Flight Control of Tilt Rotor UAV During Transition Mode Based on Finite-Time Control Theory

Abstract

This paper focuses on the finite time convergence problem of system states in the course of the transition flight control for a small tilt rotor unmanned aerial vehicle (UAV). A controller design method using nonsingular terminal sliding mode surface and extended state observers (ESOs) is proposed. Due to the velocity and structure of tilt rotor UAV vary significantly with the variation of tilt angle, the transition mode is divided into two parts. To adapt to complex aerodynamic characteristics and maneuvering characteristics, and the vibrational control structure in different part of the transition mode, a nonsingular terminal sliding mode control method is applied to make the states converge to the reference trajectories in finite time. Moreover, ESOs are provided to enhance the robustness of the system for uncertainties. Finally, a numerical example is given to verify the effectiveness and robustness of the proposed approach. Regardless of disturbances, the aircraft can achieve the mode transition safely and smoothly.