Robust design of mimo feedback systems having an uncertain non-linear plant

An n x n non-linear multiple-input multiple-output system W is presented, known only to belong to a set (W). Wis embedded in a two-degree-of-freedom feedback structure. (r) is a set of possible command inputs, where for each r ϵ (r) there is a set (A^r) of acceptable outputs. The two degrees of freedom have to be selected such that in response to each command input r, the plant's output Y ϵ (A^r) for all W ϵ (W). A design technique is presented for solving this problem, based on the Horowitz design method for t-lIMO linear time invariant feedback systems. Sufficient conditions are given under which a solution is guaranteed. A design example is provided.