A new electric encoder position estimator based on the Chinese Remainder Theorem for the CMG performance improvements

Electric Encoders (EEs) are extensively used for position measurement in precise motion control. They are characterized by high resolution and simple circuit interface. Some EEs gauge the angle value exploiting a combination of coarse and fine measures. In both cases the outputs are the sine and cosine of angle. In this context the most delicate operation regards the measurement of initial angle, corresponding to the absolute position of EE. In some commercial systems the process for absolute position computation is based on an M-N algorithm, which has limitations in terms of hardware and flexibility because uses memory. In this paper, a new method based on Chinese Remainder Theorem (CRT) is proposed for absolute position computation. This method is based on Residue Number System (RNS) and has advantages in terms of hardware and flexibility because doesnt use memories. For this reason, the same hardware can be used with different EEs just changing the value of few registers.