Disturbance Observer-based Nonsingular Fast Terminal Sliding Mode Fault Tolerant Control of a Quadrotor UAV with External Disturbances and Actuator Faults

This paper addresses a nonsingular fast terminal sliding mode fault tolerant control (NFTSMFTC) scheme based on disturbance observer (DO) for a quadrotor UAV in the presence of external disturbances and actuator additive faults. Firstly, by analyzing the dynamic characteristics of a quadrotor UAV, the model is decoupled into outer-loop (position subsystem) and inner-loop (attitude subsystem). Secondly, the DO is utilized to deal with external disturbances and actuator additive faults effectively. Furthermore, nonsingular fast terminal sliding mode control (NFTSMC) can avoid the chattering problems of traditional sliding mode control (SMC) and singularity problems of terminal SMC. Moreover, compared with nonsingular terminal SMC, it behaves the faster convergence rate. So the NFTSMC method is applied to design controller. Finally, in the framework of Lyapunov theory, the stability of the closed-loop system is analyzed, and the tracking error is asymptotically stable. The effectiveness of the proposed control scheme is verified by simulation results.