SERVO CONTROL SYSTEM WITH POSITION COMPENSATION FUNCTION FOR DRIVEN MEMBER

• US 20140156080A1
• Filed: 11/29/2013
• Published: 06/05/2014
• Est. Priority Date: 11/30/2012
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: IWASHITA, Yasusuke, TAKAYAMA, Kenichi, IKAI, Satoshi
• Granted Patent: US 10,247,301 B2
• Time in Patent Office: Days
• US Class Current: 700/275
• CPC Class Codes: F16H 61/0202 the signals being electric F16H61/04 takes precedence
• 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 2219/41138 Torque compensation
• CPC Class Codes: H02P 1/00 Arrangements for starting electric motors or dynamo-electric converters starting of synchronous motors with electronic commutators except reluctance motors, H02P6/20, H02P6/22; starting dynamo-electric motors rotating step by step H02P8/04; vector control H02P21/00
• CPC Class Codes: H02P 23/00 Arrangements or methods for the control of AC motors characterised by a control method other than vector control

Abstract

A servo control system including a servo motor, a driven member driven, a coupling mechanism coupled with the servo motor and the driven member, and a motor control part controlling the servo motor. The motor control part includes a position command generating part generating a position command value of the driven member, a force estimating part estimating the drive force acting on the driven member, a compensating part compensating the position command value based on the drive force estimated by the force estimating part, and a control signal output part outputting a control signal to the servo motor based on a position command value compensated by the compensating part.

Claims

1. A servo control system comprising:

a servo motor;

a driven member driven by the servo motor;

a coupling mechanism coupled with the servo motor and the driven member, the coupling mechanism using the servo motor as a power source to generate a drive force acting on the driven member at a coupling part of the driven member and the coupling mechanism; and

a motor control part controlling the servo motor, wherein

the motor control part comprises

a position command generating part generating a position command value of the driven member,

a force estimating part estimating the drive force acting on the driven member at the coupling part,

a compensating part compensating the position command value generated by the position command generating part based on the drive force estimated by the force estimating part, and

a control signal output part outputting a control signal to the servo motor based on a position command value compensated by the compensating part.

2. The servo control system according to claim 1, wherein

the motor control part further comprises

a motor torque calculating part calculating a motor torque which the servo motor generates and

a required torque calculating part calculating a required torque required for driving the servo motor and the coupling mechanism, and

the force estimating part estimates the drive force based on the motor torque calculated by the motor torque calculating part and the required torque calculated by the required torque calculating part.

3. The servo control system according to claim 1, wherein

the motor control part further comprises

a motor torque calculating part calculating a motor torque which the servo motor generates,

an acceleration/deceleration torque calculating part calculating an acceleration/deceleration torque required for acceleration and deceleration of the servo motor and the coupling mechanism, and

a disturbance torque calculating part calculating a disturbance torque occurring due to a disturbance acting on the servo motor and the coupling mechanism, and

the force estimating part estimates the drive force based on the motor torque calculated by the motor torque calculating part, the acceleration/deceleration torque calculated by the acceleration/deceleration torque calculating part, and the disturbance torque calculated by the disturbance torque calculating part.

4. The servo control system according to claim 1, wherein

the motor control part further comprises a disturbance torque estimating part estimating an total disturbance torque occurring due to a disturbance acting on the servo motor, the coupling mechanism, and the driven member, and

the force estimating part estimates the drive force based on the total disturbance torque estimated by the disturbance torque estimating part.

5. The servo control system according to claim 4, wherein

the motor control part further comprises an acceleration/deceleration torque calculating part calculating an acceleration/deceleration torque required for acceleration and deceleration of the driven member, and

the force estimating part estimates the drive force based on the total disturbance torque estimated by the disturbance torque estimating part and the acceleration/deceleration torque calculated by the acceleration/deceleration torque calculating part.

6. The servo control system according to claim 4, wherein

the motor control part further comprises

an acceleration/deceleration torque calculating part calculating an acceleration/deceleration torque required for acceleration and deceleration of the driven member and

a disturbance torque calculating part calculating a disturbance torque occurring due to a disturbance acting on the servo motor and the coupling mechanism, and

the force estimating part estimates the drive force based on the total disturbance torque estimated by the disturbance torque estimating part, the acceleration/deceleration torque calculated by the acceleration/deceleration torque calculating part, and the disturbance torque calculated by the disturbance torque calculating part.

7. The servo control system according to claim 1, wherein

the compensating part multiplies a predetermined constant with the drive force estimated by the force estimating part to compensate the position command value.

8. The servo control system according to claim 1, wherein

the compensating part comprises a compensation limiting part limits an amount of compensation of the position command value.

9. The servo control system according to claim 2, further comprising

a position detecting part detecting an angular position of the servo motor, and

a speed detecting part detecting a rotational speed of the servo motor, wherein

the motor control part further comprises

a speed command generating part generating a speed command value of the servo motor based on the position command generated by the position command generating part and the angular position detected by the position detecting part, and

a torque command generating part generating a torque command value of the servo motor based on the speed command value generated by the speed command generating part and the rotational speed detected by the speed detecting part,

wherein the motor torque calculating part calculates the motor torque based on the torque command value generated by the torque command generating part.

10. The servo control system according to claim 2, further comprising a current detecting part detecting a current flowing to the servo motor,

wherein the motor torque calculating part calculates the motor torque based on the current detected by the current detecting part.

11. The servo control system according to claim 4, further comprising

a position detecting part detecting an angular position of the servo motor, and

a speed detecting part detecting a rotational speed of the servo motor, wherein

the motor control part further comprises

a speed command generating part generating a speed command value of the servo motor based on the position command value generated by the position command generating part and the angular position detected by the position detecting part, and

a torque command generating part generating a torque command value of the servo motor based on the speed command value generated by the speed command generating part and the rotational speed detected by the speed detecting part, and

the disturbance torque estimating part estimates the total disturbance torque based on the rotational speed detected by the speed detecting part and the torque command value generated by the torque command generating part.

12. The servo control system according to claim 1, wherein

the coupling mechanism includes at least one of a ball screw, deceleration mechanism, and coupling.