Barrier Function Adaptive Nonsingular Terminal Sliding Mode Control Approach for Quad‐Rotor Unmanned Aerial Vehicles

Abstract

This paper proposes a barrier function adaptive non‐singular terminal sliding mode controller for a six‐degrees‐of‐freedom (6DoF) quad‐rotor in the existence of matched disturbances. For this reason, a linear sliding surface according to the tracking error dynamics is proposed for the convergence of tracking errors to origin. Afterward, a novel non‐singular terminal sliding surface is suggested to guarantee the finite‐time reachability of the linear sliding surface to origin. Moreover, for the rejection of the matched disturbances that enter into the quad‐rotor system, an adaptive control law based on barrier function is recommended to approximate the matched disturbances at any moment. The barrier function‐based control technique has two valuable properties. First, this function forces the error dynamics to converge on a region near the origin in a finite time. Secondly, it can remove the increase in the adaptive gain because of the matched disturbances. Lastly, simulation results are given to demonstrate the validation of this technique.