Simultaneous Compensation of Unknown Time-Varying State and Input Delays for Uncertain Nonlinear Systems

Abstract

The paper presents the design of a robust control law for a class of nonlinear dynamical systems subjected to parametric uncertainty and simultaneous unknown, variable state and input delays. Knowing a bound of the input delay, we develop a novel controller using a filtered tracking error and integral of past control values. Lyapunov-Krasovskii functionals based stability analysis guarantees a global uniformly ultimately bounded (GUUB) tracking result where sufficient conditions on controller gains and maximum allowable delay are derived. The performance and robustness of the controller is evaluated by simulation on a two-link robot manipulator for different combinations of time-varying state and input delays.