大型地基光电望远镜风载扰动抑制与补偿关键技术研究

As the diameter of the ground-based telescope increases, its resonance frequency decreases, which results in the increasingly influence of the external wind load on the system performance. The wind disturbance has become a difficulty in this research field. The two main axes and the primary and secondary mirror of the telescope are all controllable, a great advantage to cope with the external wind load disturbance. In this research, based on the combination of the advantages mentioned above, a new way that was used to suppress and compensate the effect of the wind load disturbance is presented. This research will use the theoretical analysis and numerical simulation method to analyze the dynamic properties of the telescope components and then to establish the mixed flexible-rigid dynamic model of the telescope. The reasonable model reduction method will be studied using this dynamic model, and then the overall performance oriented system model of the telescope can be established based on the linear optical model. In addition, this research will also study the strategies of the wind load disturbance suppression and compensation for the large ground-based telescope. To solve the difficulties of measuring the state variables and the coupling between the main axes control and the primary and secondary mirror control, the real-time wavefront information of the telescope is used as the feedback of the control system. This research can not only overcome the jitters of the telescope caused by the wind load disturbance, but also can compensate the optical aberrations introduced by the changes of the relative position of the primary and secondary mirror and the primary mirror deformation, which would maximize the system performance of the telescope. It will provide a theoretical basis for developing a larger scale ground-based telescope in the future, and has important significance in theory and practice.

随着地基望远镜口径的不断增大，谐振频率降低，外界风载扰动对系统性能的影响越来越显著，已成为该领域内的研究难点。针对风载问题，本项研究利用望远镜主轴伺服及主次镜可控这一优势，提出了一种基于望远镜主轴伺服控制与主次镜控制相结合的方式来抑制与补偿风载扰动。围绕该方式，拟采用理论分析与数值仿真相结合的方法，分析望远镜各部分的动态特性，建立结构刚柔混合动力学模型，研究合理的模型降阶方法，并基于线性光学模型建立面向总体性能的望远镜系统模型；研究望远镜风载扰动抑制与补偿策略，以系统实时波前信息作为控制系统的反馈来解决系统状态变量难以测量以及伺服控制与主次镜控制之间相互耦合的问题。本项研究不仅能够克服风载扰动造成的望远镜视轴抖动，还能够补偿因主次镜相对位置变化及主镜镜面变形而引入的系统像差，能够最大限度的提高望远镜系统性能，为未来研制更大尺度的地基望远镜提供理论依据，具有显著的理论研究意义和应用价值。

人们对宇宙奥秘的深入探索，推动了地基光学望远镜朝越来越大口径方向发展。然而，风扰动是影响地基大型光学望远镜系统性能的关键因素，随着望远镜口径的不断增大，影响越来越显著。风扰动分析与抑制问题是目前设备研制中的难点和热点问题。.本项目基于长春光机所研制的4m级地基光学望远镜，该望远镜是目前国内最大口径的地基望远镜，研究了望远镜风扰动分析与抑制问题，具体包括三个方面。在望远镜系统建模方面，建立了望远镜系统集成模型，包含结构动力学特性，光学系统偏差，主轴控制以及次镜位置控制，利用该模型实现了风扰动环境下望远镜光学系统性能模拟以及扰动抑制与补偿模拟。为了使所建立的结构动力学模型更符合实际情况，采用模态测试仪实测了望远镜的结构动态特性，并在此基础上进行了望远镜模型修正，从结果上看，低阶模态特性理论与实测结果基本一致。此外，针对原始望远镜结构动力学模型复杂计算效率低的问题，提出了一种有效的模型降阶方法，在同等条件下可以使模态阶数降低1/3，从而显著提高计算效率。在风速模拟方面，考虑到望远镜周围的实际风速环境，提出了一种基于二维随机场的风速模拟方法，所生成的风速场同时考虑时间和空间频率特性。在风扰动抑制方面，从仿真分析角度分别对几种不同扰动条件下的抑制效果进行了模拟，从结果上看，通过次镜位置控制补偿，可有效的降低风扰动的对望远镜光学系统的影响，在4望远镜上风扰动实验测试工作将在后续继续开展。.到目前为止，本项目已取得了多项研究成果，共发表论文10篇，其中SCI收录4篇，EI收录4篇，申请并授权发明专利5项。本项目中的关于望远镜系统集成建模仿真分析方法以及结构动态特性测试方法等为4米望远镜运行以及后续的工程项目论证提供了技术支持。