Fractional Order Fast Terminal Sliding Mode Controller Design with Finite-Time Convergence: Application to Quadrotor UAV

In this paper, a controller is proposed for a quadrotor Unmanned Aerial Vehicle (UAV) based on a Fractional Order Fast Terminal Sliding Mode Control (FOFTSMC) scheme. In order to obtain better tracking performance in the position and attitude of the system, the system model is re-formulated into a fully actuated subsystem and an under-actuated subsystem. Then, the flight controllers are designed such that to guarantee the finite-time convergence of the tracking errors of all the system state variables to zero. The developed FOFTSMC approach helps to reduce the amplitude of the control signals, which leads to enhancing the closed-loop relative stability of the quadrotor. The proposed FOFTSMC technique is chattering free and robust against the air drag, aerodynamic forces, and moments considered as the external disturbances. Furthermore, the Lyapunov direct method is used to analyze the stability of the closed-loop systems. The simulation results show the promising results of the proposed method in practice.