Fixed-time safety tracking control of QUAV under external disturbances using robust high-order time-varying control barrier function

This study proposes a robust fixed-time safety control scheme for a quadrotor unmanned aerial vehicle (QUAV) operating in environments with obstacles and external disturbances. Firstly, a robust high-order time-varying control barrier function (R-HO-TV-CBF) is designed as an obstacle avoidance constraint. This method achieves robustness without relying about any prior assumptions on the bounds of the disturbance and its derivative, effectively handles dynamic obstacle avoidance, suppresses oscillation and ensures optimal trajectory tracking. Subsequently, a nonsingular fixed-time sliding mode control (NFxSMC) method is developed to guarantee fixed-time convergence, independent of the initial state. Finally, simulation results demonstrate the superior performance of the proposed scheme in obstacle avoidance, disturbance rejection and error convergence.