Research on zero-finding method for the incremental encoder of hydraulic position servo motor

Incremental encoders are widely used for position measurement in angular position hydraulic position motor servo system for its simple structure and low cost. While in the situation that need absolute positioning, a relatively long time is needed to find the zero position. In this paper a special distance-coded mechanism of incremental encoder is addressed, as well as the zero-finding algorithm based on it. The proposed algorithm is applied in a hydraulic servo control system which is presented in the paper. Both theoretical analysis and experimental study show that the method is of good characteristics in speed, precision and robustness. This method finds the zero position without passing by the zero reference mark and is equivalent to use an incremental encoder as an absolute encoder, which means its theory innovation value and great extended significance in engineering.