Patent ID: 9020774
Filing Date: 2015-04-28
Classification: G01B,G01D,G05B,G05D

Abstract:
1. An encoder system comprising: a first absolute position encoder that is a single-rotation absolute encoder and that outputs a first detection signal corresponding to an angular position of a rotating input shaft; a second absolute position encoder that is a single-rotation absolute encoder and that outputs a second detection signal corresponding to an angular position of an output shaft rotating at a predetermined transmission ratio in response to the rotation of the input shaft; a first position data detection circuit that detects first position data representing the angular position of the input shaft through first predetermined signal processing based on the first detection signal input from the first absolute position encoder; a second position data detection circuit that detects second position data representing the angular position of the input shaft through second predetermined signal processing based on the second detection signal input from the second absolute position encoder; a position data combination circuit that combines the first position data and the second position data to generate combined position data representing a multiple-rotation count of the input shaft and the angular position within one rotation of the input shaft; an error correction value storage section in which an error correction value for correcting the combined position data is stored in advance, the error correction value being a value which is obtained by driving an entire power transmission device that rotates the output shaft in advance in a state where the entire power transmission device is incorporated into the encoder system; and an error correction circuit that corrects the combined position data generated by the position data combination circuit based on the error correction value read out from the error correction value storage section, wherein the error correction value includes an error angle which is obtained by comparing a second detection angle based on the second position data detected by the second data detection circuit based on the second detection signal input from the second absolute position encoder and an angle measured with reference to a first detection angle based on the first position data detected by the first data detection circuit based on the first detection signal input from the first absolute position encoder.