NONLINEAR H-INFINITY OPTIMIZATION - A CAUSAL POWER-SERIES APPROACH

In this paper, using a power series methodology a design procedure app licable to analytic nonlinear plants is described. The technique used is a generalization of the linear H-infinity theory. In contrast to pr evious work on this topic ([Indiana J. Math., 36 (1987), pp. 693-709], [Oper. Theory Adv. Appl., 41 (1989), pp. 255-277], [SIAM J. Control O ptim., 27 (1989), pp. 842-860]), the authors are now able to incorpora te explicitly a causality constraint into the theory. In fact, it is s hown that it is possible to reduce a causal optimal design problem (fo r nonlinear systems) to a classical interpolation problem solvable by the commutant lifting theorem [Harmonic Analysis of Operators on Hilbe rt Space, North-Holland, Amsterdam, 1970], [The Commutant Lifting Appr oach to Interpolation Problems, Birkhauser, Boston, 1990].