大比例尺立体测绘缩比相机主支撑结构设计

	大比例尺立体测绘缩比相机主支撑结构设计
其他题名	Design of Supporting Structure forthe Large-scale Stereo-mapping Shrunken Space Camera
	席佳利
学位类型	硕士
导师	张雷
	2015
学位授予单位	中国科学院大学
学位专业	机械工程
关键词	主支撑结构随机响应动力学优化设计立体测绘相机离轴三反相机桁架
摘要	随着立体测绘技术的不断发展，立体测绘相机光学系统对焦距、视场角，入瞳直径方面的要求愈来愈高，立体测绘相机的设计和加工难度愈来愈大。离轴三反光学系统通过多次转折光路，可以在保持焦距不变的条件下有效缩短相机尺寸。一方面，离轴三反光学系统具有较容易控制系统的杂散辐射，没有中心遮拦损失，能量利用率高，不存在色差，可设计变量多等优点，在立体测绘相机领域具有很大的应用潜力。另一方面，离轴三反光机系统结构非轴对称，其主支撑结构设计和系统装调是公认的难点。针对当前由传统结构设计方法向优化设计方法，由基于静载荷的设计方法向基于动载荷设计方法转变的必要性和趋势，本课题以某立体测绘缩比相机研制为背景进行离轴三反立体测绘相机主支撑结构的优化设计方法研究。针对该相机在立体测图精度和结构质量等方面的要求，将随机响应最小化拓扑优化设计方法引入到离轴三反立体测绘相机主支撑结构设计中。主要进行了以下几方面研究工作： 1.分析了该立体测绘缩比相机及其前/后视相机的光学系统，其前/后视相机具有相同的结构形式，采用了相同的离轴三反光学系统，其主支撑结构设计是该立体测绘缩比相机主支撑结构设计的关键。从立体测图角度分析了测绘相机对交会角、内方位元素和传递函数等指标的要求，对总体给出的相机主支撑结构设计指标进行了说明。2.针对光学系统的特点和要求，优选了主支撑结构形式和材料；根据总体对重力载荷下相机的位移、随机振动下次镜的响应以及相机结构一阶频率方面的要求，进行了该结构的随机响应最小化拓扑优化设计，所得结果具有较高的参考价值。在此基础上得到了结构的尺寸优化初始有限元模型，经动力学尺寸优化得到了前/后视相机的桁架式主支撑结构，其质量约为3.8Kg。该主支撑结构的动力学分析和该相机的热分析表明主支撑结构满足各项设计要求。 3.对该相机主支撑结构进行了0.1g的正弦扫描试验和2gRMS的随机振动试验。试验表明主支撑结构的一阶频率为291.4Hz，随机振动试验前后次镜特征点在X、Y、Z 向的扫描响应曲线吻合程度很高，说明该主支撑结构具有较好的刚度和稳定性。次镜沿光轴方向的随机响应放大率得到了有效控制。有限元分析结果与动力学试验结果间最大误差为6.0%，满足工程分析精度要求。证明了本文提出的主支撑结构设计方法的正确性和该结构的合理性。 4.设计工装连接前/后视相机，保持前视相机坐标系X 轴竖直向上，后视相机坐标系X 轴竖直向下状态，进行了该测绘相机交会角、传递函数和内方位元素的标定。标定结果表明：立体测绘缩比相机交会角为22.6023°，相对偏差约为0.01%。前/后视相机在Nyquist 频率处的调制传递函数均大于0.1。前/后视相机的相对畸变均约为0.05%。相机的各种光学性能指标均满足要求，说明了该相机主支撑结构具有很好的刚度和稳定性。本文提出的设计方法可以将随机响应纳入离轴三反立体测绘相机的结构设计过程，能在较大程度上降低结构关键部位的随机响应，优化结构的动力学特性。本文提出的优化策略也可用于其他同型相机主承力结构设计。
其他摘要	With the development of stereo-mapping camera technology, the design and processing of the stereo-mapping camera is more and more difficult because of the more and more strict requirements to the key index of the optical system. The off-axis three-mirror optical system has the great advantage of making the space camera shorter in the application process. On the one hand, the off-axis three-mirror optical system could be used widely because of the unique advantages. On the other hand, the design of the supporting structure for this optical system is a generally acknowledged difficulty. The optimization design method based on dynamic load of the supporting structure for the off-axis three-mirror optical system applied in the stereo-mapping space camera was studied in this paper. In order to meet the requirements on mapping accuracy and the weight of the camera, the topology optimization design theory to minimize the random response was introduced to the processing of designing the supporting structure for the stereo-mapping space camera. The main work is as follows: 1. The optical systems of the stereo-mapping space camera and its optical lenses were analyzed. The same off-axis optical system was used for these two lenses. The design of the supporting structure for these two lenses was the key to the design of the supporting structure for the stereo-mapping space camera. The requirements to supporting structure for this space camera were given. 2. According to the characteristics and requirements of this optical system, the form and the materials of the supporting structure were determined. According to the design requirements of the space camera, a topology optimization design to minimize the random response was conducted, which could provide the references to the design of the supporting structure for other space cameras. Based on the result of the topology optimization design, a dynamic dimension optimization was conducted. Then a supporting structure was obtained. The dynamic analysis and the thermal analysis were conducted. It shows that this supporting structure could meet the major requirements of the key index. 3. The sine sweep test of 0.1g and the random vibration test of 2gRMS were carried out to this supporting structure for the camera. The difference between the secondary mirror’s response curve under sinusoidal scan before the random vibration test and that after the random vibration test is very small. It shows that the fundamental frequency reaches 181.4Hz and the supporting structure has a good quality of stability. The random response of the secondary mirror in optical axis is controlled effectively. The maximum error between the data from the finite element analysis and the data from test is 6%, which meets the requirements to engineering analysis accuracy. The correctness of the design theory of this supporting structure and the rationality of the structure are Indicated. 4. Various important parameters of the camera were detected. The intersection angle of this stereo-mapping space camera is 22.6023, and the relative deviation is about 0.01%. The modulation transfer function of the optical lenses is all more than 0.1 in the frequency of Nyquist. The relative distortion of the two optical lenses is all about 0.05%. All kinds of design indexes could be met, which shows that the supporting structure of this camera has a good rigidity and stability. The design method proposed in this paper could be used to control the random response of the space cameras. The optimization strategy of this trussed supporting structure could provide some references to the other space cameras with the same type.
语种	中文
文献类型	学位论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/49290
专题	中科院长春光机所知识产出
推荐引用方式 GB/T 7714	席佳利. 大比例尺立体测绘缩比相机主支撑结构设计[D]. 中国科学院大学,2015.

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