Adaptive output feedback controllers for a class of nonlinear mechanical systems

Even from the early days of adaptive control theory, it has been a primary target for several researchers to guarantee global stability using as limited assumptions as possible. Currently, there exist applicable theories for output feedback adaptive control with which we can often guarantee only semi-global stability. When compared to the corresponding non-adaptive (deterministic) case, these solutions need several extra assumptions in the synthesis of the adaptive controller. In this dissertation, we introduce the definition of a specific class of nonlinear systems, which can be guaranteed global asymptotical stability. This is one of the main result of this dissertation. We named this class as “Passivity Based Globally Stabilizable Systems via Adaptive Output feedback(PBGSS/AOF)”. During the arguments, we show how to construct passivity based adaptive controller. As examples of actual systems, spacecraft attitude control problem and n degree of freedom(DOF) robot arm problem are chosen. For each case, The method to construct a controller and an estimator is shown with its stability proof and its effectiveness is displayed with numerical simulation results.