Delay-range-dependent static anti-windup compensator design for nonlinear systems subjected to input-delay and saturation

Abstract

This paper presents the novel delay-range-dependent schemes for computing the static anti-windup compensator (AWC) gain for nonlinear systems with input time-delay and saturation constraints. By utilizing the Lyapunov–Krasovskii functional, sector conditions, Lipschitz inequality, and Wirtinger-based inequality and by employing the range of input lags, time-derivative bound of delay, and L2 gain reduction for exogenous input, sufficient conditions are derived in order to ensure global and local stability of the overall closed-loop system. In contrast to the conventional approaches, the resulting AWC design methodology can be applied to nonlinear systems with input delays (due to distant placement of a system from the controller), supports static AWC design (computationally straightforward for implementation), and employs range of the input delay (rather than trivial selection of the lower delay bound as zero). Simulations are carried out for two electro-mechanical systems, namely, a nonlinear DC motor and a nonlinear flexible-link robot under input time-delay and input saturation constraints.