Adaptive Constrained Control of Nonlinear Systems with Time-Varying Delays and Unknown Control Directions

In this paper, the control design for a class of strict feedback nonlinear systems with full-state time-varying delays, unknown control directions, and full-state constraints is investigated. To deal with the time-varying coefficients and unknown control directions, Nussbaum-type gains are designed for each-subsystem. Barrier Lyapunov functions are introduced to construct full state constraints and improve tracking performance. To overcome the influences of full-state time-varying delays, Lyapunov-Krasovskii functionals are employed. Dynamic surface control technique is utilized to avoid the explosion of complexity. In the end, a numerical example is provided to validate the effectiveness of the method developed.