JP2023003109A - Robot system and control method of robot system - Google Patents

Abstract

To enable introduction of a robot system having a higher picking success rate at low cost.SOLUTION: A robot system, which has a transfer mechanism that transfers an object while gripping the object with a plurality of fingers of a gripping part, comprises: a recognizing part that recognizes a space into which at least a portion of the gripping part can be inserted as well as the position and the posture of the object, around the object not yet transferred; a position and posture grasping part that moves the gripping part in a direction of the object to bring the gripping part into contact with the object, while inserting at least a portion of the gripping part into a first space in the space recognized by the recognizing part and not inserting the gripping part into spaces other than the first space, thereby grasping the position of the object more accurately than the recognizing part, and a gripping control part that identifies a position where the object can be gripped on the basis of information concerning the shape of the object as well as the position of the object grasped by the position and posture grasping part, and makes the gripping part grip the object at the identified position.SELECTED DRAWING: Figure 2

Description

The present invention relates to a robot system and a control method for the robot system.

2. Description of the Related Art In recent years, in order to make up for the shortage of personnel for picking work in distribution warehouses and the like, robot systems that perform picking work have been introduced. In such a robot system, in order to properly grip an object with the gripping part, for example, "the first finger is brought into contact with the object, and the output value output from the force detection part is equal to or greater than a predetermined first threshold value. After the first action, a state in which the output value output from the force detection unit is equal to or greater than the first threshold is maintained, and the first finger and the arm to cause the object to perform a second action of contacting the first finger and the second finger, and in the second action, an output value output from the force detection unit is smaller than the first threshold When the value is smaller than the predetermined second threshold, the difference between the value corresponding to the output value output from the first position detection unit and the predetermined first value is within a predetermined range. is gripped by the first finger and the second finger in a predetermined state" (see Patent Document 1).

In addition, in order to autonomously pick various items with a high success rate, the robot system is configured to include an expensive recognition device including a camera or the like for highly accurate recognition of the target and peripheral items of the target. It is common to As a result, the robot system can grip the object at an appropriate gripping position with the gripper so as not to interfere with surrounding items, and achieve a higher picking success rate.

JP 2019-202360 A

However, in the above-described conventional technology, the recognition device including the camera for highly accurately recognizing the target object and surrounding items is expensive, which increases the introduction cost of the robot system and is one of the factors that hinder the introduction. ing.

On the other hand, if a robot system is configured using an inexpensive recognition device in order to reduce the introduction cost of the robot system, measurement errors in the positions and orientations of the target object and peripheral objects will increase. Therefore, when trying to grip an object with the gripping part, the gripping part interferes with surrounding objects, or an appropriate gripping part of the object cannot be gripped, resulting in a decrease in the picking success rate. be.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and one object of the present invention is to enable introduction of a robot system with a higher picking success rate at low cost.

In order to solve the above-described problems, according to one aspect of the present invention, there is provided a robot system having a transfer mechanism for grasping and transferring an object with a plurality of fingers of a grasping part, wherein the object before transfer is a space into which at least a part of the gripping part can be inserted; a recognition part that recognizes the position and orientation of the object; In a state in which at least a portion of the gripping portion is inserted and the gripping portion is not inserted into a space other than the first space, the gripping portion is moved toward the object to move the gripping portion toward the object. A position/orientation grasping unit that grasps the position of the object with higher accuracy than the recognition unit by contacting the object, information about the shape of the object, and information about the object grasped by the position/orientation grasping unit. and a gripping control unit that identifies a position where the object can be gripped based on the position and grips the object at the specified position with the gripping unit.

According to the present invention, for example, a robot system with a higher picking success rate can be introduced at low cost.

1 is a diagram showing a configuration example of a robot system according to Embodiment 1; FIG. FIG. 4 is an explanatory diagram of an operation example of the robot system according to the first embodiment; 4 is a flowchart showing an example of gripping processing of the robot system of the first embodiment; FIG. 9 is an explanatory diagram of an operation example of the robot system according to the second embodiment; FIG. 11 is an explanatory diagram of an operation example of the robot system of Embodiment 3; 11 is a flowchart showing an example of gripping processing of the robot system of the third embodiment; FIG. 11 is an explanatory diagram of an operation example of the robot system of Embodiment 4; FIG. 11 is an explanatory diagram of an operation example of the robot system of Embodiment 5; 14 is a flowchart showing an example of gripping processing of the robot system of Embodiment 5; FIG. 11 is an explanatory diagram of an operation example of the robot system of Embodiment 6; 14 is a flowchart showing an example of gripping processing of the robot system of the sixth embodiment; 14 is a flowchart showing an example of gripping processing of a robot system according to a modification of the sixth embodiment; FIG. 12 is an explanatory diagram of an operation example of the robot system of Embodiment 7; 14 is a flowchart showing an example of gripping processing of the robot system of Embodiment 7; The figure which shows the structural example of the computer which implement|achieves the control apparatus of a robot system.

Embodiments of the present invention will be described below with reference to the drawings. The embodiments are merely examples for explaining the present invention, and do not limit the present invention, and are appropriately omitted and simplified for clarity of explanation. The present invention can also be implemented in various other forms and in forms in which part or all of each form is combined. Unless otherwise specified, each component may be singular or plural.

When there are a plurality of components having the same or similar functions, they may be described with the same reference numerals and different suffixes. Further, when there is no need to distinguish between these constituent elements, the subscripts may be omitted in the description.

In the description of the embodiments to be described later, the differences from the previous embodiments will be mainly described, and the description of overlapping parts will be omitted as appropriate.

[Embodiment 1]
(Configuration of Robot System S of Embodiment 1)
FIG. 1 is a diagram showing a configuration example of a robot system S according to Embodiment 1. As shown in FIG. The robot system S is a system that performs a picking operation of gripping and transferring an object placed in a placement space at a work site such as a distribution warehouse. The robot system S includes a control device 1 that controls the entire system, a recognition section 20 and an arm 30 .

The recognition unit 20 processes an image of the placement space 6 partitioned by the walls 60a and 60b, which is captured by an image sensor such as a camera. Position P1, pose A1, height H1 of 50, and space S1 around object 50 are detected.

The position P1, the orientation A1, and the height H1 are represented by coordinates of, for example, a normal three-dimensional coordinate system (hereinafter referred to as an XYZ coordinate system) virtually defined in the mounting space 6. FIG. The posture A1 is the orientation of the object 50 in the mounting space 6 when viewed from above, and is the longitudinal direction of the object 50 when viewed in plan.

A space S1 around the object 50 is a space in contact with one side surface of the object 50 and a space into which at least a portion of a first finger 40a of an end effector 40, which will be described later, can be inserted. Whether or not the space is the space S1 into which at least part of the first finger 40a of the end effector 40 can be inserted is determined based on the conditions of the space S1 given in advance. The recognition unit 20 inputs information on the detected position P<b>1 , orientation A<b>1 , height H<b>1 and space S<b>1 of the target object 50 to the control device 1 .

The arm 30 is an example of a transfer mechanism that grips and transfers the object 50 placed in the placement space 6 . The arm 30 is a manipulator that is mounted on a base 31, rotates around the base 31, and bends and stretches or contracts. The arm 30 has an end effector 40 at its tip extending from the base 31 . An end effector is also called a hand. Any transfer mechanism other than the arm 30 may be used as long as it has a function of gripping and transferring the object 50 placed in the placement space 6 .

The end effector 40 has multiple fingers (or claws) for gripping the object 50 . In this embodiment, the end effector 40 has at least two fingers, a first finger 40a and a second finger 40b, facing each other so as to be able to grip the object 50. As shown in FIG. The end effector 40 rotates around the axis of attachment to the arm 30 or the vertical axis, and chucks or clamps the object 50 with the first finger 40a and the second finger 40b. Gripping in this embodiment includes chucking and clamping. The end effector 40 may grip the object 50 with the first finger 40a and the second finger 40b, or may grip the object 50 with a plurality of fingers including the first finger 40a and the second finger 40b. It may be something to hold.

The control device 1 includes a storage section 2 and a control section 3 . The storage unit 2 is a volatile or nonvolatile storage device, and stores object shape information 2a and error information 2b. The object shape information 2a is information representing the shape of the object 50, and is information including defining coordinates of vertices and faces. For example, when the object 50 has a rectangular parallelepiped shape, the object shape information 2a includes three-dimensional coordinates of eight vertices of the rectangular parallelepiped and definition information of three-dimensional coordinates of four vertices forming six faces. including. The coordinates in the object shape information 2a are represented by, for example, the coordinates of a normal three-dimensional coordinate system virtually defined along each object 50 .

The error information 2b is the maximum value of the recognition error of the position P1 of the object 50 recognized by the recognition unit 20 (hereinafter referred to as recognition error E). The recognition error E is obtained by statistical processing of simulation or actual measurement results. A recognition error E is a recognition error in the X-axis direction of the XYZ coordinate system. Note that the error information 2b is, as in Embodiment 2 described later, the recognition error E to secure a margin for the insertion position when a part of the end effector 40 is inserted into the space S1, and to move the end effector 40 from the object 50. It is used as the movement distance when moving in a direction. In this embodiment, the error information 2b can be omitted.

The control unit 3 is a processing device such as a CPU (Central Processing Unit) such as a microprocessor, an ASIC (Application Specific Integrated Circuit), or a PLD (Programmable Logic Device) such as an FPGA (Field Programmable Gate Array). The control unit 3 includes a position/orientation grasping unit 3a and a grasping control unit 3b realized by executing a program.

The position/orientation grasping unit 3a grasps the position P2 of the target object 50 with higher accuracy than the position P1 of the target object 50 detected by the recognition unit 20. FIG. The position/orientation grasping unit 3a inserts part of the first finger 40a of the end effector 40 into the space S1 and does not insert the other part of the end effector 40 into the space S0 around the object 50 excluding the space S1. , the end effector 40 is moved toward the object 50 . For example, the end effector 40 is moved in the direction perpendicular to the posture A1 of the object 50 . Then, the position/orientation grasping unit 3 a contacts the side surface of the object 50 with the first finger 40 a. The position/orientation grasping unit 3a thus calculates the motion to be performed by the arm 30, outputs a motion command, and the arm 30 moves according to the motion command.

The position/orientation grasping unit 3a regards the position of the contact portion of the end effector 40 with the side surface of the object 50 when the end effector 40 and the object 50 contact (or can be regarded as having contacted) as the position P2 of the object 50. do. The contact portion of the end effector 40 with the side surface of the object 50 is, for example, the tip portion of the first finger 40a. The position P2 is represented by coordinates in the XYZ coordinate system.

The gripping control unit 3b determines whether the target object 50 can be gripped based on the target object shape information 2a, the position P2 of the target object 50 grasped by the position/orientation grasping unit 3a, and the orientation A1 detected by the recognition unit 20. Determine the parts. As the grippable part, an optimum part is selected from grippable part candidates defined in advance in consideration of the shape of the object 50, taking into account the position P2 and the orientation A1 of the object 50. FIG. The grip control unit 3b calculates the motion of the arm 30 and the end effector 40 for gripping a grippable portion of the object 50 with the end effector 40, and outputs a motion command. The arm 30 and the end effector 40 operate according to the operation command, and grip the object 50 with the first finger 40a and the second finger 40b.

(Operation of Robot System S of Embodiment 1)
FIG. 2 is an explanatory diagram of an operation example of the robot system S of the first embodiment. In FIG. 2, the X-axis positive direction of the XYZ coordinate system is the direction from the wall 60a to the wall 60b, and the Z-axis positive direction is the direction in which the walls 60a and 60b rise. 4, 5, 7, 8, 10, and 13, the same way of setting coordinate axes is used.

First, as shown in 1-(1) of FIG. 2, the recognition unit 20 detects the position P1 and the posture A1 of the object 50, as well as the space S1 around the object 50 into which at least part of the first finger 40a can be inserted. to detect At least part of the first finger 40a includes the tip of the first finger 40a.

Next, as shown in 1-(2) of FIG. 2, the position/orientation grasping unit 3a inserts the first finger 40a into the space S1, and moves the other part of the end effector 40 including the second finger 40b to the object 50. (no other part of the end effector 40 is inserted into the space S0 surrounding the object 50 except for the space S1), the first finger 40a is placed on the object 50 move in the direction of When the first finger 40a is moved in the direction of the object 50, the first finger 40a contacts the object 50, and by this contact, the position P2 of the object 50 is grasped with high accuracy.

Next, as shown in 1-(3) of FIG. 2, the grasping control unit 3b controls the position P2 of the object 50 grasped by the position/orientation grasping unit 3a, the orientation A1 detected by the recognition unit 20, and the object The object 50 is gripped with the first finger 40a and the second finger 40b based on the shape information 2a.

(Gripping process of robot system S of embodiment 1)
FIG. 3 is a flowchart showing an example of gripping processing of the robot system S of the first embodiment.

First, in step S<b>11 , the recognition unit 20 detects the position P<b>1 and orientation A<b>1 of the object 50 . Next, in step S12, the recognition unit 20 detects the space S1. Next, in step S13, the position/orientation grasping unit 3a inserts at least part of the first finger 40a of the end effector 40 into the space S1.

Next, in step S<b>14 , the position/orientation grasping section 3 a moves the end effector 40 toward the object 50 . Next, in step S<b>15 , the position/orientation grasping section 3 a stops the movement of the end effector 40 . Next, in step S16, the position/orientation grasping unit 3a grasps the position of the object 50 with higher accuracy than the position P1, with the current position of the end effector 40 being the position P2. Next, in step S17, the grasping control unit 3b controls the object 50 based on the object shape information 2a, the position P2 grasped by the position/orientation grasping unit 3a, and the orientation A1 detected by the recognition unit 20. Determine the grippable part. Then, the grip control unit 3b grips the determined part with the first finger 40a and the second finger 40b of the end effector 40. FIG.

In this embodiment, by bringing the end effector 40 closer to and contacting the target object 50, the position, orientation, and height of the target object 50 can be recognized with high accuracy even if the low-accuracy recognition unit 20 is employed. , the position of the object 50 can be grasped, and the picking success rate can be increased. This eliminates the need to adopt expensive 3D robot vision, lowers the cost of building an automatic picking system, and allows customers who operate warehouses and factories to introduce automatic picking systems and logistics automation solutions at low initial introduction costs. .

[Embodiment 2]
(Operation of Robot System S of Embodiment 2)
FIG. 4 is an explanatory diagram of an operation example of the robot system S of the second embodiment. In the present embodiment, as shown in 2-(2)-1 in FIG. 4, the position/orientation grasping unit 3a inserts a part of the end effector 40 including the first finger 40a into the space S1 (see 2-(2)-1 in FIG. 3). Step S13), the object 50 is inserted at a distance corresponding to the recognition error E from the side surface of the object 50 . By inserting a part of the end effector 40 into the space S1 while securing a distance corresponding to the recognition error E from the object 50, the end effector 40 caused by the recognition error of the recognition unit 20 when the end effector 40 is inserted. Interference of the object 50 can be avoided.

Furthermore, as shown in 2-(2)-2 in FIG. 4, the position/orientation grasping unit 3a moves the end effector 40 toward the target object 50 (step S14 in FIG. 3). only move. By moving the end effector 40 by a distance corresponding to the recognition error E, the tip of the first finger 40 a can be reliably brought into contact with the side surface of the object 50 when the end effector 40 moves toward the object 50 .

It is desirable that a space having a size equal to or larger than the recognition error E exists on the opposite side of the object 50 to the space S1. This prevents the object 50 from being pushed and pinched between the first finger 40a and the wall 60b and crushed when the end effector 40 is moved toward the object 50 by a distance corresponding to the recognition error E. It's for.

[Embodiment 3]
In the second embodiment, the end effector 40 is moved toward the object 50 by a distance corresponding to the recognition error E, but the actual recognition error may be smaller than the recognition error E in some cases. Therefore, if the end effector 40 is moved toward the object 50 by a distance corresponding to the recognition error E, the amount of movement becomes excessive, and the end effector 40 may crush the object 50 . This embodiment solves this problem.

(Operation of Robot System S of Embodiment 3)
FIG. 5 is an explanatory diagram of an operation example of the robot system S of the third embodiment. First, as shown in 3-(1) of FIG. 5, the recognizing unit 20 scans the space S1 and the space S1 around the object 50a into which the first finger 40a can be inserted in the positive direction of the X axis. It is determined whether or not there is a space S2 in which the object 50a can be moved by a distance corresponding to the recognition error E between the wall 60b on the opposite side. Whether or not the space is the space S2 in which the object 50a can be moved is determined based on the conditions of the space S2 given in advance.

When the space S2 exists, the position/orientation grasping unit 3a controls the end effector 40 to move the object 50a to the first position by a distance corresponding to the recognition error E, as shown in 3-(2) of FIG. Positioning when gripping the object 50a is performed by pushing and moving with the finger 40a. Then, as shown in 3-(3) of FIG. 5, the grip control unit 3b controls the end effector 40 to grip the object 50a, as in the first and second embodiments.

On the other hand, if the space S2 does not exist, the position/orientation grasping unit 3a does not move the end effector 40 and stops the grasping process of the object 50a.

Note that FIG. 5 shows a case where the target object 50b exists between the target object 50a and the space S2. Either move the effector 40 or stop the gripping process. This is because the purpose of this embodiment is to prevent the movement of the end effector 40 from crushing all the objects 50 between the end effector 40 and the wall 60b.

(Gripping process of robot system S of embodiment 3)
FIG. 6 is a flowchart showing an example of gripping processing of the robot system S of the third embodiment. Compared to the gripping process of the first embodiment shown in FIG. 3, the gripping process of the third embodiment includes step S12C1 after step S12, and adds step S12C2 that is executed when the determination in step S12C1 is No. and step S14C is executed instead of step S14. Others are the same as the gripping process of the first embodiment.

In step S12C1 following step S12, the recognition unit 20 determines whether or not the space S2 has been detected. The recognition unit 20 shifts the process to step S13 when the space S2 is detected (step S12C1 Yes). On the other hand, when the space S2 is not detected (step S12C1No), the recognition unit 20 shifts the process to step S12C2 and stops the gripping process (step S12C2).

In step S14C, the position/orientation grasping unit 3a moves the end effector 40 toward the object 50 by a distance corresponding to the recognition error E. FIG.

In this embodiment, by moving the end effector 40 only when the space S2 exists, it is possible to prevent the object 50 from being crushed when the end effector 40 is moved without a force sensor.

[Embodiment 4]
In the first to third embodiments described above, details of the operation of the end effector 40 gripping the object 50 with the first finger 40a and the second finger 40b are not mentioned. In the fourth embodiment, the order in which the end effector 40 restrains the object 50 using the first finger 40a and the second finger 40b will be described.

(Operation of Robot System S of Embodiment 4)
FIG. 7 is an explanatory diagram of an operation example of the robot system S of the fourth embodiment. As shown in 4-(2) of FIG. 7, the position/orientation grasping unit 3a inserts the first finger 40a of the end effector 40 into the space S1 and moves it with the object 50a, as in the first to third embodiments. make contact. After the first finger 40a of the end effector 40 contacts the surface of the object 50 on the side of the space S1, the grip control unit 3b moves the first finger 40a to The contact with the object 50 is temporarily released, and the second finger 40b is brought into contact with the surface of the object 50 opposite to the space S1 in the positive direction of the X axis. After that, as shown in 4-(3)-2 of FIG. 7, the grip control unit 3b moves the first finger 40a to constrain the object 50 in the space S1 together with the second finger 40b.

In this way, after positioning by the position/orientation grasping unit 3a, the finger is first inserted into the space where the allowable range of recognition error is small, and then the finger is inserted into the space S1 where the allowable range of recognition error is large. , grasping failure can be prevented.

[Embodiment 5]
In the fifth embodiment, the force sensor 9 is provided to detect that the first finger 40a of the end effector 40 inserted into the space S1 has come into contact with the surface of the object 50 on the space S1 side.

(Operation of Robot System S of Embodiment 5)
FIG. 8 is an explanatory diagram of an operation example of the robot system S of the fifth embodiment. First, as shown in 5-(1) of FIG. 8, the recognition unit 20 detects the object 50 and the space S1 as in the first to fourth embodiments. Next, as shown in 5-(2) of FIG. 8, the position/orientation grasping unit 3a secures a distance corresponding to the recognition error E from the object 50, inserts the first finger 40a into the space S1, and is moved in the direction of the object 50 . When the force sensor 9 detects the reaction force that the first finger 40a receives from the object 50, the position/orientation grasping unit 3a stops the end effector 40 from moving. Then, as in the first to fourth embodiments, the grip control unit 3b brings the second finger 40b into contact with the surface of the object 50 on the side opposite to the space S1 of the object 50 in the positive direction of the X axis, An instruction is given to grip the object 50 together with the first finger 40a.

(Gripping process of robot system S of embodiment 5)
FIG. 9 is a flowchart showing an example of gripping processing of the robot system S of the fifth embodiment. Compared to the gripping process of the first embodiment shown in the flowchart of FIG. 3, in the gripping process of the fifth embodiment, step S14E is inserted after step S14, and step S14E is repeated until the determination in step S14E becomes Yes. . Others are the same as the gripping process of the first embodiment.

In step S14E, the position/orientation grasping unit 3a determines whether the output value of the force sensor 9 is equal to or greater than a predetermined threshold value, that is, whether or not a reaction force from the surface of the object 50 corresponding to contact with the surface of the object 50 has been detected. judge. If the reaction force is not detected (step S14ENo), the position/orientation grasping unit 3a repeats step S14E, and if the reaction force is detected (step S14EYes), the process proceeds to step S15.

According to the present embodiment, the force sensor 9 can prevent the first finger 40 a from applying an unnecessarily large force to the object 50 .

[Embodiment 6]
In Embodiment 6, the end effector 40 includes a plurality of first fingers 40a (two first fingers 40a1 and 40a2). Each of the plurality of first fingers 40a includes a force sensor 9 that detects contact with the surface of the object 50 on the space S1 side. The number of first fingers 40a is not limited to two, and may be three or more.

(Operation of Robot System S of Embodiment 6)
FIG. 10 is an explanatory diagram of an operation example of the robot system S of the sixth embodiment. As shown in 6-(3)-1 of FIG. 10, the position/orientation grasping unit 3a moves the end effector 40 in the direction of the object 50 after inserting the first fingers 40a1 and 40a2 into the space S1. Then, if the force sensor 9 of one of the first fingers 40a (the first finger 40a1 in 6-(3)-1 in FIG. 10) first detects contact with the surface of the object 50 on the side of the space S1, FIG. 6-(3)-2, by rotating the other first finger 40a2 for which contact is not detected around the first finger 40a1 as the center of rotation, the first finger 40a2 also moves toward the object 50. make contact. For example, the direction of rotation of the end effector 40 is given by the direction represented by the outer product r of Equation (1). In equation (1), vector d is the moving direction of end effector 40 toward object 50, and vector p is the vector from first finger 40a1 that has previously contacted object 50 to first finger 40a2.
r=p×d (1)

The amount of rotation of the end effector 40 based on Expression (1) is the maximum value of the recognition error of the orientation A1 of the object 50, and is information included in the error information 2b. The end effector 40 may be rotated until the force sensor 9 of the first finger 40a2 detects the reaction force of the object 50 instead of using the maximum value of the recognition error of the orientation A1 as the amount of rotation.

Alternatively, by rotating the end effector 40 around the vertical axis, the first finger 40a1 for which contact with the surface of the object 50 on the space S1 side has been previously detected, and the other finger for which contact has not been detected. The first finger 40a2 can be brought into contact with the surface of the object 50 on the space S1 side.

(Gripping process of robot system S of embodiment 6)
FIG. 11 is a flowchart showing an example of gripping processing of the robot system S of the sixth embodiment. Compared to the gripping process of the first embodiment shown in the flowchart of FIG. 3, in the gripping process of the sixth embodiment, step S13F is executed instead of step S13, step S14F1 is executed instead of step S14, and step S14F1 is executed instead of step S14. Next, determination processing in step S14F2 is added. Step S15F is added after step S15. Others are the same as the gripping process of the first embodiment.

In step S13F, the position/orientation grasping unit 3a inserts the plurality of first fingers 40a into the space S1. Next, in step S<b>14</b>F<b>1 , the position/orientation grasping unit 3 a moves the plurality of first fingers 40 a toward the object 50 . Next, in step S14F2, the position/orientation grasping unit 3a determines whether or not a reaction force indicating that at least one first finger 40a is in contact with the surface of the object 50 on the space S1 side is detected. If the position/orientation grasping unit 3a detects a reaction force indicating that at least one first finger 40a is in contact with the surface of the object 50 on the space S1 side (step S14F2 Yes), the process proceeds to step S15, and the reaction force is detected. is not detected (step S14F2 No), step S14F2 is repeated.

In step S15F, the position/orientation grasping unit 3a rotates the end effector 40 until all the first fingers 40a contact the surface of the object 50 on the space S1 side.

(Modification of Embodiment 6)
In this embodiment, all the first fingers 40a are provided with the force sensors 9, but the first fingers 40a may not be provided with the force sensors 9 at all. In this case, the movement amount m of the end effector 40 in the direction of the object 50 shown in 6-(3)-1 of FIG.

(Gripping process of robot system S according to modification of embodiment 6)
FIG. 12 is a flowchart showing an example of gripping processing of the robot system S according to the modification of the sixth embodiment. Compared with the gripping process of the sixth embodiment shown in the flowchart of FIG. 11, in the gripping process of the modification of the sixth embodiment, step S14F11 is executed instead of step S14F1, and step S14F2 is omitted. Others are the same as the gripping process of the sixth embodiment. In step S<b>14</b>F<b>11 , the position/orientation grasping unit 3 a moves the plurality of first fingers toward the object 50 by a distance corresponding to the recognition error E.

According to the present embodiment and its modified example, by correcting the recognition error of the orientation A1 by turning the end effector 40, the gripping success rate can be increased.

[Embodiment 7]
In the seventh embodiment, the end effector 40 includes the force sensor 9 for at least the first finger 40a, and the reaction force detected by the force sensor 9 when the first finger 40a is vertically lowered. Recognize the height of the surface you are on.

(Operation of Robot System S of Embodiment 7)
FIG. 13 is an explanatory diagram of an operation example of the robot system S of the seventh embodiment. First, as shown in 7-(1) of FIG. 13, the recognition unit 20 detects the position P1 and posture A1 of the object 50b, and the space S1 around the object 50 into which at least the first finger 40a can be inserted. . Next, as shown in 7-(2)-1 of FIG. 13, the position/orientation grasping unit 3a secures a distance equivalent to the recognition error E from the object 50, inserts the first finger 40a into the space S1, and The end effector 40 is moved downward (in the Z-axis negative direction) until the first finger 40a detects the reaction force. When the first finger 40a detects the reaction force, it means that the surface of the height where the object 50 is arranged is detected.

After that, as shown in 7-(2)-2 of FIG. 13, the position/orientation grasping unit 3a moves the end effector 40 to the height of the appropriate gripping position of the object 50 determined from the object shape information 2a. While maintaining this height, move the second finger 40 b toward the object 50 by a distance corresponding to the recognition error E to bring the second finger 40 b into contact with the object 50 . Thereby, the position P2 of the object 50 is grasped. Then, as shown in 7-(2)-3 of FIG. 13, based on the object shape information 2a, the position P2 of the object grasped by the position/orientation grasping unit 3a, and the orientation A1 grasped by the recognition unit 20, A grippable portion of the object 50 is gripped by the end effector 40 .

(Gripping process of robot system S of embodiment 7)
FIG. 14 is a flowchart showing an example of gripping processing of the robot system S of the seventh embodiment. Compared to the gripping process of the fifth embodiment shown in the flowchart of FIG. 9, in the gripping process of the seventh embodiment, step S13G is executed instead of step S13, and steps S14G1, S14G2, and S14G3 are executed instead of step S14E. be done. Others are the same as the gripping process of the seventh embodiment.

In step S13G, the position/orientation grasping unit 3a inserts at least the first finger 40a into the space S1 while securing the recognition error E from the object 50, and moves it downward. Next, in step S14G1, the position/orientation grasping unit 3a detects whether the output value of the force sensor 9 is equal to or greater than a predetermined threshold value, that is, the reaction force from the placement surface corresponding to contact with the placement surface of the object 50 in the placement space 6. It is determined whether or not it has been detected. If the reaction force is not detected (step S14G2No), the position/orientation grasping unit 3a repeats step S14G2, and if the reaction force is detected (step S14G2Yes), the process proceeds to step S14G3.

In step S14G3, the position/orientation grasping unit 3a moves the end effector 40 by the recognition error E toward the target object 50 at a predetermined height.

In this embodiment, when the end effector 40 is moved toward the object 50 by a distance corresponding to the recognition error E, the end effector 40 may be moved while maintaining the height of the placement surface.

In this embodiment, when picking the objects 50 that are randomly piled up in many layers from the top layer, or when picking the objects 50 whose shapes in the height direction differ at different height positions, it is possible to detect with high accuracy. An appropriate gripping position height of the object 50 is determined based on the placement surface, and the object 50 is gripped at this height. Therefore, it is possible to prevent gripping failure due to gripping an inappropriate position based on low-accuracy height recognition, and increase the picking success rate.

(Configuration of computer 500 realizing controller 1 of robot system S)
FIG. 15 is a diagram showing a configuration example of a computer 500 that implements the controller 1 of the robot system S. As shown in FIG. In computer 500, processor 510, memory 520 such as RAM (Random Access Memory), storage 530 such as SSD (Solid State Drive) and HDD (Hard Disk Drive), and network I/F (Inter/Face) 540 are connected to a bus. connected through

In computer 500 , control device 1 is realized by reading a program for realizing control device 1 from storage 530 and executing it by cooperation of processor 510 and memory 520 . Alternatively, the control device 1 is realized by configuring the processor 510 , which is a PLD such as FPGA, by a program for realizing the control device 1 . Alternatively, the program for realizing the control device 1 may be acquired from an external computer having a non-temporary storage device through communication via the network I/F 540 . Alternatively, the control device 1 may be acquired by being recorded on a non-temporary recording medium and read by a medium reading device.

The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the configurations described. Also, as long as there is no contradiction, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, and to add the configuration of another embodiment to the configuration of one embodiment. Moreover, it is possible to add, delete, replace, integrate, or distribute a part of the configuration of each embodiment. Also, the configurations and processes shown in the embodiments can be appropriately distributed, integrated, or replaced based on processing efficiency or implementation efficiency.

S: robot system, 1: control device, 2: storage unit, 2a: object shape information, 2b: error information, 3: control unit, 3a: position and orientation grasping unit, 3b: gripping control unit, 9: force sensor, 20: recognition unit, 30: arm, 40: end effector (grasping unit), 50, 50a, 50b: object, 500: computer, 510: processor

Claims (13)

A robot system having a transfer mechanism for holding and transferring an object with a plurality of fingers of a holding part,
a recognition unit that recognizes a space in which at least part of the gripping unit can be inserted, and the position and orientation of the object, around the object before transfer;
the grasping unit in a state in which at least part of the grasping unit is inserted into a first space among the spaces recognized by the recognition unit and the grasping unit is not inserted into a space other than the first space; a position and orientation grasping unit that grasps the position of the target object with higher accuracy than the recognition unit by moving the gripping unit toward the target object and bringing the grasping unit into contact with the target object;
A position where the object can be grasped is specified based on information about the shape of the object and the position of the object grasped by the position/orientation grasping unit, and the grasping unit grasps the object at the position. A robot system comprising: a grasping control unit for grasping with and The robot system according to claim 1,
The position/orientation grasping unit
While inserting a first finger of the plurality of fingers into the first space and maintaining a position higher than the object with fingers other than the first finger, the grip portion is moved to the object. A robot system characterized by moving in the direction of The robot system according to claim 1,
The position/orientation grasping unit
inserting at least part of the gripping unit into the first space while securing a distance corresponding to a recognition error when the recognition unit recognizes the position of the object with respect to the object; A robot system characterized by moving the gripper toward the object by a distance of . The robot system according to claim 3,
A robot system, wherein a space having a size equal to or greater than the distance corresponding to the recognition error exists on the opposite side of the object with respect to the first space. The robot system according to claim 1,
The recognition unit
On the opposite side of the object to the first space, there is a second space having a size that allows the object to be moved by a distance corresponding to a recognition error when the recognition unit recognizes the position of the object. determine whether to
The position/orientation grasping unit
When the recognizing unit determines that the second space exists, inserting at least part of the gripping unit into the first space and inserting the gripping unit into a space other than the first space. The robot system moves the gripping part in the direction of the object by a distance corresponding to the recognition error in a state in which the gripping part is not moved. The robot system according to claim 1,
The grip portion has a first finger and a second finger facing the first finger,
The grip control unit
The position/orientation grasping unit moves the grasping unit in the direction of the object while inserting the first finger into the first space and not inserting any fingers into spaces other than the first space. to bring the first finger into contact with the object,
The grip control unit
When the grip control unit causes the first finger to contact the object, the contact between the first finger and the object is temporarily released, and a third grip on the opposite side of the object with respect to the first space is held. inserting the second finger into the space of the third space, and grasping the object with the first finger and the second finger in a state in which the second finger is inserted into the third space; A robot system characterized by: The robot system according to claim 6,
the first finger has a sensor that detects a reaction force received from the object when it contacts the object;
The position/orientation grasping unit
In a state in which at least part of the grip portion is inserted into the first space and the grip portion is not inserted into a space other than the first space, the grip is continued until the reaction force is detected by the sensor. A robot system characterized by moving a part in the direction of the object. The robot system according to claim 1,
The grip portion has a plurality of first fingers and a second finger facing the plurality of first fingers,
The position/orientation grasping unit
In a state in which at least a part of the plurality of first fingers is inserted into the first space and the second finger is not inserted into a space other than the first space, the grip portion is moved to the Move in the direction of the object,
The grip control unit
After any one of the plurality of first fingers contacts the object by the position/orientation grasping unit, the finger of the plurality of first fingers that has come into contact with the object is taken as a starting point and the object is detected. Rotating the gripping portion about a predetermined axis in a direction indicated by a cross product of a first vector whose end point is a finger that is not in contact with the gripping portion and a second vector representing movement of the gripping portion toward the object. to bring the plurality of first fingers into contact with the object. The robot system according to claim 8,
The grip control unit
A robot system, wherein the grasping section is rotated about the predetermined axis by an angle corresponding to a recognition error when the recognition section recognizes the posture of the object. The robot system according to claim 8,
The plurality of first fingers have sensors for detecting a reaction force received from the object upon contact with the object,
The position/orientation grasping unit
any one of the first fingers while inserting at least part of the plurality of first fingers into the first space and not inserting the second finger into a space other than the first space; until the reaction force is detected by the sensor of the robot system. The robot system according to claim 8,
The position/orientation grasping unit
In a state in which at least part of the plurality of first fingers are inserted into the first space and the second finger is not inserted into a space other than the first space, the recognition unit recognizes the target object. A robot system that moves the gripper toward the object by a distance corresponding to a recognition error in recognizing the position. The robot system according to claim 1,
A first finger of the plurality of fingers has a sensor for detecting a reaction force received in the vertical direction when moved vertically downward,
The position/orientation grasping unit
The first finger is inserted into the first space, moved vertically downward until receiving the reaction force, and is positioned at the first vertical height position or the first height position when receiving the reaction force. While maintaining a second height position that is vertically upwardly moved from the height position by a predetermined height, the first finger is moved in the direction of the object, and the first finger is moved to the above-mentioned position. A robot system that grasps the position and orientation of an object with higher accuracy than the recognition unit by bringing the object into contact with the object. A control method for a robot system having a transfer mechanism for grasping and transferring an object with a plurality of fingers of a grasping part, comprising:
The recognition unit of the robot system recognizes a space in which at least part of the gripping unit can be inserted and the position and orientation of the object around the object before transfer,
A position/orientation grasping unit of the robot system inserts at least part of the grasping unit into a first space among the spaces recognized by the recognition unit, and grasps the grasping unit into a space other than the first space. The position of the target object is grasped with higher accuracy than the recognition unit by moving the gripping unit in the direction of the target object and bringing the gripping unit into contact with the target object without inserting the unit,
A gripping control unit of the robot system identifies a position where the object can be gripped based on information about the shape of the object and the position of the object grasped by the position/orientation grasping unit. A control method for a robot system, comprising: each process of gripping the object at a position with the gripping unit.

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