Control device, robot hand system, and method for generating holding position

Abstract

This control device, using a control unit, hand information, and first information that includes the external shape of a workpiece, generates, as a holding position, a position of a hand of which a first adhesion section has been identified, which is an adhesion section that is among a plurality of adhesion sections and is to be used to hold the workpiece. If the workpiece is smaller than the hand, the control unit: determines the number of reference sides to be used to generate at least one candidate position that is a candidate for the holding position; and sets reference sides for a workpiece circumscribed rectangle. The control unit generates, from a first state in which the workpiece circumscribed rectangle and a hand circumscribed rectangle overlap, a second state in which the hand has been shifted so that the hand circumscribed rectangle does not extend beyond the reference sides. From among the plurality of adhesion sections in the second state, the control unit identifies, as the first adhesion section, an adhesion section overlapping the workpiece. The control unit, using the position of the hand in the second state in which the first adhesion section was identified, generates at least one candidate position.

Description

Control device, robot hand system, and holding position generation method

[0001] The present disclosure relates to a control device that generates a holding position, a robot hand system, and a method for generating a holding position.

[0002] A technology for holding a workpiece using a hand equipped with multiple suction pads is known. JP 2019-162684 A describes a control device that determines the holding position of the hand based on multiple models of suction (holding) modes by the suction pads, which are determined by the number and arrangement of the suction pads, and information about the workpiece. The models are registered in advance in the control device.

[0003] In the technology described in JP 2019-162684 A, the number of models increases depending on the number of suction pads, and it may take time to register the models in the control device. In addition, determining the holding position from multiple models may increase the calculation load on the control device. As a result, there is a risk of the speed of the workpiece transport operation decreasing.

[0004] The present disclosure has been made to solve at least part of the above-mentioned problems, and can be realized, for example, in the following forms.

[0005] According to a first aspect of the present disclosure, a control device is provided that generates a holding position for holding a workpiece placed at a transfer source using a hand having multiple suction units and placing the workpiece at a transfer destination. The control device includes a control unit that generates the holding position using hand information including the outer shape of the hand and the shape and arrangement of the multiple suction units on the hand, and first information including the outer shape of the workpiece at the transfer source. The holding position includes a position of the hand at which a first suction unit, which is a suction unit used to hold the workpiece, is identified among the multiple suction units. When the workpiece is smaller than the hand, the control unit determines the number of reference edges used to generate at least one candidate position as a candidate for the holding position, and sets the reference edges to a workpiece circumscribing rectangle tangent to the outer shape of the workpiece. The control unit generates a second state in which the hand is shifted from a first state in which the workpiece circumscribing rectangle and a hand circumscribing rectangle tangent to the outer shape of the hand are overlapped so that the hand circumscribing rectangle does not protrude from the reference edges. The control unit identifies an suction unit, among the multiple suction units, that overlaps the workpiece in the second state as the first suction unit. The control unit generates the at least one candidate position using a position of the hand in the second state in which the first suction unit is identified.

[0006] According to a second aspect of the present disclosure, a robot hand system is provided. The robot hand system includes a handling device including a hand with multiple suction parts, configured to hold a workpiece placed at a transfer source using the hand and place the workpiece at a transfer destination; a first control device, a second control device, and a third control device. The first control device is configured to generate a holding position, which is a position of the hand at which a first suction part, which is a suction part used to hold the workpiece, is identified, using hand information including the outer shape of the hand and the shape and arrangement of the multiple suction parts on the hand, and first information including the outer shape of the workpiece at the transfer source. When the workpiece is smaller than the hand, the first control device determines the number of reference edges used to generate at least one candidate position for the holding position, and sets the reference edges relative to a workpiece circumscribing rectangle tangent to the outer shape of the workpiece. The first control device generates a second state in which the hand is shifted from a first state in which the workpiece circumscribing rectangle and a hand circumscribing rectangle tangent to the outer shape of the hand are superimposed, so that the hand circumscribing rectangle does not protrude from the reference edges. The first control device identifies, as the first suction portion, a suction portion that overlaps with the workpiece among the plurality of suction portions in the second state. The first control device generates the at least one candidate position using the position of the hand in the second state in which the first suction portion was identified. The second control device determines the holding position and a route from the transfer source to the transfer destination using the at least one candidate position output from the first control device. The third control device controls the handling device to hold the workpiece at the holding position and move the hand along the route.

[0007] According to a third aspect of the present disclosure, there is provided a method for generating a holding position for holding a workpiece placed at a transfer source using a hand having multiple suction parts and placing the workpiece at a transfer destination. The holding position is a position of the hand at which a first suction part, which is a suction part used to hold the workpiece among the multiple suction parts, is identified. The method for generating the holding position is a method for generating the holding position using hand information including an outer shape of the hand and the shape and arrangement of the multiple suction parts on the hand, and first information including the outer shape of the workpiece at the transfer source. The holding position generation method includes: (i) when the workpiece is smaller than the hand, (ii) determining the number of reference edges to be used to generate at least one candidate position that is a candidate for the holding position; (iii) setting the reference edges with respect to a work circumscribing rectangle that is tangent to the outline of the workpiece; (iv) generating a second state in which the hand is shifted from a first state in which the work circumscribing rectangle and a hand circumscribing rectangle that is tangent to the outline of the hand are superimposed so that the hand circumscribing rectangle does not protrude from the reference edges; (v) identifying an suction portion among the multiple suction portions that overlaps the workpiece as the first suction portion in the second state; and (vi) generating the at least one candidate position using the position of the hand in the second state in which the first suction portion is identified.

[0008] 1 is a schematic diagram of a robot hand system according to a first embodiment; FIG. 2 is a block diagram illustrating the configuration of a robot hand system; FIG. 3 is a bottom view of a hand; FIG. 4 is a flowchart of a pick-and-place process; FIG. 5 is a flowchart of a holding position generation process; FIG. 6 is a diagram illustrating step S130 of the holding position generation process; FIG. 7 is another diagram illustrating step S130 of the holding position generation process; FIG. 8 is a flowchart of a candidate position generation process; FIG. 9 is a diagram illustrating step S210 of the candidate position generation process; FIG. 10 is a diagram illustrating a process of setting a reference edge and a shift process; FIG. 11 is a diagram illustrating a process of identifying a first suction unit; FIG. 12 is a diagram illustrating a correction process; FIG. 13 is a diagram illustrating a shift process when a reference edge is set for edges w2 and w3; FIG. 14 is a diagram illustrating a shift process when a reference edge is set for edges w3 and w4; FIG. 15 is a diagram illustrating a shift process when a reference edge is set for edges w4 and w1; FIG. 16 is a diagram illustrating an example of a hand orientation; FIG. 17 is a diagram illustrating evaluation of a candidate position; FIG. 18 is a diagram illustrating an example of a candidate position generated by the candidate position generation process using a hand according to a second embodiment; FIG. 19 is a diagram illustrating another example of a hand used in a robot hand system.

[0009] First Embodiment FIG. 1 is a diagram illustrating an example of a robot hand system 10 including a handling device 20 according to a first embodiment. FIG. 2 is a schematic block diagram of the robot hand system 10. The robot hand system 10 according to this embodiment is configured to perform a pick-and-place operation by controlling the handling device 20 to hold a workpiece W located at a source location and place the held workpiece W at a destination location. The robot hand system 10 is not limited to systems whose primary purpose is to transport the workpiece W, such as a picking system for logistics, but also includes systems that transport the workpiece W as part of another purpose, such as product assembly. In this embodiment, the source location is a container 501, and the destination location is a container 502. The workpiece W has a substantially box shape. Note that the source and destination locations are not limited to the containers 501 and 502, but may be conveyors, parts of products, or the like, depending on the intended use of the robot hand system 10. The workpiece W is not limited to a substantially box shape and may have various shapes, such as a bag shape.

[0010] As shown in FIG. 1 , the robot hand system 10 includes a handling device 20 , a control device 200 , a first detection device 301 , a second detection device 302 , and an input device 400 .

[0011] The handling device 20 of this embodiment is a robot arm (hereinafter referred to as robot arm 20). The robot arm 20 is a vertical articulated robot having six degrees of freedom. The handling device 20 includes a plurality of joints J, a plurality of links L, a hand 100, and a first actuator 25 (see FIG. 2 ). The first actuator 25 includes a known actuator for operating the robot arm 20, such as a servo motor, an encoder, or a reducer. The handling device 20 is not limited to a robot arm, and may be any robot having a hand 100, and may be configured as, for example, an aircraft that lifts and moves the hand 100.

[0012] The hand 100 is attached to the arm tip 22 of the robot arm 20. The hand 100 is also called a robot hand, an end effector, or a tool. The hand 100 includes a base 101, a plurality of suction units S protruding from a bottom surface 102 of the base 101, and a second actuator 110 (see FIG. 2) that operates the suction units S. The suction units S are also called suction pads. The second actuator 110 includes, for example, a vacuum pump and an electric valve. In this embodiment, the arm tip 22 is configured as an attachment unit having a mechanism for attaching and detaching the hand 100. The arm tip 22 has a known locking mechanism 221 that can lock the base 101 by pressing against it. The arm tip 22 may have bolt attachment holes for fastening the base 101 of the hand 100 with bolts.

[0013] FIG. 3 is a bottom view of an example hand 100 applied to the robot hand system 10. FIG. 3 is also a view of the hand 100 viewed from a position directly facing the suction portion S. In FIG. 3, an outline Ph is indicated by a thick line. The outline Ph is the outline (outer frame, outer shape) of the hand 100 when multiple suction portions S and the bottom surface 102 are projected onto an imaginary plane Q (see FIG. 1) extending along the tip T of the suction portion S. FIG. 3 also shows a circumscribing rectangle Rh of the hand 100 that contacts the outline Ph. As shown in FIG. 3, in this embodiment, the circumscribing rectangle Rh contacts the suction portion S.

[0014] In this embodiment, the bottom surface 102 includes a substantially square first portion 104 and a substantially triangular second portion 105 with one side of the first portion 104 as its base. The multiple suction units S include suction units S1 to S5 with identical specifications. Suction units S1, S2, S3, and S4 are located at each corner of the first portion 104, and suction unit S5 is located at the vertex of the second portion 105. FIG. 3 also shows a rotation axis AX of the hand 100. The rotation axis AX is not limited to the position illustrated in FIG. 3 and may be perpendicular to any point on the bottom surface 102. In this embodiment, the suction units S1 to S5 are arranged rotationally asymmetrically with respect to the axis AX. The hand 100 can rotate around the axis AX by actuating the arm tip 22.

[0015] The robot arm 20 described above operates by the control device 200, which will be described later, controlling the first actuator 25 and the second actuator 110. The position and orientation of the hand 100 change by the control device 200 controlling the first actuator 25. The orientation is also called "posture." In this embodiment, the orientation of the hand 100 is determined by the angle of the hand 100 (bottom surface 102) relative to a predetermined reference plane and the rotation angle of the hand 100 around the axis AX. The suction units S1 to S5 of the hand 100 are selectively activated by the control device 200 controlling the second actuator 110. The suction units S1 to S5 suck in air and stop sucking in air by the control device 200 controlling the second actuator 110.

[0016] 1 and 2, the first detection device 301 is disposed near the container 501. The second detection device 302 is disposed near the container 502. In this embodiment, the first detection device 301 and the second detection device 302 are vision sensors equipped with a camera and a computer that processes images.

[0017] The first detection device 301 acquires first information including the shape of the workpiece W in the container 501. The first information is information for holding the workpiece W and includes, for example, the position of each vertex of the workpiece W relative to a predetermined reference position or reference plane, the position of the centroid of the workpiece W, and the posture of the workpiece W. In this embodiment, the position of each vertex of the workpiece W is, for example, the position (XYZ) of each vertex of the workpiece W when the Z axis is defined as the vertical direction. Note that if the shape of the workpiece W is configured by a curve, the first information may include a set of points (XYZ) that constitute the curve instead of the positions (XYZ) of each vertex of the workpiece W. In this embodiment, the first detection device 301 generates, as the first information, an outline Pw of the workpiece W generated by converting the positions of each vertex onto a virtual plane (XY) perpendicular to the vertical direction (Z direction), and a circumscribing rectangle Rw tangent to the outline Pw, and outputs the generated first information to the control device 200. The first information includes the position of the centroid Cw of the circumscribing rectangle Rw of the workpiece W on the two-dimensional plane. 1 , when a plurality of workpieces W are accommodated in the container 501, the first information includes the centroids, outer shapes Pw, and circumscribing rectangles Rw of the plurality of workpieces W. The first detection device 301 outputs the detected first information to the control device 200.

[0018] The second detection device 302 acquires second information regarding the shape of an object located at the destination. The second information is information about an object that may become an obstacle when placing the workpiece W to be transported in the container 502. The second information is used to determine the number of reference edges E, which will be described later. The second information includes, for example, position information about the inner wall 31 of the container 502 and the wall-like portion 30 formed by a virtual wall 32 defined by the surface of the workpiece W already placed in the container 502. The second detection device 302 outputs the detected second information to the control device 200.

[0019] The input device 400 is configured to be able to input various instructions to the control device 200. The instructions include, for example, an instruction to start a picking operation. As the input device 400, for example, various input terminals such as a touch panel can be applied.

[0020] The control device 200 generates a holding position for suction-holding the workpiece W placed in the container 501 by the hand 100 and placing it in the container 502. The holding position is the position of the hand 100 at which the suction unit to be used among the multiple suction units S is identified. Hereinafter, the position of the hand 100 (holding position) includes the posture of the hand 100. The holding position generated by the control device 200 of this embodiment is a holding position that can improve the filling rate of the workpiece W in the container 502. Note that, although the position of the hand 100 in this embodiment is a position relative to predetermined reference coordinates, in other embodiments, the position of the hand 100 may be a relative position of the hand 100 with respect to the workpiece W to be transported.

[0021] The control device 200 also generates a path for the hand 100 to hold the workpiece W at the generated holding position and place it in the container 502. Furthermore, the control device 200 controls the entire robot arm 20 including the hand 100 so that the hand 100 holds the workpiece W at the generated holding position and moves the hand 100 along the generated path. The control device 200 will be described in detail below.

[0022] 2, the control device 200 includes a CPU (Central Processing Unit) 210, which is a processor, a memory 220, and an interface circuit 230. The control device 200 is communicably connected to peripheral devices including the robot arm 20, a first detection device 301, a second detection device 302, and an input device 400 via the interface circuit 230. These communications can be performed using wireless communication or wired communication according to a known communication method.

[0023] The memory 220 includes a volatile memory and a non-volatile memory. The memory 220 stores a holding position generation program P1, a path generation program P2, and an operation control program P3. The CPU 210 functions as a first control unit 211, a second control unit 212, and a third control unit 213 by deploying and executing the programs P1, P2, and P3 stored in the memory 220. The first control unit 211 generates holding position candidates and holding positions for the hand 100 by executing a holding position generation process described below. The second control unit 212 generates a path for the hand 100 to hold the workpiece W at the holding position and transport the workpiece W to the container 502. The third control unit 213 controls the robot arm 20 so as to hold the workpiece W at the holding position and operate the hand 100 (robot arm 20) along the path. The first control unit 211 and the second control unit 212 are examples of a "control unit" in the present disclosure. Furthermore, the first control unit 211 is an example of a "first control device" in the present disclosure, the second control unit 212 is an example of a "second control device" in the present disclosure, and the third control unit 213 is an example of a "third control device" in the present disclosure.

[0024] The memory 220 also stores hand information 250. The hand information 250 includes information on the outer shape Ph of the hand 100 and the plurality of suction portions S. The hand information 250 is also design information specific to the hand 100. As described above, the outer shape Ph of the hand 100 is defined by the shape of the hand 100 projected onto the imaginary plane Q. The information on the suction portions S includes the outer shape, such as the diameter of each of the suction portions S1 to S5, the suction force, and the position on the bottom surface 102. The memory 220 also stores various types of information used by the second control unit 212 to generate a path, such as the configuration, singular posture, and movable range of the robot arm 20.

[0025] 4 is a flowchart of the pick-and-place process executed by the control device 200. The pick-and-place process is also called a workpiece transport process. This process is started when a start command is input to the control device 200 via the input device 400. The pick-and-place process includes a process of generating a holding position (step S100), a process of generating a path for holding the workpiece W at the holding position and transporting the workpiece W to a placement position (step S400), and a process of controlling the robot arm 20 to hold the workpiece W at the holding position and move the hand 100 along the path (step S500).

[0026] FIG. 5 is a flowchart of the holding position generation process. First, in step S110, the first control unit 211 acquires first information via the first detection device 301. In this embodiment, when the holding position generation process starts, the first detection device 301 processes an image of the container 501 captured from above to generate, as first information, the centroid Cw and outline Pw of the workpiece W in the container 501, as well as a circumscribing rectangle Rw based on the outline Pw, and outputs the first information to the control device 200. Also, in step S110, the first control unit 211 uses the first information to determine the workpiece W to be held. In this embodiment, as shown in FIG. 1, multiple workpieces W are irregularly arranged in the container 501. The first control unit 211 determines, among the multiple workpieces W in the container 501, for example, the workpiece W that is closest to the current position of the hand 100 or the workpiece W with the largest area defined by the outline Pw as the workpiece W to be held.

[0027] In step S120, the first control unit 211 acquires second information via the second detection device 302. As described above, the second information includes position information of the wall-like portion 30 defined by the inner wall 31 of the container 502 and the virtual wall 32 of the workpiece W. In step S120, the first control unit 211 uses the second information to determine a placement position for placing the workpiece W to be transported in the container 502. In order to improve the filling rate of the workpiece W in the container 502, it is preferable to place the workpiece W to be transported in a position close to or abutting the wall-like portion 30, such as the position indicated by the dashed line M in FIG. 1 . Therefore, the first control unit 211 determines, as the placement position, a position where the workpiece W is within a predetermined range of the wall-like portion 30 or a position M where the workpiece W abuts the wall-like portion 30.

[0028] In step S130, the first control unit 211 determines whether the workpiece W to be transported is smaller than the hand 100. In this embodiment, the first control unit 211 makes the determination in step S130 using the circumscribing rectangle Rw of the workpiece W and the circumscribing rectangle Rh of the hand 100. Note that the circumscribing rectangles Rw and Rh of the workpiece W and the hand 100 are all circumscribing rectangles that take rotation into consideration. More specifically, the circumscribing rectangle Rw of the workpiece W is a circumscribing rectangle that takes rotation into consideration. The circumscribing rectangle Rh of the hand 100 is a circumscribing rectangle that takes rotation into consideration so that it is parallel to the circumscribing rectangle Rw.

[0029] 6 and 7 are diagrams for explaining the determination in step S130. In FIGS. 6(a) and 7(a), the outline Pw of the workpiece W is represented by a solid line, the interior of the outline Pw is represented by hatching, and the circumscribing rectangle Rw of the workpiece W is represented by a dashed line. In addition, in FIGS. 6(b) and 7(b), the bottom surface 102 and suction portion S of the hand 100, i.e., the outline (outline, boundary) Ph of the hand 100, are represented by a solid line, and the circumscribing rectangle Rh of the hand 100 is represented by a dashed line. Note that the circumscribing rectangle Rh of the hand 100 shown in FIGS. 6(b) and 7(b) is generated using the hand information 250 stored in memory 220.

[0030] In step S130, the first control unit 211 generates a first state in which the circumscribing rectangle Rh of the hand 100 is virtually superimposed on the circumscribing rectangle Rw of the workpiece W, as shown in FIGS. 6(c) and 7(c). In the first state, the first control unit 211 aligns the centroid Cw of the circumscribing rectangle Rw of the workpiece W with the centroid Ch of the circumscribing rectangle Rh of the hand 100, and compares the sizes of the workpiece W and the hand 100. In FIG. 6(c), the circumscribing rectangle Rh of the hand 100 is smaller than the circumscribing rectangle Rw of the workpiece W (FIG. 5, step S130, NO). Therefore, the first control unit 211 advances the holding position generation process of FIG. 5 to step S140. On the other hand, in FIG. 7(c), the circumscribing rectangle Rh of the hand 100 is larger than the circumscribing rectangle Rw of the workpiece W (FIG. 5, step S130, YES). In this case, the first control unit 211 advances the holding position generation process to step S200.

[0031] First, a process performed when a negative judgment is made at step S130 in FIG. 5 will be described. If the circumscribing rectangle Rw of the workpiece W is larger than the circumscribing rectangle Rh of the hand 100, the first control unit 211 generates, as the holding position, a position of the hand 100 where the circumscribing rectangle Rh of the hand 100 fits within the circumscribing rectangle Rw of the workpiece W in step S140 in FIG. 5. In this embodiment, the first control unit 211 determines, as the holding position, the position of the hand 100 when a first position F1 based on the centroid Cw of the workpiece W and a third position F3 based on the centroid Ch of the hand 100 are aligned, as shown in FIG. 6C. The first position F1 may be the position of the centroid Cw of the workpiece W, or a position within a predetermined range centered on the centroid Cw of the workpiece W. The third position F3 may be the position of the centroid Ch of the hand 100, or a position within a predetermined range centered on the centroid Ch of the hand 100. In this embodiment, the first position F1 is the centroid Cw, and the third position F3 is the centroid Ch. If step S130 returns a negative judgment, that is, if the workpiece W is larger than the hand 100, all of the suction portions S1 to S5 of the hand 100 can be used to hold the workpiece W. Therefore, the first control unit 211 identifies the suction portions S1 to S5 as suction portions for holding the workpiece W. Hereinafter, the suction portion S for holding the workpiece W will also be referred to as the "first suction portion Ss." Thus, in step S140, the first control unit 211 generates, as a holding position, the position of the hand 100 at which the first suction portion Ss is identified. The first control unit 211 stores the generated holding position in the memory 220. Note that in step S140, the first control unit 211 may generate multiple candidate positions as holding position candidates by varying the orientation (posture) of the hand 100 and store the candidate positions in the memory 220.

[0032] On the other hand, if step S130 is judged to be positive, that is, if the circumscribing rectangle Rw of the workpiece W is smaller than the circumscribing rectangle Rh of the hand 100, the first control unit 211 advances the holding position generation process shown in Figure 5 to step S200 and executes the candidate position generation process.

[0033] 8 is a flowchart of the candidate position generation process. First, in step S210, the first control unit 211 determines the number of reference sides E. The reference sides E are sides set for the circumscribing rectangle Rw of the workpiece W. The number of reference sides E is less than the number of sides that make up the circumscribing rectangle Rw of the workpiece W.

[0034] FIG. 9 is a diagram illustrating step S210 of the candidate position generation process. In FIG. 9A, the placement position M of the workpiece W determined in step S120 is indicated by a dashed line. As shown in FIG. 9A, placement position M is a position where, when the workpiece W is placed, the workpiece W will be close to or in contact with two points: the inner wall 31 and the virtual wall 32. Therefore, the first control unit 211 determines the number of reference sides E to be two. The inner wall 31 and the virtual wall 32 form corners of placement position M. Therefore, as shown in FIG. 9B, the first control unit 211 determines the number of reference sides E to be two and determines the positional relationship of the two reference sides E to be two consecutive sides. After determining the number and positional relationship of the reference sides E, the first control unit 211 proceeds to step S220 of the candidate position generation process in FIG. 8 and sets the reference sides E for the circumscribed rectangle Rw of the workpiece W.

[0035] 10A is a diagram illustrating step S220 of the candidate position generation process. In step S220, the first control unit 211 sets a reference side E for the circumscribing rectangle Rw of the workpiece W. When setting the reference side E for two consecutive sides among the sides w1 to w4 that define the circumscribing rectangle Rw of the workpiece W, there are four possible combinations of sides: (i) sides w1 and w2, (ii) sides w2 and w3, (iii) sides w3 and w4, and (iv) sides w4 and w1. In this embodiment, as shown in FIG. 10A, the first control unit 211 sets the reference side E for (i) sides w1 and w2 among the sides w1 to w4 that define the circumscribing rectangle Rw of the workpiece W.

[0036] Next, the first control unit 211 advances the candidate position generation process of FIG. 8 to step S230 and executes a shift process. The shift process is a process of shifting the position of the hand 100 relative to the reference edge E so that the circumscribed rectangle Rh of the hand 100 does not protrude from the circumscribed rectangle Rw of the workpiece W. As shown in FIG. 10B, the first control unit 211 shifts the position of the hand 100 in a direction D1 away from the edges w1 and w2 of the workpiece on which the reference edge E is set. By performing the shift process, the circumscribed rectangle Rh of the hand 100 is moved to a position where it does not protrude from the reference edge E, as shown in FIG. 10C. The state in which the hand 100 is shifted so that the circumscribed rectangle Rh of the hand 100 does not protrude from the reference edge E, as shown in FIG. 10C, is also referred to as a second state. The shift process is also a process of generating the second state.

[0037] After executing the shift process, the first control unit 211 proceeds to step S240 of the candidate position generation process in FIG. 8 to identify first suction portions Ss, which are suction portions S for holding the workpiece W. The first control unit 211 identifies the suction portions S that overlap the workpiece W as the first suction portions Ss. In this embodiment, the first control unit 211 determines, for each suction portion S, whether or not it is located within the outline Pw of the workpiece W using the relationship between the half lines and the outline Pw, and identifies the suction portions S within the outline Pw as the first suction portions Ss. Specifically, the first control unit 211 generates, for each suction portion S, multiple half lines extending radially from the center C. The first control unit 211 calculates the intersections of each of the multiple half lines extending from one suction portion S with the outline Pw of the workpiece W. The first control unit 211 determines, for all half lines, whether the number of intersections is odd. If the number of intersections of all the ray lines is odd, the suction part S is identified as the first suction part.

[0038] FIG. 11 is a diagram for explaining the process of identifying the first suction portion Ss. FIG. 11 illustrates the outer shapes Pw of samples 1 and 2 of the workpiece W, which are different shapes. In the example shown in FIG. 11, the first control unit 211 generates eight half lines L1 to L8 at intervals of 45°. Note that the number of half lines used in the process of identifying the first suction portion Ss may be changed as appropriate depending on the shape of the workpiece W and the hand information 250.

[0039] In FIG. 11 , the intersections n between the outline Pw of samples 1 and 2 and the half lines L1 to L8 are indicated by black circles. The number of intersections n in sample 1 is 1 for half lines L1 to L7 and 3 for half line L8. That is, in sample 1, the suction portion S satisfies the condition that the number of intersections n is an odd number for all half lines L1 to L8. In this case, the first control unit 211 identifies the suction portion S of sample 1 as the first suction portion Ss. On the other hand, the number of intersections n in sample 2 is 1 for half lines L1 to L4, 2 for L5, and 0 for L6 to L8. That is, in sample 2, the suction portion S does not satisfy the condition that the number of intersections n is an odd number for all half lines L1 to L8. In this case, the first control unit 211 does not identify the suction portion S of sample 2 as the first suction portion Ss. In other words, the first control unit 211 uses the suction portion S of the sample 1 to hold the workpiece W, and does not use the suction portion S of the sample 2 to hold the workpiece W.

[0040] The first control unit 211 executes the process of identifying the first suction portion Ss described in Fig. 11 for each of the suction portions S1 to S5 of the hand 100 after the shift process. In Fig. 10(c), the suction portions S1, S2, S3, and S4 are identified as the first suction portions Ss. After identifying the first suction portion Ss, the first control unit 211 advances the candidate position generation process of Fig. 8 to step S250 and executes a correction process to correct the position of the hand 100.

[0041] FIG. 12 is a diagram illustrating the correction process. FIG. 12A shows the centroid Ch of the hand 100, for which the shift process has been performed and the first suction portion Ss has been identified, the centroid Cw of the workpiece W, and the centroid Cs of the first suction portions S1, S2, S3, and S4. In the correction process, the first control unit 211 calculates a second position F2 based on the centroid Cs of the first suction portion Ss and shifts the position of the hand 100 so that the second position F2 coincides with the first position F1 based on the centroid Cw of the workpiece W. The second position F2 may be the position of the centroid Cs of the first suction portion Ss or a position within a predetermined range centered on the centroid Cs. In this embodiment, the second position F2 is the position of the centroid Cs. As shown in FIG. 12B, the first control unit 211 moves the hand 100 so that the centroid Cs coincides with the centroid Cw of the workpiece. If the centroid Cs of the workpiece W and the center of gravity of the hand 100 are positioned approximately the same, the correction process can prevent the hand 100 from tilting when the hand 100 is held using the suction units S1, S2, S3, and S4 as the first suction unit Ss. Note that if the centroid Cs and the center of gravity are positioned differently or if the suction force of the first suction unit Ss is equal to or greater than a predetermined standard stored in memory 220, the correction process of step S250 may be omitted.

[0042] In this manner, the first control unit 211 generates the position of the hand 100 where the first suction unit Ss is identified by executing the processes of steps S220 to S250 shown in Fig. 8. This generates one candidate position.

[0043] After generating the candidate positions, the first control unit 211 advances the candidate position generation process of FIG. 8 to step S260 and determines whether the first condition is satisfied. The first condition is to change the edge set as the reference edge E for multiple edges in the circumscribed rectangle Rw of the workpiece W and execute steps S220 to S250. As described above, there are four edge combinations when setting the reference edge E for two consecutive edges: (i) edges w1 and w2, (ii) edges w2 and w3, (iii) edges w3 and w4, and (iv) edges w4 and w1. The first condition is that steps S220 to S250 have been executed for all of (i) to (iv). In this embodiment, the processes of steps S220 to S250 have not yet been executed for combinations (ii) to (iv) other than (i) edges w1 and w2 shown in FIG. 10. Therefore, the first control unit 211 returns the candidate position generation process to step S220, (ii) sets a reference edge E for sides w2 and w3, and executes a shift process (step S230), identification of the first suction portion Ss (step S240), and correction process (step S250). Similarly, the first control unit 211 (iii) sets a reference edge E for sides w3 and w4, and executes steps S230 to S250. Furthermore, the first control unit 211 (iv) sets a reference edge E for sides w4 and w1, and executes steps S230 to S250.

[0044] FIG. 13 illustrates the shift process when a reference edge E is set for the sides w2 and w3. As shown in FIG. 13( a), the first control unit 211 sets the reference edge E for the sides w2 and w3 in step S220. Then, as shown in FIG. 13( b), in step S230, the first control unit 211 shifts the position of the hand 100 in a direction D2 away from the sides w2 and w3 (reference edge E) so that the circumscribing rectangle Rh of the hand 100 does not extend beyond the circumscribing rectangle Rh of the workpiece. FIG. 13( c) illustrates the position of the hand 100 after the shift process. In the example shown in FIG. 13( c), the first control unit 211 identifies the suction portions S1, S3, and S4 as the first suction portion Ss.

[0045] FIG. 14 illustrates the shift process when a reference edge E is set for the edges w3 and w4. As shown in FIG. 14( a), the first control unit 211 sets the reference edge E for the edges w3 and w4 in step S220. Then, as shown in FIG. 14( b), in step S230, the first control unit 211 shifts the position of the hand 100 in a direction D3 away from the edges w3 and w4 (reference edge E) so that the circumscribing rectangle Rh of the hand 100 does not extend beyond the circumscribing rectangle Rh of the workpiece. FIG. 14( c) illustrates the position of the hand 100 after the shift process. In the example shown in FIG. 14( c), the first control unit 211 identifies the suction portions S1 and S4 as the first suction portion Ss.

[0046] FIG. 15 illustrates the shift process when a reference edge E is set for the edges w4 and w1. As shown in FIG. 15( a), the first control unit 211 sets the reference edge E for the edges w4 and w1 in step S220. Then, as shown in FIG. 15( b), in step S230, the first control unit 211 shifts the position of the hand 100 in a direction D4 away from the edges w4 and w1 (reference edge E) so that the circumscribing rectangle Rh of the hand 100 does not extend beyond the circumscribing rectangle Rh of the workpiece. FIG. 15( c) illustrates the position of the hand 100 after the shift process. In the example shown in FIG. 15( c), the first control unit 211 identifies the suction portions S1, S2, and S4 as the first suction portion Ss.

[0047] 8 for (i) to (iv), that is, when the first condition is satisfied (YES in step S260), the first control unit 211 advances the candidate position generation process to step S270 and determines whether or not the second condition is satisfied. The second condition is to change the orientation (posture) of the hand 100 with respect to the workpiece W and execute the processes of steps S220 to S260. The "orientation" in the second condition is stored in advance in the memory 220. Changing the "orientation" of the hand 100 with respect to the workpiece W also means changing the angle of the hand 100 around the axis AX.

[0048] FIG. 16 is a diagram showing an example of the orientation of the hand 100 under the second condition. In FIG. 16, Samples 3, 4, 5, and 6 are shown as examples of the orientation of the hand 100 relative to the workpiece W. In FIGS. 10 to 15, the setting of the reference edge E, the shifting process, the identification of the first suction portion Ss, and the correction process (steps S220 to S250) are performed for the orientation shown in Sample 3. For the orientations shown in Samples 4 to 6, the processes of steps S220 to S260 have not yet been performed. Therefore, the first control unit 211 advances the candidate position generation process of FIG. 8 to step S280 and changes the orientation of the hand 100 to the orientation shown in Sample 4. After changing the orientation of the hand 100, the first control unit 211 performs the processes of steps S220 to S260 for the changed orientation. After performing the processes of steps S220 to S260 for all orientations, the first control unit 211 makes a positive determination in step S270 of FIG. 8 and terminates the candidate position generation process.

[0049] Upon completion of the candidate position generation process, the first control unit 211 advances the holding position generation process of FIG. 5 to step S300 and evaluates the candidate positions. The first control unit 211 evaluates the candidate positions with respect to various factors that affect the transport stability of the workpiece W and calculates an evaluation value. The higher the transport stability of the workpiece W, the larger the evaluation value. The factors include, for example, the number of first suction units Ss and the size of the area of ​​the polygon formed by the first suction units Ss. The first control unit 211 calculates an overall evaluation value by multiplying each evaluation value of the multiple factors by a predetermined weighting coefficient and adding the results. Note that if the shapes or suction forces of the multiple suction units S are different, the factors may include the shape and suction force of the suction units S.

[0050] FIG. 17 is a diagram for explaining the evaluation of candidate positions. FIG. 17 shows sample 7 and sample 8 as candidate positions of the hand 100 relative to the workpiece W. In both sample 7 and sample 8, the reference edge E is set relative to the edges w1 and w2, but the orientation (posture) of the hand 100 is different. Sample 7 has four first suction portions Ss, namely, suction portions S1, S2, S3, and S4, while sample 8 has three first suction portions Ss, namely, S1, S4, and S5. Therefore, the evaluation value for the number of first suction portions Ss is larger in sample 7 than in sample 8. Furthermore, as shown in FIG. 17 , the area of ​​polygon Ar7 formed by the first suction portions S1, S2, S3, and S4 in sample 7 is larger than the area of ​​polygon Ar8 formed by the first suction portions S1, S4, and S5 in sample 8. Therefore, the evaluation value for the polygon area is larger in sample 7 than in sample 8. In this way, the first control unit 211 calculates evaluation values ​​for the generated plurality of candidate positions. The first control unit 211 outputs the plurality of candidate positions to the second control unit 212 in descending order of evaluation value. In this embodiment, the first control unit 211 associates evaluation values ​​with the candidate positions and outputs them to the second control unit 212 in descending order of evaluation value. In this way, the holding position generation process of FIG. 5 ends.

[0051] When the holding position generation process is completed, in step S400 of FIG. 4 , the second control unit 212 generates a path for holding the workpiece W to be transported at the holding position and transporting it to the placement position M. The second control unit 212 generates a path for holding the workpiece W at the candidate position with the highest evaluation value, for example. If interference between the workpiece W and the hand 100 and an obstacle occurs on the generated path, the second control unit 212 generates a path using the candidate position with the next highest evaluation value and determines whether or not interference occurs. Interference occurs between the workpiece W to be held and an obstacle such as the containers 501 and 502 or another workpiece W. The second control unit 212 may further generate a path using information such as the configuration, singular posture, and movable range of the robot arm 20 stored in the memory 220. By executing step S400, the holding position and path of the workpiece W are determined. In this embodiment, the second control unit 212 further refers to a predetermined relationship between the evaluation value and the transport mode of the workpiece W and determines the transport mode of the workpiece W depending on the evaluation value of the holding position. The "evaluation value of a holding position" refers to an evaluation value associated with a candidate position determined as a holding position. The transport mode includes the acceleration and speed of the hand 100. A holding position with a high evaluation value has a higher acceleration and speed than a holding position with a low evaluation value.

[0052] If the hand 100 is smaller than the workpiece W (FIG. 5, step S130, NO) and one holding position is generated in step S140, the second control unit 212 generates a path using the holding position. If interference occurs on the path, the second control unit 212 may generate a path using a candidate position in which the orientation (posture) of the holding position has been changed.

[0053] Once the holding position, path, and transport mode have been determined as described above, in step S500 (FIG. 4), the third control unit 213 controls the operation of the robot arm 20 so that the workpiece W to be transported is held at the determined holding position, transported along the path, and placed at the placement position M. The third control unit 213 also controls the operation of the robot arm 20 so that the workpiece W is moved at an acceleration and speed according to the evaluation value.

[0054] According to the embodiment described above, the first control unit 211 generates candidate positions using the hand information 250 and the first information including the outer shape Pw of the workpiece W, so there is no need to register candidate positions in advance in the control device 200. This can reduce the workload of the administrator of the robot hand system 10.

[0055] Furthermore, the generated candidate positions are positions of the hand 100 where the circumscribing rectangle Rh of the hand 100 does not extend beyond the reference side E, so interference between the hand 100 and an object outside the reference side E is suppressed.

[0056] Since the reference side E is set for two consecutive sides of the circumscribing rectangle Rw of the workpiece W, the workpiece W to be transported can be placed close to or in contact with a corner of the container 502 at the destination of the hand 100 or a corner formed by the container 502 and a workpiece W already placed in the container 502. This makes it possible to improve the filling rate of the workpiece W in the container 502.

[0057] The first control unit 211 changes the reference side E for multiple sides w1 to w4 in the circumscribing rectangle Rw of the workpiece W, and executes the shift process (FIG. 8, step S230) and the process of identifying the first suction portion Ss (FIG. 8, step S240), thereby increasing the variety of candidate positions. This increases the variety of routes for holding the workpiece W at the holding position and transporting it to the placement position M. This reduces the possibility of path planning failure.

[0058] Furthermore, the first control unit 211 changes the angle of the hand 100 around the axis AX, i.e., the orientation of the hand 100, and executes a process of setting the reference edge E (FIG. 8, step S220), a shift process (FIG. 8, step S230), and a process of identifying the first suction unit Ss (FIG. 8, step S240), thereby further increasing the variety of candidate positions and further reducing the possibility of path planning failure.

[0059] Furthermore, the first control unit 211 calculates evaluation values ​​for candidate positions for various factors that affect the transport stability of the workpieces W, and outputs the evaluation values ​​to the second control unit 212 in descending order of evaluation value. The second control unit 212 generates routes in descending order of candidate positions evaluation value, and if no interference occurs on the generated routes, it does not generate routes for other candidate positions. This reduces the calculation load on the control device 200. Therefore, when placing multiple workpieces W in the container 501 into the container 502, the time required for the operation can be shortened.

[0060] Furthermore, the second control unit 212 determines the transport mode of the workpiece W according to the evaluation value of the holding position by referring to the relationship between a predetermined evaluation value and the transport mode of the workpiece W. The transport mode includes the acceleration and speed of the hand 100, and a holding position with a high evaluation value has a higher acceleration and speed than a holding position with a low evaluation value. Therefore, it is possible to transport the workpiece W quickly and stably and place it in the container 502.

[0061] As described above, according to this embodiment, a holding position can be created that does not interfere with the wall-like portion 30 when placed in the container 502, and that prevents the workpiece W from shaking and falling during transport.

[0062] Furthermore, the hand 100 is detachable from the arm tip 22 of the robot arm 20, and the control device 200 generates a holding position using hand information 250 stored in the memory 220, first information acquired via the first detection device 301, and second information acquired via the second detection device 302. Therefore, even when a hand with a design different from the hand 100 described above is attached to the arm tip 22, the first control unit 211 can execute the pick-and-place process, the holding position generation process, and the candidate position generation process. Below, the candidate position generation process using a hand 100A different from the hand 100 will be described.

[0063] Second Embodiment Figure 18 is a diagram showing an example of candidate positions generated by the candidate position generation process using a hand 100A of the second embodiment. The hand 100A shown in Figure 18(a) has a bottom surface 102A with a shape different from the bottom surface 102 of the hand 100 of the first embodiment. Furthermore, suction portions S11 to S15 with different diameters and suction forces are arranged on the bottom surface 102A. The suction forces of the suction portions S11 to S15 increase in the order of S11, S12, S13, S14, and S15. The circumscribing rectangle (not shown) of the hand 100A shown in Figure 18(a) is larger than the circumscribing rectangle Rw of the workpiece W shown in Figure 18(b) (Figure 5, step S130, YES).

[0064] FIG. 18(c) shows candidate positions 1A to 4A generated in the candidate position generation process. The evaluation value is highest for candidate position 1A, followed by candidate positions 2A, 3A, and 4A, decreasing in order. Candidate position 1A has the largest number of suction points identified as the first suction points Ss and the strongest suction force. Candidate positions 2A, 3A, and 4A have the same number of suction points identified as the first suction points Ss, but candidate position 2A has the strongest suction force, followed by candidate positions 3A and 4A, decreasing in order. In this way, the first control unit 211 can generate candidate positions regardless of the shape of the hand. Therefore, the control device 200 and robot hand system 10 disclosed herein can easily generate candidate positions and holding positions even if the hand attached to the arm tip 22 of the robot arm 20 is changed.

[0065] Other Embodiments At least one of the first detection device 301 and the second detection device 302 may be configured as a camera or a sensor. In this case, the computer functions of the first detection device 301 and the second detection device 302 may be executed by the control device 200. Furthermore, the first detection device 301 and the second detection device 302 may be attached to the robot arm 20. Furthermore, one detection device may have the functions of the first detection device 301 and the second detection device 302.

[0066] In the above-described embodiment, the first control unit 211 determines the placement positions M of the workpieces W in the container 502 and the number and positional relationship of the reference sides E corresponding to the wall-like portion 30 using the second information acquired via the second detection device 302. However, the placement positions M and the number and positional relationship of the reference sides E may be registered in advance in the memory 220. For example, the shape of the container 502 and the relationship between the number of workpieces W transferred to the container 502 and the placement positions M may be stored in advance in the memory 220, and the first control unit 211 may then refer to the memory 220 to acquire the placement positions M of the workpieces W to be transported from the container 501 to the container 502. Alternatively, the relationship between the placement positions M and the number of reference sides E may be stored in advance in the memory 220, and the first control unit 211 may acquire the number of reference sides E by referring to the memory 220.

[0067] The number of reference sides E is not limited to 2, and other numbers such as 1 or 3 are applicable. For example, when the number of reference sides E is 1, the workpiece W can be placed in contact with one surface of the wall-like portion 30 from which the workpiece W is transported. The number of reference sides E may also be three, and the arrangement of the three reference sides E may be, for example, U-shaped with right-angled corners.

[0068] In the process of identifying the first suction portion Ss (FIG. 8, step S240), the first control unit 211 determines whether the workpiece W and the suction portion S overlap using the number of intersections n between the half line and the outline Pw of the workpiece W. Alternatively, the first control unit 211 may determine the overlap between the workpiece W and the suction portion S using a known method using image processing.

[0069] Various factors that affect the transport stability of the workpiece W may include the relationship between the arrangement of the first suction units Ss and the movement direction of the hand 100. The movement direction of the hand 100 may be, for example, the direction from the container 501 to the container 502. The first control unit 211 may set a higher evaluation value the greater the degree of coincidence between the movement direction and the arrangement direction of the first suction units Ss. The evaluation value can be set in this manner because, when the movement direction and the arrangement direction of the first suction units Ss approximately coincide, the suction force of the suction units Ss on the workpiece W can be sufficiently exerted when the hand 100 moves, compared to when they do not coincide.

[0070] The hand used in the robot hand system 10 may be a deformable hand. FIG. 19 is a diagram showing another example of a hand 100B used in the robot hand system 10. The hand 100B has three suction units S21 to S23. The bottom surface 102B of the hand 100B has a triangular base 104B and three arms 103B that rotate around the corners of the base 104B. The suction units S21 to S23 are attached to the tips of the arms 103B. The arm 103B rotates under the control of the third control unit 213, changing the shape of the hand 100B from the minimum shape shown in FIG. 19(a) through the transition state shown in FIG. 19(b) to the maximum shape shown in FIG. 19(c). Accordingly, the positions of the suction units S21 to S23 also change. In this way, when a shape-changing hand 100B is used, design information for the hand 100B may be stored in the memory 220 of the control device 200, and the first control unit 211 may select a shape of the hand 100B corresponding to the outer shape Pw of the workpiece W using the first information and the hand information 250. For example, in step S130 of the holding position generation process of FIG. 5 , the first control unit 211 may select a shape of the hand 100B that is smaller than the workpiece W from among multiple shapes of the hand 100B. If there is no shape smaller than the workpiece W from among the multiple shapes of the hand 100B, the process of step S130 may proceed to step S200, and the candidate position generation process may be performed using the multiple shapes of the hand 100B. Note that the candidate position generation process using multiple shapes is not limited to the case where a deformable hand is used, and can be similarly performed when hands with different shapes (hand information) are selectively attached to the arm tip 21.

[0071] The order of the steps in the pick-and-place process, the holding position generation process, and the candidate position generation process described above may be interchanged, or any of the steps may be performed simultaneously. For example, step S110 of acquiring first information and step S120 of acquiring second information in the holding position generation process of FIG. 5 may be interchanged or performed simultaneously.

[0072] In the above embodiments, the suction unit S, which suctions the workpiece W by air suction, is exemplified as the hand 100, 100A, 100B. However, the suction unit is not limited to air suction. Other suction methods, such as magnetism or temporary adhesion, may be used as long as it is configured to contact and suction the workpiece W. Furthermore, in the hands of the above embodiments, the shape of the bottom surfaces 102, 102A, 102B may be arbitrarily changed. Furthermore, the suction unit S does not have to be located at a vertex of the bottom surfaces 102, 102A, 102B, and may be located at any position. The outer shape Ph of the hand and the elements contacting the circumscribed rectangle Rh may vary depending on the shape of the bottom surface of the hand and the arrangement of the suction unit. The suction unit S does not need to be selectively operated by control of the second actuator 110. The configuration of the valve and the vacuum device (vacuum valve) may be changed as long as the suction unit Ss is configured to ensure vacuum. The axis AX may be perpendicular to the bottom surface at any point on the bottom surface. Furthermore, the hand may have a shape that is rotationally symmetric about the axis AX. Even in a hand that is rotationally symmetric about the axis AX, the options for the posture of the handling device 20 can be increased by changing the angle of the hand 100 about the axis AX in the candidate position generation process ( FIG. 8 , step S280). As such, the hands 100, 100A, and 100B illustrated in the above embodiment are merely examples, and each process in the above embodiment can be applied to various hands with different hand information.

[0073] In the holding position generation process (FIG. 5) in the above embodiment, in step S110, the first control unit 211 determined that, among the multiple workpieces W in the container 501, the workpiece W that is closest to the current position of the hand 100 or the workpiece W with the largest area defined by the outer shape Pw is the workpiece W to be held. In contrast to this, the first control unit 211 may execute the holding position generation process (FIG. 4, step S100) for the multiple workpieces W, and then determine the workpiece W to be held in consideration of the path in the path generation process (FIG. 4, step S400).

[0074] The circumscribing rectangle Rh used in the holding position generation process and the like in the above embodiment and defined by the outline Ph of the hands 100, 100A, and 100B is not limited to a rectangle and may be a triangle as long as it is defined by sides that are tangent to the outline Ph of the hands 100, 100A, and 100B. In other words, the circumscribing rectangles Rw and Rh in the above embodiment can also be read as circumscribing shapes.

[0075] The number of candidate positions generated by the first control unit 211 may be one. This configuration also makes it possible to save the effort of registering candidate positions in the control device 200 in advance.

[0076] In the above embodiment, the robot hand system 10 includes a single control device 200 that has the functions of the first control unit 211, the second control unit 212, and the third control unit 213. However, the robot hand system 10 may include at least one of the functions of the first control unit 211, the second control unit 212, and the third control unit 213 as separate control devices. For example, the robot hand system 10 may include a first control device that has the functions of the first control unit 211, a second control device that has the functions of the second control unit 212, and a third control device that has the functions of the third control unit 213, all of which are separate devices.

[0077] Additionally, 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. In the case of a processor, where the hardware 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.

[0078] The present disclosure is not limited to the above-described embodiments and can be realized in various forms without departing from the spirit thereof. For example, the present disclosure can also be realized in the following aspects. The technical features in the above embodiments corresponding to the technical features in each aspect described below can be appropriately replaced or combined to solve some or all of the problems of the present disclosure or to achieve some or all of the effects of the present disclosure. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted.

[0079] <1> According to a first aspect of the present disclosure, a control device is provided that generates a holding position for holding a workpiece placed at a transfer source using a hand having multiple suction parts and placing the workpiece at a transfer destination. The control device includes a control unit that generates the holding position using hand information including the outer shape of the hand and the shape and arrangement of the multiple suction parts on the hand, and first information including the outer shape of the workpiece at the transfer source. The holding position includes a position of the hand at which a first suction part, which is a suction part used to hold the workpiece, is identified among the multiple suction parts. When the workpiece is smaller than the hand, the control unit determines the number of reference sides used to generate at least one candidate position as a candidate for the holding position, and sets the reference sides to a workpiece circumscribing rectangle tangent to the outer shape of the workpiece. The control unit generates a second state in which the hand is shifted from a first state in which the workpiece circumscribing rectangle and a hand circumscribing rectangle tangent to the outer shape of the hand are overlapped so that the hand circumscribing rectangle does not protrude from the reference sides. The control unit identifies an suction part of the multiple suction parts that overlaps the workpiece in the second state as the first suction part. The control unit generates the at least one candidate position using the position of the hand in the second state in which the first suction unit is identified. According to this embodiment, the control unit generates at least one candidate position using hand information and first information. This eliminates the need to pre-register candidate positions in the control device. Furthermore, the generated candidate position is a hand position that does not extend beyond the reference edge of the workpiece, thereby suppressing interference between the hand and other objects outside the reference edge of the workpiece. For example, when placing the held workpiece at a destination, interference between the hand and objects located at the destination is suppressed, thereby improving the workpiece filling rate at the destination.

[0080] <2> In the above aspect, the control unit may determine the number of reference sides using second information related to the shape of the object located at the destination. According to this aspect, when placing the held workpiece at the destination, interference between the hand and the object located at the destination is suppressed. Therefore, the workpiece filling rate at the destination can be improved.

[0081] <3> In the above-described embodiment, the reference sides may be two consecutive sides of the workpiece circumscribing rectangle. According to this embodiment, the generated candidate positions are hand positions that do not extend beyond the two consecutive sides of the workpiece's outline, thereby preventing interference between the hand and other objects outside the two consecutive sides. Furthermore, when placing the held workpiece at its destination, the workpiece to be transferred can be placed close to or in contact with the two specified sides of the destination.

[0082] <4> In the above-described aspect, the at least one candidate position may be a plurality of candidate positions. The control unit may generate the plurality of candidate positions by changing the side set as the reference side among a plurality of sides in the workpiece circumscribing rectangle and executing the process of generating the second state and the process of identifying the first suction unit. According to this aspect, the control device can generate a plurality of candidate positions by changing the reference side set in the workpiece.

[0083] <5> In the above aspect, the at least one candidate position may be a plurality of candidate positions. The hand may be configured to rotate around an axis perpendicular to a bottom surface of the hand on which the plurality of suction units are arranged. The control unit may generate the plurality of candidate positions by changing the angle of the hand around the axis and executing a process of setting the reference edge, a process of generating the second state, and a process of identifying the first suction unit. According to this aspect, the control device can generate the plurality of candidate positions by changing the angle of the hand around the axis. Note that the bottom surface may be a virtual surface.

[0084] <6> In the above aspect, in the process of identifying the first suction portion, the control unit may (i) generate a plurality of half lines extending radially from each of the plurality of suction portions, and (ii) identify, as the first suction portion, a suction portion that has an odd number of intersections with the outline of the workpiece for all of the plurality of half lines. According to this aspect, it is possible to easily identify the suction portion located on the workpiece.

[0085] <7> In the above-described embodiment, the control unit may calculate a centroid defined by the first suction unit, and generate the at least one candidate position by correcting the position of the hand in the second state so that a first position based on the centroid of the workpiece coincides with a second position based on the centroid defined by the first suction unit. This embodiment can prevent the workpiece from tilting when held by the hand. The centroid of the first suction unit is (i) the centroid of a figure defined by the multiple suction units when multiple suction units are identified as first suction units, or (ii) the center C of the single suction unit when only one suction unit is identified as the first suction unit.

[0086] <8> In the above embodiment, the control unit may (i) calculate an evaluation value for each of the plurality of candidate positions based on a predetermined factor that affects the transport stability of the workpiece when the workpiece is held by the hand, the factor having a larger evaluation value as the transport stability increases, (ii) generate a route from the source to the destination among the plurality of candidate positions in descending order of the evaluation value, and (iii) determine the candidate position to be used for the route when no interference occurs as the holding position. According to this embodiment, a route that does not cause interference can be generated using a candidate position with a high evaluation value among the plurality of candidate positions. This can improve the transport stability of the workpiece.

[0087] <9> In the above aspect, the control unit may determine the transfer mode for the path using the holding position by using a predetermined relationship between the evaluation value and a transfer mode including the speed of the hand. According to this aspect, it is possible to improve the workpiece transfer speed while improving the workpiece transfer stability.

[0088] <10> In the above-described embodiment, the workpiece circumscribing rectangle may be formed using the shape of the workpiece when projected onto an imaginary plane perpendicular to a predetermined direction. The hand circumscribing rectangle may be formed using the shape of the hand when the suction portions and the bottom surface of the hand on which the suction portions are arranged are projected onto an imaginary plane extending along the tips of the suction portions. According to this embodiment, candidate positions can be generated regardless of the shape of the workpiece.

[0089] <11> In the above-described embodiment, the hand may be deformable into a plurality of hand shapes, each having different hand information. The at least one candidate position may be a plurality of candidate positions. The control unit may generate the plurality of candidate positions by executing a process of setting the reference edge, a process of generating the second state, and a process of identifying the first suction unit for each hand shape included in the plurality of hand shapes. According to this embodiment, the position of the suction unit can be changed depending on the workpiece, thereby generating holding positions that can accommodate a variety of workpieces. In this embodiment, the control unit may select a hand shape according to the outer shape of the workpiece. (i) When the workpiece is larger than the hand, the control unit may select, from the plurality of hand shapes, a hand shape having a hand circumscribing rectangle smaller than the workpiece circumscribing rectangle, and generate, as the holding position, a hand position where the hand circumscribing rectangle fits within the workpiece circumscribing rectangle. (ii) When the workpiece is smaller than the hand, the control unit may execute a process of setting the reference edge, a process of generating the second state, and a process of identifying the first suction unit for each hand shape included in the plurality of hand shapes.

[0090] <12> According to a second aspect of the present disclosure, a robot hand system is provided. The robot hand system includes a handling device that includes a hand having multiple suction parts and that uses the hand to hold a workpiece placed at a source and place the workpiece at a destination, a first control device, a second control device, and a third control device. The first control device is configured to generate a holding position, which is the position of the hand at which a first suction part, which is a suction part used to hold the workpiece, is identified, using hand information including the outer shape of the hand and the shape and arrangement of the multiple suction parts on the hand, and first information including the outer shape of the workpiece at the source. When the workpiece is smaller than the hand, the first control device determines the number of reference edges used to generate at least one candidate position that is a candidate for the holding position, and sets the reference edges relative to a workpiece circumscribing rectangle that is tangent to the outer shape of the workpiece. The first control device generates a second state in which the hand is shifted from a first state in which the workpiece circumscribing rectangle and a hand circumscribing rectangle that is tangent to the outer shape of the hand are superimposed, so that the hand circumscribing rectangle does not protrude from the reference edges. The first control device identifies, as the first suction device, a suction device that overlaps with the workpiece among the multiple suction devices in the second state. The first control device generates the at least one candidate position using the position of the hand in the second state in which the first suction device was identified. The second control device determines the holding position and a route from the source to the destination using the at least one candidate position output from the first control device. The third control device controls the handling device to hold the workpiece at the holding position and move the hand along the route. This configuration eliminates the need to pre-register candidate positions in the control device. Furthermore, the generated candidate position is a hand position that does not extend beyond the reference edge of the workpiece. Therefore, interference between the hand and other objects outside the reference edge of the workpiece can be suppressed. Furthermore, when the third control device places the held workpiece at the destination, interference between the hand and objects located at the destination is suppressed, thereby improving the workpiece filling rate at the destination.

[0091] <13> In the above aspect, the handling device may have a mounting portion to which the hand is detachably attached. According to this aspect, the robot hand system can be used with different hands.

[0092] <14> In the above aspect, the hand may be transformed into a plurality of hand shapes, the hand information of which differs from one another, under the control of the third control device. The at least one candidate position may be a plurality of candidate positions. The first control device may generate the plurality of candidate positions by executing a process of setting the reference edge, a process of generating the second state, and a process of identifying the first suction portion for each hand shape included in the plurality of hand shapes. According to this aspect, the hand shape can be changed depending on the workpiece, thereby providing a robot hand system capable of holding workpieces of a wider variety of shapes and sizes.

[0093] <15> According to a third aspect of the present disclosure, there is provided a method for generating a holding position for holding a workpiece placed at a transfer source using a hand having multiple suction parts and placing the workpiece at a transfer destination. The holding position is a position of the hand at which a first suction part, which is a suction part used to hold the workpiece among the multiple suction parts, is identified. The method for generating the holding position is a method for generating the holding position using hand information including an outer shape of the hand and the shape and arrangement of the multiple suction parts on the hand, and first information including the outer shape of the workpiece at the transfer source. The holding position generation method includes: (i) when the workpiece is smaller than the hand, (ii) determining the number of reference edges to be used to generate at least one candidate position that is a candidate for the holding position; (iii) setting the reference edges with respect to a work circumscribing rectangle that is tangent to the outline of the workpiece; (iv) generating a second state in which the hand is shifted from a first state in which the work circumscribing rectangle and a hand circumscribing rectangle that is tangent to the outline of the hand are superimposed so that the hand circumscribing rectangle does not protrude from the reference edges; (v) identifying an suction portion among the multiple suction portions that overlaps the workpiece as the first suction portion in the second state; and (vi) generating the at least one candidate position using the position of the hand in the second state in which the first suction portion is identified.

[0094] <16> According to a fourth aspect of the present disclosure, there is provided a program for generating a holding position for holding a workpiece placed at a transfer source using a hand having multiple suction parts and placing the workpiece at a transfer destination. The program generates the holding position using hand information including an outer shape of the hand and the shape and arrangement of the multiple suction parts on the hand, and first information including an outer shape of the workpiece at the transfer source. The holding position includes a position of the hand at which a first suction part, which is an suction part used to hold the workpiece among the multiple suction parts, is identified. The program causes a computer to execute the following steps: determine the number of reference edges used to generate at least one candidate position that is a candidate for the holding position when the workpiece is smaller than the hand; set the reference edges to a work circumscribing rectangle that is tangent to the outline of the workpiece; generate a second state in which the hand is shifted from a first state in which the work circumscribing rectangle and a hand circumscribing rectangle that is tangent to the outline of the hand are superimposed so that the hand circumscribing rectangle does not protrude from the reference edges; identify an suction portion among the multiple suction portions that overlaps with the workpiece as the first suction portion in the second state; and generate the at least one candidate position using the position of the hand in the second state in which the first suction portion is identified.

[0095] The present disclosure may be realized in various forms other than those described above, such as a non-transitory storage medium on which a computer program for implementing at least one function of the control device 200, the first control unit 211, the second control unit 212, and the third control unit 213 is recorded.

[0096] 10: Robot hand system, 20: Handling device, robot arm, 22: Arm tip, 25: First actuator, 30: Wall-like portion, 31: Inner wall, 32: Virtual wall, 100, 100A, 100B: Hand, 101: Base, 102, 102A, 102B: Bottom surface, 104: First part, 105: Second part, 103B: Arm, 104B: Base, 110: Second actuator, 200: Control device, 210: CPU, 211: First control unit, 212: Second control unit, 213: Third control unit, 220: Memory, 230: Interface circuit, 250: Hand information, 301: First detection device, 302: Second detection device, 400: Input device, 501, 502: Container, AX: Axis, Ar7, Ar8: Polygon, C: Center of suction portion, Ch: centroid of the circumscribed rectangle of the hand, Cs: centroid of the first suction part, Cw: centroid of the circumscribed rectangle of the workpiece, D1, D2, D3, D4: shift direction, E: reference side, F1: first position, F2: second position, F3: third position, J: joint, L: link, L1, L2, L3, L4, L5, L6, L7, L8: half line, M: placement position, Q: virtual plane, P1: holding position generation program, P2 : Path generation program, P3: Motion control program, Ph: Outer shape of hand, Rh: Circumscribed rectangle of hand, Pw: Outer shape of workpiece, Rw: Circumscribed rectangle of workpiece Ph, S, S1, S2, S3, S4, S5, S11, S12, S13, S14, S15, S21, S22, S23: Suction part, Ss: First suction part, T: Tip of suction part, W: Workpiece, w1, w2, w3, w4: Side

Claims

1. A control device that generates a holding position for holding a workpiece arranged at a conveying source by a hand having a plurality of suction portions and arranging the workpiece at a conveying destination, the control device comprising: a control unit that generates the holding position using hand information including the outer shape of the hand and the shape and arrangement of the plurality of suction portions in the hand, and first information including the outer shape of the workpiece at the conveying source; the holding position is the position of the hand at which a first suction portion, which is a suction portion used for holding the workpiece among the plurality of suction portions, is specified; when the workpiece is smaller than the hand, the control unit determines the number of reference sides used for generating at least one candidate position that is a candidate for the holding position, sets the reference sides with respect to a workpiece circumscribed rectangle that contacts the outer shape of the workpiece, generates a second state in which the hand is shifted from a first state in which the workpiece circumscribed rectangle and a hand circumscribed rectangle that contacts the outer shape of the hand are overlapped so that the hand circumscribed rectangle does not protrude from the reference sides, specifies, as the first suction portion, a suction portion among the plurality of suction portions that overlaps the workpiece in the second state, and generates the at least one candidate position using the position of the hand in the second state in which the first suction portion is specified.

2. The control device according to claim 1, wherein the control unit determines the number of reference sides using second information regarding the shape of an object located at the conveying destination.

3. The control device according to claim 1, wherein the reference sides are two consecutive sides in the workpiece circumscribed rectangle.

4. The control device according to claim 1, wherein the at least one candidate position is a plurality of candidate positions, and the control unit generates the plurality of candidate positions by changing the sides to be set as the reference sides among the plurality of sides in the workpiece circumscribed rectangle and executing the process of generating the second state and the process of specifying the first suction portion.

5. The control device according to claim 1, wherein the at least one candidate position is a plurality of candidate positions, the hand is configured to rotate about an axis orthogonal to the bottom surface of the hand on which the plurality of suction portions are arranged, and the control unit changes the angle of the hand about the axis to execute a process of setting the reference side, a process of generating the second state, and a process of specifying the first suction portion, thereby generating the plurality of candidate positions.

6. The control device according to claim 1, wherein in the process of specifying the first suction portion, the control unit generates a plurality of half-lines extending radially from each suction portion of the plurality of suction portions, and specifies, as the first suction portion, a suction portion for which the number of intersections with the outer shape of the workpiece is odd for all of the plurality of half-lines.

7. The control device according to claim 1, wherein the control unit calculates the centroid defined by the first suction portion, and corrects the position of the hand in the second state so that a first position based on the centroid of the workpiece coincides with a second position based on the centroid defined by the first suction portion, thereby generating the at least one candidate position.

8. The control device according to claim 4, wherein for each candidate position of the plurality of candidate positions, the control unit calculates an evaluation value based on a predetermined factor that affects the conveyance stability of the workpiece when the workpiece is held by the hand, and the evaluation value increases as the conveyance stability increases, generates a path from the conveyance source to the conveyance destination in order from the candidate position having the largest evaluation value among the plurality of candidate positions, and determines the candidate position used in the path as the holding position when no interference occurs in the path.

9. The control device according to claim 8, wherein the control unit determines the conveyance mode in the path using the holding position by using a predetermined relationship between the evaluation value and the conveyance mode including the speed of the hand.

10. The control device according to claim 1, wherein the work circumscribed rectangle is formed using the shape of the work when the work is projected onto a virtual plane orthogonal to a predetermined direction, and the hand circumscribed rectangle is formed using the shape of the hand when the plurality of suction parts and the bottom surface of the hand on which the plurality of suction parts are arranged are projected onto a virtual plane extending along the tips of the plurality of suction parts.

11. The control device according to claim 1, wherein the hand is configured to be deformable into a plurality of hand shapes having different hand information, the at least one candidate position is a plurality of candidate positions, and the control unit generates the plurality of candidate positions by executing a process of setting the reference side, a process of generating the second state, and a process of specifying the first suction part for each hand shape included in the plurality of hand shapes.

12. A robot hand system, comprising: a handling device that includes a hand having a plurality of suction portions, holds a workpiece disposed at a transfer source by the hand, and disposes the workpiece at a transfer destination; a first control device that generates a holding position, which is a position of the hand at which a first suction portion, which is a suction portion used for holding the workpiece among the plurality of suction portions, is specified, using hand information including an outer shape of the hand and shapes and arrangements of the plurality of suction portions in the hand, and first information including an outer shape of the workpiece at the transfer source, wherein when the workpiece is smaller than the hand, a number of reference sides used for generating at least one candidate position that is a candidate for the holding position is determined, the reference sides are set with respect to a workpiece circumscribed rectangle that contacts the outer shape of the workpiece, a second state is generated by shifting the hand from a first state in which the workpiece circumscribed rectangle and a hand circumscribed rectangle that contacts the outer shape of the hand are overlapped so that the hand circumscribed rectangle does not protrude from the reference sides, a suction portion among the plurality of suction portions that overlaps the workpiece in the second state is specified as the first suction portion, and the at least one candidate position is generated using the position of the hand in the second state in which the first suction portion is specified; a second control device that determines the holding position and a path from the transfer source to the transfer destination using the at least one candidate position output from the first control device; and a third control device that controls the handling device to hold the workpiece at the holding position and move the hand along the path.

13. The robot hand system according to claim 12, wherein the handling device has a mounting portion to which the hand is detachably attached.

14. A robot hand system according to claim 12, wherein the hand is deformed into a plurality of hand shapes with different hand information under the control of the third control device, the at least one candidate position is a plurality of candidate positions, and the first control device executes a process of setting the reference side, a process of generating the second state, and a process of specifying the first suction part for each hand shape included in the plurality of hand shapes, thereby generating the plurality of candidate positions.

15. A method for generating a holding position for holding a workpiece disposed at a transfer source by a hand having a plurality of suction parts and disposing the workpiece at a transfer destination, wherein the holding position is the position of the hand at which a first suction part, which is a suction part used for holding the workpiece among the plurality of suction parts, is specified. When the workpiece is smaller than the hand, the number of reference sides used for generating at least one candidate position, which is a candidate for the holding position, is determined, the reference side is set for a workpiece circumscribed rectangle that contacts the outer shape of the workpiece, a second state is generated by shifting the hand so that the hand circumscribed rectangle does not protrude from the reference side from a first state in which the workpiece circumscribed rectangle and the hand circumscribed rectangle that contacts the outer shape of the hand are overlapped, the suction part that overlaps the workpiece among the plurality of suction parts in the second state is specified as the first suction part, and the at least one candidate position is generated using the position of the hand in the second state in which the first suction part is specified.

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