Model reference robust control of weakly non-minimum phase systems

This paper continues to explore applicability of model reference robust control (MRRC) technique. It is shown that MRRC design works for a class of non-minimum phase SISO systems. A system under study contains not only parametric uncertainties, disturbances, uncertain high-order nonlinearities associated with output, but also both additive and multiplicative unmodelled dynamics of input. Although admissible input unmodelled dynamics have to be small and stable, the presence of these unmodelled dynamics may cause the overall system to be non-minimum phase. The system studied here includes those systems existing in literature as special cases. The proposed result relaxes the current restriction imposed on MRRC that the system has to be minimum phase, and therefore makes MRRC more attractive. The feature of MRRC distinct from adaptive control results is that nonlinear uncertainties not satisfying the Lipschitzian condition can be treated. And, because of the combination of nonlinear uncertainties and the non-minimum phase property, the resulting stability is local uniform ultimate bounded