Servo control system with position compensation function for driven member

• US 10,247,301 B2
• Filed: 11/29/2013
• Issued: 04/02/2019
• Est. Priority Date: 11/30/2012
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: Iwashita, Yasusuke, Takayama, Kenichi, Ikai, Satoshi
• Primary Examiner(s): Dhakal, Bickey
• Assistant Examiner(s): Laughlin, Charles S
• Application Number:
  US14/093,372
• Publication Number:
  US 20140156080A1
• Time in Patent Office: 1,950 Days
• 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 table configured to be driven by the servo motor;

a coupling mechanism coupled with the servo motor and the table, the coupling mechanism configured to use the servo motor as a power source to generate a table drive torque acting on the table at a coupling part of the table and the coupling mechanism; and

a motor control part configured to control the servo motor, wherein

the motor control part comprises

a position command generating part configured to generate a position command value of the table,

a force estimating part configured to estimate the table drive torque acting on the table at the coupling part,

a compensating part configured to compensate the position command value generated by the position command generating part based on the table drive torque estimated by the force estimating part,

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

a disturbance torque estimating part configured to estimate a total disturbance torque occurring due to a disturbance acting on the servo motor, the coupling mechanism, and the table,

an acceleration/deceleration torque calculating part configured to

calculate angular acceleration of the servo motor based on an angular position of the servo motor or a detected value of a rotational speed of the servo motor, and

calculate an acceleration/deceleration torque required for acceleration or deceleration of the table based on the calculated angular acceleration, and

a disturbance torque calculating part configured to calculate a disturbance torque occurring due to a disturbance acting on the servo motor and the coupling mechanism based on the detected value of the rotational speed of the servo motor,

wherein

the force estimating part is configured to estimate the table drive torque by subtracting the disturbance torque calculated by the disturbance torque calculating part from a sum of

the total disturbance torque estimated by the disturbance torque estimating part, and

the acceleration/deceleration torque calculated by the acceleration/deceleration torque calculating part.

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

the compensating part is configured to multiply a predetermined constant with the table drive torque estimated by the force estimating part to compensate the position command value.

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

the compensating part comprises a compensation limiting part configured to limit an amount of compensation of the position command value.

4. The servo control system according to claim 1, further comprising

a position detecting part configured to detect the angular position of the servo motor, and

a speed detecting part configured to detect the rotational speed of the servo motor, wherein

the motor control part further comprises

a speed command generating part configured to generate 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 configured to generate 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 is configured to estimate 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.

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

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

6. A servo control system, comprising:

a servo motor;

a driven member configured to be driven by the servo motor;

a coupling mechanism coupled with the servo motor and the driven member, the coupling mechanism configured to use 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 configured to control the servo motor,

wherein

the motor control part comprises

a position command generating part configured to generate a position command value of the driven member,

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

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

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

a disturbance torque estimating part configured to estimate a total disturbance torque occurring due to a disturbance acting on the servo motor, the coupling mechanism, and the driven member,

an acceleration/deceleration torque calculating part configured to

calculate angular acceleration of the servo motor based on an angular position of the servo motor or a detected value of a rotational speed of the servo motor, and

calculate an acceleration/deceleration torque required for acceleration or deceleration of the driven member based on the calculated angular acceleration, and

a disturbance torque calculating part configured to calculate a disturbance torque occurring due to the disturbance acting on the servo motor and the coupling mechanism based on the detected value of the rotational speed of the servo motor, and

the force estimating part is configured to estimate the drive force by subtracting the disturbance torque calculated by the disturbance torque calculating part from a sum of

the total disturbance torque estimated by the disturbance torque estimating part, and

the acceleration/deceleration torque calculated by the acceleration/deceleration torque calculating part.