ROTATION ANGLE DETECTION APPARATUS HAVING FUNCTION OF DETECTING ENTRY OF FOREIGN SUBSTANCE BASED ON FREQUENCY CHARACTERISTIC OF SIGNALS

• US 20170059366A1
• Filed: 08/29/2016
• Published: 03/02/2017
• Est. Priority Date: 08/31/2015
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: Nishioka, Akira, Odaka, Shunichi, Imai, Keisuke
• Granted Patent: US 10,066,971 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01D 5/24461 by redundancy or plausibility
• CPC Class Codes: G01D 5/24471 Error correction
• CPC Class Codes: G01D 5/34715 Scale reading or illumination devices
• CPC Class Codes: G01D 5/3473 Circular or rotary encoders

Abstract

A rotation angle detection apparatus includes a rotator having a track unit to detect the rotation angle of a rotation axis; a detection unit disposed in correspondence with the track unit; a rotation angle calculation unit for calculating the rotation angle of the rotation axis based on signals generated by the detection unit; a rotation speed calculation unit for calculating the rotation speed of the rotation axis; and an abnormality detection unit for detecting an abnormality. The abnormality detection unit includes a frequency analyzing unit for calculating the frequency characteristic of the signals; a storage unit for storing the number of the signals per revolution of the rotator; a signal frequency calculation unit for calculating a signal frequency; and a determination unit for detecting the abnormality in the detection apparatus, when the frequency characteristic includes a component of a higher order than the signal frequency.

Claims

1. A rotation angle detection apparatus comprising:

a rotator having a track unit to detect the rotation angle of a rotation axis;

a detection unit disposed in correspondence with the track unit;

a rotation angle calculation unit for calculating the rotation angle of the rotation axis based on signals generated by the detection unit;

a rotation speed calculation unit for calculating the rotation speed of the rotation axis based on the signals; and

an abnormality detection unit for detecting an abnormality based on the signals, wherein

the abnormality detection unit includes;

a frequency analyzing unit for calculating the frequency characteristic of the signals;

a storage unit for storing the number of the signals generated from the track unit per revolution of the rotator;

a signal frequency calculation unit for calculating a signal frequency that is the product of the number of the signals stored in the storage unit and the rotation speed calculated by the rotation speed calculation unit; and

a determination unit for detecting the abnormality, when the frequency characteristic includes a component of a higher order than the signal frequency.