On direct adaptive stabilization of nonminimum phase systems

A linear periodically time-varying controller structure is proposed as the underlying design for direct adaptive control. With such a controller the author addresses the problem of stabilization of minimal plants with known order and with no assumptions on the zero locations. The proposed controller is a direct implementation of the indirect scheme of R. Lozano (1989). The author determines a plant prior knowledge condition under which global stabilization is possible without parameter projections or external signal injection. The additional prior information is quantitatively compared with that required in classical indirect pole-placement schemes