Abstract
Recently, the authors have proposed a design method of discrete-time iterative controller on the assumption that the correct impulse response sequence of a controlled system is available. In the present paper, we discuss the design using an uncertain impulse response sequence. First, the performance of the controller designed by the previous method using an errorneous impulse response sequence is analyzed. It is shown that, unlike the design using the correct impulse response, the increase of the order of the error correction algorithm does not necessarily provide better transient performance. A method of the order determination using an upper bound of the error of the impulse response is suggested. Unfortunately, it is pointed out that this method often provides conservative result except for a special case. To mitigate this drawback, an alternative design method is proposed on the assumption that the uncertainty of the impulse response sequence is represented by known probability distribution. The coefficients of the algorithm are determined by minimizing the averaged quadratic performance index. It is shown that a proper order is easily determined by using the minimized average performance indices. A numerical example is presented to demonstrate the effectiveness of the proposed method.
