Control device for motor drive device, control device for multi-axial motor, and control method for motor drive device

• US 10,029,366 B2
• Filed: 11/16/2015
• Issued: 07/24/2018
• Est. Priority Date: 11/21/2014
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Nakajima, Yohji
• Primary Examiner(s): Sample, Jonathan L
• Application Number:
  US14/942,711
• Publication Number:
  US 20160144508A1
• Time in Patent Office: 981 Days
• Field of Search: 700245-264, 31856811, 901 2, 901 9, 901 10, 901 14, 901 46
• CPC Class Codes: B25J 9/126 Rotary actuators
• CPC Class Codes: B25J 9/1633 compliant, force, torque control, e.g. combined with position control
• CPC Class Codes: G05B 2219/37344 Torque, thrust, twist, machining force measurement
• CPC Class Codes: G05B 2219/39186 Flexible joint
• CPC Class Codes: G05B 2219/41372 Force estimator using disturbance estimator observer
• CPC Class Codes: G05B 2219/41428 Feedforward of position and speed
• CPC Class Codes: Y10S 901/09 Closed loop, sensor feedback controls arm movement

Abstract

Motion control of a robot arm is performed via a reducer connected to a motor. A controller thereof includes a thrust control unit that generates motor position command value based on an input thrust command value, and a motor control unit that generates a current value based on the motor position command value. The motor control unit feeds back a motor position detected by a motor encoder, and the thrust control unit feeds back thrust detected by a thrust meter. The feedback from the motor control unit suppresses vibration phenomena at the reducer, and the feedback from the thrust control unit suppresses transmission error, thereby enabling motion control of the arm with rapidity and precision.

Claims

1. A motor drive device configured to perform motion control of a moving member via a transmission mechanism connected to a motor, the motor drive device comprising:

a thrust control unit configured to generate a position command value for the motor based on an input thrust command value; and

a motor control unit configured to generate a current value to control the motor based on the position command value for the motor,

wherein

the motor control unit executes a first feedback control according to detection results of a motor position detecting unit configured to detect a position of an output member that outputs rotation of the motor, and

the thrust control unit executes a second feedback control according to detection results of a thrust detecting unit configured to detect thrust occurring at the moving member.

2. The motor drive device according to claim 1,

wherein the motor control unit includes

a motor position control unit configured to generate a speed command value for the motor, based on the position command value for the motor generated by the thrust control unit,

a motor speed control unit configured to generate the thrust command value for the motor based on the speed command value for the motor generated by the motor position control unit, and

a current control unit configured to generate the current value based on the thrust command value for the motor generated by the speed control unit,

wherein detection results from the motor position detecting unit are at least one of

the detected position of the output member of the motor,

speed of the output member of the motor obtained by differentiation of the detected position of the output member, and

acceleration of the output member of the motor obtained by second order differentiation of the detected position of the output member,

and wherein at least one of

feedback control by the motor position control unit in accordance with the position of the output member of the motor,

feedback control by the motor speed control unit in accordance with the speed of the output member of the motor, and

feedback control by the current control unit in accordance with acceleration of the output member of the motor,

is performed as the first feedback control.

3. The motor drive device according to claim 1, further comprising:

a motor feed-forward (FF) control unit configured to generate a feed-forward value to perform feed-forward control of the motor control unit, in accordance with the position command value for the motor generated by the thrust control unit.

4. The motor drive device according to claim 3,

wherein the motor FF control unit generates the feed-forward value using an ideal model where the motor control unit has been modeled.

5. The motor drive device according to claim 4,

wherein the ideal model includes

an inertia virtual model where inertia of the motor has been modeled, and

a circuit virtual model where a feeder circuit of the motor has been modeled with a predetermined control gain having been set.

6. The motor drive device according to claim 1, further comprising:

a dynamics model control unit configured to generate a prediction value of dynamic thrust, from the externally input position command value for the moving member, by a dynamics model where the motor drive device has been modeled according to dynamics.

7. The motor drive device according to claim 6,

wherein the thrust control unit executes feed-forward control in accordance with the prediction value of dynamic thrust.

8. The motor drive device according to claim 6, further comprising:

a twist amount control unit configured to generate a prediction value of a twist amount of the motor drive device from the prediction value of dynamic thrust, based on rigidity of the motor drive device.

9. The motor drive device according to claim 1, further comprising:

a drive device control unit configured to generate the thrust command value to be input to the thrust control unit, based on the externally input position command value for the moving member,

wherein the drive device control unit executes a third feedback control in accordance with detection results from a moving member position detecting unit configured to detect the position of the moving member.

10. The motor drive device according to claim 9,

wherein the drive device control unit includes

a moving member position control unit configured to generate a speed command value for the moving member, based on the externally input position command value for the moving member, and

a moving member speed control unit configured to generate a thrust command value for the moving member, based on the speed command value for the moving member generated by the moving member position control unit, and

wherein detection results from the moving member position detecting unit are at least one of

the detected position of the moving member, and

speed of the moving member obtained by differentiation of the detected position of the moving member,

and wherein at least one of

feedback control by the moving member position control unit in accordance with the position of the moving member, and

feedback control by the moving member speed control unit in accordance with the speed of the moving member,

is performed as the third feedback control.

11. The motor drive device according to claim 9, further comprising:

a drive device FF control unit configured to generate a feed-forward value for feed-forward control of the drive device control unit, in accordance with the externally input position command value for the moving member.

12. The motor drive device according to claim 11,

wherein the drive device FF control unit generates the feed-forward value by an ideal model where the motor drive device has been modeled.

13. The motor drive device according to claim 9, further comprising:

a monitoring control unit configured to generate thrust occurring at the moving member due to disturbance, based on the detection results from the thrust detecting unit and the detection results from the moving member position detecting unit,

wherein the thrust control unit executes a fourth feedback control in accordance with the thrust occurring due to disturbance.

14. A robot device having a plurality of arms driven via a plurality of joints, one joint of the plurality of joints that drives one arm of the plurality of arms comprising:

a reducer connected to an output shaft of a motor, the reducer including a driving flange;

a thrust meter configured to obtain thrust transmitted from the reducer to the one arm, the thrust meter being connected to the driving flange of the reducer and the one arm;

a device encoder configured to obtain the position of the one arm, the device encoder being coupled to the one arm or the driving flange of the reducer; and

a motor encoder configured to obtain a rotational position of the output shaft of the motor.

15. A robot device having a plurality of arms driven via a plurality of joints, one joint of the plurality of joints that drives one arm of the plurality of arms comprising:

a reducer;

a thrust meter;

a device encoder; and

a motor encoder configured to obtain a rotational position of an output shaft of a motor,

wherein a high-speed rotational shaft of the reducer is connected to the output shaft of the motor, and the reducer includes a driving flange,

wherein the thrust meter is connected to the driving flange of the reducer and the one arm, and

wherein the device encoder is connected to the arm and the high-speed rotational shaft of the reducer.