Positional control of a controlled object during movement initiation

• US 20030201746A1
• Filed: 04/28/2003
• Published: 10/30/2003
• Est. Priority Date: 04/30/2002
• Status: Active Grant

• Current Assignee: Okuma Corporation
• Original Assignee: Okuma Corporation
• Inventors: Eguchi, Satoshi
• Granted Patent: US 6,861,816 B2
• Time in Patent Office: Days
• US Class Current: 318/567
• CPC Class Codes: G05B 19/404 characterised by control arrangements for compensation, e.g. for backlash, overshoot, tool offset, tool wear, temperature, machine construction errors, load, inertia G05B19/19, G05B19/41 take precedence
• CPC Class Codes: G05B 2219/41154 Friction, compensation for friction

Abstract

In a positional control device for controlling a position of a controlled object using a motor, when generating a torque command value τc which serves as the command value for the servo motor of the controlled object system (112), a friction compensation value for use when the controlled object initiates a movement is calculated based on a velocity command value V and a torque command value τc determined according to a positional command value Xo supplied from a superordinate device. More specifically, an initial friction compensation calculating section calculates a torque compensation amount Vsfc1 corresponding to a difference between torque being generated during the standstill state and torque required by the controlled object to initiate the movement, and a torque compensation amount Vsfc2 corresponding to an amount of change in friction that occurs during a transition from static friction to kinetic friction in a period immediately before and after initiation of the movement. Vsfc1 and Vsfc2 are then used to calculate compensated values of the torque command value τc. Positional tracking deviation generated due to friction during a movement initiation can thereby be reduced, regardless of operational conditions during the standstill state or of the movement direction and velocity effected thereafter.

Claims

1. A positional control device for controlling a position of a controlled object by generating a command for a drive motor of a controlled object system in accordance with a positional command value supplied from a superordinate device, comprising:

means for calculating, using the positional command value, a velocity command value which serves as a command concerning velocity of the controlled object; and

means for calculating, using the positional command value and the velocity command value, a torque command value which serves as a command concerning torque generated by the drive device;

wherein

the means for calculating the torque command value includes means for calculating a torque compensation amount concerning friction occurring when the controlled object initiates a movement, the means for calculating the torque compensation amount being used when calculating the torque command value; and

the means for calculating the torque compensation amount calculates, based on the velocity command value and the torque command value, a torque compensation amount corresponding to a difference between torque being generated during a standstill state and torque required by the controlled object to initiate the movement.

4. A positional control device as defined in claim 1, wherein the torque compensation amount is a fixed value determined according to the sign of the velocity command value.

7. A positional control device as defined in claim 1, wherein the torque compensation amount is a value varied corresponding to a change in the velocity command value.

2. A positional control device for controlling a position of a controlled object by generating a command for a drive motor of a controlled object system in accordance with a positional command value supplied from a superordinate device, comprising:

means for calculating, using the positional command value, a velocity command value which serves as a command concerning velocity of the controlled object; and

means for calculating, using the positional command value and the velocity command value, a torque command value which serves as a command concerning torque generated by the drive device;

wherein

the means for calculating the torque command value includes means for calculating a torque compensation amount concerning friction that occurs when the controlled object initiates a movement, the means for calculating the torque compensation amount being used when calculating the torque command value; and

the means for calculating the torque compensation amount calculates, based on the velocity command value and the torque command value, a torque compensation amount corresponding to an amount of change in friction that occurs during a transition from static friction to kinetic friction in a period immediately before and after initiation of the movement.

5. A positional control device as defined in claim 2, wherein the torque compensation amount is a fixed value determined according to the sign of the velocity command value.

8. A positional control device as defined in claim 2, wherein the torque compensation amount is a value varied corresponding to a change in the velocity command value.

3. A positional control device for controlling a position of a controlled object by generating a command for a drive motor of a controlled object system in accordance with a positional command value supplied from a superordinate device, comprising:

means for calculating, using the positional command value, a velocity command value which serves as a command concerning velocity of the controlled object; and

means for calculating, using the positional command value and the velocity command value, a torque command value which serves as a command concerning torque generated by the drive device;

wherein

the means for calculating the torque command value includes means for calculating a torque compensation amount concerning friction that occurs when the controlled object initiates a movement, the means for calculating the torque compensation amount being used when calculating the torque command value; and

the means for calculating the torque compensation amount calculates, based on the velocity command value and the torque command value, a first torque compensation amount corresponding to a difference between torque being generated during a standstill state and torque required by the controlled object to initiate the movement, and a second torque compensation amount corresponding to an amount of change in friction that occurs during a transition from static friction to kinetic friction in a period immediately before and after initiation of the movement.

6. A positional control device as defined in claim 3, wherein the torque compensation amount is a fixed value determined according to the sign of the velocity command value.

9. A positional control device as defined in claim 3, wherein the torque compensation amount is a value varied corresponding to a change in the velocity command value.

10. A positional control method for controlling a position of a controlled object by generating a command for a drive motor of a controlled object system in accordance with a positional command value supplied from a superordinate device, comprising:

calculating, using the positional command value, a velocity command value which serves as a command concerning velocity of the controlled object; and

calculating, using the positional command value and the velocity command value, a torque command value which serves as a command concerning torque generated by the drive device;

wherein

the calculation of the torque command value includes calculating a torque compensation amount concerning friction that occurs when the controlled object initiates a movement; and

the calculation of the torque compensation amount includes calculating, based on the velocity command value and the torque command value, a torque compensation amount corresponding to a difference between torque being generated during a standstill state and torque required by the controlled object to initiate the movement.

13. A positional control method as defined in claim 10, wherein the torque compensation amount is a fixed value determined according to the sign of the velocity command value.

16. A positional control method as defined in claim 10, wherein the torque compensation amount is a value varied corresponding to a change in the velocity command value.

11. A positional control method for controlling a position of a controlled object by generating a command for a drive motor of a controlled object system in accordance with a positional command value supplied from a superordinate device, comprising:

calculating, using the positional command value, a velocity command value which serves as a command concerning velocity of the controlled object; and

calculating, using the positional command value and the velocity command value, a torque command value which serves as a command concerning torque generated by the drive device;

wherein

the calculation of the torque command value includes calculating a torque compensation amount concerning friction that occurs when the controlled object initiates a movement; and

the calculation of the torque compensation amount includes calculating, based on the velocity command value and the torque command value, a torque compensation amount corresponding to an amount of change in friction that occurs during a transition from static friction to kinetic friction in a period immediately before and after initiation of the movement.

14. A positional control method as defined in claim 11, wherein the torque compensation amount is a fixed value determined according to the sign of the velocity command value.

17. A positional control method as defined in claim 11, wherein the torque compensation amount is a value varied corresponding to a change in the velocity command value.

12. A positional control method for controlling a position of a controlled object by generating a command for a drive motor of a controlled object system in accordance with a positional command value supplied from a superordinate device, comprising:

calculating, using the positional command value, a velocity command value which serves as a command concerning velocity of the controlled object; and

calculating, using the positional command value and the velocity command value, a torque command value which serves as a command concerning torque generated by the drive device;

wherein

the calculation of the torque command value includes calculating a torque compensation amount concerning friction that occurs when the controlled object initiates a movement; and

the calculation of the torque compensation amount includes calculating, based on the velocity command value and the torque command value, a first torque compensation amount corresponding to a difference between torque being generated during a standstill state and torque required by the controlled object to initiate the movement, and a second torque compensation amount corresponding to an amount of change in friction that occurs during a transition from static friction to kinetic friction in a period immediately before and after initiation of the movement.

15. A positional control method as defined in claim 12, wherein the torque compensation amount is a fixed value determined according to the sign of the velocity command value.

18. A positional control method as defined in claim 12, wherein the torque compensation amount is a value varied corresponding to a change in the velocity command value.