无人机固定时间路径跟踪容错制导控制

针对无人机存在外部环境干扰及执行机构故障情况下的固定时间路径跟踪容错制导控制进行研究，提出了固定时间收敛的视线制导控制算法，利用反步法及固定时间收敛的视线制导控制算法确保无人机路径跟踪误差在固定时间内收敛。通过在视线制导控制算法中引入指令滤波器及误差补偿器，避免反步法中虚拟控制量微分项的复杂计算。为了抑制制导控制过程中系统状态剧烈变化，引入障碍李雅普诺夫函数对偏航角速度误差进行限制。通过非线性固定时间观测器对不确定性进行估计补偿，消除执行机构故障及外部环境干扰等因素对跟踪性能的影响。仿真结果表明:所提算法具备有效性和鲁棒性，具有良好的路径跟踪容错制导控制性能。 

Fault-tolerant fixed-time path following guidance control of UAV

A fault-tolerant fixed-timepath following guidance control method for the UAVs subject to thedisturbancesand actuator faults is studied. Both backstepping and fixed-time convergence techniques are employed for developing the line-of-sight path following control strategies to guarantee the convergence of the UAV to its reference trajectory in fixed time with elegant transient performance. Command filters and auxiliary systems are introduced in the guidance control algorithms design to avoid the arduous calculation of derivatives of virtual control terms in backstepping. To address turning rates constraints of the UAV, the barrier Lyapunov functions are incorporated with the control scheme to prevent the drastic change of the guidance control system states. A nonlinear fixed-time observer is designed for estimating complex unknown external disturbances and eliminating the actuator faults and the influence of external environment disturbance on following performance. Simulation results show the effectiveness and robustness of the proposed line-of-sight path following guidance control algorithm, and it has good path following fault-tolerant control performance.