DIGITAL SERVO CONTROL SYSTEM

In a digital closed loop servo control system, state variables of a plant are input to an inverse system having an opposite characteristic to an internal model, and the output of the inverse system is input to the internal model. If the state variables of the plant cannot be directly observed, a state estimator is used. In that case, the inverse system receives input and output of the plant and provides output thereof to the state estimator. Input of the internal model may be inputted to the state estimator instead of inputting the input of the plant to the inverse system. In this manner, it is possible to provide a digital servo control system in which the number of bits required in calculation (dynamic range) does not depend on the amplitude of the target value.