| 其他摘要 | With the development of aerospace activities in various countries, the exploration of spatial goals has entered a new wave. In actual tracking and observation, if the focus is not correct, it will be impossible to obtain a clear image of the observed target.Driven by modern information technology, a convenient, efficient, and excellent image processing automatic focus technology has been widely used in the telescope system. This thesis studies the application of autofocus technology based on digital image processing in the 1.2m telescope of Yunnan Observatory from the perspective of feasibility and practicality, ensuring that the telescope remains in the optimal optical state to improve the detection ability of the ranging system for space targets. The main research work carried out is as follows:(1) Explore the system departure mechanism from the perspective of image convolution,and discuss the impact of the focusing process of optical parameter focusing in depth of field. The advantages and disadvantages and applicable scope of the mainstream focus algorithm were analyzed, and the focus depth method was selected as the focus algorithm based on the focus requirements.(2) Based on the imaging characteristics of the telescope and the reasons that affect the defocusing of the 1.2m telescope system at Yunnan Observatory, a detailed algorithm for achieving automatic focusing of the telescope has been designed.The algorithm mainly includes: image pre -processing, determine the centroid of the star image,focus evaluation, and focus search.A HFD-ICA focusing evaluation algorithm has been proposed, which can handle heavily defocused targets by improving the accuracy of star image centering. It is proven by experiments that the algorithm effectively improves accuracy of focus detection and meets the single peak, non -biased, stability,noise resistance, and real -time requirements.(3)According to different focusing conditions, three focus search algorithms are designed:iterative method, hyperbola fitting method and quadratic function fitting method.The iterative method is suitable for targets with small external interference and small defocus.The hyperbola fitting method is suitable for focusing 90% of the target, and its fitted V curve reflects the characteristics of the optical system composed of focus, telescope and imaging equipment. If such a V-shaped focusing model can be found in the system, the computer can save time and cost by calling algorithms during the actual focusing process. The quadratic function fitting method is a supplement to the hyperbolic fitting method, which is used in the scenario where the hyperbola fitting method fails. Finally, a temperature compensation module and a visibility compensation module were designed to further optimize the focusing model, resulting in higher accuracy of the obtained focal position. (4) The automatic focusing system based on INDI is implemented. The hardware part includes imaging control components, CMOS cameras, focus control modules,communication modules, etc. Software development is based on Ubuntu 20.04.3LTS system. It uses QT framework to create technical independent interfaces for related astronomical devices (cameras, focus, etc.),The software consists of data collection,information processing, focus search, and information transmission. The software interface is easy to operate, and has the advantages of flexibility, stability, and security.For Linux, use INDI to achieve hardware communication, and select CMAKE as the construction tool. After the analysis of the automatic focus experiment, the function of the automatic focus system fulfillment the design requirements and can enhance the observation efficiency of the telescope. |
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