Analysis and error compensation of electric sine/cosine encoder

Electric encoder is extensively used for position measurement in precise motion control, due to its performances of high resolution, small profile and simplicity of interface circuit. The Electric encoder employs a combination of coarse and fine mode. In each mode the outputs are sine/cosine. The offset voltage error, which produces the 1^st harmonic cycle error and is not repeatable from unit to unit, should be compensated before performing the position calculation. In this paper, a geometry method based on Lissajous curve is proposed to compensate the offset voltage error. Experimental results verify the effect of the proposed compensation algorithm.