DISCRETE-TIME LQG/LTR TECHNIQUE FOR SYSTEMS WITH TIME DELAYS

Loop transfer recovery (LTR) is applied for LQG controllers with prediction estimators for a class of square minimum-phase discrete-time linear systems with time delays. We consider the class of plants described by the triple (A, B, C) whose time-delay structure is characterized by the following hypothesis on the plant impulse response: CB = CAB = ... = CAd-2B = 0, det(CAd-1B) ≠ 0. When the estimator gain is fixed by recovery technique, it is shown that the loop transfer matrix at the plant input is equal to the transfer matrix obtained with the optimal digital regulator having d-sample controller delays described in [6]. The dual result corresponding to the situation where the feedback gain is fixed by recovery technique is also analysed. © 1990.