Observer-based adaptive super-twisting fast terminal sliding mode control for attitude of quadrotor with mismatched disturbances

This paper presents an adaptive super-twisting fast terminal based on disturbance observer sliding mode control method for the attitude tracking of a quadrotor unmanned aerial vehicle in the presence of mismatched disturbances. The attitude tracking controller is formulated based on the introduced adaptive super-twisting technique. The utilization of dynamically adaptive gains in the controllers enhances the system’s robustness while reducing chattering effects. Additionally, a non-singular fast terminal sliding surface based on finite-time disturbance observer is defined. This approach effectively addresses the issue of mismatched disturbances while accelerating the convergence of tracking error. The stability analysis of the closed-loop system is established employing Lyapunov function. Finally, the effectiveness and success of the proposed method are validated through simulation and experimental results, with further comparisons to other techniques in terms of tracking performance and robustness.