推力协同的大柔性飞行器纵向姿态控制

为了研究大柔性飞行器飞行/结构耦合动力学特性，提出了改进的面向控制的大柔性飞行器多体模型，开展了大柔性飞行器纵向动力学耦合特性分析与推力协同下纵向姿态控制律设计。采用二面角动态近似描述大柔性飞行器结构动力学特征，并推导了纵向耦合动力学模型。根据改进模型在配平点处的线性化模型，分析了飞行/结构耦合系统的纵向稳定性与结构变形量之间的关系。针对大柔性飞行器姿态稳定与跟踪，设计了纵向姿态控制器。与常规飞行器相比，大柔性飞行器飞行过程中会发生大变形，当载荷较大时，配平构型近似“U”形，此时纵向动力学具有长周期不稳定的特征。分析结果表明:大柔性飞行器各模态之间的耦合程度随着变形的增大而增大。此外，纵向姿态控制需要升降舵与推力协同控制速度和俯仰角并且考虑结构动力学的影响，否则飞行/结构的耦合作用会导致姿态跟踪误差衰减缓慢甚至发散。 

Longitudinal attitude control for very flexible aircraft with thrust cooperation

The improved multi-body model of very flexible aircraft was proposed to analyse the flight/structure coupled dynamics characteristics of very flexible aircraft,the longitudinal dynamics characteristics of very flexible aircraft were studied and the longitudinal attitude controller was designed.The dynamics of dihedral angle was used to approximate the structural dynamics characteristics of very flexible aircraft,and the coupled longitudinal dynamics model was derived.The improved model was trimmed under different load conditions,and the relationship between the stability and deformation of the system was analyzed according to the linearized model at the equilibrium point.The longitudinal attitude controller was designed for attitude stabilization and tracking of very flexible aircraft.Compared with conventional aircrafts,large deformation occurs during the flight of very flexible aircraft.When the load was large,the trimmed configuration was approximately “U” shaped,and the longitudinal phugoid period was unstable.The results showed that as the deformation increased,the coupling between the modes increased.The longitudinal attitude control of very flexible aircraft needed to control the velocity at the same time and takes the coupled structure dynamics into account,otherwise,due to the coupling effect between structure and flight dynamics,the system will even be divergent.