Motor control apparatus for compensating reverse delay of motor

• US 9,760,082 B2
• Filed: 10/06/2015
• Issued: 09/12/2017
• Est. Priority Date: 10/07/2014
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: Ikai, Satoshi, Nakamura, Tsutomu
• Primary Examiner(s): Brown, Michael J
• Application Number:
  US14/875,755
• Publication Number:
  US 20160098031A1
• Time in Patent Office: 707 Days
• Field of Search: 700 95, 700 96, 700114
• CPC Class Codes: G05B 19/291 the positional error is used to control continuously the servomotor according to its magnitude
• 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 2219/41032 Backlash
• CPC Class Codes: G05B 2219/41036 Position error in memory, lookup table for correction actual position
• CPC Class Codes: G05B 2219/41071 Backlash for non orthogonal axis
• CPC Class Codes: G05B 2219/41078 Backlash acceleration compensation when inversing, reversing direction
• CPC Class Codes: G05B 2219/41085 Compensation pulses on inversion of direction of rotation, movement
• CPC Class Codes: G05B 2219/41208 Lookup table for load, motor torque as function of actual position error
• CPC Class Codes: G05B 2219/41209 Lookup table with compensation as function of reference and feedback value
• CPC Class Codes: G05B 2219/41261 Flexible coupling between carriage, slide and actuator, motor
• CPC Class Codes: G05B 2219/41394 Estimate speed and position error from motor current, torque
• CPC Class Codes: G05B 2219/41426 Feedforward of torque
• CPC Class Codes: H02P 23/24 Controlling the direction, e.g. clockwise or counterclockwise
• CPC Class Codes: H02P 6/16 Circuit arrangements for detecting position

Abstract

A motor control apparatus includes an error calculation unit which calculates an error between a position of a movable unit and a position of a driven unit, a memory unit which memorizes the error in association with a torque command value as an initial error, and a compensation amountcompensation amount calculation unit which calculates a compensation amountcompensation amount for compensating an elastic deformation amount of an elastic factor between the movable unit and the driven unit. The compensation amountcompensation amount calculation unit calculates the compensation amountcompensation amount based on the initial error held by the memory unit, the torque command value held in association with the initial error, and a torque command value calculated by a torque command calculation unit when a motor rotates reversely.

Claims

1. A motor control apparatus including a movable unit driven by a motor and a driven unit driven by the movable unit, the motor control apparatus comprising:

a torque command calculation unit configured to calculate a torque command value with respect to the motor;

a first position detection unit configured to detect a position of the movable unit;

a second position detection unit configured to detect a position of the driven unit;

an error calculation unit configured to calculate an error between a first position detection value detected by the first position detection unit and a second position detection value detected by the second position detection unit;

a memory unit configured to memorize the error calculated by the error calculation unit in association with the torque command value as an initial error; and

a compensation amount calculation unit configured to calculate a compensation amount for compensating an elastic deformation amount of an elastic factor between the movable unit and the driven unit,

wherein the compensation amount calculation unit calculates the compensation amount based on the initial error held by the memory unit, the torque command value held in association with the initial error, and a torque command value calculated by the torque command calculation unit when the motor rotates reversely.

2. The motor control apparatus according to claim 1, wherein the compensation amount calculation unit calculates a spring constant of the elastic factor from the initial error held by the memory unit and the torque command value held in association with the initial error, and

calculates the compensation amount by subtracting a current error from a value obtained by dividing a torque command value calculated by the torque command calculation unit when the motor rotates reversely by the spring constant.

3. The motor control apparatus according to claim 1, wherein the memory unit memorizes the error and the torque command value as the initial error when the movable unit moves while accelerating or at a constant speed.