FAST望远镜两轴转向机构结构方案优化  

Optimal Designs of the Structure Configuration of the Two-Axis Steering Mechanism of the FAST

作　　者：张新宇[1,2] 李辉[1] 杨世模[1] 

机构地区：[1]中国科学院国家天文台,北京100012 [2]中国科学院研究生院,北京100049

出　　处：《天文研究与技术》2011年第3期220-228,共9页Astronomical Research & Technology

基　　金：国家自然科学基金(10973023);中国科学院国家天文台青年人才基金资助

摘　　要：FAST馈源支撑系统承载和驱动馈源运动,进行对天体的高精度跟踪观测。在实时的定位调整中,两轴转向机构起着辅助调整接收机姿态角的作用。为满足FAST两轴转向机构的重量及刚度要求,选择了一种空间刚架式的结构构型。提出了反映结构柔顺度及重量约束的目标函数,以各类杆件的截面面积以及整个结构的高度、半径等几何参数作为优化变量,采用以无量纲的参数灵敏度为基础,通过一维搜索实现的最速下降法作为优化算法,对不同初始条件下的优化参数进行了优化设计。优化结果偏离度较小,可以认为在一定优化变量范围内达到了目标函数最优解。利用同样的方法,以各个高度控制点高度为优化参数,通过改变控制点高度沿圆环的高度分布得到一种变高度形式的结构方案,经验证变高度结构方案优于等高度结构方案。The feed support system of the Five-hundred-meter Aperture Spherical Telescope（FAST）suspends and drives the receiver to track astronomical objects in high precision for observation.A two-axis steering mechanism has an auxiliary function in the process of real-time adjustment of the feed position and altitude angle.We design such a mechanism of truss configuration to satisfy requirements on mass and rigidity.In numerical optimization of the designs,we use an objective function reflecting constraints on compliance and weights and adopt cross sections of various rigid rod components and geometrical parameters of the structure as variables.The optimization is subsequently achieved by the steepest descent method of 1-dimensional search,which is based on the sensitivity analysis of the variables（reduced to be dimensionless）in each iteration.Several sets of initial conditions for optimization have been randomly generated.Corresponding optimum results have small mutual deviations.With the similar optimization method but using nine controlling points of heights as variables,we find a design of configuration with varying heights along the ring of the mechanism.Numerical experiments favor the varying-height design as it has higher stiffness-to-mass ratios.

关 键 词：结构优化 大射电望远镜 馈源支撑 有限元 形状优化 

分 类 号：O342[理学—固体力学]