Barrier function-based adaptive continuous higher-order sliding mode controllers

In this paper, two classes of continuous higher order adaptive sliding mode controllers based on barrier functions are developed for a perturbed chain of integrators with perturbations bounded by unknown functions. Both classes provide finite-time convergence of the state of the system to a predefined domain using a continuous control signal. The first class of adaptive controllers require few assumptions about the perturbation. However, it can provide unbounded control gains in general. To ensure bounded control gains in the case of a Lipschitz perturbation, a second class of adaptive controllers, called the adaptive higher order Super-Twisting (HOST) algorithm, is developed. The effectiveness of the proposed adaptive controllers is specifically assessed for a cart-pendulum system. Simulation results illustrate high performance in achieving stabilization, even in cases where the disturbance upper bound and its derivative are unknown.