c around which the other belt member 22a is wound rotate in conjunction with each other about a common rotation axis. Specifically, the pair of belt members 22a are wound around the common pulleys 32a, 32b, and 32c, respectively.

[0024] As shown in FIG. 4 , the workpiece 101 is, for example, a cap bolt having a cylindrical cap 101a with a hexagonal hole and a rod-shaped threaded portion 101b. The winding unit 22 winds up the workpieces 101, each having a cap 101a and a threaded portion 101b, between a pair of fingers 21 one by one and moves them toward the base end 21b. The winding unit 22 winds up the workpiece 101 in the Z1 direction toward the base end 21b, with the cap 101a of the workpiece 101 positioned on the Y2 side where the rod portion 24 is positioned and the rod-shaped threaded portion 101b extending in the Y1 direction. Note that the extension direction of the workpiece 101 while being wound up by the winding unit 22 may be tilted from the Y direction.

[0025] Furthermore, a guide portion 22b is disposed at the end of the tip portion 21a of each of the pair of fingers 21 on the Z2 direction side, separate from the belt member 22a. The guide portion 22b is a cylindrical member that rotates integrally with the pulley 32c disposed at the tip of the finger 21. The guide portion 22b is formed of, for example, urethane or rubber. The guide portion 22b is disposed between the pair of belt members 22a in the Y direction and is disposed so as to be wound around the rotating shaft member of the pulley 32c. The pulley 32a is rotated by the drive of the motor 32, and the belt member 22a wound around the pulley 32a rotates, thereby rotating the pulleys 32b and 32c. The guide portion 22b rotates integrally with the pulley 32c in conjunction with the rotation of the belt member 22a. Therefore, at the tip 21 a of the finger 21 of the robot hand 20 , the belt member 22 a and the guide portion 22 b work together to wind up the workpiece 101 .

[0026] <Holding Unit> As shown in FIG. 5 , the holding unit 23 holds the multiple workpieces 101 wound up by the winding unit 22, aligned along the Z direction between the pair of fingers 21 from the tip end 21 a to the base end 21 b. The holding unit 23 includes a pair of elastic members 23 a arranged on each of the pair of fingers 21. One elastic member 23 a is arranged on each of the pair of fingers 21. The elastic members 23 a are arranged facing each other on each of the pair of fingers 21, for a total of two elastic members 23 a arranged on the robot hand 20. That is, one elastic member 23 a is arranged on the X2 direction side of one finger 21 on the X1 direction side, and the other elastic member 23 a is arranged on the X1 direction side of the other finger 21 on the X2 direction side. Each of the pair of elastic members 23 a presses the multiple workpieces 101 by elastic force along the closing direction in which the pair of fingers 21 face each other. The elastic member 23a includes, for example, a leaf spring that flexes and deforms to apply an elastic force to press the plurality of workpieces 101. That is, the holding unit 23 holds the workpieces 101 by applying a force to the workpieces 101 using the elastic force of the elastic member 23a, separately from the opening and closing movement of the finger unit 21 by the driving unit 30.

[0027] The pair of elastic members 23a are deflected and deformed outward in the X direction by the multiple workpieces 101 held side by side in the Z direction. As a result, the pair of elastic members 23a apply an elastic force to the multiple workpieces 101 so as to push them inward in the X direction. The elastic members 23a are bent plate-like members. The elastic member 23a has a linear portion extending linearly from the base end 21b of the finger 21 to the end of the belt member 22a on the Z1 direction side, and bent portions at both ends in the Z direction. The holding portion 23 also includes a flexible contact member 23b. The contact member 23b is a plate-like member disposed on the surface of the elastic member 23a facing the pair of finger portions 21. The contact member 23b abuts against the workpiece 101 on the surface of the elastic member 23a, thereby deforming to conform to the shape of the workpiece 101. The contact member 23b is, for example, a rubber member. The pair of holding parts 23 hold the workpiece 101 while abutting on the opposing surfaces thereof due to deformation of an elastic member 23a including a leaf spring and a contact member 23b arranged on the surface of the elastic member 23a. A rough surface member that generates a friction force on the contact surface that abuts on the workpiece 101 may be arranged on the elastic member 23a.

[0028] As shown in FIG. 4 , the elastic member 23a is disposed along the pair of finger portions 21 from the pair of belt members 22a toward the base ends 21b. One end of the elastic member 23a is disposed at the end of the pair of belt members 22a on the Z1 direction side, and the other end is disposed at the base ends 21b. The end of the elastic member 23a closer to the tip ends 21a of the pair of belt members 22a is disposed between the belt members 22a at the end closer to the base ends 21b. Specifically, the end of the elastic member 23a on the tip ends 21a side, which is on the Z2 direction side, is disposed between the end of the pair of belt members 22a on the base ends 21b side, which is on the Z1 direction side. That is, the end of the elastic member 23a on the Z2 direction side is disposed so as to overlap the end of the pair of belt members 22a on the Z1 direction side when viewed from the Y direction. The workpiece 101 wound up in the Z1 direction by the belt member 22a is pressed and held by the elastic member 23a of the holding portion 23 at the end of the belt member 22a on the Z1 direction side.

[0029] <Rod Portion> As shown in FIG. 3 , the rod portion 24 is disposed on the Z2 direction side of the main body portion 20a. Driven by the motor 33, the rod portion 24 moves retractably along the Z direction on the Y2 direction side of the pair of fingers 21. As shown in FIG. 4 , the rod portion 24 has an abutting portion 24a and an extendable portion 24b. The abutting portion 24a is disposed on the Z2 direction side and abuts against the cap 101a of the workpiece 101 held by the holding portion 23. The extendable portion 24b is connected to the Z1 direction side of the abutting portion 24a and is a rod-shaped member extending along the Z direction. As the extendable portion 24b moves along the Z direction by drive of the motor 33, the abutting portion 24a presses the workpiece 101 held by the holding portion 23 in such a way as to push it out toward the Z2 direction.

[0030] <Sensor Unit> As shown in Fig. 3 , the sensor unit 25 is disposed on each of the pair of fingers 21. The sensor unit 25 detects each of the multiple workpieces 101 held by the pair of fingers 21. The sensor unit 25 includes, for example, a photoelectric sensor that detects the workpiece 101 using detection light, or a pressure sensor that detects the pressure received from the workpiece 101 when the workpiece 101 is gripped. As shown in Fig. 4 , the sensor unit 25 is disposed, for example, between the pair of belt members 22a on each of the fingers 21. The sensor unit 25 detects that the workpiece 101 wound up by the belt member 22a has passed, and outputs a detection signal indicating the detection result of the workpiece 101. The detection signal from the sensor unit 25 is output to the control unit 90.

[0031] <Transmission of Driving Force in Main Body> As shown in FIG. 6 , a transmission mechanism for transmitting the driving forces of motors 31, 32, and 33 is disposed in the main body 20a. For example, to open and close the pair of fingers 21, the driving force of motor 31 is transmitted by a transmission mechanism including connecting members 31a and screw members 31b. One connecting member 31a is disposed in the main body 20a, one corresponding to each of the pair of fingers 21. One screw member 31b is disposed in common for the pair of connecting members 31a. The driving force of motor 31 of the drive unit 30 is transmitted via the pair of connecting members 31a and the single screw member 31b, causing the pair of fingers 21 to move in the X direction, which is the opening and closing direction. That is, the pair of fingers 21 are opened and closed by the motor 31, which is a common drive source. Specifically, screw member 31b is, for example, a rod-shaped member extending in the X direction. The screw member 31b rotates around the X-direction as a rotation axis by transmitting the rotational drive of the rotary shaft of the motor 31 via gears or the like. The screw member 31b has threads facing opposite directions on the X1 and X2 sides. The connecting member 31a is connected to the base ends 21b of each of the pair of fingers 21 on the Z2 side and is threadedly engaged with the screw member 31b on the Z1 side. As a result, when the motor 31 rotates, the pair of fingers 21 move in opposite directions in the opening / closing direction in response to the rotation of the motor 31. That is, the connecting member 31a to which one finger 21 is connected and the connecting member 31a to which the other finger 21 is connected are threadedly engaged with the common screw member 31b so that the threads face in opposite directions. Therefore, when the motor 31 is rotated in one direction, the pair of fingers 21 move toward each other in the closing direction, whereas when the motor 31 is rotated in the other direction, the pair of fingers 21 move away from each other in the opening direction.

[0032] Furthermore, in order to rotationally drive the pair of belt members 22a of the hoisting section 22, the driving force of the motor 32 is transmitted to the pulley 32a by a transmission mechanism including, for example, a shaft member 32d and a parallel link mechanism formed by pulleys 32e, 32f, 32g, and 32h. The shaft member 32d is, for example, a rod-shaped spline shaft extending in the X direction. The rotational drive of the rotating shaft of the motor 32 is transmitted to the shaft member 32d by gears or the like, and the shaft member 32d rotates about its rotation axis in the X direction. A spline nut is attached to the shaft member 32d, which slides along the X direction along which the shaft member 32d extends and which meshes with the shaft member 32d to rotate integrally with the shaft member 32d about its rotation axis in the X direction. The gear mounted on the spline nut and the gear mounted on the pulley 32e engage with each other as screw gears, thereby transmitting the rotation of the shaft member 32d to the pulley 32e while changing the direction of the rotation axis from the X direction to the Y direction. Pulleys 32e, 32f, 32g, and 32h are arranged in pairs on each of the pair of connecting members 31a, forming a parallel link mechanism. That is, the pulleys 32e, 32f, 32g, and 32h are arranged to form a parallelogram with the Y direction as the rotation axis, and adjacent pulleys are connected by link members. Pulley 32e is fixed to the connecting member 31a, and pulley 32g is fixed to the finger 21. Meanwhile, pulleys 32f and 32h are arranged to be movable relative to the connecting member 31a and the finger 21 in the XZ plane perpendicular to the rotation axis. That is, pulleys 32e, 32f, 32g, and 32h are arranged so that they form a parallelogram, while pulleys 32e and 32g, which are arranged diagonally, are arranged so that their relative positions can be changed.

[0033] A belt member is wound around the pulleys 32e, 32f, 32g, and 32h that form a parallelogram, and the pulley 32e rotates when the rotation of the shaft member 32d is transmitted to it. Thus, the rotational drive of the motor 32 is transmitted to each of the pulleys 32e, 32f, 32g, and 32h via the shaft member 32d. The belt member is wound around the fingers 21 so that the rotation of the pulley 32g fixed to the fingers 21 is transmitted to the pulley 32a that rotates the belt member 22a. Here, the fingers 21 are movably connected to the connecting member 31a. Meanwhile, as described above, a link mechanism is provided having the pulleys 32e and 32g that are arranged so that their positions can be changed relative to each other, thereby transmitting the rotational drive of the motor 32 to the pulley 32a that rotates the belt member 22a. 6 shows only an example of a transmission mechanism including pulleys 32f, 32g, and 32h arranged on the finger 21 on the X1 side, and the transmission mechanism arranged on the finger 21 on the X2 side is omitted because it has the same structure. The driving force of the motor 33 is also transmitted to the rod 24 by a transmission mechanism including a ball screw mechanism, a sliding screw mechanism, a belt and pulley mechanism, a rack and pinion mechanism, or a combination of multiple gear mechanisms.

[0034] <Using Portion> As described above, the pair of fingers 21 are connected to the connecting member 31a so as to be movable relative to the connecting member 31a. For example, the fingers 21 are connected to the connecting member 31a so as to be movable within the XZ plane via a linear guide portion that slides the fingers 21 in the X direction and a linear guide portion that slides the fingers 21 in the Z direction. The main body 20a is provided with the urging portion 34a and the urging portion 34b. The urging portion 34a urges the pair of fingers 21 toward the closing directions, which are opposite to each other. The urging portion 34b urges the pair of fingers 21 toward the tip end 21a, which is the Z2 direction. Each of the urging portions 34a and 34b includes, for example, a coil spring. For example, the urging portion 34a is provided on the connecting member 31a. When each of the pair of fingers 21 moves in the opening direction relative to the connecting member 31a, the urging portion 34a is pressed and compressed along the X direction. As a result, the biasing portion 34a presses the finger portions 21 in the closing direction by elastic force. For example, in this embodiment, when the pair of fingers 21 sandwich and hold each of the multiple workpieces 101, the sandwiched workpieces 101 spread apart in the opening direction against the elastic force of the biasing portion 34a. That is, the pair of fingers 21 apply an elastic force in the closing direction to the sandwiched and held workpieces 101 by the biasing portion 34a. Then, when the pair of fingers 21 are biased in the closing direction by the biasing portion 34a, the workpiece 101 is wound up by the winding portion 22 and held by the holding portion 23. Furthermore, the biasing portion 34b is disposed on the connecting member 31a, and is pressed and compressed along the Z1 direction when each of the pair of fingers 21 moves in the Z1 direction toward the base end 21b relative to the connecting member 31a. As a result, the biasing portion 34b uses its elastic force to press the finger portion 21 back in the Z2 direction toward the tip portion 21a.

[0035] As described above, the pair of fingers 21 actively move due to the driving force of the driving unit 30, and also passively move due to contact with the workpiece 101, etc. The biasing units 34a and 34b bias the fingers 21 by elastic force, independently of the operation of the driving unit 30. That is, each of the pair of fingers 21 moves in the opening / closing direction and in the Z1 direction toward the base end 21b when a force is applied, independently of the opening / closing operation by the driving unit 30, and moves back to its original position due to the elastic force when the applied force is removed. In other words, the pair of fingers 21 are allowed to move elastically in the X direction and the Z direction by the biasing units 34a and 34b, and have mechanical compliance.

[0036] (Control Processing of Workpiece Transport Method) Next, the control processing of the workpiece transport method according to this embodiment will be described based on flowcharts with reference to Fig. 7 to Fig. 13. The control processing of the workpiece transport method from step S1 to step S6 shown in Fig. 7 is executed by the control unit 90.

[0037] First, in step S1, a captured image 40a is acquired. As shown in Fig. 8 , the control unit 90 acquires a signal from the imaging unit 40, and generates a two-dimensional captured image 40a of a plurality of workpieces 101 in a state of being randomly stacked in a container 102, captured by the imaging unit 40, based on the acquired signal from the imaging unit 40.

[0038] Next, in step S2, the workpieces 101 are detected. Specifically, the central position and orientation of each of the multiple workpieces 101 included in the captured image 40a are detected. The control unit 90 detects the central position and orientation of the workpieces 101, for example, by performing control processing of image recognition. As an example, the control unit 90 pre-stores a trained model trained by machine learning. Then, the control unit 90 uses the trained model to detect the central position and orientation of each of the multiple workpieces 101 from the captured image 40a acquired in step S1. The trained model is trained, for example, by deep learning using a convolutional neural network.

[0039] Next, in step S3, the workpiece 101 is held. As shown in FIG. 9 , the control unit 90 holds one of the multiple workpieces 101 with the pair of fingers 21 based on the center position and orientation of the workpiece 101 detected in step S2. The control unit 90 stores, for example, the posture of the robot arm unit 10 at the time the captured image 40a was captured and the spatial coordinates at which the robot hand 20 and the imaging unit 40 are located relative to the robot arm unit 10. Based on the stored posture of the robot arm unit 10 and the spatial coordinates of the robot hand 20 and the imaging unit 40, the control unit 90 controls the operation of the robot arm unit 10 so that the tip 21a of the finger 21 of the robot hand 20 is located at the position of the workpiece 101 detected in the captured image 40a. The control unit 90 also controls the operation of the robot arm unit 10 and the robot hand 20 so that the cap 101a of the workpiece 101 is positioned on the Y2 direction side where the rod unit 24 is positioned, and so that the central portion of the threaded portion 101b of the workpiece 101 is sandwiched between the pair of fingers 21. In this case, the drive unit 30 adjusts the distance between the finger units 21 so that the width between the belt members 22a of each of the pair of fingers 21 is smaller than the width of the threaded portion 101b of the workpiece 101. The control unit 90 then moves the robot hand 20 toward the detected position of the workpiece 101 while rotating the pair of belt members 22a of the hoisting unit 22. For example, the control unit 90 detects the center position and orientation of the workpiece 101 in the horizontal plane based on the captured image 40a, and holds the workpiece 101 by moving the robot hand 20 vertically downward by a predetermined distance. Since the fingers 21 move within the XZ plane relative to the main body 20a while being biased by the biasing portions 34a and 34b, even if the detected position of the workpiece 101 is misaligned, the fingers 21 passively move to match the position of the workpiece 101 placed on the container 102, thereby causing the belt member 22a to wind up the workpiece 101. Figure 9 shows an example of a state in which the fingers 21 on the X2 direction side have moved so as to be misaligned toward the Z1 direction side compared to the fingers 21 on the X1 direction side.

[0040] Next, in step S4, it is determined whether or not a predetermined number of workpieces 101 have been held. If it is determined that the predetermined number of workpieces 101 have been held, the process proceeds to step S5. If it is determined that the predetermined number of workpieces 101 have not been held, the process returns to step S1, and steps S1 to S3 are performed again to hold a new workpiece 101 in the holder 23.

[0041] As shown in FIG. 10 , by repeating the operations from step S1 to step S3, the control unit 90 sequentially clamps and holds each of the multiple workpieces 101 stacked in bulk with the pair of fingers 21. Furthermore, the control unit 90 controls the holding unit 23 to hold the multiple workpieces 101 in the same orientation based on the captured image 40a captured by the imaging unit 40. When repeating the operations from step S1 to step S3, the control unit 90 controls the operation of the robot arm unit 10 and the robot hand 20 so that the caps 101a of the multiple workpieces 101 held by the holding unit 23 are all aligned in the Y2 direction when holding the workpieces 101 in step S3. That is, the multiple workpieces 101 are held in the holding unit 23 in the same orientation. When repeating the operations from step S1 to step S3 to sequentially clamp and hold the multiple workpieces 101, the control unit 90 prevents the pair of fingers 21 from opening and closing each other. That is, the control unit 90 holds the plurality of workpieces 101 in order without rotating the motor 31 of the drive unit 30 and without actively moving the finger unit 21 .

[0042] When multiple workpieces 101 are successively held by the elastic member 23a of the holding portion 23, the pair of belt members 22a in the finger portion 21 are arranged in directions parallel to each other from the tip end 21a to the base end 21b. Therefore, even if the workpiece 101 is wound up in a state inclined obliquely with respect to the Y direction in which the pair of belt members 22a are aligned, a moment of force that rotates the workpiece 101 to eliminate the inclination is generated at the ends of the pair of belt members 22a on the Z1 direction side toward the base end 21b. In other words, the workpiece 101 wound up in a state inclined obliquely receives force from only one of the pair of belt members 22a at the end of the hoisting portion 22 on the Z1 direction side near the base end 21b, and does not receive force from the other. Then, a force acts between one belt member 22a and the elastic member 23a of the holding unit 23, causing the wound-up workpiece 101 to rotate between the pair of fingers 21 at the end of the winding unit 22 near the base end 21b on the Z1 direction side, with the rotation axis being the direction in which the pair of fingers 21 face each other. As a result, a force acts between the pair of belt members 22a and the elastic member 23a to rotate the workpiece 101 so that it is oriented along the Y direction, which is the direction in which the pair of belt members 22a are aligned. In this way, the inclination of each of the multiple workpieces 101 wound up by the winding unit 22 is eliminated, and the multiple workpieces 101 are held in the holding unit 23 with their orientation aligned along the Y direction.

[0043] For example, Figure 10 shows an example in which the workpiece 101 is wound up by the pair of belt members 22a while tilting so that the Y1 direction side of the workpiece 101 faces the Z1 direction. When the workpiece 101 is wound up to the end of the belt members 22a on the Z1 direction side, the central portion of the workpiece 101 is pressed against the elastic member 23a of the holding unit 23. No force is applied to the workpiece 101 from the belt member 22a on the Y1 direction side, but a force toward the Z1 direction is applied from the belt member 22a on the Y2 direction side. Then, due to the action of the force between the belt member 22a on the Y2 direction side and the elastic member 23a, a moment about the X direction is generated on the workpiece 101 so that the workpiece 101 is positioned along the Y direction. This moment about the X direction moves the workpiece 101 from the winding unit 22 to the holding unit 23 while it is positioned along the Y direction. Then, the caps 101a of the workpiece 101 already held by the holding portion 23 and the newly held workpiece 101 are pressed against each other in the Z direction, so that each of the multiple workpieces 101 is aligned along the Y direction and held side by side by the holding portion 23.

[0044] 11 , while performing the control of step S3, the control unit 90 acquires the number of workpieces 101 held by the pair of fingers 21 by acquiring a detection signal from the sensor unit 25. The control unit 90 stores the number of workpieces 101 acquired based on the detection signal from the sensor unit 25, and makes a determination in step S4 based on the stored number of workpieces 101.

[0045] In step S5, the positions of the multiple workpieces 101 held by the holder 23 are adjusted. As shown in FIG. 12 , the control unit 90 adjusts the positions of the multiple workpieces 101 by moving the pair of fingers 21 in an opening direction away from each other while the elastic member 23a of the holder 23 holds the multiple workpieces 101 in a line. Specifically, the control unit 90 controls the operation of the robot arm 10 to change the orientation of the robot hand 20 so that the fingers 21 extend horizontally while holding the multiple workpieces 101. The control unit 90 changes the orientation of the robot hand 20 so that the rod 24 and the caps 101a of the held workpieces 101 are positioned on the Y2 direction, which is the upper side in the vertical direction. The "vertical direction" here refers to the direction in which gravity acts on the workpieces 101. The "horizontal direction" refers to a direction along a horizontal plane perpendicular to the vertical direction. Then, the control unit 90 moves the pair of fingers 21 in the opening direction so that the width between the pair of fingers 21 in the X direction is smaller than the width of the cap 101a of the workpiece 101 and larger than the width of the threaded portion 101b of the workpiece 101. Specifically, the control unit 90 moves the pair of fingers 21 so that the distance between the holding portions 23 of the pair of fingers 21 in the X direction, i.e., the distance between the contact members 23b, is smaller than the width of the cap 101a of the workpiece 101 and larger than the width of the threaded portion 101b of the workpiece 101. As a result, the multiple workpieces 101 held in a row by the holding portions 23 are temporarily released from a state in which they are pressed by the elastic members 23a of the holding portions 23. Then, the plurality of workpieces 101 move due to gravity toward the Y1 direction, which is the downward side in the vertical direction, and the Y1 direction surface of the cap 101a abuts against the Y2 direction sides of the pair of finger portions 21, so that the caps 101a are aligned in a state where they are lined up along the Z direction on the finger portions 21. After aligning the plurality of workpieces 101, the control unit 90 again moves the pair of finger portions 21 in the closing direction facing each other, thereby causing the holding unit 23 to hold the plurality of workpieces 101 in an aligned state.

[0046] Next, in step S6, each of the multiple workpieces 101 held by the elastic member 23a of the holder 23 is discharged to a predetermined position in the container 103. As shown in FIG. 13 , the control unit 90 discharges each of the multiple workpieces 101 pressed by the rod 24 from the base end 21b toward the tip end 21a of the finger 21 by reverse rotational driving of the hoisting unit 22. Specifically, the control unit 90 operates the robot arm 10 to move the robot hand 20 to a position where the workpiece 101 is discharged based on preset parameters so that the workpiece 101 is delivered to a predetermined position in the container 103, which is the destination. Then, the control unit 90 drives the motor 33 of the drive unit 30 to move the rod 24 in the Z2 direction. As a result, the caps 101a of the multiple workpieces 101 arranged in line along the Z direction are pressed toward the Z2 direction by the rod portion 24, and one of the multiple workpieces 101 that is arranged furthest in the Z2 direction is moved from the elastic member 23a of the holding portion 23 to the position of the belt member 22a. The control unit 90 pre-stores the number of workpieces 101 being held and the amount of movement of the rod portion 24 corresponding to one cap 101a of the workpiece 101. When discharging one workpiece 101, the control unit 90 controls the amount of movement of the rod portion 24 so that the multiple workpieces 101 are pressed and pushed out by an amount corresponding to one workpiece 101. Then, when only one of the multiple workpieces 101 held by the elastic member 23a of the holder 23 is positioned at the position of the belt member 22a, the control unit 90 reversely rotates the pair of belt members 22a of the hoisting unit 22 in the direction opposite to that for winding up the workpiece 101, thereby discharging only the single workpiece 101 and transporting it to a predetermined position in the container 103. For example, the container 103 has a hole through which one workpiece 101 is arranged in a predetermined orientation. The control unit 90 repeats the operation of step S6 while changing the position of the robot hand 20, thereby transporting the multiple held workpieces 101 one by one to different predetermined positions. The rod unit 24 is disposed on the Y2 direction side of the robot hand 20, and the imaging unit 40 is also disposed on the Y2 direction side of the robot hand 20 via the support unit 13.This prevents the imaging unit 40 from physically interfering when the workpiece 101 is discharged into a container 103 arranged on the Y1 side of the robot hand 20 by pressing the cap 101a of the workpiece 101 with the rod unit 24.

[0047] [Effects of this embodiment] In this embodiment, as described above, the robot hand 20 includes the holding unit 23, which is disposed closer to the base ends 21 b of the pair of fingers 21 than the hoisting unit 22, and which presses and holds the plurality of workpieces 101 wound up by the hoisting unit 22. This allows the holding unit 23 to hold the plurality of workpieces 101 together, so that the robot hand 20 can hold the plurality of workpieces 101 together. Therefore, the work time required to transport the plurality of workpieces 101 can be shortened compared to when the robot hand 20 holds the workpieces 101 one by one. As a result, an increase in work time can be suppressed when transporting the plurality of workpieces 101.

[0048] The holding unit 23 holds the multiple workpieces 101 wound up by the hoisting unit 22 in a lined-up state between the pair of fingers 21 from the tip end 21 a toward the base end 21 b. As a result, the multiple workpieces 101 wound up by the hoisting unit 22 are held in the holding unit 23 in a lined-up state from the tip end 21 a toward the base end 21 b, so that the multiple held workpieces 101 can be easily discharged one by one from the robot hand 20. Therefore, when multiple workpieces 101 are held together, each of the multiple workpieces 101 can be easily transported to different positions. As a result, even when multiple workpieces 101 are transported to different positions, an increase in operation time can be suppressed.

[0049] The holder 23 includes an elastic member 23a that uses elastic force to press the multiple workpieces 101. As a result, compared to when a drive mechanism such as an actuator is used to press the multiple workpieces 101 collectively at the holder 23, pressing the multiple workpieces 101 using elastic force eliminates the need for a drive mechanism, thereby reducing the complexity of the structure of the robot hand 20. Therefore, the structure of the robot hand 20 can be reduced in complexity, and an increase in operation time when transporting multiple workpieces 101 can be reduced.

[0050] The robot hand 20 includes a pair of elastic members 23a arranged on each of the pair of fingers 21 while facing each other. The pair of elastic members 23a press the multiple workpieces 101 with elastic force in the direction in which the pair of fingers 21 face each other. As a result, compared to a case in which the elastic member 23a is arranged on only one of the pair of fingers 21, the multiple workpieces 101 can be more securely held in the holder 23 because the elastic member 23a is arranged on each of the pair of fingers 21. Therefore, it is possible to prevent the multiple workpieces 101 held by the robot hand 20 from falling off, and therefore the stability of the transport operation can be improved when transporting multiple workpieces 101.

[0051] The elastic member 23a includes a leaf spring that flexes and deforms to press the multiple workpieces 101 with its elastic force. This allows the multiple workpieces 101 to be held by the elastic member 23a, which includes a leaf spring with a relatively simple structure, with its elastic force, thereby preventing the robot hand 20 from becoming too complicated in configuration. The holding unit 23 also includes a flexible contact member 23b that is disposed on the surface of the elastic member 23a in the direction in which the pair of fingers 21 face each other. This allows the flexible contact member 23b to abut against the workpiece 101 while deforming to conform to the shape of the workpiece 101 on the surface of the elastic member 23a, thereby allowing the elastic force of the elastic member 23a to be effectively applied to the workpiece 101. This allows the holding unit 23 to hold the workpiece 101 more reliably.

[0052] The hoisting unit 22 includes a pair of belt members 22a arranged spaced apart from each other on at least one of the pair of fingers 21. The pair of belt members 22a hoist each of the multiple workpieces 101 along directions parallel to each other toward the base ends 21b of the pair of fingers 21. As a result, the pair of belt members 22a hoist the workpieces 101 along directions parallel to each other and toward the base ends 21b of the pair of fingers 21. Therefore, even if the workpiece 101 is hoisted in a state inclined obliquely with respect to the direction in which the pair of belt members 22a are aligned, a moment of force that rotates the workpiece 101 to eliminate the inclination can be generated at the ends of the pair of belt members 22a toward the base ends 21b of the pair of belt members 22a. In other words, to the workpiece 101 hoisted in a state inclined obliquely, no force is applied from one of the pair of belt members 22a to the ends of the pair of belt members 22a toward the base ends 21b of the pair of belt members 22a, but only from the other. Therefore, at the end of the pair of belt members 22a facing the base end 21b, the wound-up workpiece 101 rotates with the direction in which the pair of finger portions 21 face each other as the rotation axis. This eliminates the tilt of each of the multiple workpieces 101 wound up by the winding portion 22, so that the multiple workpieces 101 can be held in a state in which the tilts of the multiple workpieces 101 are aligned in the holding portion 23. As a result, the multiple workpieces 101 can be held more stably than when the tilts of the multiple workpieces 101 held by the holding portion 23 vary.

[0053] The elastic member 23a is arranged along the pair of finger portions 21 from the pair of belt members 22a toward the base end 21b, with the end portion closer to the tip end 21a being positioned between the pair of belt members 22a. This allows the workpiece 101 wound up by the pair of belt members 22a to be more securely held by the elastic force of the elastic member 23a. Therefore, since multiple workpieces 101 can be more securely held, the increase in operation time when transporting multiple workpieces 101 can be suppressed and the stability of the transport operation can be further improved. Furthermore, for workpieces 101 wound up in an oblique state in the hoisting section 22, a force acts between one of the pair of belt members 22a applying a force to the workpiece 101 at the end of the pair of belt members 22a toward the base end 21b and the elastic member 23a arranged overlapping between the pair of belt members 22a. This allows a rotational force to be applied to align the orientation of the workpiece 101 along the direction in which the pair of belt members 22a are aligned. This makes it easy to align the orientation of multiple workpieces 101 held in the holding section 23.

[0054] The robot hand 20 includes a rod portion 24 as a pressing portion that presses the multiple workpieces 101 held by the holding portion 23 from the base end portion 21 b toward the tip end portion 21 a. As a result, when the multiple workpieces 101 held by the finger portions 21 are to be discharged from the robot hand 20, the rod portion 24 presses the multiple workpieces 101, thereby making it possible to easily move the workpieces 101 toward the tip end portion 21 a. Therefore, the operation of discharging the held workpieces 101 can be performed more smoothly, and an increase in the operation time when transporting multiple workpieces 101 can be further suppressed.

[0055] The robot hand 20 includes a biasing unit 34a that biases the pair of fingers 21 by elastic force at least toward the closing directions that face each other. When the pair of fingers 21 sandwich and hold each of the multiple workpieces 101, the sandwiched multiple workpieces 101 cause the fingers 21 to spread in the opening direction away from each other while resisting the elastic force of the biasing unit 34a. As a result, the sandwiched workpieces 101 cause the fingers 21 to spread in the opening direction away from each other while resisting the elastic force of the biasing unit 34a, so that the workpieces 101 can be more reliably hoisted up by the hoisting unit 22. This makes it possible to more reliably perform the operation of holding the workpieces 101 between the fingers 21. Furthermore, in this embodiment, the pair of fingers 21 move with an elastic force applied by the biasing portions 34 a and 34 b, and therefore even if the distance between the pair of fingers 21 when holding the workpiece 101 is smaller than the width of the workpiece 101 or if the positions of the pair of fingers 21 are misaligned with respect to the position of the workpiece 101, the pair of fingers 21 can move against the biasing forces of the biasing portions 34 a and 34 b, thereby allowing the hoisting portion 22 to hoist and hold the workpiece 101. Therefore, even if the positional accuracy of the opening and closing operations of the pair of fingers 21 or the accuracy of detecting the position of the workpiece 101 is low, the workpiece 101 can be held, which facilitates control when holding multiple workpieces 101 by the robot hand 20.

[0056] The robot hand 20 includes a sensor unit 25 that detects each of the multiple workpieces 101 held by the pair of fingers 21. As a result, when multiple workpieces 101 are held, the sensor unit 25 can detect each of the multiple workpieces 101 held by the pair of fingers 21. Therefore, based on the detection result by the sensor unit 25, it is possible to easily perform control such as determining whether a workpiece 101 has been held or detecting the number of workpieces 101 held by the pair of fingers 21. Therefore, the accuracy of the control for holding multiple workpieces 101 can be easily improved. Furthermore, when the sensor unit 25 is disposed on the pair of fingers 21, the workpieces 101 held by the pair of fingers 21 can be detected more accurately than when the sensor unit 25 is disposed at the base end of the robot hand 20. Furthermore, when a pressure sensor that detects pressure is disposed as the sensor unit 25, the pressure from the workpiece 101 sandwiched between the pair of fingers 21 can be detected, thereby accurately detecting the held workpiece 101 regardless of the weight of the workpiece 101.

[0057] The control unit 90 clamps and holds each of the multiple workpieces 101 stacked in bulk one by one with a pair of fingers 21. By clamping and holding each of the multiple workpieces 101 stacked in bulk one by one, the held workpieces 101 can be easily discharged one by one in order. Therefore, each of the multiple workpieces 101 can be easily transported to a predetermined position one by one.

[0058] The robot system 100 includes an imaging unit 40 that captures an image of the plurality of workpieces 101 before they are held by the pair of fingers 21. The control unit 90 controls the holding unit 23 to hold the plurality of workpieces 101 with the same orientation based on the image 40a captured by the imaging unit 40. This allows the plurality of workpieces 101 to be easily transported with the same orientation, and allows the workpieces 101 held with the same orientation to be easily discharged from the destination. Therefore, in a kitting operation, which is an operation of arranging parts, the workpieces 101 can be easily arranged with the same orientation.

[0059] The holding unit 23 holds the multiple workpieces 101 wound up by the hoisting unit 22, aligned between the pair of fingers 21 from the tip end 21a toward the base end 21b. When the holding unit 23 is holding the multiple workpieces 101 aligned, the control unit 90 adjusts the positions of the multiple workpieces 101 by moving the pair of fingers 21 in an opening direction away from each other. By moving the pair of fingers 21 in the opening direction, the multiple workpieces 101 held by the holding unit 23 can be temporarily released from their pressed state. Therefore, by moving the pair of fingers 21 in the opening direction, the multiple workpieces 101 held in a misaligned state by the holding unit 23 can be moved and adjusted to align their positions. As a result, the positions at which the multiple workpieces 101 are held by the pair of fingers 21 can be aligned, allowing the operation of discharging the held multiple workpieces 101 to be performed more accurately.

[0060] The robot system 100 includes a rod portion 24 as a pressing portion that presses the multiple workpieces 101 held by the holding portion 23 from the base end portion 21 b toward the tip end portion 21 a. The control portion 90 ejects each of the multiple workpieces 101 pressed by the rod portion 24 from the base end portion 21 b toward the tip end portion 21 a by rotating the hoisting portion 22 in the reverse direction. This allows the robot system 100 to easily control the ejection of each of the multiple workpieces 101 held by the robot hand 20. Therefore, each of the multiple workpieces 101 can be transported to a predetermined position with high precision.

[0061] [Modifications] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present disclosure is defined by the claims, not by the description of the above-mentioned embodiments, and includes all modifications (modifications) within the meaning and scope of the claims.

[0062] In the above embodiment, an example was shown in which the robot arm unit 10 to which the robot hand 20 is attached is a six-axis vertically articulated robot arm, but the present disclosure is not limited to this. In the present disclosure, the robot arm unit may be a vertically articulated robot arm having a number of axes other than six, or may be a horizontally articulated robot arm. The robot arm unit may also have a parallel link mechanism. Furthermore, the robot hand holding the workpiece may be moved by a movement mechanism other than a robot arm, such as a linear movement mechanism having a slide mechanism.

[0063] In the above embodiment, an example has been described in which the support unit 13 connected to the tip of the robot arm unit 10 is arranged on the Z1 direction side of the main body unit 20 a, opposite to the direction in which the finger units 21 are arranged, but the present disclosure is not limited to this. In the present disclosure, the support unit may be arranged on a side surface of the main body unit that is perpendicular to the direction in which the finger units extend. In other words, the tip of the robot arm unit may be connected to the side of the main body unit.

[0064] In the above embodiment, an example has been shown in which the robot arm unit 10 to which the robot hand 20 is attached is attached to a stand 12 arranged on a floor surface, but the present disclosure is not limited to this. In the present disclosure, the robot arm unit may be arranged on a wall surface or a ceiling surface. Also, the robot arm unit may be arranged on a movable cart unit having wheels and a drive unit for driving the wheels. Also, the robot hand according to the present disclosure may be arranged on a robot that moves using legs, such as a bipedal robot or a quadrupedal robot.

[0065] In the above embodiment, an example was shown in which the holding portion 23 including the elastic member 23a that presses the multiple workpieces 101 by elastic force is disposed on each of the pair of fingers 21, but the present disclosure is not limited to this. In the present disclosure, the holding portion may be configured to include an actuator that is operated by electric drive or the like, and the multiple workpieces may be pressed by the driving force of the actuator. Also, the holding portion may be disposed on only one of the pair of fingers.

[0066] In the above embodiment, an example was shown in which the elastic member 23a of the holding portion 23 includes a leaf spring having bent portions at both ends, but the present disclosure is not limited to this. In the present disclosure, the holding portion may press the workpiece using an elastic member other than a leaf spring. For example, the elastic member may include a coil spring or a torsion spring. The elastic member may also include an elastic material such as rubber. The elastic member may also be a cantilever-shaped leaf spring having a bent portion at only one end. A combination of multiple leaf springs may also be arranged in the holding portion. The holding portion may also not include a contact member arranged on the surface of the elastic member. That is, the elastic member may directly abut the workpiece.

[0067] In the above embodiment, an example has been shown in which a hoisting unit 22 including a pair of belt members 22a is arranged on each of a pair of fingers 21, but the present disclosure is not limited to this. In the present disclosure, the hoisting unit may include one belt member. Also, a hoisting unit may be arranged on only one of a pair of fingers. Also, a pair of belt members may be arranged on one of the pair of fingers, and one belt member may be arranged on the other. Also, the hoisting unit may not include a belt member. For example, the hoisting unit may include a cylindrical roller member that is rotationally driven to hoist up a workpiece, and the roller member may hoist up multiple workpieces.

[0068] In the above embodiment, an example was shown in which a portion of the elastic member 23a was disposed between the pair of belt members 22a, but the present disclosure is not limited to this. In the present disclosure, the elastic member does not have to be disposed between the pair of belt members. That is, the elastic member may be disposed at a position separated from the belt members in the direction from the distal end to the proximal end of the finger portion.

[0069] In the above embodiment, an example was shown in which the rod portion 24 serving as a pressing portion that presses the multiple workpieces 101 held by the holding portion 23 and the motor 33 serving as a drive source for the rod portion 24 are provided, but the present disclosure is not limited to this. In the present disclosure, a pressing portion may not be provided. In that case, for example, the robot hand may be tilted so that the held workpieces are moved toward the tip end by gravity. Furthermore, when a pressing portion is provided, a driving portion such as a motor that drives the pressing portion may not be provided. For example, the pressing portion may be moved by the elastic force of an elastic member such as a coil spring, and the multiple workpieces held by the holding portion may be pressed toward the tip end of the fingers.

[0070] In the above embodiment, an example was described in which the pair of fingers 21 move relative to the main body 20a independently of the drive by the drive unit 30 and are biased by the biasing units 34a and 34b. However, the present disclosure is not limited to this. In the present disclosure, a biasing unit for biasing the fingers may not be provided. Furthermore, the biasing unit may bias the fingers at least in a direction toward each other, but not in a direction toward the tip of the finger. Furthermore, the fingers may not move independently of the drive by the drive unit. In other words, the fingers may not move passively due to contact with the workpiece, for example. Furthermore, the biasing unit may be configured to bias the fingers with an elastic force using a leaf spring or a torsion spring. Furthermore, the biasing unit may be provided in the central portion of the finger rather than the base end of the finger. For example, a movable portion may be provided at the end of the central portion of the finger toward the base end of the roll-up portion, and a biasing unit may be provided in the movable portion. Furthermore, in a movement separate from the driving of the finger portion by the driving portion, rotation by a rotating member may be performed instead of linear movement by a linear guide. In this case, the pair of finger portions may be rotated so as to move away from each other. The finger portions may be configured to swing in a direction moving away from each other and a direction moving closer to each other.

[0071] In the above embodiment, an example was shown in which the sensor unit 25, which is a photoelectric sensor that detects each of the multiple workpieces 101 held by the fingers 21, is disposed. However, the present disclosure is not limited to this. In the present disclosure, a weight sensor that detects the held workpieces may be disposed as the sensor unit. For example, a load cell type or strain detection type weight sensor may be disposed as the sensor unit. The sensor unit may be disposed between the robot hand and the robot arm. In this case, the wiring for outputting a signal from the sensor unit can be shortened compared to when the sensor unit is disposed at the tip of the robot hand, such as the fingers, thereby suppressing the complexity of the configuration of the robot hand.

[0072] In the above embodiment, a plurality of bolts stacked in bulk as the plurality of workpieces 101 are clamped and held one by one between the pair of fingers 21, and the holding unit 23 holds the plurality of workpieces 101 in a lined state between the pair of fingers 21 from the tip end 21 a to the base end 21 b. However, the present disclosure is not limited to this. In the present disclosure, the plurality of workpieces may be held all at once rather than one by one. Furthermore, the holding unit may hold the plurality of workpieces in a non-lined state. Furthermore, workpieces that are not stacked in bulk but arranged in an order may be held by the pair of fingers. Furthermore, the plurality of workpieces do not have to be fastening members such as bolts. For example, the plurality of workpieces may be cylindrical or prismatic assembly parts. Furthermore, the plurality of workpieces may have a shape other than a cylindrical shape, such as a cubic shape or a spherical shape.

[0073] In the above embodiment, the positions and orientations of the multiple workpieces 101 are detected based on the captured image 40a by the imaging unit 40, and the multiple workpieces 101 are held in a state where their orientations are aligned. However, the present disclosure is not limited to this. In the present disclosure, the orientations of the multiple workpieces held in the holder may be different from each other. For example, if the workpieces are fastening members such as bolts having caps and threaded portions, the caps of the multiple workpieces may be held in the holder with their caps oriented in different directions. Furthermore, the imaging unit may not be provided. The positions at which the multiple workpieces are placed may be set in advance so that the positions of the workpieces are not detected. Furthermore, the workpieces may be detected before they are held by a proximity sensor such as a capacitance sensor or a photoelectric sensor, which is different from the imaging unit. Furthermore, the workpieces may be detected before they are held by a distance sensor such as a ToF (Time of Flight) system or a triangulation system.

[0074] The imaging unit may also be a 3D camera that captures three-dimensional images instead of two-dimensional images. For example, a stereo camera or a structured illumination 3D camera may be disposed as the imaging unit. Here, the accuracy of the workpiece position detected by a stereo 3D camera from a three-dimensional image is relatively low compared to a structured illumination 3D camera. In the present disclosure, the pair of fingers move while an elastic force is applied by the biasing unit. Therefore, even when the accuracy of the workpiece position detection is relatively low, the finger movement can reliably hold the workpiece. Furthermore, the imaging unit may be disposed on a side of the robot hand's main body rather than attached to a support portion disposed on the base end side of the main body. Alternatively, the imaging unit may be disposed on the robot arm. Alternatively, the imaging unit may be disposed on the robot main body to which the robot arm is attached, or on a stand, etc. Alternatively, the imaging unit may be disposed separately from the robot arm and the robot hand. For example, the imaging unit may be disposed on a ceiling or a wall, or on a workpiece placement portion on which the workpiece is placed.

[0075] In the above embodiment, an example was shown in which the positions of the multiple workpieces 101 were adjusted by gravity by moving the pair of fingers 21 in the opening direction away from each other while the holder 23 was holding the multiple workpieces 101 in a line. However, the present disclosure is not limited to this. In the present disclosure, the workpieces may be transported without moving the pair of fingers in the opening direction to adjust the positions of the multiple workpieces held by the holder. Furthermore, while the pair of fingers are moved in the opening direction, the positions of the multiple workpieces may be adjusted by a driving force from an actuator arranged separately from the fingers. Furthermore, while the pair of fingers are moved in the opening direction, the positions of the multiple workpieces may be adjusted to be aligned by moving them so that they abut against a member such as a jig.

[0076] In the above embodiment, an example was shown in which the positions of the multiple workpieces 101 were adjusted by gravity by moving the pair of fingers 21 in the opening direction away from each other while the holder 23 was holding the multiple workpieces 101 in a line. However, the present disclosure is not limited to this. In the present disclosure, the workpieces may be transported without moving the pair of fingers in the opening direction to adjust the positions of the multiple workpieces held by the holder. Furthermore, while the pair of fingers are moved in the opening direction, the positions of the multiple workpieces may be adjusted by a driving force from an actuator arranged separately from the fingers. Furthermore, while the pair of fingers are moved in the opening direction, the positions of the multiple workpieces may be adjusted to be aligned by moving them so that they abut against a member such as a jig.

[0077] In the above embodiment, an example has been shown in which the rod portion 24 as a pressing portion presses the multiple workpieces 101 one by one to the hoisting portion 22, and the workpieces 101 are discharged one by one by the reverse rotation of the hoisting portion 22, but the present disclosure is not limited to this. In the present disclosure, when discharging the workpieces, the multiple workpieces may be moved collectively to the position of the hoisting portion. In this case, the multiple workpieces may be discharged one by one by controlling the amount of movement of the rotation drive of the hoisting portion.

[0078] In the above embodiment, an example was shown in which the drive unit 30, which serves as a drive source for the operation of the robot hand 20, includes a motor 31 that drives the opening and closing movement of the pair of fingers 21, a motor 32 that drives the belt member 22a of the hoisting unit 22, and a motor 33 that drives the rod unit 24 serving as a pressing unit. However, the present disclosure is not limited to this. In the present disclosure, the operation of the robot hand may be performed by a drive source other than a motor. For example, an air actuator may be provided for opening and closing the fingers. Furthermore, each of the pair of fingers may be operated by a drive unit that is separately provided. Furthermore, in the robot hand, the transmission mechanism that transmits the driving force of the drive unit is not limited to the example in the above embodiment. It is also possible to use multiple types of transmission mechanisms, including a rack-and-pinion mechanism, a ball-screw mechanism, a belt-and-pulley mechanism, or a combination of multiple gear mechanisms.

[0079] In the above embodiment, an example was shown in which the pair of belt members 22a were rotated in the same direction in parallel in conjunction with each other, but the present disclosure is not limited to this. In the present disclosure, the pair of belt members may be rotated in opposite directions. That is, the direction of rotation of the pair of belt members may be changed separately for each of the pair of belt members. By aligning the rotational drive directions of the pair of belt members, it is possible to wind up the workpiece, and by reversing the rotational drive directions of the pair of belt members, it is possible to rotate the workpiece while holding it. For example, by separately controlling the rotational drive of the pair of belt members, the orientation of the workpiece at the hoisting section may be rotated to align the orientation of multiple workpieces held in the holding section.

[0080] In the above embodiment, an example has been shown in which the control of the operation of the robot arm unit 10 and the robot hand 20 and the control of the detection of the workpiece 101 based on the captured image 40a are performed by a common control unit 90, but the present disclosure is not limited to this. In the present disclosure, the control of the operation of the robot arm unit and the robot hand and the control of the detection of the workpiece may be performed by separate control devices.

[0081] The functions of the elements disclosed herein can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuitry. In this disclosure, a circuit, unit, or means is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where the hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or processor.

[0082] Aspects It will be appreciated by those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0083] (Aspect 1) A robot hand comprising: a pair of fingers that clamp and hold each of a plurality of workpieces; a hoisting portion that is disposed at the tip end of the pair of fingers and that winds up each of the plurality of workpieces by rotational drive; and a holding portion that is disposed closer to the base end of the pair of fingers than the hoisting portion and that holds the plurality of workpieces hoisted up by the hoisting portion together by pressing them.

[0084] (Aspect 2) The robot hand according to Aspect 1, wherein the holding unit holds the plurality of workpieces wound up by the hoisting unit in a lined-up state from the tip end toward the base end between the pair of fingers.

[0085] (Aspect 3) The robot hand according to aspect 1 or aspect 2, wherein the holding portion includes an elastic member that presses the plurality of workpieces with an elastic force.

[0086] (Aspect 4) The robot hand according to Aspect 3, wherein the elastic members include a pair of the elastic members arranged on each of the pair of fingers in a state facing each other, and the pair of elastic members press the plurality of workpieces with elastic force along the direction in which the pair of fingers face each other.

[0087] (Aspect 5) The robot hand according to aspect 3 or 4, wherein the elastic member includes a leaf spring that flexes and deforms to press the plurality of workpieces with an elastic force.

[0088] (Aspect 6) The robot hand according to any one of Aspects 3 to 5, wherein the hoisting section includes a pair of belt members arranged spaced apart from each other on at least one of the pair of fingers, and the pair of belt members hoist each of the plurality of workpieces toward the base end along directions parallel to each other.

[0089] (Aspect 7) The robot hand according to Aspect 6, wherein the elastic member is disposed along the pair of finger portions from the pair of belt members toward the base end, and an end portion closer to the tip end is disposed between the pair of belt members.

[0090] (Aspect 8) The robot hand according to any one of Aspects 1 to 7, further comprising a pressing unit that presses the plurality of workpieces held by the holding unit from the base end toward the tip end.

[0091] (Aspect 9) A robot hand according to any one of Aspects 1 to 8, further comprising a biasing portion that biases the pair of finger portions at least toward opposing closing directions with an elastic force, and when the pair of finger portions clamp and hold each of the multiple workpieces, the clamped multiple workpieces cause the pair of finger portions to spread in an opening direction away from each other while resisting the elastic force of the biasing portion.

[0092] (Aspect 10) The robot hand according to any one of Aspects 1 to 9, further comprising a sensor unit that detects each of the plurality of workpieces held by the pair of fingers.

[0093] (Aspect 11) A robot system comprising: a robot hand including a pair of fingers that clamp and hold each of a plurality of workpieces, a hoisting section that is located at the tip of the pair of fingers and that hoists each of the plurality of workpieces by rotational drive, and a holding section that is located closer to the base end of the pair of fingers than the hoisting section and that holds the plurality of workpieces hoisted by the hoisting section together by pressing them; a robot arm section to which the robot hand is attached; and a control section that controls the operation of the robot hand and the robot arm section.

[0094] (Aspect 12) The robot system according to aspect 11, wherein the control unit clamps and holds each of the plurality of randomly stacked workpieces with the pair of fingers in turn, one by one.

[0095] (Aspect 13) The robot system according to aspect 11 or aspect 12, further comprising an imaging unit that images the plurality of workpieces before they are held by the pair of fingers, wherein the control unit causes the holding unit to hold the plurality of workpieces in an aligned orientation based on the image captured by the imaging unit.

[0096] (Aspect 14) The robot system according to any one of Aspects 11 to 13, wherein the holding unit holds the plurality of workpieces wound up by the hoisting unit in a lined-up state between the pair of fingers from the tip end toward the base end, and the control unit adjusts positions of the plurality of workpieces by moving the pair of fingers in an opening direction away from each other while the holding unit is holding the plurality of workpieces in a lined-up state.

[0097] (Aspect 15) The robot system according to any one of Aspects 11 to 14, further comprising a pressing unit that presses the plurality of workpieces held by the holding unit from the base end toward the tip end, and the control unit ejects each of the plurality of workpieces pressed by the pressing unit from the base end toward the tip end by rotating the hoisting unit in the reverse direction.

Claims

1. A robot hand comprising: a pair of fingers that clamp and hold each of a plurality of workpieces; a hoisting section that is located at the tip of the pair of fingers and that winds up each of the plurality of workpieces by rotational drive; and a holding section that is located closer to the base end of the pair of fingers than the hoisting section and that holds the plurality of workpieces hoisted up by the hoisting section together by pressing them.

2. A robot hand as described in claim 1, wherein the holding portion holds the plurality of workpieces wound up by the hoisting portion in a lined-up state from the tip end to the base end between the pair of fingers.

3. The robot hand according to claim 1, wherein the holding portion includes an elastic member that presses the plurality of workpieces with an elastic force.

4. The robot hand described in claim 3, wherein the elastic members include a pair of elastic members arranged on each of the pair of fingers in a state facing each other, and the pair of elastic members press the multiple workpieces with elastic force along the direction in which the pair of fingers face each other.

5. A robot hand according to claim 3, wherein the elastic member includes a leaf spring that flexes and deforms to press the plurality of workpieces with an elastic force.

6. A robot hand as described in claim 3, wherein the hoisting section includes a pair of belt members arranged spaced apart from each other on at least one of the pair of fingers, and the pair of belt members hoist each of the plurality of workpieces toward the base end in directions parallel to each other.

7. A robot hand according to claim 6, wherein the elastic member is arranged along the pair of fingers from the pair of belt members toward the base end, and the end portion closer to the tip end is arranged between the pair of belt members.

8. The robot hand according to claim 1, further comprising a pressing section that presses the plurality of workpieces held by the holding section from the base end toward the tip end.

9. A robot hand as described in claim 1, further comprising a biasing section that biases the pair of finger sections by elastic force at least in opposing closing directions, and when the pair of finger sections clamp and hold each of the multiple workpieces, the clamped multiple workpieces cause the pair of finger sections to spread apart in opening directions against the elastic force of the biasing section.

10. The robot hand according to claim 1, further comprising a sensor unit that detects each of the plurality of workpieces held by the pair of fingers.

11. A robot system comprising: a robot hand including a pair of fingers that clamp and hold each of a plurality of workpieces, a hoisting section that is located at the tip of the pair of fingers and that winds up each of the plurality of workpieces by rotational drive, and a holding section that is located closer to the base end of the pair of fingers than the hoisting section and that holds the plurality of workpieces wound up by the hoisting section together by pressing them; a robot arm section to which the robot hand is attached; and a control section that controls the operation of the robot hand and the robot arm section.

12. The robot system according to claim 11, wherein the control unit clamps and holds each of the plurality of randomly stacked workpieces one by one with the pair of fingers.

13. The robot system according to claim 11, further comprising an imaging unit that images the plurality of workpieces before they are held by the pair of fingers, and the control unit causes the holding unit to hold the plurality of workpieces in an aligned orientation based on the image captured by the imaging unit.

14. The robot system described in claim 11, wherein the holding unit holds the multiple workpieces wound up by the hoisting unit in a lined-up state between the pair of fingers from the tip end to the base end, and the control unit adjusts the positions of the multiple workpieces by moving the pair of fingers in an opening direction away from each other while the holding unit is holding the multiple workpieces in a lined-up state.

15. The robot system according to claim 11, further comprising a pressing unit that presses the plurality of workpieces held by the holding unit from the base end toward the tip end, and the control unit ejects each of the plurality of workpieces pressed by the pressing unit from the base end toward the tip end by rotating the hoisting unit in the reverse direction.

Images