JPH1142575A - Robot control method and device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] The present invention relates to a robot which can specify a direction in which a robot manipulator escapes in a coordinate system when an external force is applied without using a force sensor and the robot manipulator is pressed without completely restraining the robot manipulator. It is an object to provide a control method and device. SOLUTION: Servo motors 1 to 1N for driving a robot manipulator, and the servo motors 1 to 1N
A motor current detector 2 to 2N for detecting a current of N;
Motor rotational speed detectors 5 to 5N for detecting the rotational speeds of the servo motors 1 to 1N, and disturbance detectors 6 to 6N for detecting a disturbance load torque applied to a robot manipulator from the motor rotational speed and the motor current. A force control calculator 8 for outputting a compliance operation command value according to the magnitude of the disturbance load torque detected by the disturbance detector 6 to 6N, and a force control operation command value for a normal position command value of the robot manipulator. A method and a control device for a robot including an operation restriction calculator 10 for adding and restricting operation in a coordinate system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a robot control method and apparatus for driving a robot manipulator by a servomotor to flexibly escape an external force applied to an end effector of the robot, that is, a compliance operation.

[0002]

2. Description of the Related Art Conventionally, a robot controller (Japanese Patent Application Laid-Open No. Hei 6-39760) has been proposed which does not use a force sensor, and when an external force is applied to a robot manipulator, operates the manipulator in accordance with the external force to perform a compliance operation. Are known.

In this conventional example, when an external force is applied to a robot manipulator, the position is added to a position command value as a position change in accordance with a motor current command value increased compared to when the robot manipulator is stopped, and the robot manipulator is operated. A compliance operation can be performed by following an external force without installing a force sensor or the like at the tip of the robot.

[0004]

However, in the above conventional example, since the external force is calculated based on the motor current when the robot is stopped, it cannot be used when the robot is moving in a playback operation. There is a point, and when an external force is applied, the escape direction of the robot manipulator etc. is not specified, so if the person applying the external force is pushing without completely restraining the robot manipulator,
The escape direction of the robot manipulator is unstable,
There is a problem that a collision occurs when there is a jig or the like near the robot operation.

An object of the present invention is to solve the above-mentioned conventional problems. In a control device for a robot that performs a flexible operation when an external force is applied to a robot manipulator without using a force sensor, that is, a compliance operation, A robot control method and device that can be used even when moving in a playback operation and that can specify a direction in which the robot manipulator escapes when an object that applies an external force is pushing without completely restraining the robot manipulator. Aim.

[0006]

In order to achieve this object, a first means of the present invention is to detect a motor current value of a servomotor driving a robot manipulator, to detect a motor rotation speed of the servomotor, A disturbance load torque applied to the robot manipulator is detected from the motor current value and the motor rotation speed, and a compliance operation command value of the robot manipulator is calculated in accordance with the magnitude of the detected disturbance load torque. A robot control method comprising adding a position command value of an operation, calculating a position command value whose operation position is restricted in a coordinate system, and performing a compliance operation.

According to a second aspect of the present invention, in the operation position limiting method of the first means, the operation of the tool center point of the robot is limited to an operation position in a world coordinate system.

Next, a third means of the present invention is the method according to the first means, wherein the operation of the tool center point of the robot is restricted in the base coordinate system.

Next, a fourth means of the present invention is the method according to the first means, wherein the operation of the tool center point of the robot is restricted in an operation position in a mechanical interface coordinate system.

Next, a fifth means of the present invention is the method according to the first means, wherein the operation of the tool center point of the robot is restricted in the operation coordinate system in the operation coordinate system.

Next, a sixth means of the present invention is the method according to the first means, wherein the operation of the tool center point of the robot is restricted in the operation position in the end effector coordinate system.

Next, a seventh means of the present invention comprises a servo motor for driving a robot manipulator, a motor current detector for detecting a current for driving the servo motor, and a motor rotation for detecting a rotation speed of the servo motor. A speed detector, a disturbance detector that detects a disturbance load torque applied to the robot manipulator from the motor rotation speed and the motor current, and a compliance operation of the robot manipulator according to the magnitude of the disturbance load torque detected by the disturbance detector. It comprises a force control calculator for calculating a command value, and an operation limit calculator for adding the position command value to a normal position command value to limit the operation position in the coordinate system and calculate the position command value.

Next, an eighth means of the present invention is configured such that the operation of the tool center point of the robot is operated in a world coordinate system and the position command value is restricted as an operation restriction calculator of the seventh means. is there.

Next, the ninth means of the present invention is configured to calculate a position command value in which the operation of the tool center point of the robot is limited to the operation position in the base coordinate system as the operation restriction calculator of the seventh means. is there.

Next, the tenth means of the present invention is configured to calculate a compliance operation command value in which the operation of the tool center point of the robot is restricted in the operation position in the mechanical interface coordinate system as the operation restriction operation unit of the seventh means. Things.

Next, an eleventh means of the present invention is configured such that the operation of the tool center point of the robot is operated by the operation restriction operation unit of the seventh means to calculate a position command value whose operation position is restricted by a work coordinate system. is there.

Next, the twelfth means of the present invention is configured so that the operation of the tool center point of the robot is operated by the end effector coordinate system to calculate a position command value whose operation position is restricted by the end effector coordinate system as the operation restriction operation unit of the seventh means. It is.

[0018]

According to the above-mentioned means, according to the method of the first means of the present invention and the apparatus of the seventh means for using the method, the force sensor can be used even when the robot is moving in a playback operation. It has the function of performing a compliance operation when an external force is applied to the robot manipulator without using it.

Further, according to the method of the second means of the present invention and the apparatus of the eighth means for using the method, the robot manipulator can be used when an external force applies without completely restraining the robot manipulator. The tool center point of the robot has an operation of specifying an escape position where the escape position is restricted in the world coordinate system.

Further, according to the method according to the third means of the present invention and the apparatus according to the ninth means for using the method, the robot manipulator can be used in a case where an external force applies without completely restraining the robot manipulator. Has the function of specifying the escape direction as the operation position where the tool center point of the robot is restricted in the operation position in the base coordinate system.

Further, according to the method of the fourth aspect of the present invention and the apparatus of the tenth aspect for using the method, the robot manipulator can be used in a case where an external force applies without completely restraining the robot manipulator. The tool center point of the robot has an action of specifying the direction in which the tool escapes at the operation position whose operation position is restricted in the mechanical interface coordinate system.

Further, according to the method of the fifth aspect of the present invention and the apparatus of the eleventh means for using the method, the robot manipulator can be used in a case where an external force applies without completely restraining the robot manipulator. Has a function of specifying the direction in which the robot escapes at the operation position where the operation center of the robot is restricted by the tool center point of the robot.

Further, according to the method of the sixth aspect of the present invention and the apparatus of the twelfth means for using the method, the robot manipulator can be used when an object that applies an external force pushes the robot manipulator without completely restraining it. The tool center point of the robot has a function to specify the direction in which the robot escapes at the operation position whose operation position is restricted in the end effector coordinate system.

FIG. 1 shows an embodiment of the present invention.
This will be described with reference to FIG.

As shown in FIG. 1, this embodiment employs servo motors 1 to 1N for driving a robot manipulator.
And motor current detectors 2 to 2N for detecting currents for driving the servo motors 1 to 1N. The rotation of the servo motors 1 to 1N is detected in the servo devices 3 to 3N based on signals from the rotary encoders 4 to 4N. Motor rotation speed detectors 5 to 5N for detecting the speed, and disturbance detectors 6 to 6 for detecting a disturbance load torque applied to the robot manipulator from the motor rotation speed and the motor current.
And a force control calculator 8 for calculating a compliance operation amount from a disturbance load torque in the arithmetic unit 7.
And a normal operation calculator 9 for calculating an operation amount such as a normal playback operation, and a compliance operation command value Sk added to the normal position command value So, and the tool center point of the robot is subject to operation restrictions in the coordinate system. And an operation limit calculator 10 for calculating a position command value so as to operate, and when the disturbance load torques T1 to TN are applied to the robot manipulator, the arithmetic unit 7 calculates the disturbance load torques T1 to TN from the detected disturbance load torques T1 to TN. Position command value S1
Or SN is calculated, and the robot manipulator is operated in a direction to escape from the disturbance load torques T1 to TN. Since the robot is usually composed of a plurality of N-axis manipulators, servo motors 1 to 1N, rotary encoders 4 to 4N, and servo devices 3 to 3N are required for N axes.

Normally, the disturbance detector calculates the disturbance load torque T1 or TN by subtracting the motor current multiplied by the time derivative of the motor rotation speed by the load inertia.

FIG. 2 shows a case where the operation is restricted on the X coordinate of the world coordinate system by the operation restriction arithmetic unit 10 for calculating the position where the compliant operation is performed by applying a disturbance load torque when the robot handles the conveyed object.

In FIG. 2, 100 is the wrist of the robot,
101 is a transported object, 102 is a world coordinate system (a coordinate system set on the ground or the work floor). When the disturbance B1 is applied to the tool center point TP, the compliance operation is calculated so as to move to the point P1 when the operation is not restricted, but when the operation is restricted in the X coordinate direction X1 of the world coordinate system, a straight line is formed from the point P1. The tool center point TP is operated so as to operate to the point P2 which is perpendicular to the point P2.

Next, FIG. 3 shows a case where the operation is restricted on the X coordinate of the base coordinate system of the operation restriction calculator 10 for calculating a position where a compliant operation is performed by applying a disturbance load torque when the robot handles a conveyed object. .

In FIG. 3, reference numeral 200 denotes a wrist of the robot,
201 is a transported object, 202 is a base coordinate system (coordinate system set on the bottom surface of the robot base). Here, when the disturbance B2 is applied to the tool center point TP, the compliance operation calculation is performed so that the operation is performed to the point P3 when the operation is not restricted, but when the operation is restricted in the X coordinate system direction X2 of the base coordinate system, the point is determined. The operation is performed so as to operate from P3 to a point P4 which is a perpendicular line, and the tool center point TP operates.

Next, FIG. 4 shows a case where the operation is restricted at the X coordinate of the mechanical interface coordinate system of the operation restriction calculator 10 for calculating a position where a compliant operation is performed by applying a disturbance load torque when the robot handles a conveyed object. Show.

In FIG. 4, reference numeral 300 denotes a wrist of the robot,
Reference numeral 301 denotes a conveyed object, and 302 denotes a mechanical interface coordinate system (a coordinate system set on the bottom of the mechanical interface). Here the disturbance B3 is the tool center point TP
When the operation is not restricted, the compliance operation is calculated so as to move to the point P5. However, when the operation is restricted in the X coordinate system direction X3 of the mechanical interface coordinate system, the point P6 which is perpendicular to the point P5 is lowered. Then, the tool center point TP is operated.

Next, FIG. 5 shows a case where the operation is restricted on the X coordinate of the working coordinate system of the operation restriction computing unit 10 which calculates a position where a compliant operation is performed by applying a disturbance load torque when the robot handles a conveyed object. .

In FIG. 5, reference numeral 400 denotes a wrist of the robot,
401 is a conveyed object, 402 is an end effector, 403 is a work coordinate system (a coordinate system determined by work). Here, when the disturbance B4 is applied to the tool center point TP, the compliance operation is calculated so that the operation moves to the point P7 when the operation is not restricted, but when the operation is restricted in the X coordinate system direction X4 of the working coordinate system, the point is determined. The operation is performed so as to move from P7 to a point P8, which is a perpendicular line, and the tool center point TP operates.

Next, FIG. 6 shows a case where the operation is restricted on the X coordinate of the end effector coordinate system of the operation restriction calculator 10 for calculating a position where a compliant operation is performed by applying a disturbance load torque when the robot handles a conveyed object.
Shown in

In FIG. 6, reference numeral 500 denotes a wrist of the robot,
501 is a conveyed object, 502 is an end effector, 503 is an end effector coordinate system (coordinate system set for the end effector). Here the disturbance B5 is the tool center point T
When the operation reaches P, the compliance operation is calculated so as to operate to the point P9 when the operation is not restricted. However, when the operation is restricted in the X coordinate system direction X5 of the end effector coordinate system, a point perpendicular to the point P9 is dropped. The operation is performed to move to P10, and the tool center point TP operates.

In the above example, the X coordinate has been described. However, the coordinate may be specified when the coordinate is specified as the Y coordinate or the Z coordinate, or may be combined. Generally, in any of the above five types of coordinate systems, the disturbance load torque detected at each robot joint axis is converted into the operation of the tool center point TP by forward kinematics, and after the operation is restricted by each coordinate system, the inverse kinematics is used. The position command values S1 to SN are calculated by converting the operation into the operation of each joint.

[0038]

As described above, according to the method of the first means of the present invention and the apparatus of the seventh means for using the method,
A servo motor that drives the robot manipulator, a motor current detector that detects the servo motor current, a motor rotation speed detector that detects the rotation speed of the servo motor, and a disturbance applied to the robot manipulator from the motor rotation speed and the motor current A disturbance detector that detects a load torque, a force control calculator that calculates a compliance operation command value of the robot manipulator according to the magnitude of the disturbance load torque detected by the disturbance detector, and a compliance operation command value and a normal operation command value. By providing an operation limit calculator that adds to the position command value, compliance operation is performed when external force is applied to the robot manipulator without using a force sensor, and force control is performed even when the robot is moving by playback operation. Which has the excellent effect of being able to do That.

According to the method of the present invention and the apparatus of the eighth means for using the method, the first method
The operation limit operation unit of the means is configured to add the compliance operation command value to the normal position command value so that the tool center point of the robot operates only in the operation limit direction specified in the world coordinate system,
When an external force is pressed without completely restraining the robot manipulator, the robot manipulator can determine the direction in which the robot maneuver escapes by specifying the direction of the robot's tool center point in the motion restriction direction specified in the world coordinate system. To play.

Further, according to the method of the third aspect of the present invention and the apparatus of the ninth means for using the method, the first aspect of the present invention is provided.
The operation restriction operation unit of the means is configured to add the compliance operation instruction value to the normal position instruction value so that the robot tool center point operates only in the operation restriction direction specified in the base coordinate system. When an external force is applied without completely restraining the robot manipulator, the robot manipulator specifies the direction in which the robot manipulator escapes in the direction of the motion limit specified by the base coordinate system of the robot tool center point. To play.

Further, according to the method according to the fourth means of the present invention and the apparatus according to the tenth means for using the method, the operation limit operation unit of the first means can be configured such that the tool center point of the robot is a mechanical interface coordinate system. A configuration that adds the compliance operation command value to the normal position command value so that the robot manipulator operates only in the specified motion restriction direction. In addition, there is an excellent effect that the direction in which the robot manipulator escapes is specified by the tool center point of the robot in the operation restriction direction specified by the mechanical interface coordinate system.

According to the method of the fifth aspect of the present invention and the apparatus of the eleventh means for using the method, the operation limit operation unit of the first means is specified by the tool center point of the robot in the working coordinate system. The compliance operation command value is added to the normal position command value so that the robot manipulator is operated only in the restricted direction. This has an excellent effect that the direction in which the robot manipulator escapes is specified by the tool center point of the robot in the operation restriction direction specified in the work coordinate system.

Further, according to the method of the sixth aspect of the present invention and the apparatus of the twelfth aspect for using the method, the operation limit operation unit of the first means is configured such that the tool center point of the robot is in the end effector coordinate system. A configuration that adds the compliance operation command value to the normal position command value so that the robot manipulator operates only in the specified motion restriction direction. In addition, there is an excellent effect that the tool center point of the robot specifies the direction in which the robot manipulator escapes in the operation restriction direction specified by the end effector coordinate system.

[Brief description of the drawings]

FIG. 1 is a block diagram of a robot control device according to an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram showing that an operation restriction operation unit restricts an operation direction to an X coordinate in a world coordinate system in the embodiment.

FIG. 3 is an operation explanatory diagram showing that an operation restriction operation unit restricts an operation direction to an X coordinate in a base coordinate system in the embodiment.

FIG. 4 is an operation explanatory diagram showing that an operation restriction operation unit restricts an operation direction to an X coordinate in a mechanical interface coordinate system in the embodiment.

FIG. 5 is an operation explanatory diagram showing that the operation restriction arithmetic unit restricts the operation direction to the X coordinate in the working coordinate system in the embodiment.

FIG. 6 is an operation explanatory diagram showing that the operation restriction operation unit restricts the operation direction to the X coordinate in the end effector coordinate system in the embodiment.

[Explanation of symbols]

 1 to 1N Servo motor 2 to 2N Motor current detector 5 to 5N Motor rotational speed detector 6 to 6N Disturbance detector 8 Force control calculator 10 Operation limit calculator So Normal position command value Sk Compliance operation command value S1 to SN Position command value X1 X coordinate direction of world coordinate system X2 X coordinate direction of base coordinate system X3 X coordinate direction of mechanical interface coordinate system X4 X coordinate direction of working coordinate system X5 X coordinate direction of end effector coordinate system TP Tool center point

Claims (12)

[Claims] 1. A motor current value of a servomotor for driving a robot manipulator is detected, a motor rotation speed of the servomotor is detected, and a disturbance load torque applied to the robot manipulator is determined from the motor current value and the motor rotation speed. Detecting and calculating the compliance operation command value of the robot manipulator according to the magnitude of the detected disturbance load torque, adding the compliance operation command value and the position command value of the normal operation to the position command in which the operation position is restricted in the coordinate system. A robot control method comprising calculating a value and performing a compliance operation. 2. The robot control method according to claim 1, wherein the operation of the tool center point of the robot calculates a position command value whose operation position is restricted in the world coordinate system, and performs a compliance operation. 3. The robot control method according to claim 1, wherein the operation of the tool center point of the robot calculates a position command value whose operation position is restricted in the base coordinate system, and performs a compliance operation. 4. The robot control method according to claim 1, wherein the operation of the tool center point of the robot calculates a position command value whose operation position is restricted in the mechanical interface coordinate system, and performs a compliance operation. 5. The robot control method according to claim 1, wherein the operation of the tool center point of the robot calculates a position command value whose operation position is restricted in the work coordinate system, and performs a compliance operation. 6. The robot control method according to claim 1, wherein the operation of the tool center point of the robot calculates a position command value whose operation position is restricted in the end effector coordinate system, and performs a compliance operation. 7. A servomotor for driving a robot manipulator, a motor current detector for detecting a current of the servomotor, a motor rotation speed detector for detecting a rotation speed of the servomotor, the motor rotation speed and a motor. A disturbance detector that detects a disturbance load torque applied to the robot manipulator from the current, and a force control calculator that calculates a compliance operation command value of the robot manipulator according to the magnitude of the disturbance load torque detected by the disturbance detector. A control device for a robot performing a compliance operation, comprising an operation restriction calculator for adding the compliance operation command value to a normal position command value to calculate a position command value whose operation position is restricted in a coordinate system. 8. The control device for a robot according to claim 7, wherein the operation restriction calculator is configured to calculate a position command value in which the operation of the tool center point of the robot is restricted in the operation position in the world coordinate system. 9. The operation restriction arithmetic unit is configured to calculate a position operation command value in which the operation of the tool center point of the robot is restricted in the operation position in the base coordinate system.
The control device of the described robot. 10. The robot control device according to claim 7, wherein the operation restriction calculator is configured to calculate a position command value obtained by restricting the operation of the tool center point of the robot to the operation position in the mechanical interface coordinate system. 11. The robot control device according to claim 7, wherein the operation restriction calculator is configured to calculate a position command value obtained by restricting the operation of the tool center point of the robot to the operation position in the work coordinate system. 12. The robot control device according to claim 7, wherein the operation restriction calculator is configured to calculate a position command value obtained by restricting an operation position of the operation of the tool center point of the robot in an end effector coordinate system.