Motor control system

• US 20040000890A1
• Filed: 06/16/2003
• Published: 01/01/2004
• Est. Priority Date: 06/28/2002
• Status: Active Grant

• Current Assignee: Fanuc Ltd (Fanuc Corporation)
• Original Assignee: Fanuc Ltd (Fanuc Corporation)
• Inventors: Iwashita, Yasusuke, Kawamura, Hiroyuki, Genma, Eiji
• Granted Patent: US 7,248,014 B2
• Time in Patent Office: Days
• US Class Current: 318/638
• CPC Class Codes: B30B 1/103 operated by screw means
• CPC Class Codes: G05B 19/19 characterised by positioning or contouring control systems, e.g. to control position from one programmed point to another or to control movement along a programmed continuous path

Abstract

A motor control system capable of securing stability and rapidity of motion even in a machine where the stability varies in accordance with a position of a driven member. The driven member and a motor for driving the driven member are operatively connected through a transmission mechanism including a nonlinear element such that a rate of change of the position of the driven member with respect to the position of the motor varies in dependence on the position of the motor. Optimum values of multiplier factors of operation constants with respect to the position of the driven member or the rotational position of the motor for the position control and the velocity control are stored in a data table. The values of the multiplier factors of the operation constants for a present position of the driven member or a present position of the motor are determined using the data table and the determined values of the multiplier factors are multiplied by reference operation constants to update the operation constants. The position and/or velocity control processing is performed using the updated optimum operation constants in accordance with the present position of the driven member or the present rotational position of the motor.

Claims

1. A motor control system for controlling a servomotor for driving a driven member through a transmission mechanism for mechanically connecting the servomotor and the driven member, comprising:

a servo controller having a position control section for performing position control processing for feedback controlling a position of the driven member, and a velocity control section for performing velocity control processing for feedback controlling a velocity of the driven member; and

operation constant varying means for varying operation constants for the position control processing to be performed by the position control section and/or the velocity control processing to be performed by the velocity control section in accordance with a present position of the driven member.

2. A motor control system according to claim 1, further comprising a host controller for commanding said servo controller, wherein the present position of the driven member is determined based on a position command issued from said host controller or a position feedback signal from a detector for detecting a position of the driven member.

3. A motor control system according to claim 1, wherein said operation constant varying means comprises storage means for storing data representing relation between the position of the driven member and the operation constants, and determines values of the operation constants for the present position of the driven member using the data table.

4. A motor control system according to claim 3, further comprising a host controller for commanding the servo controller, wherein said storage means is provided in said host controller.

5. A motor control system according to claim 1, said operation constant varying means comprises storage means for storing an mathematical equation representing relation between the position of the driven member and the operation constants, and determines values of the operation constants for the present position of the driven member using the mathematical equation.

6. A motor control system according to claim 5, further comprising a host controller for commanding said servo controller, wherein said storage means is provided in said host controller.

7. A motor control system according to claim 1, wherein said operation constant varying means starts varying of the operation constants upon receipt of a signal from an external device or a signal produced by internal processing in the motor control system.

8. A motor control system according to claim 7, further comprising a host controller for commanding said servo controller, wherein the determination of values of the operation constants is performed by said host controller.

9. A motor control system according to claim 1, wherein said operation constant varying means starts varying of the operation constants upon receipt of a program command.

10. A motor control system according to claim 9, further comprising a host controller for commanding said servo controller, wherein the determination of values of the operation constants is performed by said host controller.

11. A motor control system according to claim 1, wherein said operation constant varying means determines values of the operation constants to be varied smoothly.

12. A motor control system according to claim 11, further comprising a host controller for issuing commands to the servo controller, wherein the varying of the operation constant is performed by said host controller.

13. A motor control system according to claim 1, wherein the operation constants for the position control section and/or the velocity control section are set to upper limit values until an initial position of the driven member is established after a power supply to the motor control system is turned on.

14. A motor control system according to claim 1, wherein the driven member comprises a mold of an electric press machine for performing a press work, and the operation constants have different values at a position where the press work is performed and at a position where the press work is not performed.

15. A motor control system according to claim 1, wherein said operation constant varying means varies the operation constants in accordance with a present rotational position of the servomotor mechanically connected with the driven member by the transmission mechanism.

16. A motor control system according to claim 15, further comprising a host controller for commanding said servo controller, wherein the present rotational position of the servomotor is determined based on a position command issued from said host controller or a position feedback signal from a detector for detecting a rotational position of the servomotor.

17. A motor control system according to claim 15, wherein said operation constant varying means stores a data table representing relation between the rotational position of the servomotor and the operation constant, and determines values of the operation constants for the present rotational position of the servomotor using the data table.

18. A motor control system according to claim 17, further comprising a host controller for issuing a position command to the servo controller, wherein said data table is provided in said host controller.

19. A motor control system according to claim 15, said operation constant varying means stores an mathematical equation representing relation between the rotational position of the servomotor and values of the operation constants, and determines values of the operation constants for the present rotational position of the servomotor using the mathematical equation.

20. A motor control system according to claim 19, further comprising a host controller for issuing a position command to the servo controller, wherein the determination of values of the operation constants for the present rotational position of the servomotor is performed by said host controller.