# US 5,015,935 A · Servo-control apparatus

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- Number: US 5,015,935 A
- Document ID: US5015935A
- Status: Granted
- Kind: A
- Application number: 07/490,564
- Filed: 1990-05-21
- Granted: 1991-05-14
- Earliest claimed: 1988-09-30
- Assignees: Fanuc Corporation
- Inventors: Yasusuke Iwashita
- Web page: https://patentgrep.com/patent/US5015935A

## CPC

- 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)
- G05B 2219/41078: Backlash acceleration compensation when inversing, reversing direction
- G05B 2219/41082: Timer, speed integration to control duration of backlash correction
- G05B 2219/41084: Compensation speed axis with changing, reversing direction, quadrant circle
- G05B 2219/41085: Compensation pulses on inversion of direction of rotation, movement
- G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G)

## Abstract

A servo-control apparatus generates a velocity command by applying backlash correction data to position error data when direction of rotation of a servomotor is reversed, and performs a backlash correction by adding an amount of backlash acceleration to the velocity command. In order to terminate backlash acceleration at an appropriate time, velocity feedback pulses are accumulated by a counter from the moment acceleration control starts, and the accumulated value of velocity feedback is monitored by an acceleration-stop instructing unit. When the accumulated value attains a predetermined value, an acceleration output unit is caused to halt the output of the amount of backlash acceleration to complete control of backlash acceleration.

## Claims

### Claim 1

A servo-control apparatus for generating a velocity command by applying backlash correction data to position error data when direction of rotation of a servomotor is reversed, and performing a backlash correction by adding an amount of backlash acceleration to said velocity command, comprising:
means for detecting reversal of the direction of rotation of the servomotor;
means for detecting that an accumulated value of velocity feedback has become equal to a predetermined value after backlash acceleration is started; and
means for outputting the amount of backlash acceleration when direction of rotation of a servomotor is reversed, and terminating output of the amount of backlash acceleration when the accumulated value of velocity feedback becomes equal to the predetermined value.

### Claim 2 (depends on 1)

A servo-control apparatus according to claim 1, wherein said predetermined value is two.

### Claim 3 (depends on 1)

A servo-control apparatus according to claim 1, wherein said predetermined value is three.

### Claim 4

A servo-control method for generating a velocity command by applying backlash correction data to position error data when direction of rotation of a servomotor is reversed, and performing a backlash correction by adding an amount of backlash acceleration to said velocity command, said method comprising the steps of:
detecting reversal of the direction of rotation of the servomotor;
detecting that an accumulated value of velocity feedback has become equal to a predetermined value after backlash acceleration is started;
outputting the amount of backlash acceleration when direction of rotation of a servomotor is reversed; and
terminating output of the amount of backlash acceleration, when the accumulated value of velocity feedback becomes equal to the predetermined value.