Abstract
A new method of designing a digital controller is proposed in this paper. We consider the design problem that the closed-loop system with a cascade compensator approximates the reference model endowed with desirable characteristics. A integrated square error criterion is introduced as a measure of the approximation. Minimizing the criterion, a linear equation is obtained for unknown parameters of the reduced-order controller. The method is not based on the approximation of the high-order controller which realizes exactly the specified reference model, but on the approximation of the open-loop transfer function. Strong points of the method are that the order of the controller can be arbitrarily specified and that the order of the plant model is not required as a priori knowledge. A example is given to illustrate the effectiveness of this design method.
