Feedback designs of nonlinearly parameterized systems.

摘要

This dissertation addresses various control problems for nonlinearly parameterized systems. Unlike most of the existing results, the uncertain parameters considered here are not assumed to be in a known compact set nor satisfy a certain type of nonlinearity, e.g. convex/concave or polynomial conditions.; The first part of this dissertation addresses global regulation problems for uncertain systems by using a time-varying approach. First, two new time-varying control designs are introduced and used to solve the problem of global regulation for both lower-triangular and upper-triangular systems with nonlinear parameterization. The time-varying approach presents a unified framework to deal with both lower-triangular and upper-triangular systems. Then, time-varying output feedback is explicitly constructed to solve the problem of global regulation for a class of uncertain nonlinear systems dominated by a linear growth triangular system. Using this approach, a so-called universal output, feedback controller in which one controller can globally regulate a whole family of systems, can be developed.; In the second part, we consider the problem of practical output tracking for nontriangular systems with nonlinear parameterization. This class of the systems represents high-order nonlinear systems with uncontrollable unstable linearization which, in general, asymptotic output tracking is not possible. Using a universal, adaptive controller, we show that the practical output tracking problem is solvable without requiring knowledge of the bound of uncertain parameters.