Sine-cosine Alternative Subdivision for Incremental Optical-electrical Encoder

High accuracy servo control requires high precision angle measurement. The common method to improve resolution of incremental type optical-electrical encoder is electronic subdivision. A new subdivision method, sine-cosine alternative subdivision for incremental type optical-electrical encoder, was proposed in this paper. The original signals of optical-electrical encoder were filtered and differentially amplified into normal sinusoidal signals. Then they were converted into digital signals by A/D converters. In the processor, each cycle of the digital signals was partitioned into 4 regions from which the rough code was generated. By alternatively resolving the phase angle from the digital sinusoidal signals in each region, the subdivided precise code was generated. Combination of the rough code and precise code eliminated the subdivision error of each cycle. The results of experiment show that sine-cosine alternative subdivision has a good uniformity and fast response of subdivision. And it has a good application prospect.