Dynamic Smooth Sliding Control Applied to UAV Trajectory Tracking

Abstract

This paper proposes a sliding mode controller with a smooth control signal for a class of linear plants with nonlinear input state-dependent disturbance. The proposed controller is obtained by allowing some constant parameters of the earlier Smooth Sliding Control (SSC) to vary as a function of the output tracking error and its time derivative, improving the control chattering alleviation in practical implementations. Furthermore, during the sliding mode, the new scheme can synthesize a range of controllers, such as fixed gain PI controllers and approximations of the Super-Twisting Algorithm (STA). A complete closed-loop stability analysis is provided, leading to global stability properties, exact output regulation, and practical output tracking. In addition, realistic simulation results with an Unmanned Aerial Vehicle (UAV) model, incorporating aerodynamic effects and internal closed-loop controllers, are obtained and validated via experiments with a commercial hexacopter.

Keywords

• Chattering avoidance
• sliding-mode control
• super-twisting algorithm (STA)
• unmanned aerial vehicle (UAV)
• unmodelled dynamics