Abstract
A disturbance observer is well known as a control system which can reduce the adverse effect of disturbances. In order to synthesize the disturbance observer, the exact dynamical model of disturbance is required. However, in general, it is difficult to obtain the exact disturbance model. On the other hand, an observer with a function of estimating unmeasurable inputs has been already proposed. By using this observer, unmeasurable disturbances can be estimated without the exact disturbance model. However, disturbance attenuation problem based on the observer still remains as an open issue. In this paper, a synthesis method of the control system for disturbance attenuation based on an observer with a function of estimating unmeasurable inputs is proposed and the class of compensators which guarantee the internal stability of the closed loop system is clarified.
