谷神星一号运载火箭的时变模态参数辨识

Time-varying modal parameter estimation of the CERES-1 launch vehicle

针对运载火箭这一大型复杂系统,单纯依靠机理分析难以建立能够精确描述其时变特征的动力学模型,借助模态辨识技术获取其在飞行状态下的时变动力学特性尤为必要。面向运载火箭的飞行模态辨识需求,发展基于时变自回归滑动平均模型的仅输出递推辨识方法,引入指数加权遗忘机制进行时变特性跟踪,能够在激励未知的情况下仅基于响应数据准确快速辨识运载火箭的时变模态。以谷神星一号运载火箭为例,开展飞行遥测数据的快速处理,准确辨识发射准备阶段和飞行阶段的关键低阶时变模态,辨识结果与有限元分析结果的变化规律相互吻合,验证了所提时变模态仅输出递推辨识方法是有效可行的,服务了运载火箭有限元模型修正和姿控系统设计的实际工程需求。

It is usually difficult to establish the dynamic model of a launch vehicle that accurately describes its time-varying characteristics.Therefore modal identification techniques are particularly necessary to obtain the time-varying dynamic characteristics of launch vehicles under flight conditions.Aiming at the problem of in-flight modal identification of launch vehicles,an output-only recursive identification method based on the time-dependent autoregressive moving average model is developed by using exponentially weighted mechanisms to track the time-varying characteristics.Without measuring the natural excitation forces,the proposed method can accurately and quickly identify the time-varying modal parameters of launch vehicles by exclusively using the measured response signals.Taking the CERES-1 launch vehicle as an example,time-varying modal parameters before liftoff and during the flight phase are accurately estimated by processing the flight telemetry data.Identification results are consistent with the variation of the finite element analysis results,demonstrating the high achievable accuracy of the proposed method.The proposed in-flight modal identification method can obtain the full-cycle modal information of launch vehicles,which meets the engineering requirements for the finite element model updating and attitude control system design.