Servo motor controller

Patent metadata

Field	Value
Publication number	US-11886205-B2
Application number	US-202016924599-A
Country	US
Kind code	B2
Filing date	Jul 9, 2020
Priority date	Jul 10, 2019
Publication date	Jan 30, 2024
Grant date	Jan 30, 2024

Abstract

A servo motor controller capable of eliminating inconvenience that the position of a shaft or the like of a servo motor is detected or set erroneously due to influence of noise or the like is provided. A servo motor controller that detects Z-phase signals of an incremental-type encoder that detects rotation of a servo motor to perform driving control of the servo motor includes: a position detection unit that detects a reference position of a rotating shaft of the servo motor on the basis of the Z-phase signal of the encoder; a signal interval detection unit that measures intervals of a plurality of detected Z-phase signals; and an abnormality determination unit that determines that the Z-phase signal is abnormal when the interval measured by the signal interval detection unit is equal to or larger than a prescribed threshold.

First claim

What is claimed is:

1. A servo motor controller that detects Z-phase signals of an incremental-type encoder that detects rotation of a servo motor to perform driving control of the servo motor, comprising:
a position detection unit that detects a reference position of a rotating shaft of the servo motor on the basis of the Z-phase signal of the encoder;
a signal interval detection unit that measures intervals of a plurality of detected Z-phase signals;
an abnormality determination unit that determines that the Z-phase signal is abnormal when the interval measured by the signal interval detection unit is equal to or larger than a prescribed threshold; and
a speed changing unit that changes a speed of the servo motor, wherein
the speed changing unit changes the speed of the servo motor when the abnormality determination unit determines that the Z-phase signal is abnormal.

2. The servo motor controller according to claim 1 , wherein the signal interval detection unit performs measurement again after the speed of the servo motor is changed.

3. The servo motor controller according to claim 2 , further comprising: an abnormality notifying unit that notifies a host controller of an abnormality when the interval of the Z-phase signals is equal to or larger than a prescribed threshold with respect to a latest detection value or an average value of detection values for a prescribed period at a state where the speed of the servo motor was changed to a prescribed speed.

4. A servo motor controller that detects Z-phase signals of an incremental-type encoder that detects rotation of a servo motor to perform driving control of the servo motor, comprising:
a position detection unit that detects a reference position of a rotating shaft of the servo motor on the basis of the Z-phase signal of the encoder;
a signal interval detection unit that measures intervals of a plurality of detected Z-phase signals;
an abnormality determination unit that determines that the Z-phase signal is abnormal when the interval measured by the signal interval detection unit is equal to or larger than a prescribed threshold; and
an abnormality notifying unit that notifies a host controller of an abnormality when the interval of the Z-phase signals is equal to or larger than a prescribed threshold with respect to a latest detection value or an average value of detection values for a prescribed period at a state where a speed of the servo motor was changed to a prescribed speed.

Assignees

• Fanuc Corp

Inventors

• Tajima Daisuke
• Morita Yuuki
• Okita Tadashi

Classifications

• G05D13/62 Primary

  characterised by the use of electric means, e.g. use of a tachometric dynamo, use of a transducer converting an electric value into a displacement {(electric motor control H02P)} · CPC title

• G05D3/125

  using discrete position sensor · CPC title

• G01D5/12

  using electric or magnetic means (G01D5/06 takes precedence) · CPC title

• G01D5/3473

  Circular or rotary encoders · CPC title

• H02P6/16 Primary

  Circuit arrangements for detecting position · CPC title