JP2020082217A - Control device and gripping method - Google Patents

Abstract

To easily determine a proper gripping position when an object of a given shape is gripped.SOLUTION: A control device in an embodiment is a control device for a robot hand that grips an object with a plurality of fingers arranged to be able to revolve around a prescribed revolution center, and includes a movement control unit and a gripping control unit. The movement control unit moves the robot hand so that the revolution center and a gravity center position of the object overlap. The gripping control unit positions the fingers at an intersection between a revolution circle centered at the revolution center and an offset line at which a contour line of the object is offset to the outer side by a prescribed quantity in a state where the revolution center and the gravity center position of the object overlap, and grips the object with the fingers.SELECTED DRAWING: Figure 3

Description

The present invention relates to a control device and a gripping method.

BACKGROUND ART Conventionally, there is known a robot that includes a robot hand having movable multi-finger (hereinafter, simply referred to as “hand”) and that grips an object having an arbitrary shape by the hand (for example, refer to Patent Document 1).

JP 2006-130580 A

However, the above-described conventional technique has room for further improvement in easily determining an appropriate gripping position when gripping an object having an arbitrary shape.

Specifically, in the above-described conventional technique, an object to be grasped is fitted to one of several predetermined simple shapes by image recognition, and a predetermined determination process is performed according to the type of the fitted simple shape. Based on this, the hand posture is determined.

However, according to such a conventional technique, there is a problem in that control must be complicated because different determination processing must be performed for each type of simple shape. Further, since an object having an arbitrary shape is applied to at least one of the predetermined simple shapes, there is a risk that the object may not be gripped at an appropriate gripping position, that is, stable gripping may not be performed depending on the shape of the object.

The present invention has been made in view of the above, and an object thereof is to provide a control device and a gripping method that can easily determine an appropriate gripping position when gripping an object having an arbitrary shape.

In order to solve the above-mentioned problems and to achieve the object, a control device according to one aspect of the present invention controls a robot hand that grips an object by a plurality of fingers that are revolvable around a predetermined center of revolution. The device includes a movement control unit and a grip control unit. The movement control unit moves the robot hand such that the center of revolution and the center of gravity of the object overlap. The gripping control unit, in a state in which the center of revolution and the position of the center of gravity overlap, the intersection point of an orbital circle which is a circle centered on the center of revolution and an offset line obtained by offsetting the contour line of the object outward by a predetermined amount. The finger is positioned and the object is held by the finger.

According to one aspect of the present invention, an appropriate gripping position can be easily determined when gripping an object having an arbitrary shape.

FIG. 1 is a schematic diagram showing a configuration example of a robot system according to an embodiment. FIG. 2 is a schematic diagram showing a configuration example of the hand according to the embodiment. FIG. 3 is a block diagram of the robot system according to the embodiment. FIG. 4 is an operation explanatory diagram (part 1) up to the determination of the grip position according to the embodiment. FIG. 5 is an operation explanatory diagram (part 2) up to the determination of the grip position according to the embodiment. FIG. 6 is an operation explanatory diagram (No. 3) up to the determination of the grip position according to the embodiment. FIG. 7 is an operation explanatory diagram (part 4) up to the determination of the grip position according to the embodiment. FIG. 8 is an operation explanatory diagram (1) of the grip position determination according to the modification. FIG. 9 is an explanatory diagram (part 2) of the grip position determination operation according to the modification. FIG. 10 is a flowchart showing a processing procedure executed by the control device according to the embodiment.

Hereinafter, a control device and a gripping method according to the embodiment will be described with reference to the drawings. Note that the dimensional relationship of each element in the drawings, the ratio of each element, and the like may differ from reality. Even between the drawings, there may be a case where portions having different dimensional relationships or ratios are included.

Further, in the following, a case where the robot 10 according to the embodiment is a so-called vertical articulated robot is taken as an example, but the form of the robot 10 is not limited, and the robot 10 may be, for example, a horizontal articulated robot or a parallel articulated robot. It can be replaced with a link robot or the like.

Further, hereinafter, the installation surface side on which the base 11 of the robot 10 is installed may be referred to as a “base end side”, and the periphery of the base end side of each member forming the robot 10 may be referred to as a “base end part”. Further, the object O side to be gripped by the robot 10 may be referred to as a “tip side”, and the periphery of the tip side of each member may be referred to as a “tip portion”.

FIG. 1 is a schematic diagram showing a configuration example of a robot system 1 according to the embodiment. 2 is a schematic diagram showing a configuration example of the hand 14 according to the embodiment.

As shown in FIG. 1, the robot system 1 according to the embodiment includes a robot 10, a control device 20, and a camera 30.

The robot 10 includes a base 11, a swivel base 12, an arm 13, and a hand 14. The arm unit 13 further includes a first arm 13a, a second arm 13b, and a third arm 13c.

The base portion 11 is a support base fixed to an installation surface such as a floor surface. The swivel base 12 is rotatably provided on the base 11. The first arm 13 a is rotatably provided with respect to the swivel base 12.

The second arm 13b is rotatably provided with respect to the first arm 13a. The third arm 13c is rotatably provided with respect to the second arm 13b. The hand 14 is attached to the third arm 13c. That is, the arm portion 13 supports the hand 14.

The configuration of the robot 10 will be described in more detail. As shown in FIG. 1, the robot 10 is a so-called vertical articulated robot. The swivel base 12 is connected to the base 11 so as to be swivelable about an axis a1.

The first arm 13a is rotatably connected to the swivel base 12 about an axis a2 (including a twist position) whose base end is substantially perpendicular to the axis a1. The second arm 13b is rotatably connected to the front end of the first arm 13a about a shaft a3 whose base end is substantially parallel to the shaft a2.

The third arm 13c is rotatably connected to the tip end of the second arm 13b about the axis a4 whose base end is substantially parallel to the axis a3. Further, the third arm 13c supports the hand 14 at the tip end portion thereof so as to be rotatable about an axis a5 (including a twisted position) substantially perpendicular to the axis a4. The axis a5 corresponds to an example of “revolution axis”.

The hand 14 is a so-called movable multi-fingered hand, and includes a support portion 14a and a plurality of finger portions 14b, as shown in FIG. Note that, as shown in FIG. 2, the hand 14 according to the embodiment includes three finger portions 14b, but the number of finger portions 14b may be two or more, or four. It may be more than a book.

The support portion 14a is rotatably supported by the third arm 13c around the axis a5 as described above (see the arrow 201 in the drawing), and also supports the base end portions of the finger portions 14b. Therefore, in other words, the finger portion 14b is revolvable around the axis a5.

Although FIG. 2 shows an example in which the finger portions 14b revolve around the axis a5 collectively by the single support portion 14a, each of the finger portions 14b may individually revolve around the axis a5. .. An example of such a case will be described later with reference to FIGS. 8 and 9.

Further, the finger portions 14b each have, for example, a joint portion 14ba, and are provided so as to be bendable by the joint portion 14ba (see arrow 202 in the figure). By this bending, the fingers 14b are closed so as to approach each other, so that the hand 14 can hold the object O to be held. In addition, the fingers 14b are opened so as to move away from each other, so that the hand 14 can release the grip of the object O.

In the example of FIG. 2, each finger 14b has one joint 14ba, but the number of joints 14ba is not limited, and may be two or more, or 0. May be. When it is 0, for example, an opening/closing mechanism that realizes the opening/closing operation of the finger portions 14b by moving the finger portions 14b closer to or farther from each other may be provided.

Returning to FIG. The control device 20 is connected to the robot 10 and the camera 30 so that information can be transmitted. The connection form may be wired or wireless. The control device 20 is configured to include various control devices, arithmetic processing devices, storage devices, and the like, and controls the operation of the robot 10.

For example, the control device 20 generates an operation signal for operating the robot 10 based on a job program acquired via an input device (not shown) (programming pendant or the like) or a host device not shown, and outputs the operation signal to the robot 10. By outputting, the operation of the robot 10 is controlled.

This operation signal is generated as a pulse signal to a servo motor (not shown) that is mounted on the robot 10, for example, and that realizes the above-described rotation operation around each of the axes a1 to a5 and the bending operation by the joint portion 14ba.

The camera 30 is provided at a position where a two-dimensional image of the object O having an arbitrary shape can be captured, for example, above the robot 10, captures the object O, and outputs the captured image to the control device 20.

Then, the gripping method according to the embodiment is such that, when the object O having an arbitrary shape is gripped in the robot system 1 configured as described above, the object O is easily and properly gripped at a gripping position. is there.

Therefore, in the gripping method according to the embodiment, the hand 14 is moved so that the center of revolution of the finger portion 14b and the center of gravity of the object O overlap. In the gripping method according to the embodiment, in a state where the center of revolution and the position of the center of gravity overlap, an orbital circle that is a circle centered on the center of revolution and an offset obtained by offsetting the contour line of the object O to the outside by a predetermined amount. The finger portion 14b is positioned at the intersection with the line, and the object O is grasped by the finger portion 14b.

As a result, according to the gripping method according to the embodiment, it is possible to perform stable and proper gripping on the object O having an arbitrary shape with the center of gravity at the center.

Further, in the grasping method according to the embodiment, the grasping position for locating the finger portion 14b is determined based on the center of gravity position and the offset line, and thus the determination process does not need to be divided according to the shape of the object O. Therefore, according to the gripping method according to the embodiment, the object O can be easily gripped at an appropriate gripping position regardless of the variety of shapes of the object O.

The predetermined amount of the above-mentioned offset can be set to 0, for example. That is, in the gripping method according to the embodiment, in the state where the center of revolution and the position of the center of gravity overlap, even if the intersection of the revolution circle that is a circle centered on the center of revolution and the contour line is determined as the gripping position. Good.

Hereinafter, a configuration example of the robot system 1 to which the gripping method according to the above-described embodiment is applied will be described more specifically.

FIG. 3 is a block diagram of the robot system 1 according to the embodiment. It should be noted that FIG. 3 shows only the components necessary for explaining the features of the embodiment, and omits the description of general components.

In other words, each component shown in FIG. 3 is functionally conceptual, and does not necessarily have to be physically configured as shown. For example, the specific form of distribution/integration of each block is not limited to that shown in the figure, and all or part of the block may be functionally or physically distributed/arranged in arbitrary units according to various loads and usage conditions. It can be integrated and configured.

Further, in the description using FIG. 3, description may be simplified or omitted for the components already described. Therefore, in the description using FIG. 3, a configuration example of the control device 20 will be mainly described.

As shown in FIG. 3, the robot system 1 according to the embodiment includes a robot 10, a control device 20, and a camera 30.

The control device 20 includes a storage unit 21 and a control unit 22. The storage unit 21 is realized by, for example, a semiconductor memory device such as a RAM (Random Access Memory) or a flash memory (Flash Memory), or a storage device such as a hard disk or an optical disk. In the example of FIG. The detection information 21b is stored.

The object image 21a stores a captured image of the object O captured by the camera 30. The detection information 21b is information regarding various data detected by the detection unit 22b described later, and includes the contour line of the object O, an offset line based on the contour line, and the position of the center of gravity of the object O.

The control unit 22 is a controller, and various programs stored in a storage device inside the control device 20 use a RAM as a work area by, for example, a CPU (Central Processing Unit) or an MPU (Micro Processing Unit). It is realized by being executed. Further, the control unit 22 can be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

The control unit 22 includes an acquisition unit 22a, a detection unit 22b, a movement control unit 22c, and a grip control unit 22d, and realizes or executes the functions and actions of information processing described below.

The acquisition unit 22a acquires the captured image of the object O output from the camera 30 and stores it in the object image 21a.

The detection unit 22b executes image analysis processing based on the object image 21a, detects the contour line of the object O and the position of the center of gravity of the object O, and stores the detected information 21b. Since the method of detecting the contour line and the position of the center of gravity by the image analysis processing is known, the description thereof is omitted here.

Further, the detection unit 22b detects an offset line obtained by offsetting the contour line of the object O to the outside by a predetermined amount and stores it in the detection information 21b.

The movement controller 22c moves the hand 14 based on the detection information 21b such that the center of revolution of the finger 14b and the center of gravity of the object O overlap. In other words, the center of revolution of the finger portion 14b is the axial center position of the axis a5 described above.

Specifically, the movement control unit 22c executes the inverse kinematics calculation with the center of gravity of the object O as the target position to which the center of revolution of the finger 14b should be moved, and based on the calculation result, the robot 10 described above is moved. The respective amounts of rotation about the axes a1 to a4 are derived. Further, the movement control unit 22c generates an operation signal for operating the robot 10 based on each derived rotation amount, and outputs the operation signal to the robot 10.

The gripping control unit 22d positions the finger portion 14b at the intersection of the revolution circle, which is a circle having the revolution center as a center, and the offset line in a state where the revolution center of the finger portion 14b and the center of gravity of the object O overlap each other The object O is held by the finger portion 14b.

Specifically, the grip control unit 22d executes an inverse kinematics operation with the intersection of the revolution circle and the offset line as the target position to which the finger 14b should be moved, and the hand 14 based on the operation result. A rotation amount for rotating the above-mentioned axis a5 is derived. The movement control unit 22c also generates an operation signal for operating the robot 10 based on the derived rotation amount, and outputs the operation signal to the robot 10. As a result, the finger portion 14b comes to the gripping position which is the target position.

Then, the grip control unit 22d generates an operation signal for bending the finger portion 14b by the joint portion 14ba so that the finger portions 14b approach each other, and outputs the operation signal to the robot 10. As a result, the finger portions 14b are closed so as to approach each other, and the object O is gripped.

Here, in order to make the above description easy to understand, a specific operation example until the grip position of the finger portion 14b is determined will be described with reference to FIGS. 4 to 7. FIG. 4 is an operation explanatory diagram (part 1) up to the determination of the grip position according to the embodiment. Further, FIG. 5 is an operation explanatory diagram (part 2) up to the determination of the grip position according to the embodiment.

FIG. 6 is an operation explanatory diagram (part 3) up to the determination of the grip position according to the embodiment. FIG. 7 is an operation explanatory diagram (4) up to the determination of the grip position according to the embodiment. 4 to 7, the case where the object O is viewed in plan is shown schematically.

It is assumed that there is an object O1 having an arbitrary shape shown in FIG. In such a case, first, based on the object image 21a of the object O1 acquired by the acquisition unit 22a, the detection unit 22b performs image analysis processing to perform the contour line CL of the object O1, the offset line OL, and the center of gravity position CG of the object O1. To detect.

The predetermined amount by which the contour line CL is offset may be arbitrary, but corresponds to the thickness of the finger portion 14b, for example. As an example, it is about ½ of the cross-sectional diameter of the finger portion 14b.

Then, as shown in FIG. 5, the movement control unit 22c moves the hand 14 so that the axial center position of the axis a5, which is the center of revolution of the finger 14b, and the center of gravity position CG overlap (see arrow 501 in the figure). .. This makes it possible to grip the object O1 with the center of gravity CG as the center. That is, it is possible to stably grip the object O1.

Then, the grip control unit 22d searches for an intersection of the revolution circle RC centered on the axis a5 and the offset line OL. Here, it is assumed that the finger portions 14b are collectively revolved around the axis a5 to search for a combination of intersections that can be simultaneously positioned by all the finger portions 14b. As a result, it is assumed that the intersection points P1, P2, P3 are extracted.

Then, as shown in FIG. 6, the grip control unit 22d revolves the finger portion 14b around the axis a5 and positions the finger portion 14b at the intersections P1, P2, P3 (see arrow 601 in the figure). At this position, the grip control unit 22d bends the finger portion 14b toward the center of gravity position CG, so that the object portion O1 is stably gripped by the finger portion 14b.

In order to carry out more stable gripping, as shown in FIG. 7, the intersection points P1, P2, P3 are located at positions which are rotationally symmetric with respect to the center of gravity position CG (rotational symmetry of 120° in the figure). It is preferable that the object is extracted and set as the gripping position. Therefore, in the case of the hand 14 according to the embodiment, it is preferable that the base portions of the finger portions 14b are provided on the same circumference at equal intervals of 120°.

Further, in FIG. 7, the gripping positions are set at equal intervals, but they need not be at equal intervals. FIG. 8 is an operation explanatory diagram (1) of the grip position determination according to the modification. In the description using FIG. 8, as described above, each of the finger portions 14b is individually provided so as to be able to revolve around the axis a5.

Further, as a premise of the description of FIG. 8, it is assumed that the movement control unit 22c moves the hand 14 and the orbital center of the finger portion 14b and the center of gravity position CG overlap as shown in FIG.

In such a case, the grip control unit 22d searches, for example, the intersection with the offset line OL on the revolution circle RC by the number of individually revolving finger portions 14b. At this time, the grip control unit 22d searches, for example, so that the total sum of the movement amounts of the finger portions 14b to the intersections becomes the minimum. As a result, it is assumed that the intersection points P1, P4, P5 are extracted as shown in FIG.

Then, as shown in FIG. 8, the grip control unit 22d revolves each of the finger portions 14b individually around the axis a5 and positions the finger portions 14b at the intersection points P1, P4, P5 (arrow 801 in the figure). 802, 803). At such gripping positions that are not evenly spaced, the gripping control unit 22d can also perform stable gripping around the center of gravity position CG by bending the finger 14b.

Although the object O1 having the same shape has been taken as an example so far, the gripping position can be similarly determined for the object O having a shape different from the object O1. FIG. 9 is an explanatory diagram (part 2) of the grip position determination operation according to the modification.

In FIG. 9, an object O2 having an oval shape in plan view and having a shape obviously different from the object O1 is taken as an example. As shown in FIG. 9, even if the object O2 is, for example, an oval shape, the detection unit 22b performs the image analysis processing on the basis of the object image 21a of the object O2, and the contour line CL of the object O2, The offset line OL and the center of gravity position CG of the object O2 are detected.

Then, the movement control unit 22c moves the hand 14 so that the revolving center of the finger portion 14b and the center of gravity position CG overlap. Then, the grip control unit 22d searches, for example, the intersections with the offset line OL on the revolution circle RC for the number of individually revolvable finger portions 14b.

As a result, for example, if the intersections P6, P7, P8 shown in FIG. 8 are extracted, the grip control unit 22d revolves each of the finger portions 14b individually around the axis a5, and the finger portion 14b is intersected with the intersection points P6, P6. Position to P7 and P8. Then, the grip control unit 22d bends the finger portion 14b at the grip position, so that the object O2 is stably gripped around the center of gravity position CG.

As described above, according to the gripping method according to the embodiment, the object O can be gripped easily and at an appropriate gripping position regardless of the variety of shapes of the object O. Even when the finger portions 14b revolve around the axis a5 collectively by the single support portion 14a, if the finger portions 14b are provided so that their extending directions can be freely changed, FIG. As in the example shown in FIG. 9, it is possible to position the finger portions 14b at positions that are not evenly spaced.

Until now, the finger portion 14b has only one joint portion, and when closed, each fingertip bends toward the center of gravity position CG all at once, and the finger portion 14b faces toward the same position. As an example, an example in which the robot extends in the same posture is given. However, the present invention is not limited to this, and for example, each of the finger portions 14b has multiple joints, and while each of them has different postures and extends in different directions, the fingertips can be positioned at the intersections extracted by the grip control unit 22d. The configuration makes it possible to deal with it.

Further, the control device 20 may not have the storage unit 21. That is, the control device 20 directly transfers the captured image acquired by the acquisition unit 22a to the detection unit 22b without passing through the storage unit 21, and based on this, the detection unit 22b detects the offset line OL and the center of gravity position CG. Good. Similarly, the detection unit 22b passes the detected offset line OL and the center of gravity position CG directly to the movement control unit 22c and the grip control unit 22d without passing through the storage unit 21, and based on this, the movement control unit 22c and the grip control unit 22c. The unit 22d may proceed the processing.

Next, a processing procedure executed by the control device 20 according to the embodiment will be described with reference to FIG. FIG. 10 is a flowchart showing a processing procedure executed by the control device 20 according to the embodiment. In addition, here, a processing procedure until the object O is gripped is shown.

As shown in FIG. 10, first, the acquisition unit 22a acquires a captured image of the object O (step S101). Then, the detection unit 22b detects the offset line OL and the gravity center position CG based on the captured image of the object O (step S102).

Then, the movement control unit 22c moves the hand 14 so that the center of revolution of the finger portion 14b overlaps with the center of gravity position CG (step S103). Then, in a state where the center of revolution of the finger portion 14b overlaps the center of gravity position CG, the grip control unit 22d positions the finger portion 14b at the intersection of the revolution circle RC and the offset line OL (step S104). Then, the grip controller 22d causes the finger 14b to grip the object O (step S105), and the process ends.

As described above, the control device 20 according to the embodiment is a hand 14 (corresponding to an example of a “robot hand”) that grips the object O by the plurality of finger portions 14b that are revolvable around a predetermined center of revolution. The control device includes a movement control unit 22c and a grip control unit 22d.

The movement controller 22c moves the hand 14 such that the center of revolution and the center of gravity CG of the object O overlap. The gripping control unit 22d offsets the revolution circle RC, which is a circle centered on the revolution center, and the contour line CL of the object O to the outside by a predetermined amount in a state where the revolution center and the center of gravity position CG overlap. The finger portion 14b is positioned at the intersection with and the object O is gripped by the finger portion 14b.

Therefore, according to the control device 20 according to the embodiment, an appropriate gripping position can be easily determined when gripping the object O having an arbitrary shape.

Further, the control device 20 according to the embodiment further includes a detection unit 22b. The detection unit 22b detects the offset line OL and the center of gravity position CG based on the captured image of the object O.

Therefore, according to the control device 20 according to the embodiment, it is possible to determine the gripping position for locating the finger portion 14b based on the offset line OL and the center of gravity position CG detected by the image analysis process. Need not be divided according to the shape of the object O. This makes it possible to easily and easily grip the object O regardless of the variety of shapes of the object O.

Further, the grip control unit 22d extracts a plurality of intersections on the circumference of the revolution circle RC that are symmetrical with respect to the center of gravity CG and positions the fingers 14b at the intersections. Therefore, according to the control device 20 according to the embodiment, it is possible to perform stable and proper grasping of the object O having an arbitrary shape with the center of gravity at the center.

Further, the grip control unit 22d extracts a plurality of intersections at equal intervals on the circumference of the revolution circle RC and positions the finger portions 14b at the intersections. Therefore, according to the control device 20 according to the embodiment, it is possible to perform more stable and proper gripping on the object O having an arbitrary shape, in which a force is uniformly applied with the center of gravity as the center.

In addition, the grip control unit 22d extracts a plurality of intersections that minimize the total amount of movement to the intersections of the finger portions 14b, and positions the finger portions at the intersections. Therefore, according to the control device 20 according to the embodiment, it is possible to efficiently grip the finger portion 14b with a small amount of movement.

Further, the detection unit 22b detects the offset line by setting the predetermined amount to 0. Therefore, according to the control device 20 according to the embodiment, the contour line CL of the object O can be directly used as the offset line OL, so that the efficiency of the image analysis process can be improved. Further, in such a case, the grip control unit 22d may position the finger portion 14b so that the finger portion 14b contacts the intersection of the revolution circle RC and the offset line OL.

In addition, in the above-described embodiment, an example in which the positions that are rotationally symmetric with respect to the center of gravity position CG, for example, three finger portions 14b are arranged at 120° intervals, is not limited to this. It suffices that the plurality of finger portions 14b be arranged symmetrically with respect to the center of gravity position CG. As an example, when the hand 14 has four finger portions 14b, two finger portions 14b may be arranged adjacent to each other at two points facing each other across the center of gravity position CG.

Further, in the above-described embodiment, the case where the camera 30 captures a two-dimensional image of the object O has been described, but the camera 30 is a so-called RGB-D camera, and in addition to RGB information, the depth direction (Depth). ), a three-dimensional image including the information may be captured.

In such a case, since the depth direction can be added to the determination of the gripping position, control including selection of gripping the object O with the hand 14 or gripping with the pinch is performed. Is possible. Therefore, it is possible to determine an appropriate gripping position including the height of the object O.

Further, in the above-described embodiment, so to speak, each time the shape of the object O changes, the offset line OL and the barycentric position CG of the object O are detected, and the grip position at which the finger portion 14b is arranged is calculated in real time based on this. Although the case of deciding has been described, it may be preset as preset information according to the shape of the object O.

Alternatively, machine learning may be used. In such a case, for example, by using deep learning or the like, a discriminant model of the shape of the object O and a grip position corresponding to the shape is generated in advance using the object image 21a as a positive example. Then, in actual operation, if the object image 21a to be determined is acquired, the object image 21a is input to the discriminant model, and the grip position is determined based on the output value output by the discriminant model. Good.

At this time, for example, the discriminant model also outputs the similarity of the input object image 21a to the existing classification class. If the similarity is higher than a predetermined threshold value, the discriminant model is output. The grip position may be adopted. On the other hand, if the degree of similarity does not reach the predetermined threshold value, the grip position may be determined based on the above-described embodiment, and the discriminant model may be additionally learned based on the corresponding object image 21a.

Further, in the above-described embodiment, the case where the number of axes of the robot 10 is five, that is, the axes a1 to a5 has been described as an example, but the number of axes of the robot 10 is not limited.

Further, the present invention is not limited to the above embodiment. The present invention also includes those configured by appropriately combining the constituent elements described above. Further, further effects and modified examples can be easily derived by those skilled in the art. Therefore, the broader aspect of the present invention is not limited to the above-described embodiment, and various modifications can be made.

14 hands (robot hand), 14b finger part, 20 control device, 22b detection part, 22c movement control part, 22d grip control part, a5 axis (revolution center), CG center of gravity position, CL contour line, O object, OL offset line , RC revolution circle

Claims (7)

A control device for a robot hand that grips an object with a plurality of fingers that are revolvable around a predetermined center of revolution,
A movement control unit that moves the robot hand such that the center of revolution and the center of gravity of the object overlap.
In a state where the center of revolution and the position of the center of gravity overlap, the finger portion is positioned at the intersection of the revolution circle that is a circle centered on the center of revolution and the offset line obtained by offsetting the contour line of the object outward by a predetermined amount. A grip control unit for gripping the object by the finger unit,
And a control device. A detection unit that detects the offset line and the position of the center of gravity based on a captured image of the object,
The control device according to claim 1, further comprising: The grip control unit,
On the circumference of the revolution circle, a plurality of intersections that are symmetrical with respect to the position of the center of gravity are extracted, and the fingers are respectively positioned at the intersections.
The control device according to claim 1. The grip control unit,
Extracting a plurality of intersections at equal intervals on the circumference of the revolution circle and positioning the finger portions at the intersections,
The control device according to claim 1, 2 or 3. The grip control unit,
Extracting a plurality of the intersections where the total sum of movements of the fingers to the intersections is the minimum, and positioning the fingers at the intersections, respectively.
The control device according to claim 1. The detection unit,
The offset line is detected by setting the predetermined amount to 0.
The control device according to claim 2. A gripping method using a controller for a robot hand that grips an object with a plurality of fingers that are revolvable around a predetermined center of revolution,
The robot hand is moved so that the center of revolution and the center of gravity of the object overlap,
In a state where the center of revolution and the position of the center of gravity overlap, the finger portion is positioned at the intersection of the revolution circle that is a circle centered on the center of revolution and the offset line obtained by offsetting the contour line of the object outward by a predetermined amount. , Holding the object by the finger portion,
A gripping method including:

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