A reduced-order discrete-time H-infinity norm bounding controller

Sufficient conditions to design a discrete-time reduced-order H/sub /spl infin// norm bounding controller using measurement feedback are given. The solution method is based on the bounded real lemma, and a novel approach involving matrix inequalities and repeated use of positive semi-definiteness preserving transformations. The result is given in the form of two design equations. The first is a Riccati equation fully decoupled from the second and can be solved directly using the Hamiltonian approach. The second design equation depends on the solution of the first and must be solved using an iterative technique based on the solution to a Riccati equation.