太赫兹望远镜副镜多维调整机构定标检测方法的研究

In order to overcome the pose error caused by gravity and environmental factors, a secondary mirror of an astronomical telescope often corrects for in real-time by a precision multi-degree-of-freedom(multi-DOF) mechanism to maintain its right alignment. A six-degree-of-freedom (6-DOF) parallel mechanism is the most preferable candidate, although, often, thanks to the symmetry of the optical system, the rotational DOF around the optical axis is needless to adjust. Seeing the demand for precision test and calibration of multi-DOF adjustment mechanisms used by secondary mirrors, and in view of the characteristics of that a secondary mirror operates in small displacement stroke but with high precision, the applicant hereby proposes a visual-based non-contact method for absolute position detection and calibration of secondary mirror multi-DOF adjustment mechanisms, on basis of prophase study on 6-DOF mechanisms applied in astronomy and related visual-based non-contact measurement. Specifically, first, i) We will research visual target encoding used for one-dimensional (1-D) absolute position detection and afterwards extend it to case of two-dimension (2-D)；ii) We will study algorithms of target recognition and decoding including target image processing methods; iii) We will analyse and assess the position detection performance and seek improvement methods; Afterwards, iv) we will apply the research achievements to multi-D pose measurement of telescope secondary mirrors; And finally, v) An experimental verification will be carried out. The research results of this project will first provide a convenient and practical method for the calibration demand of secondary mirrors adjustment mechanisms of China's optical/ infrared and terahertz telescopes, it will also contribute reference and knowledge to pose measurement and calibration of industrial parallel robots.

为克服重力和环境等因素造成的位姿误差，天文望远镜副镜常采用精密多维机构进行实时调整以保持其正确位姿。六自由度并联机构最常为采用，尽管往往得益于光学系统的对称性，绕光轴的转动自由度而无需调整。针对天文望远镜副镜多维调整机构位姿精密检测与标定的需求，并鉴于副镜位移具有行程小精度高等特点，本申请基于前期多维机构天文应用及其非接触检测的研究基础，提出一种非接触绝对位置检测方法用于副镜多维调整机构位姿的精密标定检测。具体地，首先开展一维绝对位置检测视觉靶标编码研究，并推广至二维；开展靶标识别算法及其图像处理方法研究，并深入研究其位置检测精度及精度提高方法；然后，将之研究应用于副镜多维机构位姿定标检测系统的构建；最后构建检测系统，开展实验验证。本项目的研究成果将首先为我国太赫兹、光学/红外望远镜研制所需求的副镜调整机构提供方便实用的检测和标定方法，也可为其它并联工业机器人的位姿检测和标定所应用和借鉴。

在执行本天文联合基金培育项目的三年内，针对项目研究内容和关键技术目标，项目组开展了认真细致的研究工作，按照项目计划，很好地完成了项目研究内容。本培育项目深入系统地研究了太赫兹望远镜副镜多维-6DOF-主动调整机构的定标检测方法，并开展了实验验证。完成了研究内容，掌握相关关键技术;构建了太赫兹/光学望远镜副镜多维调整机构位姿定标检测系统，实现了优异的技术指标目标:平动位移检测范围达+/-3 mm，定位精度 1 um RMS；角位移检测范围+/-1度，角位移测量精度达0.15” RMS。此外，面向太赫兹望远镜和光学望远镜的实际应用需求，还开展了副镜主动调整机构6DOF的在线/实时检测方法和技术研究；面向副镜位姿调整，开展了基于智能材料的大行程精密位移促动器作为位姿调整机构的支链的研究。本项目开展过程中提出的3SPS+3(SP-U)型六自由度机构，已获得发明授权并研制了原理样机，针对光学天文望远镜副镜调整机构的预期性能指标，开展了系统实验验证，与本项目完成的基于最大长度序列MLS的多维位移检测定标方法及提出的6DOF检测新方法，正开展针对性改进设计，均拟用于中国科学院云南天文台正在研制的2m环形太阳望远镜的副镜位姿调整。同时，依托本基金，与瑞典University West工程科学系主任建立了学术联系，项目合作与学生交流计划正在洽谈中。培养研究生4名，其中已毕业2名；发表论文6篇；申请发明专利7件，其中授权2件；参加相关国内学术会议5次；相关国际学术交流出访1次。