| This dissertation focuses on the problems of global output regulation and semiglobal stabilization for MIMO nonlinear systems. The output regulation problem is to design a feedback control law by which the output of a nonlinear system asymptotically tracks a trajectory generated by an exosystem, no matter how large the initial output tracking error is. Moreover, undesired disturbances are simultaneously rejected. Whenever the exosignal is absent, this control law must also be capable of globally asymptotically stabilizing the system.; Both necessary conditions and sufficient conditions for the solvability of global regulation for nonlinear systems are introduced. Constructions of control laws which achieve the regulation of a class of MIMO nonlinear systems are also demonstrated. One of the constructions is based on the technique called robust block backstepping, by which the extension to global robust output regulation can be accomplished. The theories of global output regulation are applied to a fully-actuated system; the theories of local output regulation are applied to an under-actuated system.; The semiglobal stabilization problem is also of interest. It requires the design of a control law such that any initial condition belonging to an arbitrarily large prescribed set is practically stable, i.e., its trajectory is captured by an arbitrarily small prescribed set. This work focuses on a class of uncertain MIMO nonlinear systems. The technique called unlocking zero dynamics, introduced in a previous work, is demonstrated. This technique can be applied to a system that has unstable zero dynamics. |
