Recursive Non-singular Terminal Sliding Mode Fault-tolerant Control of Multi-UAV Formation

To solve the problem that quadrotor unmanned aerial vehicle (UAV) formation flying is easily affected by external interference, air resistance, actuator failure, and other uncertain factors, we propose a recursive nonsingular terminal sliding mode control (RNTSMC) method based on a compensation function observer (CFO) to improve the performance of quadrotor UAV formation systems. First, we introduce a CFO with high-precision estimation to estimate the external disturbance and actuator fault information in real time, improve the equivalent controller of nonsingular terminal sliding mode surface by designing a recursive integral terminal sliding mode surface to compensate the estimated information and produce the initial value of the sliding mode surface, a pledge that two sliding mode surfaces, in turn, reach a balance in a row, and ensure that the tracking error converges to zero quickly in a finite time. Second, we establish a formation model according to the leader-follower method and design a formation cooperative controller based on the sliding mode control theory to ensure that the UAV formation completes the flight mission. Finally, the simulation results show that the proposed method has good fault tolerance performance for quadrotor UAV formation.