Design of the constrained controllers for uncertain nonlinear systems using the Lyapunov stability theory

This paper studies uncertain nonlinear systems when control inputs are subject to upper bounds on magnitude. The robust tracking control problem is approached and solved. In particular, an innovative design framework is developed, and the existing results are extended to synthesize the robust tracking controllers. Nonquadratic Lyapunov functions are used to perform stability analysis, and innovative integral tracking controllers with nonlinear error and state feedback maps are synthesized. Another contribution of this paper is the application of the theoretical results. The implementation of the method proposed to design robust control laws for servomechanisms with induction motors is presented to illustrate the theoretical feasibility, versatility, and practical effectiveness of the procedure. The controller designed is implemented, and experimental results are documented to validate the control algorithm and to study the servo-system performance. (C) 1999 Published by Elsevier Science Ltd. All rights reserved.