Suboptimal local feedback control for a class of constrained discrete timenonlinear control problems

In this paper, we consider a class of constrained discrete time optimal con trol problems involving general nonlinear dynamics with fixed terminal time . A method to solve the feedback control problem for a class of unconstrain ed continuous time nonlinear systems has been proposed previously. In that work, the solution is based on synthesizing an approximate suboptimal feedb ack controller locally in the neighbourhood of a certain nominal optimal tr ajectory. This paper expands on the same theme by considering problems invo lving discrete time systems. Taking advantage of the nature of discrete tim e systems, a further reduction on the computational effort of synthesising the feedback controller is made possible. Also, this paper extends the appl icability of the method to constrained systems. For illustration, a numeric al example is solved using the proposed method. (C) 1998 Elsevier Science L td. All rights reserved.