Optimal Discrete-Time Static Output-Feedback Design: a w´-Domain Approach

An alternative design methodology in the w´-domain for a discrete-time optimal control is presented in this paper. The proposed method is used to solve optimal static output-feedback design for sampled-data systems. The overall scheme involves the development of a system transformation from the z-domain to the w´-domain in state-space formula and an equivalent quadratic cost functional. A one-to-one relationship between stabilizing feedback gains in the w´-domain and in the z-domain has been established. The attractive feature of this procedure is that design solutions are entirely amenable to continuous-time domain techniques. The optimal output-feedback gain obtained from the minimization of an equivalent cost functional expressed in the w´-domain yields, as expected, the same optimum solution as the one obtained in the traditional z-domain formulation. The procedure is demonstrated by the synthesis of a stability augmentation system for a commercial transport in the longitudinal axis.