H/sub ∞/ and H/sub 2/ design techniques for a class of prefilters

This paper presents H/sub /spl infin// and H/sub 2/ techniques for the design of a certain class of prefilters. In order to avoid high order prefilters we use a particular structure in which both prefilter and feedback controller share the same dynamics. The suboptimal H/sub /spl infin// design problem is shown to be equivalent to a linear matrix inequality (LMI) constraint, and the solution of the H/sub 2/ optimal design may be obtained by a simple formula. The H/sub 2/ technique developed is illustrated on a helicopter example and compared with classical techniques.