基于扩张干扰观测器的再入飞行器终端滑模控制

摘要

针对再入滑翔飞行器存在时变非匹配不确定干扰的问题，设计了一种非线性扩张干扰观测器和新型双回路非奇异终端滑模控制律。首先将观测器状态变量扩张为干扰及其变化速率的估计值，再基于Lyapunov稳定性定理设计新型非线性干扰观测器；将再入飞行器系统方程分为姿态角外回路和姿态角速率内回路，分别设计具有干扰补偿作用的新型滑模面，以及能够有限时间收敛的非奇异终端滑模控制律。仿真结果表明，该方法可将传统非线性干扰观测器的估计精度提高约4％，控制系统跟踪误差得到明显降低，具有良好的动态特性。%This paper presents an extended nonlinear disturbance observer and novel double loop nonsingular termi⁃nal sliding mode control for reentry vehicles with time⁃varying unmatched disturbance. Firstly, the Lyapunov theo⁃rem is employed to design the extended nonlinear disturbance observer, where the state variables are extended to observe the disturbances and their changing rates simultaneously. The motion of reentry vehicle is separated into in⁃ner loop of angle and outer loop of angular rate, and a nonsingular terminal sliding mode control laws based on no⁃vel sliding mode is developed. The disturbance can be efficiently compensated and the tracking error is guaranteed to converge to zero in finite time. Simulation results and comparisons illustrate the effectiveness of the control strate⁃gy.