大口径望远镜轴系的抖动测量

发布时间：2019-01-28 10:54

【摘要】：随着太空探索的深入，大口径望远镜的跟踪精度要求越来越高。望远镜系统的抖动会引起视轴偏差，影响跟踪精度，造成成像模糊。为了达到高精度跟踪，降低系统本身误差，需要对系统的抖动进行测量评估。首先描述了抖动测量的需求分析，并据此设计系统的总体方案，包括测量工具的选择，数据采集系统核心控制器的选择等。详细介绍了测量工具——线性加速度计的测量原理及规格参数，并介绍了数据采集系统的功能，经分析比较选择DSP作为采集系统的核心控制器，辅以CPLD完成数据采集任务。其次详细阐述了数据采集系统的硬件设计和软件设计。硬件电路设计分为加速度计输出信号调理电路设计和数据采集电路设计，给出了各功能模块的电路原理图，并叙述其工作原理。软件设计包括DSP主程序设计和CPLD程序设计，给出主要任务功能模块的程序设计。对设计的CPLD程序进行了仿真，得到的时序能够符合要求，并对整个系统进行调试，结果表明设计的数据采集系统能够完成抖动数据的采集任务。再次研究了数字信号处理技术在抖动数据处理中的应用。详细分析了小波去噪技术的原理，，并对算法进行了仿真验证。详细介绍了将时域信号转为频域信号分析的功率谱估计方法，并对不同的功率谱估计方法进行了仿真比较。最后在小转台和1.23米望远镜平台上搭建了抖动测量系统，完成实验。实验结果表明，1.23米望远镜轴系的位置抖动能够保持在0.4角秒以下，小转台轴系的抖动比较大，实验验证了提出的大口径望远镜抖动测量方案的可行性。根据加速度的测量方法，提出在直流电机控制系统中加入加速度负反馈，来抑制抖动等干扰。仿真结果表明，加入加速度反馈能够提高系统对干扰的抑制能力。
[Abstract]:With the development of space exploration, the tracking accuracy of large-aperture telescope is higher and higher. The jitter of the telescope system will cause the deviation of the axis of view, affect the tracking accuracy and make the imaging blurred. In order to achieve high precision tracking and reduce the system error, it is necessary to measure and evaluate the system jitter. Firstly, the requirement analysis of jitter measurement is described, and the overall scheme of the system is designed, including the selection of measuring tools and the selection of the core controller of the data acquisition system. The measuring principle and specification parameters of linear accelerometer, a measuring tool, are introduced in detail, and the function of data acquisition system is introduced. DSP is chosen as the core controller of the acquisition system through analysis and comparison, and CPLD is used to complete the data acquisition task. Secondly, the hardware design and software design of the data acquisition system are described in detail. Hardware circuit design is divided into accelerometer output signal conditioning circuit design and data acquisition circuit design. The circuit schematic diagram of each functional module is given and its working principle is described. The software design includes DSP main program design and CPLD program design. The simulation of the designed CPLD program shows that the timing can meet the requirements and the whole system is debugged. The results show that the designed data acquisition system can complete the task of collecting jitter data. The application of digital signal processing technology in jitter data processing is studied again. The principle of wavelet denoising is analyzed in detail, and the algorithm is verified by simulation. In this paper, the power spectrum estimation method which converts time domain signal into frequency domain signal analysis is introduced in detail, and different power spectrum estimation methods are simulated and compared. Finally, the jitter measurement system is built on the small turntable and 1.23 m telescope platform, and the experiment is completed. The experimental results show that the position jitter of the 1.23m telescope shafting system can be kept below 0.4 angle seconds, and that of the small turntable shafting system is relatively large. The feasibility of the proposed method is verified by experiments. According to the measurement method of acceleration, the acceleration negative feedback is added to the DC motor control system to suppress the disturbance such as jitter. The simulation results show that adding acceleration feedback can improve the interference suppression ability of the system.
【学位授予单位】：中国科学院研究生院(长春光学精密机械与物理研究所)
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TH751

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