Fixed-time anti-saturation and fault-tolerant control for quadrotor UAVs using event-trigger adaptive barrier sliding mode control.

This paper proposes an Adaptive Barrier Nonsingular Fixed-Time Sliding Mode Control (ABNFTSMC) scheme for quadrotor Unmanned Aerial Vehicles (UAVs). The method explicitly addresses actuator faults, input saturation, and external disturbances. A Fault Detection and Isolation (FDI) unit identifies failed rotors to maintain stability, while a Virtual Controller (VC) is used to handle instability introduced by actuator failure using inputs from functioning actuators. The Barrier Function (BF) technique identifies a stable region with high bandwidth under large disturbances. A key feature of the controller is its energy efficiency, achieved through an Event-Triggered (ET) mechanism that adapts to faults, failures, and disturbances. Additionally, this method prevents the chattering problem, extending the system's lifetime and reducing energy consumption, unlike conventional SMCs that suffer from severe chattering. By substituting the sign function with a hyperbolic tangent (HT) function, the objective has been successfully achieved. The controller efficiently alleviates actuator faults, input saturation, and high-bounded disturbances while reducing chattering. The proposed nonsingular fixed-time controller guarantees fast convergence and excellent tracking performance, as demonstrated by theoretical proofs and simulation results. The HT function helps ensure smoother performance, prolonging the life of system components. This paper provides a well-configured, power-saving approach for compensating for actuator faults and disturbances in UAVs by minimizing chattering, delivering fast response, and reducing energy consumption.