Adaptive tracking control of uncertain nonlinear systems with unknown input delay

An adaptive controller is developed for a class of uncertain nonlinear systems with additive disturbance and unknown constant input delay. The control law is composed of a Desired Compensation Adaptation Law (DCAL) based feedforward term to account for the uncertain plant parameters and a robust delay compensation feedback term based on the integral of the past control. The stability analysis is performed by choosing suitable Lyapunov-Krasovskii functionals to prove semi-global uniformly ultimately bounded (SGUUB) tracking. Simulation results show the performance and robustness of controller for different values of input delay.