JP7504627B2 - Control device for gripping device and control program for gripping device - Google Patents

Description

An embodiment of the present invention relates to a control device for a gripping device and a control program for the gripping device.

There is a gripping device that grips an object by adsorbing the object to be gripped and pinching the adsorbed object between fingers that are each driven by a plurality of motors. The gripping device has fingers arranged on one side and on the other side different from the one side with respect to a main body. The suction part is arranged between the fingers on one side and the fingers on the other side.

JP 2019-051575 A JP 2019-111615 A

The problem that the present invention aims to solve is to provide a control device for a gripping device and a control program for the gripping device that can pick up an object and then grip the object by clamping it.

A control device for a gripping device according to an embodiment includes a control unit, and while maintaining a state in which an article to be gripped is sucked by a suction unit of the gripping device, the control unit drives the first drive unit with a first torque so that a first finger unit on one side of the suction unit and connected to a first drive unit and a second finger unit on the other side opposite the first finger unit across the suction unit come into contact with the article and pinch the article, and while maintaining a state in which the article is sucked by the suction unit, the control unit drives the first drive unit with a second torque larger than the first torque in a state in which the first finger unit and the second finger unit come into contact with the article with the first torque, and The rigidity of the article is estimated based on the angle of the rotation axis of the first finger portion relative to a reference position and the angle of the rotation axis of the second finger portion relative to a reference position, and while maintaining the state in which the article is adsorbed by the suction unit, the angles of the first finger portion and the second finger portion relative to a reference angle in a state in which the first driving unit is rotated with the first torque and the second torque , and target torques of the first finger portion and the second finger portion relative to the article are set according to the rigidity , and while maintaining the state in which the article is adsorbed by the suction unit, the first driving unit is driven by the first finger portion and the second finger portion at the target torque.

1 is a schematic diagram showing an object gripping system according to a first and second embodiment; FIG. 2 is a schematic perspective view showing a gripping device for gripping an object. FIG. 1 is a block diagram of an article gripping system. 11 is a schematic diagram showing an example of a state in which an object is gripped by using the suction function and the clamping function of the gripping device. FIG. 11 is a schematic diagram showing an example of a state in which an object is gripped by the suction function and the clamping function of the gripping device. FIG. 11 is a schematic diagram showing an example of a state in which an object is gripped by the suction function and the clamping function of the gripping device. FIG. FIG. 13 is a schematic diagram showing an example of a state in which an object is gripped using the gripping function of the gripping device. FIG. 13 is a schematic diagram showing an example of a state in which an article is gripped by using a suction function of the gripping device. 11 is a schematic diagram showing an example of a state in which an article is gripped using the suction function and the pressing function of the gripping device. FIG. 11 is a schematic diagram showing an example of a state in which an object is gripped by the suction function and the gripping function of the gripping device. FIG. 11 is a schematic diagram showing the gripping device and the object shown in FIG. 10 as viewed obliquely from below. 4 is a schematic flowchart showing an example of a series of operations for gripping an object using the object gripping system. FIG. 1 is a schematic diagram showing an example of an article. 12 is a flowchart showing an example of determining a gripping plan for the object shown in FIG. 4 to FIG. 11 by a control device based on the shape and size of the object. 7 is a control flowchart of a control device of a gripping device when an article is sucked and clamped using the suction function and the clamping function shown in FIGS. 4 to 6 according to the first embodiment. 7 is a schematic diagram showing a state in which an article is sucked and clamped using the suction function and clamping function shown in FIGS. 4 to 6 . FIG. 7 is a schematic diagram showing a state in which an article is sucked and clamped using the suction function and clamping function shown in FIGS. 4 to 6 . FIG. 7 is a control flowchart of a control device of a gripping device according to a second embodiment when an article is sucked and clamped using the suction function and the clamping function shown in FIGS. 4 to 6 .

[First embodiment]
1, the article gripping system 100 includes a moving device 2 that moves an article (luggage) P, a detection device 3 that detects the article P, and a control device 4. The article gripping system 100 grips one article P placed alone in a container C, or any one of a plurality of articles P, and moves the article P to any location (for example, an adjacent belt conveyor B).

The moving device 2 has, for example, a base section 21, a main arm 22, a tool 23, a solenoid valve 24, and an external piping section 25.

The base 21 is fixed to the floor, for example. The main arm 22 is fixed to the upper surface of the base 21. The tool 23 is fixed to the tip of the main arm 22. The solenoid valve 24 is fixed to any side of the main arm 22, for example. The position of the solenoid valve 24 may be fixed to the main body 11 of the tool 23.

The external piping section 25 is, for example, an air tube or a resin piping member. The external piping section 25 connects between a compressor (not shown) and the solenoid valve 24, and between the solenoid valve 24 and the tool 23, forming a flow path for compressed air. The solenoid valve 24 switches between opening (opening) and blocking (closing) the flow path.

The tool 23 has a gripping device 1 and a force sensor (force detection means) 5. One end of the force sensor 5 is attached to the tip of the main arm 22. The other end of the force sensor 5 is attached to the gripping device 1. The force sensor 5 can detect external forces and moments applied to the gripping device 1.

The detection device 3 detects the state in which one or more items P are placed. The detection device 3 is composed of, for example, an RGB camera, a 3D camera, or other sensors, or a combination of these.

The control device 4 shown in FIG. 3 acquires the shape, position, orientation, and other information of the item P based on the information obtained from the detection device 3.

The control device 4 has a planning unit 41, a control unit 42, an analysis unit 43, a main memory unit 44, and an auxiliary memory unit 45. The control device 4 may be configured as one control terminal, or may be configured as a combination of multiple control terminals. Each of these components is realized by hardware, such as the processor of the control unit 42, executing a program (software).

The control unit 42 is provided with an interface 42a. The interface 42a transmits and receives signals between the control unit 42 and the outside of the control unit 42. The control unit 42 can transmit signals to the various devices of the detection device 3, the planning unit 41, the analysis unit 43, the main memory unit 44, the auxiliary memory unit 45, and the mobile device 2 via the interface 42a, and can receive signals from the various devices of the detection device 3, the planning unit 41, the analysis unit 43, the main memory unit 44, the auxiliary memory unit 45, and the mobile device 2.

The analysis unit 43 acquires the shape, position, orientation, and other information of the item P based on the information (e.g., image information I) obtained by the detection device 3.

The control unit 42 reads the output information from the gripping device 1 and the force sensor 5, and operates the main arm 22 of the mobile device 2 and the gripping device 1 based on the gripping plan, which includes the operation plan formulated by the planning unit 41.

The planning unit 41 formulates a gripping plan for the item P. The gripping plan includes, for example, a motion plan for the main arm 22. The planning unit 41 formulates a gripping plan including a motion plan based on output information from the control unit 42 and the analysis unit 43, selects the best gripping plan from the formulated plans based on predetermined criteria, and issues a command to the mobile device 2 via the control unit 42.

The computer constituting the control device 4 includes a control unit 42 including a processor such as a CPU, a main memory unit 44 such as a read-only memory (ROM) or random access memory (RAM), and an auxiliary memory unit 45 such as a hard disk drive (HDD), a solid state drive (SSD) or a removable medium. Various programs are stored in the main memory unit 44. In this case, the control unit 42, for example, a processor such as a CPU, deploys the control program stored in the ROM of the main memory unit 44 into the RAM of the main memory unit 44 and executes it.

The auxiliary memory unit 45 stores various data including an operating system, various programs, various information tables, etc. Therefore, the control unit 42 can execute various processes by, for example, loading a program stored in the auxiliary memory unit 45 into the main memory unit 44 and executing it. The control unit 42 can execute various processes by, for example, loading a program obtained via a network into the main memory unit 44 and executing it.

The program by the control unit 42 can also be executed by a circuit (e.g., ASIC, FPGA, etc.) that realizes one or more functions.

As shown in Figures 2 and 3, the gripping device 1 has a main body portion 11, an adsorption portion 12, a vacuum generator 13, a pressure sensor 14, an internal piping portion 16, a first finger portion 17a, a second finger portion 17b, a first drive portion 18a, and a second drive portion 18b.

The suction part 12 is disposed on the main body part 11. The suction part 12 has, for example, one or more suction pads 12a made of rubber. In the example shown in FIG. 2, the suction part 12 having four suction pads 12a is attached to the main body part 11. Here, the centroid of the four suction pads 12a perpendicular to the suction direction of the suction part 12 for suction of the item P is defined as the centroid of the suction part 12. A line passing through the centroid of the suction part 12 and parallel to the suction direction of the suction part 12 is defined as the axis A of the suction part 12.

The main body 11 houses a vacuum generator 13, a pressure sensor 14, and an internal piping section 16. The internal piping section 16 connects an output end of the vacuum generator 13, the pressure sensor 14, and the suction section 12 through a single flow path. The pressure sensor 14 detects a decrease in pressure when the article P is being sucked by the suction pad 12a of the suction section 12.
When the item P is placed below the main body portion 11 and is gripped, the suction portion 12 is located below the main body portion 11 .

The vacuum generator 13 is, for example, an ejector, and is built into the main body 11 together with, for example, the pressure sensor 14.

The first finger portion 17a is disposed on one side of the main body portion 11. The second finger portion 17b is disposed on the other side of the main body portion 11, opposite the one side of the main body portion 11 across the axis of the suction portion 12. The first finger portion 17a is formed in a hook shape that is approximately L-shaped. The first finger portion 17a rotates within a predetermined range in synchronization with the rotation shaft 19a1 of the first motor 19a of the first drive portion 18a by the rotation shaft 17a0. The second finger portion 17b has a pair of fingers 17b1, 17b2. The pair of fingers 17b1, 17b2 are each formed in a hook shape that is approximately L-shaped. The pair of fingers 17b1, 17b2 of the second finger portion 17b rotates within a predetermined range in synchronization with the rotation shaft 20a1 of the second motor 20a of the second drive portion 18b by the rotation shaft 17b0.

The first finger portion 17a has a claw portion 117a. The second finger portion 17b has a claw portion 117b. The finger 17b1 of the second finger portion 17b has a claw portion 117b1. The finger 17b2 of the second finger portion 17b has a claw portion 117b2. The claw portion 117a of the first finger portion 17a and the claw portions 117b1, 117b2 of the pair of fingers 17b1, 17b2 of the second finger portion 17b do not come into contact with, for example, a corner (edge) of the item P to be grasped, but may come into contact with the side surface Pb or the bottom surface Pc of the item P.

The main arm 22 can orient the suction pad 12a of the suction part 12 of the gripping device 1 in an appropriate direction. For the sake of simplicity, an example will be described in which the suction pad 12a of the suction part 12 is oriented vertically downward. In this case, the positional relationship between the first finger portion 17a and the second finger portion 17b is such that when the article P is gripped by clamping, the claw portions 117a and 117b are positioned below the suction pad 12a of the suction part 12.

The rotation axis 17a0 of the first finger 17a and the rotation axis 17b0 of the pair of fingers 17b1, 17b2 of the second finger 17b are located opposite the upper surface Pa (the suction surface to which the suction part 12 is suctioned) of the suction pad 12a of the suction part 12 when the article P is suctioned, and are preferably located farther from the upper surface Pa of the article P than the suction pad 12a and as close as possible to the upper surface Pa of the article P. The rotation axes 17a0, 17b0 are equidistant from the axis A of the suction part 12. The rotation axis 17a0 of the first finger 17a and the rotation axis 17b0 of the pair of fingers 17b1, 17b2 of the second finger 17b are parallel and are located distal to the ends of the suction pad 12a in the width direction and the length direction (see FIG. 13) with respect to the axis A of the suction part 12.

The first drive unit 18a has a first motor 19a, a first torque sensor 19b, and a first angle sensor 19c. The second drive unit 18b has a second motor 20a, a second torque sensor 20b, and a second angle sensor 20c.

The first motor 19a of the first drive unit 18a and the second motor 20a of the second drive unit 18b are preferably servo motors, but are not limited thereto. The first motor 19a and the second motor 20a may be motors or pneumatic actuators capable of switching between a plurality of torque states. The rotating shaft 19a1 of the first motor 19a and the rotating shaft 20a1 of the second motor 20a may have a brake mechanism or a position holding function for holding the current position.
In this embodiment, an example will be described in which the first motor 19a and the second motor 20a are servo motors. The first motor 19a and the second motor 20a are used within a rated torque range.

The torque sensor 19b detects the torque of the rotating shaft 19a1 of the first motor 19a. The torque sensor 20b detects the torque of the rotating shaft 20a1 of the second motor 20a.

The angle sensor 19c detects the current angle of the rotating shaft 19a1 of the first motor 19a. The angle sensor 20c detects the current angle of the rotating shaft 20a1 of the second motor 20a. For example, a rotary encoder is used as the angle sensors 19c and 20c.

2, a rotating shaft 19a1 of the motor 19a of the first drive unit 18a is connected to a rotating shaft 17a0 of the first finger 17a via a pulley 19a2, a timing belt 19a3, and a pulley 19a4, which are examples of a transmission mechanism. Therefore, when the rotating shaft 19a1 of the first motor 19a rotates, the pulley 19a2 fixed to the rotating shaft 19a1 rotates, the timing belt 19a3 wound around the pulley 19a2 moves in the circumferential direction, and the pulley 19a4 wound around the timing belt 19a3 and fixed to the rotating shaft 17a0 of the first finger 17a rotates.
A rotating shaft 20a1 of the motor 20a of the second drive unit 18b is connected to the rotating shaft 17b0 of the second finger unit 17b via a pulley 20a2, a timing belt 20a3, and a pulley 20a4, which are examples of a transmission mechanism. When the rotating shaft 20a1 of the second motor 20a is rotated, the pulley 20a2 fixed to the rotating shaft 20a1 rotates, the timing belt 20a3 wound around the pulley 20a2 moves in the circumferential direction, and the pulley 20a4 wound around the timing belt 20a3 and fixed to the rotating shaft 17b0 of the second finger unit 17b rotates.

The rotating shaft 19a1 of the first motor 19a and the rotating shaft 17a0 of the first finger portion 17a rotate or turn at an appropriate ratio, for example, depending on the diameter ratio of the pulleys 19a2 and 19a4. The rotating shaft 20a1 of the second motor 20a and the rotating shaft 17b0 of the second finger portion 17b rotate or turn at an appropriate ratio, for example, depending on the diameter ratio of the pulleys 20a2 and 20a4. Here, for the sake of simplicity of explanation, it is assumed that the current angle of the rotating shaft 19a1 of the first motor 19a is the same as the current angle of the rotating shaft 17a0 of the first finger portion 17a. It is assumed that the current angle of the rotating shaft 20a1 of the second motor 20a is the same as the current angle of the rotating shaft 17b0 of the second finger portion 17b.

The solenoid valve 24, the force sensor 5, the vacuum generator 13, the pressure sensor 14, the first drive unit 18a, and the second drive unit 18b are connected to the control unit 42 electrically or via a communication unit (not shown) that the control unit 4 may have.

Figures 4 to 11 show examples of gripping methods for gripping an item P using the gripping device 1. In Figures 4 to 11, the area where the suction portion 12 suctions the top surface Pa of the item P (the area where the suction pad 12a is in contact) is shown by a dashed circle. The positions where the first finger portion 17a and the second finger portion 17b are in contact with the item P are shown by a solid circle for the visible part and by a dashed circle for the invisible part.

Figures 4 to 6 show a state in which a roughly rectangular parallelepiped object P is grasped using the grasping device 1 by a combination of suction and clamping. In the example shown in Figures 4 to 6, there is a surface Pa to which the suction part 12 is suctioned, but the size along the width direction, the size along the depth direction (the height of the object P along the suction direction of the suction part 12), and the shape of the side surface Pb are different.

In the example shown in FIG. 4, the claw portions 117a and 117b of the fingers 17a and 17b are located on the side surface Pb of the item P.

Figure 5 shows the state in which the gripping device 1 grips an approximately rectangular parallelepiped object P by both suction and clamping. In the example shown in Figure 5, the claws 117a and 117b of the fingers 17a and 17b are located on the bottom surface or underside of the object P.

Figure 6 shows the state in which the gripping device 1 grips an approximately elliptical cylindrical object P by combining suction and clamping. In the example shown in Figure 6, the side surface Pb of the object P is formed into a curved surface. Meanwhile, the surface Pa that is gripped by the suction portion 12 can be considered to be approximately flat. In this case, the object P can be considered to be approximately rectangular.

As shown in Figures 4 to 6, the rotation angle of the fingers 17a and 17b relative to the rotation axes 17a0 and 17b0 changes depending on the size of the item P.

Figure 7 shows the state in which the gripping device 1 is used to pinch and grip an approximately rectangular parallelepiped object P. In the example shown in Figure 7, the claws 117a and 117b of the fingers 17a and 17b are located on the side surface Pb of the object P. In the example shown in Figure 7, the suction portion 12 is not used to grip the object P.

Figure 8 shows the state in which the gripping device 1 is used to adsorb and grip an approximately rectangular parallelepiped object P. In the example shown in Figure 8, the claws 117a and 117b of the fingers 17a and 17b are located on the sides of the main body 11, as an example, and are not used to grip the object P. The size of the object P shown in Figure 8 is drawn to be approximately the same as the size of the object P shown in Figure 5. The example shown in Figure 8 is lighter in weight than the object P shown in Figure 5.

Figure 9 shows a state in which a roughly rectangular parallelepiped object P is grasped using the grasping device 1 by a combination of suction and pressure. In the example shown in Figure 9, the top surface Pa of the object P is pressed by the claw portion 117a of the first finger portion 17a and the claw portion 117b of the second finger portion 17b at a position away from the suction portion 12, thereby suppressing vibrations applied to the object P. In the example shown in Figure 9, the suction pad 12a of the suction portion 12, the claw portion 117a of the first finger portion 17a, and the claw portion 117b of the second finger portion 17b are, for example, on the same plane.

In the examples of gripping an item P using a combination of suction and clamping shown in Figures 4 to 6, the example of gripping an item P by suction shown in Figure 8, and the example of gripping an item by a combination of suction and pressure shown in Figure 9, the approximate center (centroid) of the top surface of the item P is gripped based on size and shape information from the detection device 3 described below, and if the top surface Pa is an approximately rectangular shape that is long in one direction, the preferred posture for gripping the item P is to place the fingers 17a and 17b on the long side.

Figures 10 and 11 show a state in which a roughly rectangular parallelepiped object P is grasped using the grasping device 1 by a combination of suction and gripping. In the example shown in Figures 10 and 11, the claw portion 117a of the first finger portion 17a of the fingers 17a, 17b is located on the upper side of the object P. The claw portion 117b of the second finger portion 17b is located on the lower side of the object P.

As shown in Figures 4 to 11, the gripping device 1 according to this embodiment can grip objects P of a wide range of sizes using suction, clamping, or grasping. Therefore, the gripping device 1 according to this embodiment can grip objects (target objects) P of a wide variety of shapes, positions, and orientations using a single gripping device 1.

Next, the operation of the item gripping system 100 and the gripping device 1 will be described with reference to Figures 12 to 15.

The control unit 42 of the control device 4 of the item gripping system 100 photographs, for example, an item P in a container C with the detection device 3 (step S1). The control unit 42 operates the solenoid valve 24 to a closed state. The control unit 42 operates the vacuum generator 13. At this time, the internal piping section 16 is at atmospheric pressure.

The control unit 42 processes the image I captured by the detection device 3 in the analysis unit 43 of the control device 4 (step S2).

The control unit 42 determines whether or not there are one or more items P in the container C based on the information image-processed by the analysis unit 43 (step S3).

If the control unit 42 determines that there is no item P in the container C (step S3-NO), the control unit 42 ends the process. If the control unit 42 determines that there is an item P in the container C (step S3-YES), the control unit 42 separates the items P one by one through image processing by the analysis unit 43 (step S4).

The control unit 42 selects one item P from the items P separated by image processing (step S5).

The control unit 42 obtains information regarding the shape (including size), position, and posture of the selected item P through image processing in the analysis unit 43 (step S6).
The information regarding the item P may be, for example, information regarding only the top surface Pa of the item P. When information regarding the shape of the item P is registered in an information table stored in the item gripping system 100 or in an auxiliary storage unit 45 external to the item gripping system 100, the information regarding the shape of the item P is obtained from the information table.

The control unit 42 uses the planning unit 41 to formulate a grasping plan based on information regarding the shape, position, and posture of the item P (step S7).

As shown in FIG. 13, the width direction, depth direction (height direction of the item P along the suction direction of the suction portion 12), and longitudinal direction of the item P are taken. For a certain item P, a top surface Pa, a side surface Pb, and a bottom surface Pc are set. In addition, tentative target positions of the first finger portion 17a and the second finger portion 17b for clamping the side surface Pb of the item P are calculated and set.

The control unit 42 formulates the grasping plan according to the flow shown in FIG. 14.

The control unit 42 determines whether the item P is a rectangular parallelepiped (including a cube) or an approximately rectangular parallelepiped (including an approximately cube) (step S51). If the control unit 42 determines that the item P is not a rectangular parallelepiped or an approximately rectangular parallelepiped (step S51-NO), the control unit 42 sets the gripping method appropriately depending on the shape, position, and posture of the item P (step S52).

If the control unit 42 determines that the item P is a rectangular parallelepiped or an approximately rectangular parallelepiped (step S51-YES), the control unit 42 determines whether the item P has a surface Pa (see FIG. 13), such as a flat surface, to which the suction unit 12 can be suctioned (step S53).

If the control unit 42 determines that the item P does not have a surface Pa to which the suction unit 12 can be suctioned (step S53-NO), the control unit 42 determines the gripping method to be "clamping only" as shown in Figure 7 (step S54).

If the control unit 42 determines that the item P has a surface Pa to which the suction unit 12 can be suctioned (step S53-YES), the control unit 42 determines whether the depth dimension of the item P is equal to or smaller than a certain value (step S55).

If the control unit 42 does not determine that the depth dimension of the item P is equal to or less than a certain value (step S55-NO), the control unit 42 determines the gripping method to be "vacuum suction and gripping" as shown in Figures 10 and 11 (step S56).

If the control unit 42 determines that the depth dimension of the item P is less than or equal to a certain value (step S55-YES), the control unit 42 determines whether the width direction of the item P is less than or equal to a certain value (step S57).

If the control unit 42 does not determine that the width dimension of the item P is equal to or less than a certain value (step S57-NO), the control unit 42 determines the gripping method to be "vacuum suction and clamping" as shown in Figures 4 to 6 (step S58).

If the control unit 42 determines that the width dimension of the item P is less than or equal to a certain value (step S57-YES), the control unit 42 determines whether the longitudinal dimension of the item P is less than or equal to a certain value (step S59).

If the control unit 42 does not determine that the longitudinal dimension of the item P is equal to or less than a certain value (step S59-NO), the control unit 42 determines the gripping method to be "vacuum suction and pressure" as shown in Figure 9 (step S60).

If the control unit 42 determines that the longitudinal dimension of the item P is equal to or smaller than a certain value (step S59-YES), the control unit 42 determines the gripping method to be "vacuum suction only" as shown in Figure 8 (step S61).

In this way, the control unit 42 formulates a gripping plan for the item P using one of the gripping methods shown in Figures 4 to 11.

After formulating a gripping plan for the item P (step S7), the control unit 42 executes a gripping operation (step S8) as shown in FIG. 12. Here, an example in which the gripping device 1 mainly performs "vacuum suction and clamping" on the item P will be described with reference to FIG. 15.

The control unit 42 formulates an operation plan for the moving device 2 to move the item P from inside the container C to, for example, an adjacent belt conveyor B (step S21). The operation plan is, for example, a moving path from the container C to the belt conveyor B.

The control unit 42 switches the solenoid valve 24 from closed to open (step S22). This allows the suction unit 12 of the gripping device 1 to suction the top surface Pa of the item P.

The control unit 42 sets the first driving unit 18a and the second driving unit 18b to a position control mode, and sets the first finger portion 17a and the second finger portion 17b to a standby position (step S23). The control unit 42 sets the standby position of the first finger portion 17a and the second finger portion 17b as the reference position and reference angle of the first finger portion 17a and the second finger portion 17b. The control unit 42 controls the position of the first driving unit 18a and the second driving unit 18b, and in the standby position (reference position and reference angle), for example, places the first finger portion 17a and the second finger portion 17b in the position shown by the dashed lines in Figures 16 and 17. The standby position (reference position and reference angle) may be a state in which the suction pad 12a, the claw portion 117a of the first finger portion 17a, and the claw portion 117b of the second finger portion 17b are on the same plane, as in the example shown in Figure 9. The standby posture (reference position and reference angle) may always be the same, for example, as shown by the dashed lines in FIGS. 16 and 17 or as shown in FIG. 11, or may be changed according to the position, shape, and posture of the item P to be grasped. For example, the control unit 42 may determine the standby posture as a position in which the first finger portion 17a and the second finger portion 17b are close to the item P but do not come into contact with it. As one example, the standby posture (reference position and reference angle) may be a posture that is open by a predetermined angle (for example, about 10 to 15 degrees) from the tentative target angle of the first finger portion 17a and the second finger portion 17b formulated by the grasping plan.

The control unit 42 operates the main arm 22 to move the suction pad 12a of the suction unit 12 of the gripping device 1 to a target point (e.g., a position corresponding to the centroid) on the upper surface Pa of the item P (step S24). Note that the solenoid valve 24 may be set to "open" at any point during the movement of the axis A of the main body 11 and suction unit 12 of the gripping device 1 to a tentative target angle (gripping point).

The control unit 42 checks the output of the pressure sensor 14 (step S25). If the output (detected pressure) of the pressure sensor 14 is not below the threshold (step S26-NO), the output of the pressure sensor 14 is checked again (step S25). If the output of the pressure sensor 14 is below the threshold (step S26-YES), the operation of the main arm 22 is stopped (step S27). At this time, the suction unit 12 is suctioning the upper surface Pa of the target item P. The vacuum generator 13 is allowed to continue operating, and the solenoid valve 24 is maintained in an open state. The operation of the vacuum generator 13 and the open state of the solenoid valve 24 are maintained until step S11, which will be described later.

The control unit 42 switches the control of the first drive unit 18a and the second drive unit 18b from a position control mode in which the first finger unit 17a and the second finger unit 17b maintain a predetermined standby position (reference position and reference angle) to a torque control mode. The control unit 42 sets the target torque of the first drive unit 18a and the second drive unit 18b to a primary torque T1 (step S28). The primary torque is a torque that causes the first finger units 17a and 17b to abut against the item P but does not push the item P from the abutment position of the item P. The control unit 42 drives the first motor 19a of the first drive unit 18a and the second motor 20a of the second drive unit 18b simultaneously or at the same time while controlling the torque. Therefore, the control unit 42 transitions to a clamping operation in which the side surface Pb of the item P is clamped using the first finger unit 17a and the second finger unit 17b. At this time, the first finger 17a rotates around the rotating shaft 17a0 in conjunction with the first motor 19a of the first drive unit 18a. The second finger 17b rotates around the rotating shaft 17b0 in conjunction with the second motor 20a of the second drive unit 18b.

The control unit 42 uses torque sensors 19b, 20b to perform, for example, feedback control of the motor 19a of the first drive unit 18a and the motor 20a of the second drive unit 18b, and maintains the torque of the rotating shafts 19a1, 20a1 of the motors 19a, 20a at the target primary torque T1. The control unit 42 uses angle sensors 19c, 20c to detect, for example, the rotation angles of the rotating shafts 19a1, 20a1 of the motors 19a, 20a of the first drive unit 18a and the second drive unit 18b relative to a reference angle of the standby position.

The control unit 42 monitors the angular velocity (rotational speed) of the rotating shaft 19a1 of the motor 19a of the first drive unit 18a, i.e., the angular velocity (rotational speed) of the rotating shaft 17a0 of the first finger portion 17a, and also monitors the angular velocity (rotational speed) of the rotating shaft 20a1 of the motor 20a of the second drive unit 18b, i.e., the angular velocity (rotational speed) of the rotating shaft 17b0 of the second finger portion 17b (step S29).

The control unit 42 determines whether the angular velocity of the first drive unit 18a is ≒ 0 or the angle detected by the angle sensor 19c is approximately constant at an appropriate time, and determines whether the angular velocity of the second drive unit 18b is ≒ 0 or the angle detected by the angle sensor 20c is approximately constant at an appropriate time (step S30). When the first finger portion 17a abuts against the article P (step S30-YES), the angular velocity of the rotating shaft 19a1 of the motor 19a of the first drive unit 18a is ≒ 0 and the angle is approximately constant. At this time, the first finger portion 17a is in an approximately stopped state. When the second finger portion 17b abuts against the article P (step S30-YES), the angular velocity of the rotating shaft 20a1 of the motor 20a of the second drive unit 18b is ≒ 0 and the angle is approximately constant. At this time, the second finger portion 17b is in an approximately stopped state.

If the angular velocity of the first drive unit 18a is not ≈ 0 (step S30-NO), the first finger unit 17a is not in contact with the article P, so the control unit 42 continues to rotate the rotating shaft 19a1 while maintaining the primary torque T1 of the rotating shaft 19a1 of the motor 19a of the first drive unit 18a. If the angular velocity of the rotating shaft 20a1 of the motor 20a of the second drive unit 18b is not ≈ 0 (step S30-NO), the second finger unit 17b is not in contact with the article P, so the control unit 42 continues to rotate the rotating shaft 20a1 while maintaining the primary torque T1 of the rotating shaft 20a1 of the motor 20a of the second drive unit 18b. Then, the control unit 42 continues to monitor the angular velocity of the first drive unit 18a and the angular velocity of the second drive unit 18b (step S29).

When the angular velocity of the first drive unit 18a is ≈ 0 and the angular velocity of the second drive unit 18b is ≈ 0, the control unit 42 acquires the angle θ1a at which the first drive unit 18a's angular velocity becomes ≈ 0 (e.g., an angle relative to a reference angle, such as a standby position) using the angle sensor 19c and stores it in the main memory unit 44 and/or the auxiliary memory unit 45, and acquires the angle θ1b at which the second drive unit 18b's angular velocity becomes ≈ 0 (e.g., an angle relative to a reference angle, such as a standby position) using the angle sensor 20c and stores it in the main memory unit 44 and/or the auxiliary memory unit 45 (step S31).

At this time, the control unit 42 can obtain information about the side surface Pb of the article P from the rotation angle θ1a of the rotating shaft 19a1 of the motor 19a of the first driving unit 18a relative to the standby position (reference position and reference angle) in a state in which the first finger portion 17a and the second finger portion 17b are in contact with the side surface Pb of the article P with the first torque T1, and the rotation angle θ1b of the rotating shaft 20a1 of the motor 20a of the second driving unit 18b relative to the standby position (reference position and reference angle). The control unit 42 can compare the information about the shape, position, and posture of the article P input to the control unit 42 in step S6 using the detection device 3. Therefore, the control unit 42 can detect a recognition error between the information about the side surface Pb of the article P obtained from the contact position between the first finger portion 17a and the second finger portion 17b and the article P and the information about the shape, position, and posture of the article P (including the tentative target position) detected and obtained by the detection device 3.

The control unit 42 sets the secondary torque T2a>the primary torque T1 according to the angle θ1a of the first drive unit 18a, and sets the secondary torque T2b>the primary torque T1 according to the angle θ1b of the second drive unit 18b (step S32). The control unit 42 reads out and sets the secondary torque T2a corresponding to the angle θ1a from an information table stored in the auxiliary storage unit 45, for example. The control unit 42 reads out and sets the secondary torque T2b corresponding to the angle θ1b from an information table stored in the auxiliary storage unit 45, for example. The control unit 42 may set the secondary torque T2a corresponding to the angle θ1a and set the secondary torque T2b corresponding to the angle θ1b based on a predetermined formula.

Here, Figures 16 and 17 show a state in which the suction portion 12 of the gripping device 1 adsorbs the top surface Pa of the item P, and both side surfaces Pb in the depth direction and longitudinal direction of the item P are gripped by the first finger portion 17a and the second finger portion 17b.
16, the distance D0 is the same between the side surface Pb of the article P and the axis of the main body 11 and the suction portion 12. It is preferable that the suction portion 12 is suctioned to the center of the longitudinal direction of the article P and to the centroid of the center of the width direction of the top surface Pa of the article P as shown in FIG.
As shown in Fig. 17, the suction portion 12 may suction a position shifted from the center in the width direction of the top surface Pa of the article P. In the example shown in Fig. 17, the distances between a pair of side surfaces Pb of the article P and the axis A of the main body portion 11 and the suction portion 12 are different. As an example, the distance Da on the first finger portion 17a side is larger than the distance Db on the second finger portion 17b side.

Here, we will explain an example in which the suction portion 12 is suctioned to a position shifted from the center in the width direction of the top surface Pa of the article P, as shown in Figure 17.

In this case, the contact positions of the first finger portion 17a and the second finger portion 17b may be shifted, for example, in the depth direction. The control unit 42 sets the secondary torques T2a, T2b individually according to the angle θ1a of the first drive unit 18a and the angle θ1b of the second drive unit 18b so that the forces Fa, Fb of the width direction components of the article P are balanced. It is more preferable that the control unit 42 individually sets the secondary torques T2a, T2b so that the rotational moment acting on the article P is offset according to the heights of, for example, the claw portions 117a, 117b that contact the side surface Pb of the article P, instead of balancing the forces Fa, Fb of the width direction components of the article P.
The control unit 42 increases the force Fa compared to the force acting on the side surface Pb of the article P from the first finger portion 17a in a state in which the first finger portion 17a abuts against the side surface Pb of the article P at the first torque T1. The control unit 42 increases the force Fb compared to the force acting on the side surface Pb of the article P from the second finger portion 17b in a state in which the second finger portion 17b abuts against the side surface Pb of the article P at the first torque T1 .

Therefore, the secondary torque T2a changes according to the angle θ1a. Therefore, the secondary torque T2a changes according to the contact position where the first finger portion 17a contacts the item P. The secondary torque T2b changes according to the angle θ1b. Therefore, the secondary torque T2b changes according to the contact position where the second finger portion 17b contacts the item P.

The control unit 42 drives the first motor 19a of the first drive unit 18a and the second motor 20a of the second drive unit 18b simultaneously or at the same time while controlling the torque. The control unit 42, for example, feedback controls the motor 19a of the first drive unit 18a using the torque sensor 19b, and maintains the torque of the rotating shaft 19a1 of the motor 19a at the target secondary torque T2a. The control unit 42, for example, detects the rotation angle of the rotating shaft 19a1 of the motor 19a of the first drive unit 18a relative to the reference angle of the standby position using the angle sensor 19c. The control unit 42, for example, feedback controls the motor 20a of the second drive unit 18b using the torque sensor 20b, and maintains the torque of the rotating shaft 20a1 of the motor 20a at the target secondary torque T2b. The control unit 42 uses the angle sensor 20c to detect the rotation angle of the rotation shaft 20a1 of the motor 20a of the second drive unit 18b relative to the reference angle of the standby position, for example.

The control unit 42 monitors the angular velocity (rotational speed) of the rotating shaft 19a1 of the motor 19a of the first drive unit 18a, i.e., the angular velocity (rotational speed) of the rotating shaft 17a0 of the first finger portion 17a, and also monitors the angular velocity (rotational speed) of the rotating shaft 20a1 of the motor 20a of the second drive unit 18b, i.e., the angular velocity (rotational speed) of the rotating shaft 17b0 of the second finger portion 17b (step S33).

The control unit 42 determines whether the angular velocity of the first drive unit 18a is ≒ 0 or the angle detected by the angle sensor 19c has become substantially constant continuously for a suitable period of time, such as one second, and determines whether the angular velocity of the second drive unit 18b is ≒ 0 or the angle detected by the angle sensor 20c has become substantially constant for a suitable period of time (step S34).

If the angular velocity of the first drive unit 18a is not ≈ 0 and the angular velocity of the second drive unit 18b is not ≈ 0 (step S34-NO), or if the angle detected by the angle sensor 19c is not approximately constant over a given time period, the first finger portion 17a moves with the secondary torque T2a and the second finger portion 17b moves with the secondary torque T2b. Therefore, the control unit 42 continues to monitor the angular velocity of the first drive unit 18a and the angular velocity of the second drive unit 18b (step S33).

When the angular velocity of the first drive unit 18a is ≈ 0 and the angular velocity of the second drive unit 18b is ≈ 0 (step S34-YES), or when the angle detected by the angle sensor 19c becomes substantially constant for an appropriate time, the control unit 42 acquires the angle θ2a at which the first drive unit 18a becomes ≈ 0 (for example, the angle relative to a reference position such as a standby position) by the angle sensor 19c and stores it in the main memory unit 44 and/or the auxiliary memory unit 45, and acquires the angle θ2b at which the second drive unit 18b becomes ≈ 0 (for example, the angle relative to a reference position such as a standby position) by the angle sensor 20c and stores it in the main memory unit 44 and/or the auxiliary memory unit 45 (step S35). At this time, the first finger unit 17a and the second finger unit 17b are substantially stopped.

The control unit 42 estimates a coefficient k related to the ease of deformation of the side (exterior) Pb of the item P, such as the stiffness E of the side Pb of the item P, from the first torque T1, the second torque T2a, T2b, and the angles θ1a, θ1b, θ2a, θ2b, based on an appropriate calculation formula. If the control unit 42 can estimate the coefficient k, it can estimate the stiffness E of the item P (step S36).

When estimating the stiffness E of the item P, the control unit 42 extracts the angles θ1a, θ2a of the rotation axis 17a0 of the first finger portion 17a relative to the reference position, the angles θ1b, θ2b of the rotation axis 17b0 of the second finger portion 17b relative to the reference position, the component in the width direction of the item P from the first finger portion 17a to the side surface Pb of the item P, and the component in the width direction of the item P from the second finger portion 17b to the side surface Pb of the item P, and calculates them as the compression stiffness E.

The control unit 42 uses the estimated coefficient k (rigidity E) to calculate a target tertiary torque (target torque) T3a for the first drive unit 18a to securely grip the item P, and also calculates and sets a target tertiary torque (target torque) T3b for the second drive unit 18b (step S37).

When the stiffness E of the article P is greater than a certain threshold, the control unit 42 increases the tertiary torque T3a relative to the secondary torque T2a and increases the tertiary torque T3b relative to the secondary torque T2b. When the stiffness E of the article P is lower than a certain threshold, the control unit 42 decreases the tertiary torque T3a relative to the secondary torque T2a and decreases the tertiary torque T3b relative to the secondary torque T2b. The control unit 42 sets the tertiary torques T3a and T3b individually according to the angle θ2a of the first drive unit 18a and the angle θ2b of the second drive unit 18b so that the forces Fa and Fb of the width direction components of the article P are balanced. It is more preferable that the control unit 42 sets the tertiary torques T3a and T3b individually so that the rotational moments acting on the article P are offset.
Depending on the angles θ2a, θ2b and the coefficient k (rigidity E) of the article P, the control unit 42 may make the tertiary torque T3a applied to the first driving unit 18a larger than the second torque T2a and the tertiary torque T3b applied to the second driving unit 18b smaller than the second torque T2b. Similarly, the control unit 42 may make the tertiary torque T3a applied to the first driving unit 18a smaller than the second torque T2a and the tertiary torque T3b applied to the second driving unit 18b larger than the second torque T2b.

The control unit 42 drives the first motor 19a of the first drive unit 18a and the second motor 20a of the second drive unit 18b simultaneously or at the same time while controlling the torque. The control unit 42, for example, feedback controls the motor 19a of the first drive unit 18a using the torque sensor 19b, and maintains the torque of the rotating shaft 19a1 of the motor 19a at the target tertiary torque T3a. The control unit 42, for example, detects the rotation angle of the rotating shaft 19a1 of the motor 19a of the first drive unit 18a relative to the reference angle of the standby position using the angle sensor 19c. The control unit 42, for example, feedback controls the motor 20a of the second drive unit 18b using the torque sensor 20b, and maintains the torque of the rotating shaft 20a1 of the motor 20a at the target tertiary torque T3b. The control unit 42 uses the angle sensor 20c to detect the rotation angle of the rotation shaft 20a1 of the motor 20a of the second drive unit 18b relative to the reference angle of the standby position, for example.

The control unit 42 monitors the angular velocity (rotational speed) of the rotating shaft 19a1 of the motor 19a of the first drive unit 18a, i.e., the angular velocity (rotational speed) of the rotating shaft 17a0 of the first finger portion 17a, and also monitors the angular velocity (rotational speed) of the rotating shaft 20a1 of the motor 20a of the second drive unit 18b, i.e., the angular velocity (rotational speed) of the rotating shaft 17b0 of the second finger portion 17b (step S38).

The control unit 42 determines whether the angular velocity of the first drive unit 18a is ≒ 0 or the angle detected by the angle sensor 19c has become substantially constant for an appropriate time, and determines whether the angular velocity of the second drive unit 18b is ≒ 0 or the angle detected by the angle sensor 20c has become substantially constant for an appropriate time (step S39).

If the angular velocity of the first drive unit 18a is not ≈ 0 and the angular velocity of the second drive unit 18b is not ≈ 0 (step S39-NO), the first finger portion 17a is moving with the tertiary torque T3a and the second finger portion 17b is moving with the tertiary torque T3b. Therefore, the control unit 42 continues to monitor the angular velocity of the first drive unit 18a and the angular velocity of the second drive unit 18b (step S38).

If the angular velocity of the first drive unit 18a is ≈0 and the angular velocity of the second drive unit 18b is ≈0 (step S39-YES), the control unit 42 acquires the angle θ3a at which the first drive unit 18a's angular velocity becomes ≈0 (for example, an angle relative to a reference position such as a standby position) by the angle sensor 19c and stores it in the main memory unit 44 and/or the auxiliary memory unit 45, and acquires the angle θ3b at which the second drive unit 18b's angular velocity becomes ≈0 (for example, an angle relative to a reference angle such as a standby position) by the angle sensor 20c and stores it in the main memory unit 44 and/or the auxiliary memory unit 45 (step S40). At this time, the first finger unit 17a and the second finger unit 17b are in a substantially stopped state. The angle θ3a is the angle that is the target position of the first finger unit 17a relative to the article P. The angle θ3b is the angle that is the target position of the second finger unit 17b relative to the article P. Setting a tertiary torque T3a on the rotating shaft 19a1 of the motor 19a of the first drive unit 18a is equivalent to operating at an angle θ3a as the target position. Setting a tertiary torque T3b on the rotating shaft 20a1 of the motor 20a of the second drive unit 18b is equivalent to operating at an angle θ3b as the target position.

The control unit 42 switches the first drive unit 18a and the second drive unit 18b from the torque control mode to the position control mode. In the position control mode, the control unit 42 controls the position of the first finger unit 17a while acquiring information from the angle sensor 19c so that the first finger unit 17a maintains the angle θ3a, and controls the position of the second finger unit 17b while acquiring information from the angle sensor 20c so that the second finger unit 17b maintains the angle θ3b (step S41). At this time, the control unit 42 clamps the side surface Pb of the item P with the first finger unit 17a and the second finger unit 17b while adsorbing the top surface Pa of the item P with the suction unit 12 of the gripping device 1. In the position control mode, the clamping posture is maintained even if the load applied to the first finger unit 17a and the second finger unit 17b changes due to the movement of the item P.

In this manner, in this embodiment, the control unit 42 operates the gripping device 1 to adsorb the top surface Pa of the item P, and then performs three stages of clamping using torque control to clamp and grip the side surface (exterior) Pb of the item P.

As shown in FIG. 12, the control unit 42 formulates a release operation plan for the item P by the main arm 22 of the moving device 2 (step S9). The control unit 42 formulates a movement path for the item P.

The control unit 42 operates the main arm 22 of the moving device 2 based on the formulated plan, and moves the item P to a predetermined position based on the release operation plan (step S10).

The control unit 42 operates the gripping device 1 of the main arm 22 and the tool 23 to perform a release operation of the item P from the gripping device 1 (step S11). At this time, the control unit 42 switches the solenoid valve 24 from open to closed, and sets the first drive unit 18a and the second drive unit 18b to a predetermined standby position.

The control unit 42 again photographs the inside of the container C with the detection device 3, and repeats the selection of the item P, gripping control using the gripping device 1, movement control using the movement device 2, and release control to the desired position using the gripping device 1.

In this way, one or more items P are moved from inside the container C to the desired position.

In the gripping control using the above-mentioned suction function and clamping function in combination, the control unit 42 vacuum-sucks the top surface Pa of the article P, and then simultaneously or at the same time operates the first drive unit 18a to operate the first finger unit 17a and the second drive unit 18b to operate the second finger unit 17b to clamp the side surface Pb of the article P. For example, the motor 19a of the first drive unit 18a and the motor 20a of the second drive unit 18b are switched simultaneously or at the same time between the position control mode, the torque control mode, and the position control mode. Before rotating the first drive unit 18a and the second drive unit 18b by torque control with the primary torque T1, the control unit 42 performs position control so that the first finger unit 17a and the second finger unit 17b are maintained in a reference position (standby posture). In the torque control mode, the control unit 42 switches the first drive unit 18a and the second drive unit 18b between initial torque control at a primary torque T1, intermediate torque control at secondary torques T2a and T2b, and final torque control at tertiary torques T3a and T3b.

The control unit 42 brings the first finger portion 17a and the second finger portion 17b into contact with the side surface Pb of the article P by initial torque control at the first torque T1, and then changes to the second torque T2a, T2b larger than the first torque T1 to obtain the angle change of the first finger portion 17a and the second finger portion 17b (≒ deformation amount of the article). In the initial torque control and intermediate torque control, the coefficient k (rigidity E) of the ease of deformation of the article P is estimated from the torque increment and the change in the angle θ of the first finger portion 17a and the second finger portion 17b, and the final tertiary torque T3a, T3b are determined accordingly. The motors 19a, 20a are switched from the torque control mode to the position control mode at the angles θ3a, θ3b at which the first finger portion 17a and the second finger portion 17b come to rest at the final tertiary torque T3a, T3b. The control unit 42 continues to control the positions of the motors 19a and 20a to maintain the current positions of the first finger portion 17a and the second finger portion 17b. Therefore, regardless of the change in the posture of the main arm 22, the first finger portion 17a and the second finger portion 17b of the gripping device 1 maintain the same angle relative to the main body portion 11.

17 , depending on the suction position of the suction part 12 with respect to the top surface Pa of the article P, the height position where the first finger portion 17a contacts the article P may differ from the height position where the second finger portion 17b contacts the article P. If the same clamping force is applied to the first finger portion 17a and the second finger portion 17b, the positional deviation may have an effect, a rotational moment may be applied to the article P, and a shear force may be generated between the suction part 12 and the top surface Pa of the article P. Therefore, in a state where the side surface Pb of the article P is clamped by the first finger portion 17a and the second finger portion 17b, a force may be applied to peel off the suction part 12 from the top surface Pa of the article P, depending on the suction position of the suction part 12 with respect to the top surface Pa of the article P. In this embodiment, the control unit 42 sets the secondary torque T2a to be applied to the first finger 17a according to the position where the first finger 17a contacts the article P, and sets the secondary torque T2b to be applied to the second finger 17b according to the position where the second finger 17b contacts the article P. The secondary torque T2a at this time is assumed to be a force component Fa parallel to the width direction (a force component approximately parallel to a direction perpendicular to the suction direction of the suction unit 12) applied to the side surface Pb of the article P by the first finger 17a. The secondary torque T2b at this time is assumed to be a force component Fb parallel to the width direction (a force component approximately parallel to a direction perpendicular to the suction direction of the suction unit 12) applied to the side surface Pb of the article P by the second finger 17b. The forces Fa and Fb are adjusted by the control unit 42 to be in opposite directions and have the same or approximately the same absolute values. Therefore, the forces Fa and Fb are offset. Therefore, by canceling out the forces Fa and Fb, a force (shear force) approximately parallel to the forces Fa and Fb that would peel the suction portion 12 away from the upper surface Pa of the article P is prevented from being applied between the suction portion 12 and the upper surface Pa of the article P. Therefore, the control device 4 of the gripping device 1 according to the present embodiment can cause the gripping device 1 to stably grip the article P.
Furthermore, even if the components parallel to the width direction of the forces Fa and Fb are different, the control unit 42 can set the secondary torques T2a and T2b so that no rotational moment is generated in the article P when the article P is clamped by the first finger portion 17a and the second finger portion 17b. By canceling out the rotational moments applied to the article P by the first finger portion 17a and the second finger portion 17b, a force (shear force) approximately parallel to the forces Fa and Fb that peels the suction portion 12 and the upper surface Pa of the article P from each other is suppressed from being applied between the suction portion 12 and the upper surface Pa of the article P. Therefore, the control device 4 of the gripping device 1 according to this embodiment can cause the gripping device 1 to stably grip the article P.

Even if the rigidity E of the article P varies, the control unit 42 can appropriately set the tertiary torques T3a and T3b that apply the final clamping force to the side surface Pb of the article P according to the rigidity E estimated when controlling with the secondary torques T2a and T2b when the article P is clamped by the first finger unit 17a and the second finger unit 17b, and can control the clamping force of the article P while reliably gripping the article P with the gripping device 1. Therefore, the control unit 42 can clamp the article P with appropriate tertiary torques T3a and T3b according to the suction position with respect to the upper surface Pa of the article P and according to the rigidity E of the article P. Therefore, the force (shear force) that peels the suction unit 12 and the upper surface Pa of the article P from each other is suppressed from being applied between the suction unit 12 and the upper surface Pa of the article P.

16, depending on the suction position of the suction unit 12 relative to the upper surface Pa of the article P, the height position where the first finger portion 17a contacts the article P may be the same as the height position where the second finger portion 17b contacts the article P. In this case, the same or approximately the same torque may be applied to the motor 19a of the first drive unit 18a and the motor 20a of the second drive unit 18b for the secondary torques T2a and T2b. In this case, the force Fa by the first finger portion 17a and the force Fb by the second finger portion 17b are adjusted by the control unit 42 to have the same or approximately the same absolute values in the opposite directions. Therefore, the forces Fa and Fb are offset. Therefore, the offsetting of the forces Fa and Fb suppresses the force that peels the suction unit 12 and the upper surface Pa of the article P from being applied between the suction unit 12 and the upper surface Pa of the article P. In addition, for the tertiary torques T3a and T3b, the same or approximately the same torque can be applied to the motor 19a of the first drive unit 18a and the motor 20a of the second drive unit 18b.

For example, when the rigidity E of the item P is lower than a certain threshold value, the suction by the suction unit 12 is used to minimize the third torque T3a, T3b of the first finger 17a and the second finger 17b when the item P is pinched, in order to prevent the item P from being damaged. This is also a sufficient condition from the viewpoint of gripping stability. The side surface Pb of the item P is pressed by the first finger 17a and the second finger 17b when the item P is pinched. The side surface Pb of the item P forms a curved surface with the bottom at the point where it is being pressed. In this state, the first finger 17a and the second finger 17b generate a force component parallel to the width direction as well as a component parallel to the depth direction. Therefore, the item P is prevented from falling from the state of being gripped by the suction and gripping by the gripping device 1, except when the item P is unintentionally deformed or a load is applied to the item P so as to disrupt the position control state by the control unit 42.

The control unit 42 can acquire the output of the force sensor 5. When the control unit 42 determines that the item P is relatively light from the output of the force sensor 5, the control unit 42 sets a new angle θ so that the angle θ is slightly closer to the angle θ1a than the target angle θ3a for the position control of the first finger unit 17a based on the estimated stiffness E, and is slightly closer to the angle θ1b than the target angle θ3b for the position control of the second finger unit 17b. Therefore, the control unit 42 can control the gripping device 1 to a state in which the load on the item P is reduced while securely gripping the item P.

When the control unit 42 determines in steps S21 to S26 shown in FIG. 15 that the item P is lighter than a certain threshold weight based on the output of the force sensor 5, the control unit 42 can control the first finger portion 17a and the second finger portion 17b to omit the clamping action (ultimately, the movement of the first finger portion 17a and the second finger portion 17b from the standby position (reference position) shown by the dashed line in FIG. 16 to the state shown in FIG. 5) and only perform suction gripping (see FIG. 8). Therefore, the control unit 42 can shorten the takt time when moving one item P from the container C to a desired position, such as the belt conveyor B.

As shown in Figure 17, if the contact positions of the first finger portion 17a and the second finger portion 17b and the side surface Pb of the item P shift in the depth direction, if the difference between the angle θ1a and the angle θ1b is greater than a certain threshold value, the control unit 42 may determine that it is difficult to achieve a stable grasping state, and may control the device to re-recognize the item P and re-execute the grasping plan.
When the gripping plan is executed again, the control unit 42 can perform control to operate the main arm 22 in a direction to correct the deviation from the center position of the article P estimated from the relationship between the angles θ1a and θ1b after once releasing the vacuum suction state with respect to the upper surface Pa of the article P. Therefore, when the control unit 42 executes the gripping plan again, it can cause the gripping device 1 to more reliably execute gripping.

In this embodiment, the first finger portion 17a has one arm, and the second finger portion 17b has two fingers 17b1 and 17b2. That is, the gripping device 1 has three arms. The gripping device 1 may be structured such that the first finger portion 17a has one arm, and the second finger portion 17b has one arm. The gripping device 1 may also be structured such that the first finger portion 17a has two arms, and the second finger portion 17b has two arms. The gripping device 1 may be structured such that it has five or more arms.

In step S36, the control unit 42 may read and set a coefficient k (rigidity E) corresponding to the values of the first torque T1, the second torques T2a and T2b, and the angles θ1a, θ1b, θ2a, and θ2b, for example, from an information table stored in the auxiliary memory unit 45.

In step S37, the control unit 42 may read and set a target tertiary torque T3a for the first drive unit 18a, which corresponds to the first torque T1, the second torques T2a, T2b, and the angles θ1a, θ1b, θ2a, θ2b, for securely gripping the item P, from an information table stored in the auxiliary memory unit 45, for example, and may also read and set a target tertiary torque T3b for the second drive unit 18b. For this reason, it is not necessarily necessary to estimate the coefficient k (rigidity E) in step S36.

As described above, an example has been described in which the gripping device 1 is used to grip the top surface Pa as shown in FIG. 4, and then clamp the side surface Pb.

For example, the article P shown in FIG. 5 has a planar upper surface Pa that can be adsorbed by the suction unit 12, and the side surface Pb has an appropriate depth dimension and a width dimension that is equal to or less than a certain value. Therefore, the article P in this case can be vacuum-adsorbed and clamped. At this time, the depth dimension of the article P shown in FIG. 5 is smaller than that of the example shown in FIG. 4 and FIG. 6. Instead of the claw portions 117a and 117b, an appropriate portion between the rotation axis 17a0 of the first finger portion 17a and the claw portion 117a and an appropriate portion between the rotation axis 17b0 of the second finger portion 17b and the claw portion 117b are abutted against the side surface Pb or an edge extending in the longitudinal direction, and the article P is grasped by the gripping device 1 by vacuum adsorption and clamping in the same manner as the article P shown in FIG. 4. Alternatively, the article P may be supported from the lower surface Pc. At this time, the angles θ1a and θ1b with respect to the standby posture can be larger than those of the example shown in FIG. 4 and FIG. 6.

For example, the item P shown in FIG. 6 has a flat upper surface Pa that can be adsorbed by the suction portion 12, but the side surface Pb is curved. The side surface Pb has an appropriate depth dimension. The width dimension of the item P is equal to or less than a certain value. In this case, the item P can be vacuum adsorbed and clamped. In this way, the item P shown in FIG. 6 is gripped by the gripping device 1 through vacuum adsorption and clamping, similar to the item P shown in FIG. 4. For this reason, the item P classified as an approximately rectangular parallelepiped may have an appropriate curved surface.

For example, as shown in FIG. 7, if the planar upper surface Pa of the article P is smaller than the size that can be attracted by the suction unit 12, the suction unit 12 does not vacuum-attach the upper surface Pa of the article P. Therefore, in step S22 in the flowchart shown in FIG. 15, the solenoid valve 24 is kept closed. Therefore, steps S25 and S26 are omitted.

On the other hand, when the first finger portion 17a and the second finger portion 17b grip the side surface Pb of the item P, the gripping is performed according to the flowchart shown in FIG. 15.

For example, as shown in FIG. 8, in the case where the upper surface Pa of the item P is vacuum-adsorbed without clamping the item P, the processes from step S21 to step S26 in FIG. 15 are performed, and the processes from step S27 to step S41 are omitted. If the control unit 42 determines that the output of the pressure sensor 14 is equal to or lower than a predetermined threshold value, the item P has been successfully adsorbed and grasped by the gripping device 1.

For example, as shown in FIG. 9, when the top surface Pa of the article P is adsorbed and pressed with the first finger portion 17a and the second finger portion 17b, steps S21 to S29 shown in FIG. 15 are executed, and steps S30 to S40 are jumped over. After the first finger portion 17a and the second finger portion 17b contact the top surface Pa of the article P with the first torque T1, the control unit 42 switches from the torque control mode to the position control mode. Then, the control unit 42 maintains the state in which the top surface Pa of the article P is pressed with the first finger portion 17a and the second finger portion 17b.

For example, as shown in FIG. 9, when adsorbing the top surface Pa of an article P and pressing it with the first finger portion 17a and the second finger portion 17b, steps S21 to S34 shown in FIG. 15 may be executed, and steps S35 to S40 may be skipped. In this case, the control unit 42 may set the target secondary torques T2a and T2b to individual values dedicated to the pressing operation.

When gripping the item P by suction and grasping as shown in Figures 10 and 11, the upper surface Pa is gripped near the position (edge) that is the boundary between the upper surface Pa and the side surface Pb. Then, the first finger portion 17a presses the upper surface Pa, while the second finger portion 17b supports the lower surface Pc of the item P. When gripping the item P as shown in Figures 10 and 11, the item P is gripped according to a different flow from the flow shown in Figure 15, but a description of this will be omitted here.

In this way, the control unit 42 appropriately operates the moving device 2 to grasp various items P.

The suction portion 12 may be inclined at an appropriate angle with respect to the vertical direction to match the surface Pa of the item P to which the suction portion 12 is suctioned. In this case, the entire gripping device 1 is inclined at an appropriate angle by the control unit 42. The suction portion 12 may be oriented in a direction perpendicular to the vertical direction. In this case, the positional relationship between the first finger portion 17a and the second finger portion 17b may be up-down or left-right when gripping the item P.

In the present embodiment, an example in which the first drive unit 18a and the second drive unit 18b are controlled separately has been described, but the first drive unit 18a may be connected to the second finger unit 17b as well as the first finger unit 17a. In this case, the second finger unit 17b is moved in conjunction with the first finger unit 17a by the control of the first drive unit 18a by the control unit 42, so the second drive unit 18b is not required. At this time, the first drive unit 18a moves the first finger unit 17a and the second finger unit 17b with one second torque T2, and as described above, the second torques T2a and T2b are not set separately for the first finger unit 17a and the second finger unit 17b. In this case, the target tertiary torques (target torques) T3a and T3b are not set separately, but the first finger unit 17a and the second finger unit 17b ensure an appropriate clamping state for the article P.

As described above, the control device 4 of the gripping device 1 has the control unit 42. While maintaining a state in which the suction unit 12 of the gripping device 1 suctions the article P to be gripped, the control unit 42 rotates the first drive unit 18a by a first torque so that the first finger unit 17a, which is on one side of the suction unit 12 and connected to the first drive unit 18a, and the second finger unit 17b, which is on the other side opposite the first finger unit 17a across the suction unit 12, come into contact with the article P and pinch the article P, rotates the first drive unit 18a by a second torque T2a that is greater than the first torque T1, sets target torque positions θ3a and θ3b of the first finger unit 17a and the second finger unit 17b with respect to the article P, and drives the first drive unit 18a with the target torque for the first finger unit 17a and the second finger unit 17b while maintaining a state in which the suction unit 12 suctions the article P.
The control unit 42 controls not only the first drive unit 18a but also the second drive unit 18b connected to the second finger unit 17b on the other side opposite to the first finger unit 17a, rotates the second drive unit 18b with a first torque T1, rotates the first drive unit 18a with a second torque T2a, and controls the second drive unit 18b to rotate the second drive unit 18b with the second torque T2b. The control unit 42 sets target torques T3a and T3b of the first finger unit 17a and the second finger unit 17b with respect to the article P in accordance with the respective angles of the first finger unit 17a and the second finger unit 17b with respect to the reference angle in a state in which the first drive unit 18a and the second drive unit 18b are rotated with the first torque T1 and the second torques T2a and T2b, respectively, and rotates the first finger unit 17a with the target torque T3a . a, and the second finger portion 17b is driven by the second drive portion 18b with the target torque T3b.

The control program for the gripping device 1 causes the processor to execute the following operations while maintaining the state in which the suction portion 12 of the gripping device 1 adsorbs the item P to be gripped, so that a first finger portion 17a on one side of the suction portion 12 and connected to the first drive portion 18a, and a second finger portion 17b on the other side opposite the first finger portion 17a across the suction portion 12, abut against the item P and rotate the first drive portion 18a with a first torque so as to pinch the item P; rotate the first drive portion 18a with a second torque T2a that is greater than the first torque T1; set target torques T3a, T3b of the first finger portion 17a and the second finger portion 17b with respect to the item P; and drive the first drive portion 18a with the target torque for the first finger portion 17a and the second finger portion 17b while maintaining the state in which the suction portion 12 adsorbs the item P.

Therefore, according to this embodiment, it is possible to provide a control device 4 for the gripping device 1 and a control program for the gripping device 1 that can vacuum-suck the item P and then grip the item P by clamping it.

[Second embodiment]
Next, a second embodiment will be described with reference to Fig. 18. The second embodiment is a modification of the control flow executed by the control unit 42, i.e., the control program.

As shown in FIG. 18, when performing a gripping operation in step S8, the control unit 42 can replace steps S37 to S41 described in FIG. 15 with steps S42 to S45.

After estimating the coefficient k (rigidity E), the control unit 42 switches the first drive unit 18a and the second drive unit 18b from the torque control mode to the position control mode. At this time, in the position control mode, the control unit 42 performs position control by setting the first drive unit 18a to target angle θ3a and the second drive unit 18b to target angle θ3b based on the angles θ1, θ2a, θ2b, the primary torque T1, and the secondary torque T2a, T2b with respect to the standby posture (step S42).

The control unit 42 monitors the angle of the rotating shaft 19a1 of the motor 19a of the first drive unit 18a using the angle sensor 19c, and monitors the angle of the rotating shaft 20a1 of the motor 20a of the second drive unit 18b using the angle sensor 20c (step S43). If the angle θ3a is different from the angle θ2a, the control unit 42 moves the rotating shaft 19a1 of the motor 19a of the first drive unit 18a by controlling the position of the first drive unit 18a so that the rotating shaft 19a1 of the motor 19a of the first drive unit 18a changes from the angle θ2a to the angle θ3a. If the angle θ3b is different from the angle θ2b, the control unit 42 moves the rotating shaft 20a1 of the motor 20a of the second drive unit 18b by controlling the position of the second drive unit 18b so that the rotating shaft 20a1 of the motor 20a of the second drive unit 18b changes from the angle θ2b to the angle θ3b.

The control unit 42 determines whether the rotation shaft 19a1 of the motor 19a has reached the angle θ3a, and whether the rotation shaft 20a1 of the motor 20a has reached the angle θ3b (step S44).

If the rotation shaft 19a1 of the motor 19a is between the angles θ2a and θ3a (step S44-NO), the control unit 42 controls the rotation shaft 19a1 of the motor 19a to reach the angle θ3a. If the rotation shaft 20a1 of the motor 20a is between the angles θ2b and θ3b (step S44-NO), the control unit 42 controls the rotation shaft 20a1 of the motor 20a to reach the angle θ3b.

When the rotating shaft 19a1 of the motor 19a reaches the angle θ3a (step S44-YES), the control unit 42 controls the rotating shaft 19a1 of the motor 19a of the first drive unit 18a to maintain the angle θ3a (step S45). When the rotating shaft 20a1 of the motor 20a reaches the angle θ3b (step S44-YES), the control unit 42 controls the rotating shaft 20a1 of the motor 20a of the second drive unit 18b to maintain the angle θ3b (step S45).

At this time, the control unit 42 clamps the item P between the first finger portion 17a and the second finger portion 17b while adsorbing the item P with the suction portion 12 of the gripping device 1.

Even with this control flow, the forces Fa and Fb are offset by the secondary torques T2a and T2b, preventing a force that would peel the suction portion 12 and the upper surface Pa of the article P from being applied between the suction portion 12 and the upper surface Pa of the article P.

The control unit 42 is individually set so that when the first drive unit 18a is positioned at angle θ3a and the second drive unit 18b is positioned at angle θ3b, the forces Fa and Fb of the width direction components of the article P are balanced. The control unit 42 also controls the position so that the first drive unit 18a is positioned at angle θ3a and the second drive unit 18b is positioned at angle θ3b, so that the forces Fa and Fb are offset, thereby preventing a force that would peel the suction unit 12 and the upper surface Pa of the article P from being applied between the suction unit 12 and the upper surface Pa of the article P.

In this way, in the torque control mode, after torque control is performed on the first drive unit 18a using the primary torque T1 and the secondary torque T2a, torque control using the tertiary torque T3a is not performed, and a transition is made from the torque control mode to the position control mode to clamp the side Pb of the article P. Similarly, in the torque control mode, after torque control is performed on the second drive unit 18b using the primary torque T1 and the secondary torque T2b, torque control using the tertiary torque T3b is not performed, and a transition is made from the torque control mode to the position control mode to clamp the side Pb of the article P. Therefore, the control unit 42 may set angles θ3a and θ3b, which are the target positions of the first finger portion 17a and the second finger portion 17b relative to the article P, without setting the tertiary torques T3a and T3b, in accordance with the rotation angles of the first drive unit 18a and the second drive unit 18b relative to the reference position when the first drive unit 18a and the second drive unit 18b are rotated by the first torque T1 and the second torques T2a and T2b, respectively.

Therefore, according to this embodiment, it is possible to provide a control device 4 for the gripping device and a control program for the gripping device that can vacuum-suck the item P and then grip the item P by clamping it.

In the first and second embodiments, the torque and the position or angle have a one-to-one correspondence relationship in which the other is determined when either value is determined. In addition, the control of determining the tertiary torque as the target value based on the primary torque T1 and the secondary torques T2a, T2b can also be realized when the target value (position) is determined by moving the first finger portion 17a and the second finger portion 17b from the first position (first angle θ1) to the second position (second angle θ2a, θ2b). These can ultimately obtain the same control result when the item P is clamped by the first finger portion 17a and the second finger portion 17b. In other words, the final target value of the first finger portion 17a and the second finger portion 17b is the same whether it is set by torque or by position when the item P is clamped by the first finger portion 17a and the second finger portion 17b. For this reason, the torque control by the target torque (tertiary torque) for the first drive unit 18a and the second drive unit 18b in the first embodiment is almost synonymous with the control of the target position or target angle (position control) for the first drive unit 18a and the second drive unit 18b in the first embodiment. In addition, the target torque and the target position or target angle are almost synonymous. For this reason, in this specification, the target torque is synonymous with the target position or target angle, or includes the target position and the target angle.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims.
The following is a summary of the claims of this application as filed.
[Appendix 1]
While maintaining the state in which the article to be grasped is being sucked by the suction portion of the gripping device, a first finger portion on one side of the suction portion and connected to a first drive portion and a second finger portion on the other side opposite the first finger portion across the suction portion come into contact with the article, and the first drive portion is rotated by a first torque so as to clamp the article;
While maintaining the state in which the suction portion suctions the article, the first drive portion is rotated by a second torque larger than the first torque with the first finger portion and the second finger portion abutting against the article by the first torque;
while maintaining a state in which the suction unit suctions the article, a target torque for each of the first finger unit and the second finger unit with respect to the article is set according to an angle of each of the first finger unit and the second finger unit with respect to a reference angle in a state in which the first drive unit is rotated by the first torque and the second torque;
driving the first driving unit to drive the first finger unit and the second finger unit with the target torque while maintaining a state in which the suction unit suctions the article;
A control device for a gripping device having a control unit.
[Appendix 2]
The control unit is
A second driving unit connected to the second finger unit on the other side opposite to the second finger unit is controlled to rotate the second driving unit by the first torque;
Rotating the first drive unit by the second torque and controlling the second drive unit to rotate the second drive unit by the second torque;
setting the target torques of the first finger portion and the second finger portion with respect to the object according to angles of the first finger portion and the second finger portion with respect to the reference angle in a state in which the first driving unit and the second driving unit are rotated by the first torque and the second torque, respectively;
The first finger portion is driven by the first driving unit at the target torque, and the second finger portion is driven by the second driving unit at the target torque.
2. The control device of claim 1.
[Appendix 3]
The control device according to Appendix 2, wherein the control unit sets the second torque that rotates the first finger portion connected to the first drive unit and the second torque that rotates the second finger portion connected to the second drive unit, depending on an angle of the first finger portion with respect to the reference angle in a state in which the first finger portion and the article are in contact with each other through torque control at the first torque, and an angle of the second finger portion with respect to the reference angle in a state in which the second finger portion and the article are in contact with each other through torque control at the first torque.
[Appendix 4]
The control device according to Appendix 3, wherein the control unit sets the second torque that rotates the first finger portion connected to the first drive unit and the second torque that rotates the second finger portion connected to the second drive unit to magnitudes that offset a component of force that is approximately parallel to a direction perpendicular to the suction direction of the suction portion and is applied to the article from the first finger portion and the second finger portion, or a rotational moment applied to the article, while maintaining a state in which the article is pinched between the first finger portion and the second finger portion.
[Appendix 5]
The control device according to any one of Supplementary Note 2 to Supplementary Note 4, wherein the control unit sets the target torque for rotating the first finger portion connected to the first drive portion and the target torque for rotating the second finger portion connected to the second drive portion to magnitudes that offset a component of force that is approximately parallel to a direction perpendicular to an adsorption direction of the adsorption portion and is applied to the article from the first finger portion and the second finger portion, or a rotational moment applied to the article, while maintaining a state in which the article is pinched between the first finger portion and the second finger portion.
[Appendix 6]
6. The control device according to claim 2, wherein the control unit controls the first finger portion and the second finger portion to maintain the reference angle before rotating the first drive portion and the second drive portion by the first torque.
[Appendix 7]
The control device of any one of Appendix 2 to Appendix 6, wherein the control unit estimates a coefficient related to the ease of deformation of the article based on angles of the first drive unit and the second drive unit relative to the reference angle in states in which the first drive unit and the second drive unit are rotated with the first torque, the second torque, the first torque, and the second torque, respectively, and calculates the target torque.
[Appendix 8]
The processor:
While maintaining a state in which the article to be grasped is sucked by the suction portion of the gripping device, a first finger portion connected to a first drive portion and a second finger portion on the other side opposite the first finger portion across the suction portion come into contact with the article, and the first drive portion is rotated by a first torque so as to pinch the article;
rotating the first driving unit with a second torque larger than the first torque while the first finger unit and the second finger unit are in contact with the article with the first torque, while maintaining a state in which the article is attracted to the suction unit;
while maintaining a state in which the suction unit suctions the article, setting target torques for the first finger unit and the second finger unit with respect to the article according to angles of the first finger unit and the second finger unit with respect to a reference angle in a state in which the first drive unit is rotated by the first torque and the second torque;
driving the first driving unit to drive the first finger unit and the second finger unit with the target torque while maintaining a state in which the suction unit suctions the article;
A control program for the gripping device.

1... gripping device, 2... moving device, 3... detection device, 4... control device, 11... main body, 12... suction unit, 13... vacuum generator, 14... pressure sensor, 17a... first finger unit, 17a0... rotating shaft, 17b... second finger unit, 17b0... rotating shaft, 18a... first drive unit, 18b... second drive unit, 19a... first motor, 19a1... rotating shaft, 19b... torque sensor, 19c... angle sensor, 20a... second motor, 20a1... rotating shaft, 20b... torque sensor, 20c... angle sensor, 24... solenoid valve, 41... planning unit, 42... control unit, 43... analysis unit, 44... main memory unit, 45... auxiliary memory unit.

Claims (8)

While maintaining a state in which the article to be grasped is being sucked by the suction portion of the gripping device, a first finger portion on one side of the suction portion and connected to a first drive portion and a second finger portion on the other side opposite the first finger portion across the suction portion come into contact with the article, and the first drive portion is driven by a first torque so as to pinch the article;
While maintaining the state in which the suction portion suctions the article, the first driving portion is driven by a second torque larger than the first torque in a state in which the first finger portion and the second finger portion are in contact with the article by the first torque;
Estimating a stiffness of the article based on the first torque, the second torque, an angle of a rotation axis of the first finger relative to a reference position, and an angle of a rotation axis of the second finger relative to the reference position;
while maintaining a state in which the suction unit suctions the article, set respective angles of the first finger unit and the second finger unit with respect to a reference angle in a state in which the first drive unit is driven by the first torque and the second torque, and set respective target torques of the first finger unit and the second finger unit with respect to the article in accordance with the rigidity ;
driving the first driving unit to drive the first finger unit and the second finger unit with the target torque while maintaining a state in which the suction unit suctions the article;
A control unit is provided.
A control device for a gripping device, wherein when the stiffness of the article is greater than a certain threshold, the control unit increases the target torque relative to the second torque, and when the stiffness of the article is lower than the certain threshold, the control unit decreases the target torque relative to the second torque . The control unit is
A second driving unit connected to the second finger unit on the other side opposite to the first finger unit is controlled to drive the second driving unit by the first torque;
driving the first driving unit by the second torque, and controlling the second driving unit to drive the second driving unit by the second torque;
setting the target torques of the first finger portion and the second finger portion with respect to the object according to the respective angles of the first finger portion and the second finger portion with respect to the reference angle in a state in which the first driving unit and the second driving unit are driven by the first torque and the second torque, respectively , and the rigidity ;
The first finger portion is driven by the first driving unit at the target torque, and the second finger portion is driven by the second driving unit at the target torque.
The control device according to claim 1 . 3. The control device according to claim 2, wherein the control unit sets the second torque that rotates the first finger connected to the first drive unit and the second torque that rotates the second finger connected to the second drive unit , depending on an angle of the first finger with respect to the reference angle in a state in which the first finger and the article are in contact with each other through torque control at the first torque, an angle of the second finger with respect to the reference angle in a state in which the second finger and the article are in contact with each other through torque control at the first torque, and the rigidity. The control device according to claim 3, wherein the control unit sets the second torque for rotating the first finger unit connected to the first drive unit and the second torque for rotating the second finger unit connected to the second drive unit to a magnitude that offsets a component of force that is approximately parallel to a direction perpendicular to the suction direction of the suction unit and is applied to the article from the first finger unit and the second finger unit while maintaining the article being held between the first finger unit and the second finger unit, or a rotational moment that is applied to the article. The control device according to any one of claims 2 to 4, wherein the control unit sets the target torque for rotating the first finger unit connected to the first drive unit and the target torque for rotating the second finger unit connected to the second drive unit to a magnitude that offsets a component of force that is approximately parallel to a direction perpendicular to the suction direction of the suction unit and is applied to the article from the first finger unit and the second finger unit while maintaining the article being held between the first finger unit and the second finger unit, or a rotational moment that is applied to the article. 6. The control device according to claim 2, wherein the control unit controls the first finger portion and the second finger portion to maintain the reference angle before driving the first drive portion and the second drive portion with the first torque. A control device as described in any one of claims 2 to 6, wherein the control unit estimates a coefficient related to the ease of deformation of the article based on the angles of the first driving unit and the second driving unit relative to the reference angle when the first driving unit and the second driving unit are driven with the first torque, the second torque, the first torque, and the second torque, respectively, and calculates the target torque. The processor:
While maintaining a state in which the article to be grasped is sucked by the suction portion of the gripping device, a first finger portion connected to a first drive portion and a second finger portion on the other side opposite the first finger portion across the suction portion come into contact with the article, and drive the first drive portion with a first torque so as to pinch the article;
driving the first driving unit with a second torque larger than the first torque while the first finger unit and the second finger unit are in contact with the article with the first torque, while maintaining a state in which the article is attracted to the suction unit;
estimating a stiffness of the article based on the first torque, the second torque, an angle of a rotation axis of the first finger relative to a reference position, and an angle of a rotation axis of the second finger relative to the reference position;
while maintaining a state in which the suction unit suctions the article, setting respective angles of the first finger unit and the second finger unit with respect to a reference angle in a state in which the first drive unit is driven by the first torque and the second torque , and respective target torques of the first finger unit and the second finger unit with respect to the article according to the rigidity ;
driving the first driving unit to drive the first finger unit and the second finger unit with the target torque while maintaining a state in which the suction unit suctions the article;
Run the command ,
A control program for a gripping device that causes the processor to increase the target torque for the second torque when the stiffness of the article is greater than a certain threshold, and decrease the target torque for the second torque when the stiffness of the article is lower than the certain threshold .