# US 5,101,146 A · Device for correcting mechanical errors in NC machine

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- Number: US 5,101,146 A
- Document ID: US5101146A
- Status: Granted
- Kind: A
- Application number: 07/563,390
- Filed: 1990-08-07
- Granted: 1992-03-31
- Earliest claimed: 1989-08-10
- Assignees: Mitsubishi Denki Kabushiki Kaisha
- Inventors: Takeo Teshima
- Web page: https://patentgrep.com/patent/US5101146A

## 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 2219/41036: Position error in memory, lookup table for correction actual position
- G05B 2219/41042: Switch between rapid, quick feed and cut, slow workspeed feed backlash
- G05B 2219/41059: Play in gear, screw backlash, lost motion
- 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 device for correcting mechanical errors in an NC machine, by which an incremental amount of movement of a control shaft is corrected for mechanical errors such as backlash and lost motion and the value thus corrected is transmitted to a servo control section. The incremental amount of movement of the control shaft calculated every sampling is subjected to a speed adjustment. A position command value is calculated by progressively adding a command value of the incremental amount of movement subjected to a speed adjustment. A position command correction value is obtained by adding a predetermined amount of correction for mechanical error to the position command value. A corrected incremental amount of movement is calculated by substracting a previously calculated position command correction value, and is transmitted to the servo control section.

## Claims

### Claim 1

A device for correcting mechanical errors in an NC machine, by which an incremental amount of movement of a control shaft is corrected based on an amount of correction of mechanical errors of said machine, and a corrected value is transmitted to a servo control section, said device comprising:
means for adjusting the incremental amount of movement of the control shaft calculated during each of a plurality of samplings by a speed adjustment value;
means for calculating a position command value by progressively adding a value of said incremental amount of movement subjected to said speed adjustment value;
means for obtaining a position command correction value by adding a predetermined amount of correction for mechanical error to said position command value calculated by said calculating means; and
means for calculating a corrected incremental amount of movement by subtracting a previously calculated position command correction value from a currently calculated position command correction value, both calculated by said calculating means, and means for transmitting said corrected incremental amount of movement to said servo control section.

### Claim 2 (depends on 1)

A device as claimed in claim 1, wherein said calculating means comprises an adder and an integrator.

### Claim 3 (depends on 1)

A device as claimed in claim 1, further comprising a memory table for storing the mechanical error correction amount.