高超声速再入飞行器不确定性分析与μ综合控制

Uncertainty Analysis and μ Synthesis Robust Controller Design for Hypersonic Re-Entry Flight Vehicle

针对高超声速飞行器再入过程中飞行包线大,飞行环境复杂,其间各种复杂的力学过程不可能完全精确地考虑在控制系统设计模型中,存在大量不确定参数的特点,为了便于鲁棒控制器设计,提出了基于最坏情况增益(WCG)灵敏度分析的不确定参数简化方法,在保证不丢失大量WCG信息的情况下,简化模型不确定参数个数;然后基于简化不确定模型和μ综合方法进行姿态控制系统设计;最后通过高超声速再入飞行器横侧向鲁棒控制器的实例设计与仿真分析,验证分析与设计方法的有效性。结果表明,基于WCG的参数灵敏度分析方法能有效地简化模型不确定参数,在保证控制系统鲁棒性的同时可提高控制器设计效率。

The hypersonic re-entry flight vehicle traverses a broad flight envelope in altitude and speed. The mathe- matical dynamic model used to describe the vehicle in control system design can hardly reflect all complex physical dynamic characteristics, resulting in numerous uncertain parameters in the model throughout the flight envelope. This paper proposes a new sensitivity analysis method based on worst-case gain （WCG） which can get the sensitivi- ty of the control system＇ s WCG to all the individual uncertain parameter＇ s uncertain ranges. The uncertain param- eters with small sensitivity values relatively are ignored and kept constant as nominal values in the model. The un- certain dynamic model is thus simplified and is used as the control model for the μ synthesis control law design Then, on the basis of the requirements of flight performance, a structure of the flight vehicle attitude control system is presented and the corresponding weighting functions are selected, The proposed methods of WCG sensitivity anal- ysis and μ synthesis are used to design the attitude controller of a hypersonic re-entry flight vehicle, and the nonlin- ear simulation results and their analysis show preliminarily that the μ synthesis control system which is designed based on the simplified control model also has good robust performance to the ignored uncertain parameters, and both under the nominal condition and the worst case, the closed-loop system fulfills the control characteristic requirements.