Robust control of nonlinear continuous-time systems with parameter uncertainties and input bounds

Abstract

New results and innovative procedures are presented to design nonlinear robust controllers for a class of nonlinear time-varying systems with uncertain parameters and control constraints. The straightforward techniques for designing the robust bounded controllers are developed by utilizing the theoretical foundations of the HamiltonJacobi theory and L yapunov's method. The major contribution is the development of feasible and computationally efficient algorithms to stabilize uncertain nonlinear systems. Various aspects of recent developments concerning robust control and nonlinear optimization are discussed and further researched. Necessary and sufficient conditions for optimality and robust stability are studied. By applying robust design, this paper allows one to solve practical problems in nonlinear robust control and optimization by using nonlinear models with parameter variations and input bounds. To overcome the gap between the theory and its application, two examples are thoroughly studied. Robust control of the third-order chaotic attractor with uncertain parameters is performed to illustrate the efficiency of the proposed procedures. In addition, the goal of this article is to demonstrate the feasibility of the developed concept for multivariable flight control, and a bounded controller is designed for the F-18 fighter. This robust algorithm is synthesized by using the coupled nonlinear aerodynamics for the longitudinal and lateral axes.