基于反步法的空天飞行器有限时间姿态跟踪控制

Finite-time attitude tracking control for aerospace vehicles based on back-stepping method

针对空天飞行器再入段姿态跟踪控制问题,根据反步法和控制分配技术提出了一种有限时间复合控制策略,处理在未知扰动和参数不确定性情况下RLV进行再入飞行时的姿态镇定问题。首先,根据多时间尺度,将RLV模型分为双回路子系统——姿态角子系统和姿态角速度子系统,并在反步法框架下定义误差向量,结合快速幂次趋近律设计虚拟角速度指令;然后,设计有限时间观测器,补偿包含虚拟指令微分组合的不确定项,并实时反馈给有限时间控制律,避免"参数膨胀";最后,利用分离原理和Lyapunov有限时间稳定性理论,证明了整体系统的收敛性,分析并给出了闭环系统的收敛时间。仿真结果表明了该控制策略的有效性。。

For the reentry attitude tracking control problem of aerospace vehicles,a finite-time composite control strategy is proposed based on the back-stepping and control allocation technique.This can process the problem of the RLV reentry flight attitude stabilization with unknown disturbances and the parameter uncertainties.Firstly,according to the multiple time scales,the mathematical model of RLV is divided into double loop sub-system( the attitude angle sub-system and the attitude angular velocity sub-system),and the error vectors are defined based on back-stepping.The virtual angular velocity commands are designed by combining the fast power reaching law.Then,the finite-time observer is designed.The uncertain terms containing the virtual command differential combination are compensated and fed back to the finite-time convergent control law in real time to avoid the ‘expansion of parameters’.Finally,the astringency of the system is demonstrated based on the separate principle and Lyapunov theorem of finite-time stability.The convergence time of the closed-loop system are obtained.Simulation results show the validity of the proposed control strategy.