Adaptive control of MIMO nonlinear time-varying delay systems with unknown gain signs

A design scheme of adaptive neural controller for a class of uncertain MIMO nonlinear time-varying delay systems with unknown nonlinear dead-zones and unknown function control gain is proposed,based on the principle of sliding mode control and property of Nussbaum-type functions.The approach relaxes the hypothesis that the upper bound of function control gain is unknown constant.The unknown time-varying delay uncertainties are compensated for using appropriate Lyapunov-Krasovskii functionals in the design.By using theoretical analysis,the closed-loop control systems is proved to be semi-globally uniformly ultimately bounded.Simulation results demonstrate the effectiveness of the approach.