一米太阳望远镜（New Vacuum Solar Telescope，以下简称NVST）是目前国内唯一的地平式真空太阳望远镜，主要用于实现0.3-2.5微米波段太阳的高分辨率成像和光谱观测。因此，望远镜必须能够长时间高精度地跟踪太阳。受各种因素影响，定位跟踪系统的开环长期跟踪精度达不到预期目标，表现为随观测时间的推移，太阳跨过不同天区，跟踪误差逐渐变大。考虑到跟踪的本质是连续指向的过程，可通过建立指向误差模型来提高NVST的开环长期跟踪精度。 本文首先介绍了NVST指向误差修正的相关背景，阐述了指向误差修正的原理和常用模型，对影响地平式望远镜指向的主要误差进行了分类和深入分析。在误差分析的基础上，基于地平式望远镜运动的动力学分析和简化D-H变换建立了NVST的理论初模型。结合国内外已有的一些模型进行了大量的数值模拟工作，为NVST实际指向误差模型的建立就模型函数选择、指向数据实测、局部指向修正和模型改进等方面提供相关参考。 实测阶段，首先针对跟踪信号中的小周期分量建立了位置测角系统的小周期误差模型以初步提高望远镜的跟踪精度。在此基础上采用跟踪法获取NVST在目标修正天区的指向数据并建立了NVST指向误差模型。该模型主要针对南北回归线之间的天区进行局部指向修正，不同于一般地平式望远镜的全天指向修正。实际应用表明该模型确实能够提高NVST的指向精度，基本可满足NVST的开环长期跟踪精度要求。 论文最后分析了研究工作的不足。以现在NVST所能提供的实验条件，实测误差较大，且所获取的观测资料较少，在一定程度上影响了模型性能。因此下一阶段的工作重点主要是提高实测精度和获取更多的观测数据以进一步提高模型的指向修正能力。展望了下一阶段的研究工作，包括实测方法的改进、模型参数估计精度的提高以及如何将信号分析手段应用到指向误差建模分析中等。
其他摘要
The 1m Infrared Solar Telescope (also named New Vacuum Solar Telescope, NVST for short) is the only altazimuth vacuum-tube solar telescope in China, mainly used to achieve solar high-resolution image and spectrum at wavelength range between 0.2 um to 2.5 um. Therefore, the telescope must be able to track the sun for a long time with high accuracy. Affected by various errors, the long-term open-loop tracking accuracy had not yet meet the requirement, which means the tracking error increases gradually when the sun across different sky areas. Considering that tracking is a process of continuous pointing, a pointing error model can be developed to improve the tracking accuracy of NVST. This paper firstly introduces the background of pointing error correcting for NVST, illustrates the principle of pointing error correction and then the main errors that influence the pointing direction of altazimuth telescope were analyzed and classified. Based on the error analysis, a preliminary theoreticalmodel was developed using kinematic analysis and simplified D-H convention. A lot of numerical simulation was then carried out, providing references for model function selection, pointing data measure, local pointing error model developing and model improvement and so on, which will be helpful when build the actual pointing error model for NVST. At experimental stage, a cycle model of position angle measuring system was built by analyzing the tracking error to improving the tracking accuracy. After that the required pointing data of NVST was get and then the pointing error model was developed. This model mainly aims at correcting the pointing error of the sky areas across the solar orbit, different from general ones. The application shows that the model can indeed improve the pointing accuracy and the requirement of long-term open-loop tracking accuracy of NVST is basically meet. Finally, the paper analyzes the lack of the research work. With the present experimental conditions, the quality and quantity of the obtained pointing data are not good enough and decrease the error correcting ability of the model. Thus the main focus of the next stage is to improve the measurement accuracy and get more pointing data. The prospect of future research includes improvement of measuring methods, improving model parameters estimates and how to apply the signal analysis tools to error modeling.
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