Proposal of long sampling short cycle observer for quantization error reduction

High resolution encoders are employed to industrial equipment which is required accuracy, for example, NC machine tools, exposure systems, and so on. Generally, the velocity of machines is calculated by the difference of the position given by the encoder. Although the high resolution encoder is employed, the quantization error and the half sample delay induced by the difference cannot be avoided. These are problems in the case of required high precise velocity. In this paper, we propose an observer which can estimate state variables with reducing the quantization error. Finally, simulations and experiment with experimental precision stages are performed to show the advantages of the proposed observer.