ROTATION ANGLE DETECTOR WHICH CAN DETECT ENTRY OF FOREIGN SUBSTANCES

• US 20160363469A1
• Filed: 06/09/2016
• Published: 12/15/2016
• Est. Priority Date: 06/10/2015
• Status: Active Grant

• Current Assignee: Fanuc Corporation
• Original Assignee: Fanuc Corporation
• Inventors: Nishioka, Akira, Odaka, Shunichi, Imai, Keisuke
• Granted Patent: US 10,527,467 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01D 18/00 Testing or calibrating apparatus or arrangements provided for in groups G01D1/00 - G01D15/00
• CPC Class Codes: G01D 5/12 using electric or magnetic means G01D5/06 takes precedence
• CPC Class Codes: G01D 5/24461 by redundancy or plausibility
• CPC Class Codes: G01D 5/2452 incorporating two or more tracks having an (n, n+1, ...) relationship
• CPC Class Codes: G01D 5/3473 Circular or rotary encoders

Abstract

A rotation angle detector comprises a rotating body including a plurality of track parts, and an abnormality detecting unit for detecting an abnormality based on signals generated in detection units. The detection units generate a first signal based on a first track part and a second signal based on a second track part. The abnormality detecting unit includes a judgement unit for judging an occurrence of an abnormality when the difference between the fluctuation range of the first signal and the fluctuation range of the second signal is larger than a predetermined fluctuation range judgement value.

Claims

1. A rotation angle detector comprising:

a rotating body including a plurality of track parts to detect a rotation angle of a rotary shaft;

detection units arranged in positions which correspond to the track parts; and

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

the rotating body includes a first track part and a second track part,

the detection units generate a first signal based on the first track part and a second signal based on the second track part, and

the abnormality detecting unit includes a fluctuation range calculating unit for calculating a fluctuation range of the first signal and a fluctuation range of the second signal, and a judgement unit for judging an occurrence of an abnormality when a difference between the fluctuation range of the first signal and the fluctuation range of the second signal is larger than a predetermined fluctuation range judgement value.

2. The rotation angle detector according to claim 1, further comprising a phase detecting unit for detecting a phase within one revolution of the rotary shaft, wherein

the abnormality detecting unit detects the phase in which the difference between the fluctuation range of the first signal and the fluctuation range of the second signal exceeds the fluctuation range judgement value, and

the judgement unit judges the occurrence of an abnormality when the difference between the fluctuation range of the first signal and the fluctuation range of the second signal exceeds the fluctuation range judgement value in the same phase when the rotary shaft rotates more than once.

3. The rotation angle detector according to claim 1, wherein

the abnormality detecting unit includes a correction unit for correcting signals generated in the detection units, and a storage unit for storing beforehand a correction value which causes the fluctuation range of the first signal and the fluctuation range of the second signal to be identical to each other when the rotation angle detector is in a normal state,

the correction unit uses the correction value so as to correct at least one fluctuation range among the fluctuation range of the first signal and the fluctuation range of the second signal, and

the judgement unit makes a judgement based on the first signal and the second signal after correction.