超低空空投拉平阶段混合迭代滑模控制

针对超低空空投拉平阶段地面效应、传感器测量误差以及低空气流等不确定性因素干扰轨迹精确跟踪,威胁载机的安全性和任务完成性等问题,设计了二级混合迭代滑模变结构飞行控制律.第1级滑模采用全局动态切换函数,消除了滑模运动的到达阶段,保证了系统在响应全程的鲁棒性;第2级滑模采用非线性积分切换函数,将积分项产生的超调转移到第1级滑模,保证轨迹跟踪精度的同时改善了动态性能.应用Lyapunov稳定性理论和Barbalat引理证明了该飞行控制律能完全抑制常值的模型摄动和外界扰动,可以控制动态模型摄动和外界干扰下稳态误差的上界.仿真验证了所提控制方法的良好跟踪性能和强鲁棒性.

Hybrid iteration sliding mode control for ultra-low altitude airdrop level off

For the ultra-low altitude airdrop level off stage, many uncertain factors such as ground effect, sensor measurement errors and low altitude airflow interfere the precision of trajectory tracking, which exert serious threats on the aircraft safety and mission performance, a hybrid iteration sliding mode flight controller was designed. In the first order sliding mode, a global dynamic switching function was adopted, which eliminated the reaching stage of sliding mode and ensured the whole response robustness. In the second order sliding mode, a nonlinear integral switching function was adopted and the overshoot caused by the integral term was brought to the first order sliding mode, so not only the tracking accuracy was guaranteed but also the dynamic performance was improved. Lyapunov stability theory and Barbalat lemma analysis show that the flight control law can completely reject constant model perturbation and disturbances, and can control the upper bounds of the steady errors with dynamic model perturbation and disturbances. Simulation results confirm the robustness and ascendant tracking performance of the proposed approach.