高超声速飞行器模型不确定性影响分析

吸气式高超声速飞行器具有严重的弹性机体和推进系统耦合的典型特征,其分析模型存在较大的不确定性,标称系统和真实系统之间存在偏差,因此研究不确定性对稳定性的影响对于控制器设计具有重要意义。针对典型的乘波体构型高超声速飞行器,建立了气动/结构/推进相互耦合的动力学模型,总结了建模中的不确定因素并将其以加性不确定模型的形式表示出来。以不确定性矩阵的最大奇异值为边界模型,以不确定性矩阵的H∞范数来表示不确定性因素对稳定性影响的大小,并通过不确定性矩阵的边界曲线分析不确定因素对模态特性的影响。结果表明,惯性因素的不确定性对稳定性的影响最大,而且其对飞行器的短周期模态和弹性模态均有较大的影响;同时,对于这一类飞行器的控制器设计必须考虑飞行器的弹性自由度。

Influence analysis of hypersonic flight vehicle model uncertainty

Air-breathing hypersonic flight vehicles are typically characterized by a significant degree of interaction between the highly elastic airframe and the propulsion system. Then it will result in dramatic uncertainty in the model of vehicle. So knowledge of the scale of the uncertainty to the vehicle is necessary during the process of control law design due to the enormous difference between the nominate system and the true system. A coupled longitudinal dynamical model is developed in this paper for a typical hypersonic waverider with parametric uncertainties depicted as add uncertainty model. According to H_∞ norm and boundary of the uncertain matrices'' maximum singular value, the magnitude of each uncertain factor''s influence on the stability of vehicle and the characteristics of the mode is measured. The results indicate that the inertia property has a significant influence on stability and also has dramatic effect on the short-period mode and elastic mode of the vehicle. It is also shown that the flexible degrees of freedom must be considered in the flight-control synthesis for this kind of vehicle.