Adaptive model output following control for plants with unmodelled dynamics

In this paper, an adaptive model output following control utilizing almost strictly positive real (ASPR) characteristics of the plant is considered. The plant is said to be ASPR, if there exists a static output feedback such that the resulting closed-loop transfer function is SPR. A design scheme of an adaptive model output following control system having simple structure of adaptive controller is proposed for the ASPR plant. The ASPR condition imposes severe restrictions on the plant with relation to the practical application. However, one can construct an ASPR augmented plant, which is virtually regarded as a new controlled plant, by implementing a parallel feedforward compensator or pre-compensator on the plant. The design schemes of such compensators which make the non-ASPR plant to be virtually ASPR is proposed by taking plant uncertainties into consideration. As a result, the applicable class of the proposal can be expanded