JP2021003735A - Robot control system and robot finger mechanism - Google Patents

Abstract

To provide a robot control system that determines from an image what a gripping object is, and that controls movement of the gripping object in accordance with an intrusion value of a finger mechanism based on a gripping object contour stored for each gripping object.SOLUTION: A control section 22 controls a robot arm 1 and a finger mechanism according to information from a determination section 23. The control section 22 includes a storage section. The storage section stores an intrusion value from a contour position of a gripping object to an inner region, as appropriate holding power for gripping the gripping object with the finger mechanism, for each type of gripping object. The intrusion value is determined by performing breakage and gripping (falling) testing with respect to each gripping object in beforehand. More specifically, a contour line (a profile) of a gripping object is used as a reference, and a control signal is transmitted to an actuator of the finger mechanism so that the finger mechanism intrudes to a specific position of the inner region beyond the contour line. The testing is repeated multiple times to deduce an intrusion value (a maximal intrusion value) at which the gripping object is broken or deformed.SELECTED DRAWING: Figure 2

Description

The present invention relates to a robot control system including an arm portion and a hand portion attached to the tip of the arm, and more particularly to learning of a finger mechanism gripping force constituting the hand portion.

If the gripping force is too large when the robot hand grips and lifts the object, the object will be destroyed or deformed, and if it is too small, the object will fall when lifted. Patent Documents 1 to 4 have been proposed to improve such a point.

In Patent Document 1, an actuator is driven to grip an object on which it is placed by two or more finger mechanisms (grasping members), and these finger mechanisms are raised while gradually increasing the gripping force of the object. The gripping force when the load acting in the direction along the surface of the object detected by the load detecting means becomes constant by sliding the finger mechanism with respect to the surface is determined as the gripping force required when lifting the object. It is disclosed to do.

In Patent Document 2, a sensor for detecting the slip of the gripping object is installed at the fingertip of the robot hand, and when the slip of the gripping object is detected by this sensor, the gripping force of the finger is controlled by the gripping force control device. Discloses that the gripping force is increased by a predetermined amount. In particular, in Patent Document 2, when the gripping object is handed from the robot hand to the human hand, the gripping force is not strengthened even if slippage occurs.

Patent Document 3 describes a hand portion having at least two finger portions, a contact force measuring means for measuring the contact force received by the finger portion from an object, and a contact force measuring means when the finger portion slides on the surface of the object. It is disclosed that the frequency measuring means for measuring the vibration frequency of the contact force measured by the hand unit and the gripping motion for gripping the object are adjusted based on the vibration frequency measured by the frequency measuring means.

In Patent Document 4, a force sensor provided at a connection portion between a robot arm and a hand detects an external force acting on the hand in accordance with a predetermined motion, and the grip force command device follows the value of the external force to cause the hand. It is disclosed to change the value of the gripping force commanded to the control device.

JP-A-2009-148863 Japanese Unexamined Patent Publication No. 2008-200847 Japanese Unexamined Patent Publication No. 2008-183629 JP-A-5-324025

Even if the objects grasped by the robot have the same size, such as soft objects, hard objects, light objects, and heavy objects, their properties vary widely.

In Patent Document 1, the required gripping force is determined without determining what the gripping object is, and the range of application thereof is extremely narrow, such as when the gripping object is determined.

In Patent Document 2, the gripping force is determined by whether or not slippage occurs. However, the surface of the gripping object has a slippery surface and a non-slippery surface, and the state where the gripping object does not fall even if it does not slip. It is not always held by.

Similar to Patent Document 1, Patent Document 3 does not determine what the gripping object is, but instead determines the gripping force by measuring the vibration frequency of the contact force. For this reason, it is conceivable that a fragile object may be strongly grasped.

In the method disclosed in Patent Document 4, the gripping force is determined by detecting the external force acting on the hand, but the object to be gripped is easily damaged due to the response delay.

In a conventional robot, the force for gripping an object to be gripped is considered to be slippery on the surface, and if the robot is gripped with a small gripping force within a non-slip range, it will not be destroyed and will not fall. However, even if the surface is slippery, soft objects (easy to deform) and hard objects will not break even if they are gripped strongly to some extent, but they will break if they are gripped with the same gripping force. It is easy to occur.

Further, the gripping by the robot hand disclosed in Patent Documents 1 to 4 is controlled after the robot hand touches the gripping object. Therefore, it takes time from the start to the end of gripping.

The present invention is a robot control system in which a hand portion having a plurality of finger mechanisms is attached to the tip of the arm portion.
This control system includes a control device that transmits a control signal to the arm portion and an actuator that operates the finger mechanism, a camera that acquires image information of the object to be gripped, and what is the object to be gripped based on the information from the camera. The control device is provided with a determination unit for determining the presence or absence, and the intrusion value of the finger mechanism from the external position of the gripped object to the inner region is stored in the storage unit of the control device for each type of the gripped object. A signal for taking a posture according to the shape and orientation of the object to be gripped is transmitted to the arm portion and the hand portion, and the control device further receives information on what the object to be gripped is from the determination unit, and this information. A signal for closing the finger mechanism from the outer position of the object to be gripped to the intrusion value into the inner region is transmitted to the actuator.

To determine the intrusion value into the inner region from the external position of the object to be gripped by the finger mechanism, a test is performed in advance for each type of the object to be grasped, and the intrusion value when the object is destroyed and the intrusion value when the object is dropped are determined. Knowingly, the median value (not necessarily the average value) between the intrusion value when the fracture is reached and the intrusion value when the product is dropped is set as the intrusion value from the outer position of the object to be gripped to the inner region.
The above determination method is effective for soft objects to be gripped such as cream puffs and sushi. If the object to be gripped does not break or deform even if the gripping force is increased, a gripping force stronger than the gripping force when dropped is set.

Further, as a finger mechanism for carrying out the robot control system according to the present invention, it is conceivable that the finger bends inward (right side) or outward (left side) along a plane parallel to the palm.
Specifically, it is a finger mechanism including a plurality of bone members to be connected, a plurality of link members for rotating the bone members, and a drive member for driving the plurality of link members, and the plurality of link members are The finger mechanism is opened and closed by receiving the driving force from the driving member, and one of the plurality of link members has a function of determining the initial position of the finger mechanism, and the link having the function of determining the initial position is rod-shaped. At the same time, its length is made variable by a signal from the outside, and it is arranged in pairs on the left and right, and the finger mechanism can swing along the plane whose tip is parallel to the palm with respect to the base. It is pivotally attached, with the tip of the link connected to the front of the finger mechanism and the rear end to the base of the finger mechanism.

According to the robot control system according to the present invention, before the robot hand touches the object to be gripped, it is determined in advance what the object to be gripped is, and based on this determination, the entire gripping plan is executed. It can be shortened.

In particular, even if the object to be gripped is soft, difficult to grasp, and fragile, such as fruits, cakes, and sushi, according to the control system of the robot according to the present invention, a gripping plan can be created before gripping the object to be gripped. It can be grasped and transported with a delicate touch without breaking.

According to the control system of the robot according to the present invention, based on the object to be grasped by the camera, the determination unit such as AI determines what the object to be gripped is, and the storage unit of the control unit has each subject. Since the appropriate intrusion value from the outline of the image captured by the camera to the inside is stored for each type of gripped object, the gripped object can be gripped with an appropriate gripping force without breaking or dropping the gripped object. Can be grasped.

The whole view of the robot to which the control method of the robot which concerns on this invention is applied. The figure explaining the whole of the control method of the robot which concerns on this invention. Side view of the finger mechanism of the robot. The figure seen from the A direction of FIG. The figure which shows an example of the stepping motor which constitutes a finger mechanism. The figure which shows the initial state when the link of a finger mechanism is shortened. The figure explaining the state which pushed the driving member and contracted a finger. The figure which shows the state which the finger mechanism was inversion A photograph showing a state in which an object is gripped by a hand portion of a robot according to the present invention.

The robot includes an arm portion 1 and a hand portion 20, and the support column 3 is fixed to the base 2 of the arm portion 1, and the arm 4 is rotated by an actuator 5 (motor) around the axis of the support column 3. Similarly, the arm 6 is rotated by the actuator 7 about the axis of the arm 4, the arm 9 is rotated by the actuator 10 about the axis of the arm 8, and the arm 11 is rotated by the actuator 12 around the axis of the arm 9. The hand portion 20 attached to the tip of the arm 11 is moved and rotated around the axis of the arm 11 by the actuator 13.
The method of assembling the arm is not limited to the above structure.

The illustrated hand portion 20 is a humanoid hand and includes five finger mechanisms 30. Further, a camera (3D sensor) 21 is provided at the tip of the hand unit 20 or the arm 11, and the image of the object to be grasped acquired by the camera 21 is sent to the control unit 22. A plurality of cameras 21 may be provided to observe the object to be gripped at different angles.

The control unit 22 is capable of bidirectional communication with the determination unit 23 of the object to be gripped. The determination unit 23 may be provided in a cloud computer or the like other than the control unit 22 incorporated in a part of the robot, or may be provided in a part of the control unit 22.

The image of the object to be gripped by the camera 21 is sent to the determination unit 23 via the control unit 22, and the determination unit 23 determines what the object to be gripped is by using AI (artificial intelligence). Factors used for judgment include, for example, shape, color, size, and orientation. In addition, the position of the center of gravity can be calculated after determining what the object to be gripped is.

The control unit 22 controls the robot arm 1 and the finger mechanism 30 based on the information from the determination unit 23.
Specifically, control signals are sent to the actuators 5, 7, 10, 12, and 13 constituting the arm portion 1 so that the hand portion 20 can take a posture in which the gripped object can be most easily gripped depending on the size and orientation of the object to be gripped. To move arms 4, 6, 8, 9, and 11.

The control unit 22 has a storage unit, and the storage unit has an external position of the object to be gripped as an appropriate holding force when the finger mechanism 30 grips the object to be gripped for each type of the object to be gripped. The intrusion value from to the inner region is stored.

This penetration value is determined in advance by performing a fracture and grip (drop) test on each object to be gripped. Specifically, the control signal is sent to the actuator of the finger mechanism 30 so that the finger mechanism 30 penetrates to a specific position in the region inside the outer line (contour) of the object to be gripped. The test is repeated several times to determine the penetration value (maximum penetration value) at which the object to be gripped is destroyed or deformed.
Further, the intrusion value (minimum intrusion value) that cannot be lifted because the hand portion 20 cannot grasp the object to be grasped by the weight of the gripped object is determined by grasping the object with a value smaller than the above-mentioned intrusion value.
There is an optimum intrusion value between these maximum intrusion values and the minimum intrusion values. In this example, the average value of the maximum intrusion value and the minimum intrusion value was adopted as the optimum intrusion value.

The optimum intrusion value is transmitted from the control unit 22 to the actuator of each finger mechanism 30 via the servo controller 24.

The structure of the finger mechanism 30 will be described with reference to FIGS. 3 to 8.
The finger mechanism 30 includes a base portion 31 and a tip portion 33 that can swing in a direction parallel to the palm (vertical direction in FIG. 3) with respect to the base portion 31 via a shaft 32.

The base 31 includes a first bone member 34 corresponding to the metacarpal bone of a human finger, and a linear actuator (driving member) 35 is attached to the first bone member 34. The linear actuator 35 has a structure in which the slider 36 slides along the rod 35a.

The tip 33 of the finger mechanism 30 includes a second bone member 37 corresponding to the proximal phalanx of a person, and the proximal end portion of the third bone member 38 corresponding to the intermediate phalanx rotates at the tip of the second bone member 37. It is movably connected, and a fourth bone member 39 corresponding to the distal phalanx is rotatably connected to the tip of the third bone member 38.

A pad 40 for not damaging the object when gripping the object is attached to the inner portion of the second bone member 37, and a similar pad 41 is attached to the tip of the fourth bone member 39.

A bracket 42 is provided at the tip of the first bone member 34, and an intermediate portion of the triangular link 43 is rotatably attached to the bracket 42, and one end of the triangular link 43 and the slider 36 are variable. It is connected by a long link 44.

A pair of triangular links 43 are provided on the left and right, and a pair of variable length links 44 are also provided on the left and right. As shown in FIG. 5, the variable length link 44 includes a stepping motor 45, and is a tubular female that receives a command signal from the outside and is screwed with the male screw member 46 attached to the rotation shaft of the stepping motor 45 by rotation. The screw member 47 moves, and the variable length link 44 expands and contracts.

Further, the base end portion of the link member 48 is pivotally attached near the apex of the triangle offset from both the rotation center of the triangular link 43 and the pivot point with the variable length link 44, and the tip end portion of the link member 48. Is pivotally attached to the base end portion of the third bone member 38 at a position offset from the connecting portion with the second bone member 37.

The base end portion of the link member 49 is pivotally attached to a position closer to the base end portion in the length direction of the third bone member 38, and the tip end portion of the link member 49 is the third bone member 39 base end portion. It is pivotally attached at a position offset from the connection with the bone member.

The stepping motor 45 constituting the linear actuator 35 and the variable length link 44 receives a signal from the control unit 22 and drives the stepping motor 45 so as to have a predetermined penetration value.
When the variable length link 44 is contracted, as shown in FIG. 6, the position of the slider 35 remains the same, the triangular link 43 rotates counterclockwise in the drawing, and the link member 48 causes the third bone member 38 to move. It is pushed and the portion ahead of the second bone member 37 rotates counterclockwise around the rotation center of the second link member 48. And this position becomes the initial position in the state where the variable length link 44 is contracted.

From this state, the linear actuator 35 is driven to move the slider 36 rearward. Then, the triangular link member 43 further rotates counterclockwise, and at the same time, the third bone member 38 rotates due to the pushing operation of the link member 48, and the fourth bone member 39 receives the rotation of the third bone member 38. Rotates counterclockwise around the connecting portion with the third bone member 38, so that the pad is gripped as shown in FIG.

It takes less time to reach the gripping state shown in FIG. 7 when the state shown in FIG. 6 is set as the initial state than when the state shown in FIG. 3 is set as the initial state. When the size of the object to be gripped becomes large, the stepping motor 45 is driven to lengthen the variable length link 44. The drive of the stepping motor 45 can be incorporated into the program in advance, but it is also possible to control the stepping motor 45 with a wireless signal when necessary.

Further, in this embodiment, the stepping motors 45 constituting the left and right variable length links 44 are individually controlled.
In FIG. 8, the variable length link 44a is extended and the variable length link 44b is shortened. As a result, the tip 33 slightly swings laterally with respect to the base 31 of the finger mechanism 30. By making minute movements in the lateral direction in this way, it is possible to easily grasp an object that could not be grasped in the past.

Further, in the robot according to the present invention, when the object to be gripped is located at the base 31 of the finger mechanism 30 and the linear actuator 35 is driven from that state, the link mechanism is used by the familiar mechanism without any particular computer control. Since the tip 33 bends according to the shape of the object to be gripped, the degree of freedom of the object to be gripped is high.

FIG. 9 shows a state in which the orange is gripped by using the robot control system according to the present invention. It can be confirmed that each finger mechanism 30 is bent along the shape of orange.

The robot control system according to the present invention is not limited to the number of finger mechanisms such as three fingers as well as the five-finger humanoid hand.

1 ... Arm part, 2 ... Base, 3 ... Support, 4, 6, 8, 9, 11 ... Arm, 5, 7, 10, 12, 13 ... Actuator, 20 ... Hand part, 21 ... Camera, 22 ... Control unit , 23 ... Judgment unit, 24 ... Servo controller, 30 ... Finger mechanism, 31 ... Base, 32 ... Axis, 33 ... Tip, 34 ... First bone member, 35 ... Linear actuator (drive member), 35a ... Rod, 36 ... Slider, 37 ... 2nd bone member, 38 ... 3rd bone member, 39 ... 4th bone member, 40, 41 ... Pad, 43 ... Triangular link, 44 ... Variable length link, 45 ... Stepping motor, 46 ... Male screw member, 47 ... Cylindrical female screw member, 48 ... Link member, 49 ... Link member.

Claims (3)

A control system for a robot in which a hand portion having a plurality of finger mechanisms is attached to the tip of an arm portion, and this control system is a control device that transmits a control signal to the arm portion and an actuator that operates the finger mechanism, and a cover. A camera that acquires image information of the gripped object and a determination unit that determines what the gripped object is based on the information from the camera are provided, and the storage unit of the control device is provided from the external position of the gripped object. The intrusion value of the finger mechanism into the inner region is stored for each type of the object to be gripped, and the control device transmits a signal to the arm portion and the hand portion to take a posture according to the shape and orientation of the object to be gripped. Further, the control device receives information on what the object to be gripped is from the determination unit, and based on this information, sends a signal to the actuator to close the finger mechanism from the outer position of the object to be gripped to the intrusion value into the inner region. A robot control system characterized by transmitting. In the robot control system according to claim 1, the intrusion value from the external position of the gripped object to the inner region is tested in advance, and the intrusion value when the gripped object is destroyed and the gripped object are destroyed. A robot control system characterized by adopting an intermediate value with the intrusion value when the robot falls from the hand. A finger mechanism of a robot controlled by the control system of the robot according to claim 1 or 2, wherein the finger mechanism includes a plurality of connecting bone members, a plurality of link members for rotating the bone members, and a plurality of link members. It is composed of a driving member that drives the plurality of link members, and the plurality of link members open and close the finger mechanism by receiving a driving force from the driving member, and one of the plurality of link members sets the initial position of the finger mechanism. The link, which has a function of determining the initial position, has a rod shape, and its length is made variable by a signal from the outside, and is arranged in pairs on the left and right. Is characterized in that the tip is swingably pivotally attached to the base along a plane parallel to the palm, the tip of the link is connected to the front of the finger mechanism, and the rear end is connected to the base of the finger mechanism. The finger mechanism of the robot.

Images