Robust Adaptive Stabilization of Not Necessarily Minimum-Phase Plants

Recently it was shown that first-order adaptive regulators can stabilize any linear time-invariant plant whose transfer function has arbitrary relative degree and order and is not necessarily minimum phase, provided that the dominant slow part of the plant is minimum phase and of relative degree one and the parasitic fast part is stable. Both the algorithm and the problem formulated are particular cases of the general model following problem in multivariable plants that can be stabilized via static or dynamic output feedback. This paper gives a unified presentation and a brief intuitive motivation for the different adaptive procedures that together leed to simplified robust adaptive controllers.