In this paper, a controller is designed for satisfaction of precise tracking performance under the time-varying disturbances. This controller is consisted of optimal PID controller and compensation controller to compensate the time-varying disturbance effects. The optimal PID controller is used for the tracking performance satisfaction. The compensation controller estimates the disturbances from the difference of ideal model system output from the output of real system and compensates control input for disturbance rejection. The estimation mechanism is constructed using modern control theory about the observer. The overall control system is designed in the discrete time space and is realized using microprocessor. This presented control system operates excellently in the precise tracking system under the time-varying disturbance.
