Adaptive control for a class of SISO nonlinear time-varying delay systems with unknown gain signs

A design scheme of adaptive neural controller for a class of uncertain SISO nonlinear time-varying delay systems with unknown nonlinear dead-zones and unknown function control gain is proposed. The design is 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 and the supposition further broadness to unknown function. The unknown time-varying delay uncertainties are compensated for using appropriate Lyapunov-Krasovskii functionals in the design. By theoretical analysis, the closed-loop control systems is proved to be semi-globally uniformly ultimately bounded. Simulation results demonstrate the effectiveness of the approach.