Elastic-deformation-compensation control device and control method for articulated robot

Patent metadata

Field	Value
Publication number	US-9505131-B2
Application number	US-201314403320-A
Country	US
Kind code	B2
Filing date	May 30, 2013
Priority date	May 30, 2012
Publication date	Nov 29, 2016
Grant date	Nov 29, 2016

Abstract

In an elastic-deformation-compensation control device ( 10 ), a first dynamic characteristic calculation unit ( 300 ) performs filtering processing with respect to a motor-angle command value (θmc) outputted from a motor-angle-command-value calculation unit ( 600 ), and outputs a processed motor-angle target value (θmd). A second dynamic characteristic calculation unit ( 400 ) is provided with a high-frequency cutoff characteristic having a cutoff frequency which is lower than that of the first dynamic characteristic calculation unit ( 300 ), performs filtering processing with respect to the output from an axial force torque calculation unit ( 200 ), and outputs a processed axial force torque compensation value (fd).

First claim

The invention claimed is:

1. An elastic-deformation-compensation control device for an articulated robot including a motor and an arm being coupled through an elastically deformable reduction gear in the articulated robot, a tool being attached to the articulated robot, and a plurality of joint axes each being driven by the motor to cause the tool to perform a desirable operation, the elastic-deformation-compensation control device comprising:
a joint-angle-command-value calculation unit that calculates a joint-angle command value θlc of each of the joint axes for providing the desirable operation of the tool, and outputs the joint-angle command value θlc;
an axial force torque calculation unit that calculates an axial force torque fc generated when an operation is made according to the joint-angle command value θlc and acting on each of the joint axes, from the joint-angle command value θlc based on a model of dynamics, and outputs the axial force torque fc;
a motor-angle-command-value calculation unit that calculates a motor-angle command value θmc from the joint-angle command value θlc and the axial force torque fc based on a parameter including a stiffness parameter of the joint axis, and outputs the motor-angle command value θmc;
a first dynamic characteristic calculation unit that has a high-frequency cutoff characteristic having a cutoff frequency being lower than a natural resonance frequency of the articulated robot, executes filtering processing on the motor-angle command value θmc, and outputs a processed motor-angle target value θmd;
a motor-angle control unit that receives the motor-angle target value θmd input as a target value for the motor;
a second dynamic characteristic calculation unit that has a high-frequency cutoff characteristic having a cutoff frequency being lower than or equal to the first dynamic characteristic calculation unit, executes filtering processing on at least one of an input to the axial force torque calculation unit and an output from the axial force torque calculation unit, and outputs a processed axial force torque compensation value fd; and
a motor-current control unit that receives a value input as a target value, in which the axial force torque compensation value fd is added to a motor-torque command value output from the motor-angle control unit.

2. The elastic-deformation-compensation control device for the articulated robot according to claim 1 , wherein a phase delay of the first dynamic characteristic calculation unit of an axis with a late response of the motor-angle control unit is set to be shorter than a phase delay of the first dynamic characteristic calculation unit of an axis with an early response of the motor-angle control unit.

3. The elastic-deformation-compensation control device for the articulated robot according to claim 1 ,
wherein a feedback control dynamic characteristic from the motor-angle target value θmd to an actual motor angle θm in a state without an axial force among the respective axes is calculated based on a parameter including at least one of a position feedback gain and a speed feedback gain, and
wherein the cutoff frequency in the second dynamic characteristic calculation unit is set to be lower than the cutoff frequency in the first dynamic characteristic calculation unit, and the characteristic of the first dynamic characteristic calculation unit is given to correspond to a characteristic obtained by dividing the characteristic in the second dynamic characteristic calculation unit by the feedback control dynamic characteristic.

4. The elastic-deformation-compensation control device for the articulated robot according to claim 2 ,
wherein a feedback control dynamic characteristic from the motor-angle target value θmd to an actual motor angle θm in a state without an axial force among the respective axes is calculated based on a parameter including at least one of a position feedback gain and a speed feedback gain, and
wherein the cutoff frequency in the second dynamic characteristic calculation unit is set to be lower than the cutoff frequency in the first dynamic characteristic calculation unit, and the characteristic of the first dynamic characteristic calculation unit is given to correspond to a characteristic obtained by dividing the characteristic in the second dynamic characteristic calculation unit by the feedback control dynamic characteristic.

5. The elastic-deformation-compensation control device for the articulated robot according to claim 3 , wherein, when a current control characteristic of the motor-current control unit is considered, the characteristic of the first dynamic characteristic calculation unit is given to correspond to a characteristic obtained by dividing the characteristic in the second dynamic characteristic calculation unit by the feedback control dynamic characteristic and multiplying the divided value by the current control characteristic.

6. The elastic-deformation-compensation control device for the articulated robot according to claim 4 , wherein, when a current control characteristic of the motor-current control unit is considered, the characteristic of the first dynamic characteristic calculation unit is given to correspond to a characteristic obtained by dividing the characteristic in the second dynamic characteristic calculation unit by the feedback control dynamic characteristic and multiplying the divided value by the current control characteristic.

7. The elastic-deformation-compensation control device for the articulated robot according to claim 1 ,
wherein, if a calculation period in the motor-angle-command-value calculation unit is later than a control period in the motor-angle control unit,
in the motor-angle-command-value calculation unit, a phase difference between an axial force torque calculation value or an elastic-deformation amount calculation value and a joint-angle command value is corrected, and a motor-angle command value is calculated from the axial force torque calculation value or elastic-deformation amount calculation value after the phase correction and the joint-angle command value after the phase correction.

8. An elastic-deformation-compensation control method for an articulated robot including a motor and an arm being coupled through an elastically deformable reduction gear in the articulated robot, a tool being attached to the articulated robot, and a plurality of joint axes each being driven by the motor to cause the tool to perform a desirable operation, the elastic-deformation-compensation control method comprising:
a joint-angle-command-value calculation step of calculating a joint-angle command value θlc of each of the joint axes for providing the desirable operation of the tool, and outputting the joint-angle command value θlc;
an axial force torque calculation step of calculating an axial force torque fc generated when an operation is made according to the joint-angle command value θlc and acting on each of the joint axes, from the joint-angle command value θlc based on a model of dynamics, and outputting the axial force torque fc;
a motor-angle-command-value calculation step of calculating a motor-angle command value θmc from the joint-angle command value θlc and the axial force torque fc based on a parameter including a stiffness parameter of the joint axis, and outputting the motor-angle command value θmc;
a first dynamic characteristic calculation step of having a high-frequency cutoff characteristic having a cutoff frequency being lower than a natural resonance frequency of the articulated robot, executing filtering processing on the motor-angle command value θmc, and outputting a processed motor-angle target value θmd;
a motor-angle control step of receiving the motor-angle target value θmd inp

Assignees

• Kobe Steel Ltd
• Kobe Steel Ltd

Inventors

• Nishida Yoshiharu
• Wada Takashi
• Inoue Yoshihide
• Inada Shuichi

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