CONTROL SYSTEM WITH IMPROVED ROBUSTNESS TO DISTURBANCES

A control system has a detector for obtaining a detected signal corresponding to a controlled variable of a controlled system and a controller for supplying the controlled system with a control signal corresponding to the detected signal. The controller includes an error circuit for producing an error signal corresponding to the detected signal, a storage circuit having a plurality of stored values corresponding to the error signal, and an output circuit for producing the control signal by mixing the error signal and one or more stored values of the storage circuit. The storage circuit renews the stored values sequentially and periodically with a value corresponding to a mixed value of the error signal and a set of N stored values, the N stored values having been renewed at intervals of L renewing cycle periods, where each of N and L is an integer at least equal to 2. Preferably, a microprocessor executes the tasks of the error circuit, the storage circuit and the output circuit.