Robot system and workpiece processing method

Abstract

To reduce an output required of a robot.SOLUTION: A robot system 100 comprises: a robot 600 having a robot arm 610 capable of gripping a workpiece W; and a control device 700 that controls the motion of the robot arm 610. The control device 700 brings the workpiece W into contact with the ground in a state where the robot arm 610 grips the workpiece W, and executes control for enabling the robot arm 610 to move in a first direction in which an external force is applied on the robot arm 610, and control for limiting the movement of the robot arm 610 at least in the first direction and in a direction other than a second direction opposite to the first direction. Regarding the external direction, a first force component in the first direction is larger than a second force component in a direction orthogonal to the first direction.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a robot system and a method for processing a workpiece. [Background technology]

[0002] Conventionally, a robot arm that holds a workpiece has been utilized to move the workpiece placed on a mounting table to another mounting table. For example, Patent Document 1 discloses a robot arm that clamps and lifts a workpiece placed on a mounting table between a first holding part and a second holding part, moves the workpiece toward another mounting table, and then lowers to place the workpiece on the other mounting table. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-168834 A Summary of the Invention [Problem to be solved by the invention]

[0004] When a robot arm processes a workpiece while holding it, the robot arm needs to be configured to generate a force greater than the external force applied during processing of the workpiece. However, in this case, a problem arises in that a large robot with high output is required in order for the robot arm to generate a force greater than the external force applied to the workpiece.

[0005] An object of the present disclosure is to provide a robot system and a workpiece processing method capable of reducing the output required of the robot. [Means for solving the problem]

[0006] In order to solve the above problems, the robot system disclosed herein includes a robot having a robot arm capable of grasping a workpiece, and a control device that controls the operation of the robot arm, wherein the control device executes the following: bringing the workpiece into contact with a ground surface while the robot arm is grasping the workpiece; controlling the robot arm to be movable in a first direction in which an external force acts on the robot arm; and controlling the robot arm to limit movement of the robot arm in directions other than at least the first direction and a second direction that is opposite to the first direction, wherein the first component of the external force in the first direction is greater than the second component of the external force in a direction perpendicular to the first direction.

[0007] The ground plane may be configured to be deformable.

[0008] The contact surface may be deformable according to the external shape of the workpiece.

[0009] The workpiece may be clamped by two surfaces different from the contact surface, and the clamping surfaces may be deformable according to the external shape of the workpiece.

[0010] In order to solve the above problems, the workpiece processing method of the present disclosure includes the steps of: having a robot arm grasp a workpiece; bringing the workpiece into contact with a ground surface while the robot arm is grasping the workpiece; after the step of contacting the workpiece with the ground surface, controlling the robot arm in a first control mode that restricts movement of the robot arm in at least the first direction and directions other than a second direction that is opposite to the first direction, while controlling the robot arm so that the robot arm can move in a first direction in which an external force acts on the robot arm; and, after the step of controlling the robot arm in the first control mode, executing a process in which an external force acts on the workpiece while the robot arm is grasping the workpiece, wherein a first component of the external force, which is a component of the first direction, is greater than a second component of the external force, which is a component of the force in a direction perpendicular to the first direction.

[0011] The method may include, after the step of performing a process to apply an external force to the workpiece, a step of controlling the robot arm in a second control mode that restricts movement of the robot arm in directions other than the workpiece transport direction, and, after the step of controlling the robot arm in the second control mode, a step of changing the posture of the workpiece while the robot arm is gripping the workpiece, and bringing the workpiece into contact with a ground surface. Effect of the Invention

[0012] According to the present disclosure, the output required of a robot can be reduced. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram for explaining the configuration of a robot system according to this embodiment. [Diagram 2] FIG. 2 is a block diagram showing an example of a functional configuration of the control device according to the present embodiment. [Diagram 3] FIG. 3 is a schematic diagram for explaining the configuration of the robot. [Figure 4] FIG. 4 is a schematic top view showing a part of the workpiece and the jig. [Diagram 5] FIG. 5 is a schematic diagram of the robot arm and processing device during processing of a workpiece. [Figure 6] FIG. 6 is a flow chart for explaining an example of a method for processing a workpiece using the control device according to this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present disclosure will be described with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values ​​shown in the embodiments are merely examples for ease of understanding, and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid repeated explanations, and elements not directly related to the present disclosure are not illustrated.

[0015] 1 is a schematic diagram for explaining the configuration of a robot system 100 according to this embodiment. As shown in FIG 1, the robot system 100 includes a workpiece storage device 200, an assembly device 300, a processing device 400, a welding device 500, a robot 600, and a control device 700.

[0016] The work storage device 200 stores a wide variety of multiple workpieces W. The workpieces W stored in the work storage device 200 include multiple workpieces before being assembled by the assembly device 300, multiple workpieces before being processed by the processing device 400, and multiple workpieces before being welded by the welding device 500. The workpieces W also include, for example, workpieces after being assembled by the assembly device 300, workpieces after being processed by the processing device 400, and workpieces after being welded by the welding device 500.

[0017] The assembling device 300 is a device that assembles a plurality of workpieces W that have been taken out of the workpiece storage device 200 and moved by the robot 600. However, without being limited thereto, the assembling device 300 may assemble a plurality of workpieces W that have been processed by the processing device 400 and moved by the robot 600. The assembling device 300 may also assemble a plurality of workpieces W that have been welded by the welding device 500 and moved by the robot 600. The workpieces W that have been assembled by the assembling device 300 are moved by the robot 600 to the processing device 400, the welding device 500, or the workpiece storage device 200.

[0018] The processing device 400 is a device that processes the workpiece W that has been taken out of the workpiece storage device 200 and moved by the robot 600. However, without being limited thereto, the processing device 400 may process the workpiece W that has been assembled by the assembly device 300 and moved by the robot 600. Furthermore, the processing device 400 may process the workpiece W that has been welded by the welding device 500 and moved by the robot 600. The workpiece W that has been processed by the processing device 400 is moved by the robot 600 to the assembly device 300, the welding device 500, or the workpiece storage device 200.

[0019] The welding device 500 is a device that performs welding on the workpiece W that has been taken out of the workpiece storage device 200 and moved by the robot 600. However, without being limited thereto, the welding device 500 may perform welding on the workpiece W that has been assembled by the assembly device 300 and moved by the robot 600. The welding device 500 may also perform welding on the workpiece W that has been processed by the processing device 400 and moved by the robot 600. The workpiece W that has been welded by the welding device 500 is moved by the robot 600 to the assembly device 300, the processing device 400, or the workpiece storage device 200.

[0020] The robot 600 is a device that holds and removes the workpiece W stored in the workpiece storage device 200, and moves it to the assembly device 300, the processing device 400, or the welding device 500. The robot 600 is configured to be rotatable clockwise and counterclockwise in Fig. 1. When the robot 600 rotates clockwise and counterclockwise in Fig. 1, the robot arm 610 of the robot 600 rotates clockwise and counterclockwise in Fig. 1.

[0021] For example, as shown in Fig. 1, when the robot 600 rotates in the clockwise direction of the arrow in Fig. 1, the robot arm 610 rotates in the direction of the arrow. When the robot arm 610 holds a workpiece W and rotates clockwise and counterclockwise in Fig. 1, the workpiece W can be moved between the workpiece storage device 200, the assembly device 300, the processing device 400, and the welding device 500. The robot 600 is connected to a control device 700, and the operation of the robot 600 is controlled based on a control command from the control device 700.

[0022] The control device 700 controls the entire robot system 100. That is, the control device 700 controls the workpiece storage device 200, the assembling device 300, the processing device 400, the welding device 500, and the robot 600.

[0023] The control device 700 has one or more processors 700a and one or more memories 700b connected to the processor 700a. The processor 700a includes, for example, a CPU (Central Processing Unit). The memory 700b includes, for example, a ROM (Read Only Memory) and a RAM (Random Access Memory). The ROM is a storage element that stores programs and computation parameters used by the CPU. The RAM is a storage element that temporarily stores data such as variables and parameters used in processing executed by the CPU.

[0024] Fig. 2 is a block diagram showing an example of a functional configuration of the control device 700 according to this embodiment. For example, as shown in Fig. 2, the control device 700 includes a robot control unit 710. The robot control unit 710 controls the robot 600 by sending a control command to the robot 600, and controls the operation of the robot arm 610. The detailed control of the robot control unit 710 will be described later.

[0025] Various processes including the processes described below performed by the robot control unit 710 may be executed by the processor 700a. In detail, the various processes are executed by the processor 700a executing a program stored in the memory 700b.

[0026] Fig. 3 is a schematic diagram for explaining the configuration of the robot 600. As shown in Fig. 3, the robot 600 includes a robot arm 610 and a force sensor 620. The processing device 400 includes a mounting table 410, a jig 420, and a processing device (not shown).

[0027] In this embodiment, the assembling device 300 and the welding device 500 have a similar configuration to the processing device 400. Specifically, the assembling device 300 includes a mounting table 410, a jig 420, and an assembling device (not shown). The welding device 500 includes a mounting table 410, a jig 420, and a welding device (not shown).

[0028] Thus, in this embodiment, the assembling apparatus 300, the processing apparatus 400, and the welding apparatus 500 each have the mounting table 410 and the jig 420, and the configurations and operations of the mounting table 410 and the jig 420 are the same among the assembling apparatus 300, the processing apparatus 400, and the welding apparatus 500. Therefore, here, an example in which the workpiece W transported by the robot arm 610 is processed by the processing apparatus 400 will be described, and a description of the assembling process by the assembling apparatus 300 and the welding process by the welding apparatus 500 will be omitted.

[0029] The robot arm 610 has a plurality of link portions 611, 612, 613, and 614, a plurality of joint portions 615, 616, and 617, and a base member 618. The link portions 611, 612, 613, and 614 are rod-shaped members.

[0030] The link portion 611 extends in the vertical direction. A base end of the link portion 611 is attached to an upper surface of a base member 618. The base member 618 is placed on the ground. The link portion 611 is provided so as to be rotatable around a central axis of the link portion 611. A tip end of the link portion 611 is connected to a base end of the link portion 612 via a joint portion 615. The joint portion 615 is provided so as to be rotatable around a horizontal axis. The rotational movement of the joint portion 615 causes the link portion 612 to rotate around the rotation axis of the joint portion 615.

[0031] A tip end of the link portion 612 is connected to a base end of the link portion 613 via a joint portion 616. The joint portion 616 is provided so as to be rotatable around a horizontal axis. The link portion 613 extends from the joint portion 616 to a joint portion 617. By the rotational movement of the joint portion 616, the link portion 613 rotates around the rotation axis of the joint portion 616.

[0032] The link portion 613 is provided so as to be rotatable around the center line of the link portion 613. A tip end of the link portion 613 is connected to a base end of the link portion 614 via a joint portion 617. The joint portion 617 is provided so as to be rotatable around a horizontal axis. By the rotational movement of the joint portion 617, the link portion 614 rotates around the rotation axis of the joint portion 617. The link portion 614 is provided so as to be rotatable around the center line of the link portion 614.

[0033] A gripping member 614a is attached to the tip of the link portion 614. For example, as shown in Fig. 1, a pair of gripping members 614a are provided on both sides of the workpiece W and configured to be able to grip the workpiece W from both sides. When the gripping members 614a grip the workpiece W and the link portions 611, 613, 614 and the joint portions 615, 616, 617 rotate, the robot arm 610 can move the workpiece W in three orthogonal axis directions and rotate it around the three orthogonal axes.

[0034] The force sensor 620 is a sensor that detects an external force acting on the robot arm 610. In this embodiment, the force sensor 620 is attached to the tip of the link portion 614. However, the force sensor 620 is not limited to this, and may be attached to a portion of the robot arm 610 other than the link portion 614. For example, a six-axis sensor capable of measuring forces in three orthogonal axial directions and torques around each axis is used as the force sensor 620. In this case, the force sensor 620 can detect forces of six degrees of freedom acting on the robot arm 610 and torques around the three axes. However, the force sensor 620 is not limited to this example as long as it can detect forces acting on the robot arm 610.

[0035] In the processing apparatus 400, a mounting table 410 is placed on the ground. A jig 420 is attached to the upper surface of the mounting table 410. The jig 420 has a first deformation portion 422 at a position facing the lower surface Wa of the workpiece W in the vertical direction.

[0036] The first deformation portion 422 has a ground contact surface (contact surface) 422a that can come into contact with the lower surface Wa of the workpiece W. In a state before deformation of the first deformation portion 422, the ground contact surface 422a is a plane parallel to the horizontal direction. The first deformation portion 422 can support the lower surface Wa of the workpiece W by coming into contact with the lower surface Wa of the workpiece W.

[0037] In this embodiment, the lower surface Wa of the workpiece W is not planar, but has a partially protruding protruding shape, a partially recessed recessed shape, a partially curved curved shape, or the like. However, the present invention is not limited to this, and the lower surface Wa of the workpiece W may also be planar. Note that information regarding the external shape of the workpiece W in this embodiment is stored in advance in a storage unit (not shown) of the control device 700, but other methods such as sending and receiving information between the control device 700 via communication may also be used.

[0038] The jig 420 is electrically connected to the control device 700. The jig 420 is configured to be able to receive a control command from the control device 700. The first deformation unit 422 is configured to be able to deform. When the jig 420 receives a control command from the control device 700, the jig 420 deforms the first deformation unit 422 by an actuator (not shown) based on the control command. In this embodiment, a control command including information on the outer shape of the workpiece W is transmitted to the jig 420. Based on the control command, the jig 420 deforms, for example, the ground contact surface 422a of the first deformation unit 422 according to the outer shape of the lower surface Wa of the workpiece W. The jig 420 also locks the first deformation unit 422 deformed according to the outer shape of the lower surface Wa of the workpiece W, and maintains the shape of the ground contact surface 422a.

[0039] For example, the first deformation portion 422 is composed of a plurality of pins configured to be movable in a proximity direction approaching the workpiece W and a separation direction away from the workpiece W. However, the present invention is not limited to this, and the first deformation portion 422 may be configured to be deformed and locked in accordance with the external shape of the workpiece W. For example, the first deformation portion 422 may be composed of a contact member that contacts the workpiece W and an actuator that can move the contact member in a proximity direction approaching the workpiece W and a separation direction away from the workpiece W. The actuator may be a hydraulic, pneumatic, or electric actuator.

[0040] The first deformation portion 422 deforms in accordance with the outer shape of the underside Wa of the workpiece W, and after being locked, comes into contact with the underside Wa of the workpiece W, thereby being able to support the underside Wa of the workpiece W. Here, the contact portion of the first deformation portion 422 that comes into contact with the underside Wa of the workpiece W becomes the contact surface 422a.

[0041] In this way, the jig 420 can support the lower surface Wa of the workpiece W in contact with the ground surface 422a by deforming the first deformation part 422 into a shape corresponding to the outer shape of the lower surface Wa of the workpiece W and locking the shape. In this embodiment, the lower surface Wa of the workpiece W held by the robot arm 610 is placed on the ground surface 422a of the first deformation part 422 whose shape is locked. At this time, for example, when a load (hereinafter also referred to as an external force) is applied vertically downward to the upper surface of the workpiece W by a processing device (not shown), the first deformation part 422 of the jig 420 can receive the external force applied to the upper surface of the workpiece W. In other words, the ground surface 422a of the first deformation part 422 functions as an external force receiving surface capable of receiving the external force acting on the workpiece W by contacting the workpiece W.

[0042] In this embodiment, an example will be described in which the first deformation portion 422 deforms in accordance with the external shape of the workpiece W, but the deformed shape of the first deformation portion 422 is not limited to a shape in accordance with the external shape of the workpiece W. Specifically, the first deformation portion 422 only needs to be able to support the workpiece W so as to be able to receive an external force acting on the workpiece W, and only needs to have at least three support portions that support the workpiece W at three points.

[0043] For example, when an extension line extending from a point where an external force acts on the workpiece W in the direction where the external force acts passes through a triangular area connecting the support points of three support parts, the first deformation part 422 can support the workpiece W and receive the external force acting on the workpiece W. Therefore, the first deformation part 422 may be deformed to form at least three support parts capable of forming an area through which an extension line extending from a point where an external force acts on the workpiece W in the direction where the external force acts passes.

[0044] Fig. 4 is a schematic top view showing a part of the workpiece W and the jig 420. As shown in Fig. 4, the jig 420 has second deformation portions 424 at positions facing a pair of side surfaces Wb of the workpiece W in the horizontal direction.

[0045] The second deformation portion 424 has a pair of side surfaces Wb of the workpiece W and a clamping surface (contact surface) 424a capable of coming into contact with the Wb. In a state before deformation of the second deformation portion 424, the clamping surface 424a is a plane parallel to the vertical direction. The second deformation portion 424 supports the pair of side surfaces Wb of the workpiece W by contacting the pair of side surfaces Wb of the workpiece W.

[0046] In this embodiment, the pair of side surfaces Wb of the workpiece W are not planar, but have a partially protruding protruding shape, a partially recessed recessed shape, a partially curved curved shape, etc. However, the present invention is not limited thereto, and the pair of side surfaces Wb of the workpiece W may be planar.

[0047] The second deformation portion 424 is configured to be deformable. When the jig 420 receives a control command from the control device 700, the jig 420 deforms the second deformation portion 424 by an actuator (not shown) based on the control command. In this embodiment, a control command including information regarding the outer shape of the workpiece W is transmitted to the jig 420. Based on the control command, the jig 420 deforms, for example, the clamping surface 424a of the second deformation portion 424 according to the outer shape of the pair of side surfaces Wb of the workpiece W. In addition, the jig 420 locks the second deformation portion 424 deformed according to the outer shape of the pair of side surfaces Wb of the workpiece W, and maintains the shape of the clamping surface 424a.

[0048] For example, the second deformation unit 424 is composed of a plurality of pins configured to be movable in a proximity direction approaching the workpiece W and a separation direction away from the workpiece W. However, the present invention is not limited to this, and the second deformation unit 424 may be configured to be deformed and locked in accordance with the external shape of the workpiece W. For example, the second deformation unit 424 may be composed of a contact member that contacts the workpiece W and an actuator that can move the contact member in a proximity direction approaching the workpiece W and a separation direction away from the workpiece W. The actuator may be a hydraulic, pneumatic, or electric actuator.

[0049] The second deformation portion 424 deforms according to the outer shape of the pair of side surfaces Wb of the workpiece W, and after being locked, comes into contact with the pair of side surfaces Wb of the workpiece W, thereby being able to support the pair of side surfaces Wb of the workpiece W. Here, the contact portions of the second deformation portion 424 that come into contact with the pair of side surfaces Wb of the workpiece W become the clamping surfaces 424a. The clamping surfaces 424a clamp the workpiece W with two surfaces different from the contact surface 422a.

[0050] In this way, the jig 420 can support the pair of side surfaces Wb of the workpiece W in contact with the clamping surface 424a by deforming the second deformation portion 424 into a shape corresponding to the outer shape of the pair of side surfaces Wb of the workpiece W and locking the shape. In this embodiment, the pair of side surfaces Wb of the workpiece W held by the robot arm 610 are clamped by the clamping surface 424a of the second deformation portion 424 whose shape is locked. At this time, for example, when a torque around a predetermined rotation axis is applied to the upper surface of the workpiece W by a processing device (not shown), the second deformation portion 424 of the jig 420 can receive the torque applied to the workpiece W. In other words, the clamping surface 424a of the second deformation portion 424 functions as an external force receiving surface capable of receiving an external force acting on the workpiece W by contacting the workpiece W.

[0051] 3, the robot arm 610 of this embodiment can move the workpiece W in three orthogonal axis directions and can rotate the workpiece W around the three orthogonal axes. That is, the robot arm 610 has three translational degrees of freedom to move the workpiece W in the three orthogonal axis directions and also has three rotational degrees of freedom to rotate the workpiece W around the three orthogonal axes.

[0052] 3 and 4, the jig 420 of this embodiment has a first deformation portion 422 and a second deformation portion 424. In this embodiment, the first deformation portion 422 is provided in a vertically downward direction with respect to the workpiece W, and can receive a vertically downward external force acting on the workpiece W by abutting against the workpiece W. Also, the second deformation portion 424 is provided in a pair with respect to the workpiece W, for example, at positions facing the pair of side surfaces Wb in the left-right direction, and can receive a left-right external force acting on the workpiece W by abutting against the workpiece W.

[0053] However, without being limited thereto, the first deformation part 422 may be provided in a vertically upward direction with respect to the workpiece W, and may receive an external force acting on the workpiece W in a vertically upward direction. The second deformation part 424 may be provided in a pair in the front-rear direction with respect to the workpiece W, for example, and may receive an external force acting on the workpiece W in the front-rear direction. That is, the first deformation part 422 and the second deformation part 424 are configured to be able to receive an external force acting on the workpiece W in any translation direction among the three orthogonal axial directions of the up-down direction, the left-right direction, and the front-rear direction. In other words, the first deformation part 422 and the second deformation part 424 limit the translation movement in the direction in which the external force acts on the workpiece W among the three orthogonal axial directions, and limit at least one of the three degrees of freedom of translation of the workpiece W.

[0054] In addition, the first deformation part 422 and the second deformation part 424 are configured to be able to receive torque acting around any of the three orthogonal axes, namely, the up-down direction, the left-right direction, and the front-back direction. For example, by providing a pair of the first deformation part 422 in the up-down direction with respect to the workpiece W, it is possible to receive torque around the left-right axis and the front-back axis of the workpiece W. Also, by providing a pair of the second deformation part 424 in the left-right direction with respect to the workpiece W, it is possible to receive torque around the front-back axis and the up-down axis of the workpiece W. Also, by providing a pair of the second deformation part 424 in the front-back direction with respect to the workpiece W, it is possible to receive torque around the left-right axis and the up-down axis of the workpiece W. In other words, the first deformation part 422 and the second deformation part 424 limit the rotational movement in the direction in which the torque acts on the workpiece W among the three orthogonal axes, and limit at least one of the three degrees of freedom of rotation of the workpiece W. Here, the forces acting in the translational directions of the three orthogonal axes on the workpiece W and the torque acting in the rotational directions around the three orthogonal axes are collectively referred to as external forces.

[0055] In this embodiment, an example will be described in which the second deformation part 424 deforms in accordance with the external shape of the workpiece W, but the deformed shape of the second deformation part 424 is not limited to a shape corresponding to the external shape of the workpiece W. Specifically, the second deformation part 424 only needs to be able to support the workpiece W so as to be able to receive torque, which is an external force acting on the workpiece W, and only needs to have at least one support part that supports the workpiece W at one point. That is, instead of the second deformation part 424 of this embodiment shown in FIG. 4, a support member that supports the workpiece W at at least one point and is able to receive torque may be used.

[0056] As described above, the robot arm 610 of this embodiment has three degrees of freedom of rotation that can rotate the workpiece W around three orthogonal axes. Here, for example, when a torque is applied to the workpiece W around a predetermined rotation axis among the three orthogonal axes, the workpiece W tries to rotate around the predetermined rotation axis. In order to receive the torque around the predetermined rotation axis and limit the rotational movement of the workpiece W, at least one support point that supports the workpiece W in a cross section perpendicular to the predetermined rotation axis is sufficient. The at least one support point is a point that satisfies the condition that the distance between the predetermined rotation axis and the outer surface of the workpiece W in the cross section increases in the opposite direction to the rotation direction of the torque with respect to the distance between the predetermined rotation axis and the support point. When such a support point is provided, the second deformation part 424 can support the workpiece W and receive torque, which is an external force acting on the workpiece W. Therefore, when a torque around a predetermined rotation axis is applied to the workpiece W, the second deformation part 424 may be deformed to form at least one support point that supports the workpiece W in a cross section perpendicular to the predetermined rotation axis. Alternatively, the workpiece W may be clamped as in this embodiment, and torque may be received by the static friction force between the workpiece W and the clamping surface 424a.

[0057] In this embodiment, the jig 420 has the first deformation portion 422 and the second deformation portion 424, and thus can support workpieces W having a wide variety of outer shapes regardless of the outer shape of the workpiece W. In addition, the jig 420 can receive an external force applied to the workpiece W.

[0058] Incidentally, if the robot arm 610 can generate a force greater than the external force applied to the workpiece W, the robot arm 610 can perform an assembly process, processing process, welding process, etc. of the workpiece W while holding the workpiece W. In this way, if the robot arm 610 can perform a processing process, etc. while holding the workpiece W, it is possible to save the time of having to move the robot arm 610 away from the workpiece W and holding the workpiece W again with the robot arm 610 after the processing process. However, in this case, an output is required to hold the workpiece W in the same position against the external force acting on the workpiece W from the processing tool, etc., and the output required of the robot increases.

[0059] Therefore, the robot control unit 710 of this embodiment controls the robot arm 610 to be movable in a first direction in which the external force acts on the workpiece W and in a second direction opposite to the first direction so that the external force applied to the workpiece W is received by the jig 420. That is, in order to reduce the output required of the robot 600, the external force acting on the workpiece W is received by the jig 420, and the movement of the robot arm 610 in the direction in which the external force or the reaction force acts is made free so that the robot arm 610 does not receive the external force or the reaction force. More specifically, in order to reduce the output required of the robot 600, the jig 420 receives a translational force acting on the workpiece W in at least one of the three orthogonal axial directions. Then, in order to prevent the robot arm 610 from receiving a translational force or a reaction force acting on the workpiece W in at least one of the three orthogonal axial directions, the translational movement of the robot arm 610 in the direction in which the translational force or the reaction force acts is made free.

[0060] Fig. 5 is a schematic configuration diagram of the robot arm 610 and the processing device 400 during processing of the workpiece W. As shown in Fig. 5, during processing of the workpiece W, a processing tool 430, which is a part of the processing equipment, comes into contact with the upper surface Wc of the workpiece W, and an external force F is applied by the processing tool 430 in a first direction, which is a vertically downward direction.

[0061] At this time, the robot control unit 710 controls the robot arm 610 to be movable in the first direction, so that the jig 420 can receive the external force F in the first direction acting on the upper surface Wc of the workpiece W. In addition, the robot control unit 710 controls the robot arm 610 to be movable in a second direction opposite to the first direction, so that the robot arm 610 does not receive the reaction force from the jig 420 against the external force F. In this way, the robot control unit 710 of this embodiment controls the robot arm 610 to be movable in a first direction, which is a vertical downward direction, and in a second direction, which is a vertical upward direction, as shown by the double-headed arrow in FIG. Here, being movable means that the robot arm 610 can move by the external force F or can follow the direction in which the external force F acts.

[0062] The first direction in which the external force F acts is not limited to the vertical downward direction as in this embodiment. The first direction in which the external force F acts may be a vertical upward direction, a horizontal direction, or a tilted direction inclined from the vertical direction to the horizontal direction. The first direction in which the external force F acts may be a direction around a predetermined rotation axis among the three orthogonal axes. For example, the robot control unit 710 of this embodiment controls the robot arm 610 to be movable in a first rotation direction in which the torque acts on the workpiece W and in a second rotation direction opposite to the first rotation direction so that the torque applied to the workpiece W is received by the jig 420. That is, in order to reduce the output required of the robot 600, the jig 420 is made to receive the torque around a predetermined rotation axis among the three orthogonal axes acting on the workpiece W. And, the robot arm 610 is free to rotate in the direction in which the torque or the reaction force acts so that the robot arm 610 does not receive the torque around the predetermined rotation axis acting on the workpiece W or the reaction force.

[0063] In addition, when the direction in which the external force F acts is an inclined direction inclined with respect to the vertical direction and the horizontal direction, the external force F may be decomposed into a first component in the vertical direction and a second component in the horizontal direction, and the direction in which the larger of the first and second components acts may be set as the first direction. In other words, when the external force F can be decomposed into two first and second components that are perpendicular to each other in the vertical and horizontal directions, the direction in which the larger of the first and second components acts may be set as the first direction. In this way, when the robot arm 610 is controlled to be movable in the first direction, the first component, which is a component in the first direction among the external forces acting on the workpiece W, is greater than the second component, which is a component in a direction perpendicular to the first direction.

[0064] This makes it possible to avoid the external force F acting on the workpiece W being received by the robot arm 610 and to deflect it onto the jig 420, to prevent the reaction force of the external force F acting on the workpiece W from being received by the robot arm 610, and to reduce the reaction force applied to the robot arm 610. As a result, it is only necessary for the robot arm 610 to be configured to be capable of generating a force sufficient to support and transport the weight of the workpiece W, and it is possible to reduce the output required of the robot 600. Detailed control of the robot control unit 710 of this embodiment will be described below.

[0065] The robot control unit 710 controls the robot arm 610 in two main modes. The two modes are a transport mode (second control mode) and a processing mode (first control mode). The transport mode is a mode in which the robot arm 610 transports the workpiece W between the workpiece storage device 200, the assembly device 300, the processing device 400, and the welding device 500. In the transport mode, in addition to the transport control of the workpiece W, the attitude control of the workpiece W and the positioning control of the workpiece W are also performed. The processing mode is a mode in which a process in which an external force F acts on the workpiece W is performed while the robot arm 610 is holding the workpiece W. The process in which the external force F acts on the workpiece W is, for example, a process in which the workpiece W is assembled by the assembly device 300, a process in which the workpiece W is processed by the processing device 400, and a process in which the workpiece W is welded by the welding device 500.

[0066] First, the robot control unit 710 controls the robot arm 610 in a transfer mode, moves the robot arm 610 to the work storage device 200, and controls the robot arm 610 to take out the work W from the work storage device 200. Specifically, the robot control unit 710 controls the robot arm 610 to hold and take out the work W stored in the work storage device 200.

[0067] Then, the robot control unit 710 controls the transport of the workpiece W held by the robot arm 610 to any one of the assembling device 300, the processing device 400, and the welding device 500. Here, a reference position is set in advance for each of the assembling device 300, the processing device 400, and the welding device 500.

[0068] In the transfer mode, the robot control unit 710 controls the robot arm 610 so that the workpiece W is positioned at a preset reference position. In Fig. 5, the reference position is a position where the lower surface Wa of the workpiece W contacts the ground surface 422a of the jig 420. However, the reference position does not have to be a position where the lower surface Wa of the workpiece W contacts the ground surface 422a, and may be, for example, a position where the lower surface Wa of the workpiece W is spaced a predetermined distance above the ground surface 422a.

[0069] In this manner, the robot control unit 710 controls the robot arm 610 to perform positioning control of the workpiece W so that the workpiece W is located at a reference position. At this time, the robot control unit 710 also performs posture control to control the posture of the workpiece W to a predetermined posture. The predetermined posture is, for example, the posture of the workpiece W in a state where it is stored in the workpiece storage device 200. The robot control unit 710 sequentially controls the posture of the workpiece W so as to maintain the workpiece W in the predetermined posture.

[0070] During positioning control, the robot control unit 710 detects an external force F acting on the robot arm 610 and, in turn, the workpiece W by the force sensor 620. This force sensor 620 is used to determine whether the workpiece W is in contact with the ground surface 422a and located at a reference position. When the workpiece W is not in contact with the ground surface 422a, the force sensor 620 detects a force equivalent to the weight of the workpiece W. On the other hand, when the workpiece W is in contact with the ground surface 422a and located at the reference position, the force sensor 620 detects a force less than a threshold value near 0. When the force detected by the force sensor 620 becomes less than the threshold value near 0, the robot control unit 710 determines that the workpiece W is located at the reference position.

[0071] When it is determined that the workpiece W is located at the reference position, the control device 700 controls the robot arm 610 in a processing mode, and performs drive control to drive an assembly device, a processing device, or a welding device (not shown). Here, the direction of the external force F acting on the workpiece W by the assembly device, the processing device, or the welding device is preset for each device. For example, if the assembly device is a device that assembles the workpiece W by screwing, the rotation direction of the screw is set as the direction in which the external force acts on the workpiece W. In addition, the direction of the rotation axis in which the screw enters the workpiece W is set as the direction in which the external force acts on the workpiece W. Such information regarding the direction in which the external force acts on the workpiece W, which is preset for each device, is stored in a storage unit (not shown) of the control device 700.

[0072] 5, the control device 700 drives a processing device (not shown) to perform processing such as cutting or machining of the workpiece W by the processing tool 430. In this embodiment, for example, punching is performed from the upper surface Wc of the workpiece W to the lower surface Wa. The direction of the external force F acting on the workpiece W at this time is, for example, the vertical downward direction.

[0073] At this time, the robot control unit 710 acquires the direction of the external force F acting on the workpiece W by the processing tool 430 from the memory unit of the control device 700. Here, the robot control unit 710 acquires information on the vertical downward direction (first direction) as the direction of the external force F acting on the workpiece W.

[0074] The robot control unit 710 performs posture control to maintain the posture of the workpiece W in a predetermined posture, while performing control to enable movement of the robot arm 610 in the vertically downward direction in which the external force F acts. In addition, the robot control unit 710 performs control to restrict movement of the robot arm 610 in directions other than the vertically downward direction in which the external force F acts, and the vertically upward direction opposite to the vertically downward direction.

[0075] Specifically, the robot control unit 710 controls the robot arm 610 to be movable in the vertical downward direction in which the external force F acts and in the vertical upward direction in which the reaction force of the external force F acts among the three orthogonal axial directions. Meanwhile, the robot control unit 710 controls to restrict movement in the horizontal front-back direction, horizontal left-right direction, and directions around the three axes in which the external force F does not act among the three orthogonal axial directions. However, without being limited thereto, the robot control unit 710 may control the robot arm 610 to be movable only in the vertical downward direction in which the external force F acts among the three orthogonal axial directions. In that case, the robot control unit 710 may control to restrict movement in the vertical upward direction, horizontal front-back direction, horizontal left-right direction, and directions around the three axes in which the external force F does not act among the three orthogonal axial directions.

[0076] As a result, when a vertical downward external force F is applied to the workpiece W, the workpiece W maintains a predetermined posture, and the external force F is diverted to the jig 420 via the first deformation portion 422 due to contact between the underside Wa of the workpiece W and the ground surface 422a.

[0077] As described above, the robot control unit 710 of this embodiment performs positioning control in the transfer mode to move the workpiece W to a reference position and bring the lower surface Wa into contact with the ground surface 422a. In the processing mode, the robot control unit 710 performs movement enable control to control the robot arm 610 to be movable in a first direction in which the external force F acts on the robot arm 610, and movement limit control to limit the movement of the robot arm 610 in at least the first direction and directions other than the second direction opposite to the first direction. Note that the external force F may have a first component force that is a component force in the first direction that is greater than a second component force that is a component force in a direction perpendicular to the first direction.

[0078] Here, when controlling the robot arm 610 in the transport mode, the robot control unit 710 ends the above-mentioned movable control so that the robot arm 610 can support the weight of the workpiece W. In the transport mode, the robot control unit 710 controls the robot arm 610 so as to restrict the movement of the robot arm 610 in directions other than the transport direction of the workpiece W. The control that restricts the movement of the robot arm 610 in directions other than the transport direction of the workpiece W is control that generates force in each portion of the robot arm 610 so that the robot arm 610 can support the weight of the robot arm 610 itself and the workpiece W.

[0079] Furthermore, when controlling the robot arm 610 in the processing mode, the robot control unit 710 executes the above-mentioned movement enabling control and movement limiting control. The movement enabling control refers to control that weakens the holding force that holds the workpiece W to an extent that the robot arm 610 can move in response to the external force F in a first direction of a preset external force F acting on the workpiece W. The movement limiting control refers to control in a state in which a force is generated in each part of the robot arm 610 in order to hold the workpiece W and the robot arm 610 at a reference position in at least directions other than the first direction and the second direction.

[0080] As a result, the external force F applied to the workpiece W is received by the jig 420, and even if the external force F is greater than the output of the robot arm 610 allows, the workpiece W can be held by the output of the robot arm 610. Therefore, the robot arm 610 only needs to be configured to generate a force sufficient to simply support and transport the weight of the workpiece W. As a result, the output required of the robot 600 can be reduced.

[0081] 6 is a flow chart for explaining an example of a method for processing a workpiece W using the control device 700 according to this embodiment. As shown in FIG 6, the method for processing a workpiece W according to this embodiment includes steps S101 to S109.

[0082] First, the robot control unit 710 controls the robot arm 610 in a transfer mode, and performs positioning control of the workpiece W so that the workpiece W is located at a preset reference position (step S101). Here, the robot control unit 710 executes control to bring the lower surface Wa of the workpiece W into contact with the ground surface 422a.

[0083] Next, when the workpiece W reaches the reference position, the control device 700 performs control to drive an assembly device, a processing device, or a welding device (not shown) to start processing the workpiece W (step S102). The processing of the workpiece W is processing in which an external force F is applied to the workpiece W.

[0084] When control to start processing the workpiece W is executed, the robot control unit 710 switches from the transport mode to the processing mode and controls the robot arm 610. In the processing mode, the robot control unit 710 acquires information about a first direction in which an external force acts on the workpiece W based on the type of equipment or tool that processes the workpiece W (step S103). Then, based on the acquired information about the first direction, the robot control unit 710 performs a movement enable control that enables the robot arm 610 to move in the first direction (step S104). In addition, the robot control unit 710 performs a movement limit control that limits the movement of the robot arm 610 in directions other than the first direction and a second direction opposite to the first direction (step S105).

[0085] Thereafter, the robot control unit 710 judges whether or not all the processes for the workpiece W have been completed (step S106). If all the processes for the workpiece W have not been completed (NO in step S106), the robot control unit 710 is controlled in a transport mode that restricts the movement of the robot arm 610 in directions other than the transport direction of the workpiece W (step S107). Then, the robot arm 610 changes the posture of the workpiece W while gripping it, and executes positioning control to bring the lower surface Wa of the workpiece W into contact with the ground surface 422a (step S108). This positioning control also includes control to raise and lower the workpiece W. Thereafter, the robot control unit 710 repeatedly executes the processes of steps S103, S104, S105, and S106.

[0086] On the other hand, if all processing for the workpiece W has been completed (YES in step S106), the control device 700 stops the operation of the assembly equipment, processing equipment, or welding equipment (not shown) and performs control to end the processing of the workpiece W (step S109).

[0087] Although the embodiments of the present disclosure have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to such embodiments. It is clear that a person skilled in the art can think of various modified or altered examples within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present disclosure.

[0088] In the above, an example has been described in which the jig 420 is provided with a first deformation portion 422 having a contact surface 422a that can be deformed in accordance with the external shape of the workpiece W, but the first deformation portion 422 is not a required component, and the jig 420 does not necessarily have to be provided with the first deformation portion 422.

[0089] The jig 420 only needs to have at least a ground surface 422a capable of receiving an external force acting on the workpiece W. Therefore, the jig 420 may have, for example, a ground surface 422a that does not deform according to the external shape of the workpiece W. This ground surface 422a is, for example, a plane parallel to the horizontal direction. Furthermore, the ground surface 422a that does not deform according to the external shape of the workpiece W may be provided on the mounting table 410. In that case, the jig 420 does not need to be provided on the upper surface of the mounting table 410.

[0090] In the above, an example has been described in which the jig 420 is provided with the second deformation portion 424 having a clamping surface 424a that can be deformed according to the external shape of the workpiece W, but the second deformation portion 424 is not a required component, and the jig 420 does not necessarily have to be provided with the second deformation portion 424. [Explanation of symbols]

[0091] 100 Robot System 200 Work storage device 300 Assembly equipment 400 Processing equipment 410 Placement table 420 Jig 422 First transformation section 422a ground plane 424 Second transformation section 424a Clamping surface 500 Welding Equipment 600 Robots 610 Robot Arm 620 Force Sensor 700 Control device 710 Robot Control Unit

Claims

1. A robot having a robot arm capable of gripping a workpiece; A control device for controlling the operation of the robot arm; Equipped with The control device includes: bringing the workpiece into contact with a ground surface while the robot arm is gripping the workpiece; Controlling the robot arm to be movable in a first direction in which an external force acts on the robot arm; Controlling the robot arm to limit movement in directions other than at least the first direction and a second direction opposite to the first direction; Run The external force has a first component in the first direction that is greater than a second component in a direction perpendicular to the first direction. Robot system.

2. The ground surface is configured to be deformable. The robot system of claim 1 .

3. The contact surface is configured to be deformable according to the outer shape of the workpiece. The robot system according to claim 2 .

4. The workpiece is clamped by two surfaces different from the contact surface, The clamping surface is configured to be deformable according to the outer shape of the workpiece. The robot system according to claim 1 or 2.

5. A step of gripping a workpiece by a robot arm; A step of bringing the workpiece into contact with a ground surface while the robot arm is holding the workpiece; a step of controlling the robot arm in a first control mode that limits movement of the robot arm in at least directions other than the first direction and a second direction opposite to the first direction, while controlling the robot arm to be movable in a first direction in which an external force acts on the robot arm after the step of bringing the workpiece into contact with a ground surface; After the step of controlling the robot arm in the first control mode, a step of executing a process of applying the external force to the workpiece while the robot arm is gripping the workpiece; Including, The external force has a first component in the first direction that is greater than a second component in a direction perpendicular to the first direction. How the workpiece is processed.

6. After the step of executing a process of applying the external force to the workpiece, a step of controlling the robot arm in a second control mode that limits movement of the robot arm in directions other than a conveying direction of the workpiece; After the step of controlling the robot arm in the second control mode, a step of changing a posture of the workpiece while the robot arm is gripping the workpiece, and bringing the workpiece into contact with the ground surface; Including, The method for treating a workpiece according to claim 5.

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