Abstract
A design method of digital type 1 servo-systems is proposed for n-th order single-input single-output linear systems under perfect state observation and L-step delays. The structure of the proposed controller resembles to that of Mita's digital optimal type 1 servo-system but differs in the point that it contains a stable zero. By using pole assignment technique, the controller parameters are determined so that the poles of the closed loop system consist of L zeros and n arbitrary positions with cancellation of the zero in the controller. The computation of the controller parameters is easily performed since it requires matrix inversions only for upper triangular matrices. It is shown that the zero in the controller can be used to improve feedback properties without changing the transfer function from the reference to the output. In addition, effects of the delays on feedback properties are discussed. A simple numerical example is presented to illustrate the effectiveness of the proposed method.
