【作者】 董志强；

【导师】 段宝岩；

【作者基本信息】 西安电子科技大学 ， 机械制造及其自动化， 2003， 博士

【摘要】 本文是大射电望远镜(Large Radio Telescope)馈源舱支撑结构预研工作的组成部分，主要涉及馈源舱的减振与馈源舱位姿的测量两部分内容。 一．馈源舱的减振是本文的主要工作。利用有限元方法，模拟馈源舱支撑结构在风荷作用下的动力响应，在此基础上，讨论了多调谐质量阻尼器(MTMD)的特性及其在抑制馈源舱振动中的应用。具体内容如下： 1．通过优化策略，迭代求解出馈源舱支撑结构的静平衡位置，可使六根悬索的受力尽可能均匀一致。采用修正的Davenport风速谱模拟随机风，得出了馈源舱支撑结构在不同风速作用下的位移时程。 2．分析了单自由度结构附加MTMD后的频响特性，讨论了MTMD的质量、数量、控制频带宽度、阻尼比等因素对减振效果的影响。 3．采用多组MTMD抑制馈源舱的振动，分析了MTMD的组数、频率、质量、阻尼比等因素对馈源舱位移谐响应的影响。以基于Davenport风速谱的位移谐响应根方差为目标函数，应用遗传算法，在频域上获得了MTMD的最优参数值。 4．以馈源舱振幅的极小值作为目标函数，采用调优法，在时域上获得MTMD的最优参数值。 5．当馈源舱在观测轨迹的不同位置时，分析了系统在模拟风荷作用下的振动特性，并讨论了MTMD的适用性。 6．当馈源舱沿天文观测轨迹运动时，通过Fourier分析确定出MTMD的控制频带，实验结果表明，MTMD可有效抑制馈源舱在运动过程中的振动。 7．当馈源舱在不同位置受到冲击激励时，分析了MTMD的减振效果，实验结果表明，采用MTMD可有效抑制冲击激励引起的振动。 二．为了实现对馈源舱的高精度控制，需要精确测量馈源舱上不共线的三个目标点的坐标，实时确定馈源舱的位置和姿态。本文采用如下两种测量方法，并对测量结果进行了小波去噪处理： 1．立体视觉测量方法：采用三部CCD摄像机，每个摄像机同时跟踪两个目标点，每两个摄像机确定一个目标点的世界坐标。结合相关性跟踪算法、质心跟踪算法、置信度融合、目标和波门预测等技术，实现了抗干扰的动态多目标跟踪和高精度测量。 2．激光测量方法：采用三台激光全站仪，动态跟踪并测量馈源舱上三个棱镜中心点的坐标，并通过坐标变换得到馈源舱的位置与姿态。西安电子科技大学博士论文 3.由于立体视觉和激光全站仪测量得到的坐标均有误差，采用小波去噪技 术降低测量误差，可更精确地确定馈源舱的位置及运行轨迹。 在完成上述理论工作的基础上，在西安电子科技大学馈源舱支撑结构50米室外模型上实施了大量实验，取得了众多实验数据，结果表明，采用MTMD抑制馈源舱的振动、立体视觉和激光全站仪测量目标点的坐标及小波去噪均为有效的方法，为将来应用于500米射电望远镜的减振和测量，奠定了一定的理论基础。更多还原

【Abstract】 The works in the paper are parts of research work on the Large Radio Telescope(LT). Two parts are mainly concerned here: Vibration control of cabin and measurement.Firstly. Vibration control is the main research work in the paper. The followed work have been done:1. The static equilibrium equation for the Cabin Supporting Structure is solved by iteration, which could make the six cables loaded very closely. Based on the shape of the static balance, the dynamic response of the Cabin Supporting Structure is analyzed under the stochastic wind.2. The characters of the MTMD are analyzed. The tuned mass, amount, the damper ratio and tuned frequency spacing are the main influencing parameters to the vibration control. The effects of MTMD for vibration control with different parameters are analyzed for the single-freedom structure and multiple-freedom structure like cabin supporting structure.3. The GA (Genetic Algorithm) is applied to solve the optimal parameters of the MTMD appended in cabin in frequency-domain.4. The dynamic responses of the cabin with different MTMD are compared under different wind speed. Based on the analysis, the optimal MTMD with most effective parameters in time-domain is got, which could suppresses the vibration of cabin effectively.5. The dynamic characters of LT are analyzed when the cabin is located at different position on the working trace. The applicability of the MTMD for the cabin located at different position is discussed.6. Suppressing the vibration actuated by the six motors when the cabin moves along the working trace. The MTMD for the different positions are designed based on the Fourier analysis. The experiment shows that the MTMD with rectified parameters could suppress the vibration of cabin.7. When the cabin located on different working position is inducedto vibrate by some accidental instantaneous impacting load, the MTMD could attenuate the cabin’s vibration very quickly. Secondly. In order to realize the close-loop control to the cabin, three target points on the cabin must be got to solve the position and orientation of the cabin. Two methods are introduced to realize the precise measurement and the wavelet is applied to reduce the errors of the measured coordinates:1. Stereo Vision: three CCD cameras are applied to get the coordinates of three target points on the cabin. Every camera could trace two points, and two cameras could position a point. Dual-mode tracing methods and other rectified techniques are introduced to realize tracing precisely.2. Three Leica TCA1100 Laser Total Stations are utilized to trace and measure the center of the three reflecting prisms. The coordinates of the three targets could be got by translation and rotation of reference-system.3. There are errors during the measurement for both methods. The wavelet is introduced to de-noise the measured coordinates due to its sensitivity to the white noise on different scales. More precise coordinates of the cabin could be got after de-noise by wavelet.The analysis and experiments show that two parts of research work are effective and could be reference to LT.更多还原