Robust Design of MIMO Feedback Systems Having an Uncertain Nonlinear MIMO Plant

An n×n nonlinear multiple-input multiple-output system W is presented, known only to belong to a set (W). W is embedded in a two-degree-of-freedom feedback structure. (r) is a set of possible command inputs, where for each r (r) there is given a set of acceptable outputs {A^r}. The two degree of freedom have to be chosen so that in response to each command input r, the plant output y {A^r} for all W {W}. A design technique for solving this problem is presented which is based on the Horowitz design method for MIMO linear time invariant feedback systems. Sufficient conditions under which a solution is guaranteed are given. A design example is included.