关键词: 无人机, 动态避障, 控制障碍函数, 固定时间控制, 权重调度

Abstract: This paper addresses the coupled control problem of robust trajectory tracking and safe obstacle avoidance for unmanned aerial vehicles (UAVs) operating in environments with multiple dynamic obstacles while subject to model uncertainties. A robust fixed-time trajectory tracking control scheme integrated with an obstacle avoidance mechanism is proposed. First, the UAV's positional dynamics are approximated as a controlled second-order system incorporating matched and unmatched uncertainties. An adaptive fixed-time trajectory tracking controller is designed to guarantee tracking performance in obstacle-free scenarios. Subsequently, a novel second-order Control Barrier Function (CBF) is constructed based on the safety distance constraint of dynamic obstacles. By explicitly embedding disturbance estimates and their upper bounds into the CBF constraints, a quadratic programming (QP) controller is formulated. This controller incorporates slack variables to ensure recursive feasibility and real-time solvability. Furthermore, a distance-driven weight scheduling strategy is introduced to adaptively adjust the priority: prioritizing obstacle avoidance when approaching obstacles and emphasizing tracking performance at a distance. Finally, rigorous theoretical analysis is provided to prove the robust safety guarantees and fixed-time stability of the closed-loop system. Comparative simulation results validate the effectiveness and superiority of the proposed control strategy.

Key words: Unmanned aerial vehicle (UAV), Dynamic obstacle avoidance, Control barrier function (CBF), Fixed-time control, Weight scheduling