星载天线伸展臂间隙动态效应与指向精度诊断方法研究

The pointing accuracy of an antenna reflector is the key index to measure the observation resolution of satellites. The joint clearance existing in the space arm system, the only mechanism connecting the satellite body with the space-borne antenna, is the major cause of vibration aggravation of the arm end and deterioration of pointing accuracy of the antenna. This project focusing on the dynamic clearance effects of the space arm system is to study the pointing accuracy diagnosis method based on the clearance dynamic analysis and nonlinear system identification of the space arm system. Firstly, starting with the analysis of the physical characterization presented by the clearance effect, the contact modeling method of the joint clearance and the refinement method of the locking mechanism is to be studied and the dynamic model of the space arm system with joint clearance is to be constructed to reveal the interrelationship between the joint clearance and the arm end vibration. Then, the study of the nonlinear response reconstruction algorithm to be carried out is to realize the response reconstruction at the clearance joint from the response of the measurable reference position and the combining study of the reciprocal of probability density function of the axis and the describing function is to realize the dynamic extract of the clearance characteristics and the relevant diagnosis of pointing accuracy. Lastly, the effectiveness of the proposed method is to be validated through the joint clearance test and the satellite ground vibration test. This project is expected to make breakthroughs in the modeling and identification of nonlinear clearance system and achieve dynamic compensation of antenna pointing accuracy to provide technical support for the improvement of satellite observation resolution.

天线反射器指向精度是衡量卫星观测分辨率的关键指标，而伸展臂作为连接卫星本体与星载天线的唯一机构，其关节间隙的存在是造成伸展臂末端振动加剧，进而导致指向精度下降的重要原因。本项目拟聚焦于伸展臂间隙动态效应，研究基于间隙动力学分析和间隙非线性系统辨识的星载天线指向精度诊断方法。首先，从分析间隙效应所呈现的物理表征入手，研究关节间隙的接触建模方法和锁紧机构的细化建模方法，构建含间隙伸展臂的动力学模型，揭示间隙与伸展臂末端振动的关联关系；然后，研究非线性响应重构算法，实现由可测参考位置处响应向不可测间隙位置处响应的重构，并研究轴心概率倒谱法和描述函数图法，实现间隙特征的动态提取和指向精度的关联诊断。最后，通过铰间隙试验台测试和卫星地面振动试验，验证方法有效性。项目预期在间隙非线性系统建模和识别上取得突破，为实现天线指向偏差动态补偿，提高卫星观测分辨率提供技术保障。

星载天线指向精度是衡量卫星观测分辨率的重要指标。空间伸展臂作为卫星本体与星载天线间的唯一连接机构，其展开关节中间隙的存在对系统动态稳定性和天线指向精度有着重要的影响。项目针对星载天线伸展臂间隙动态效应，研究了基于含铰间隙伸展臂动力学分析和间隙非线性系统辨识的星载天线指向精度诊断方法。建立了展开和锁紧时伸展臂碰撞-接触-分离三状态铰间隙接触力模型，分析了间隙对伸展臂末端振动的影响；考虑到间隙在装置的内部，使用中难以直接测量，提出了响应重构方法和轴心概率密度倒谱方法，实现了伸展臂铰间隙大小和接触刚度的测量；设计和搭建了模拟空间环境力学状态的含铰间隙伸展臂试验台，开展实验工作。实验结果表明，项目所提出的铰间隙识别轴心概率密度倒谱方法，在单间隙和双间隙参数识别中，间隙值识别误差<1%，接触刚度识别误差<2%。研究工作为卫星天线指向精度诊断提供基础理论和方法，为实现卫星在轨状态下天线指向偏差动态补偿，提高卫星观测分辨率提供技术保障。