转台伺服系统的无超调设计

本文通过分析国内外陀螺漂移测试转台伺服系统的现有设计方案,对其伺服系统的无超调设计进行了探讨。最后采用了粗精双回路切换方案,这为提高测试转台的精度和动态性能提供了新的途径。     

Autonomous satellite navigation using starlight refraction angle measurements

An on-board autonomous navigation capability is required to reduce the operation costs and enhance the navigation performance of future satellites. Autonomous navigation by stellar refraction is a type of autonomous celestial navigation method that uses high-accuracy star sensors instead of Earth sensors to provide information regarding Earth’s horizon. In previous studies, the refraction apparent height has typically been used for such navigation. However, the apparent height cannot be measured directly by a star sensor and can only be calculated by the refraction angle and an atmospheric refraction model. Therefore, additional errors are introduced by the uncertainty and nonlinearity of atmospheric refraction models, which result in reduced navigation accuracy and reliability. A new navigation method based on the direct measurement of the refraction angle is proposed to solve this problem. Techniques for the determination of the refraction angle are introduced, and a measurement model for the refraction angle is established. The method is tested and validated by simulations. When the starlight refraction height ranges from 20 to 50 km, a positioning accuracy of better than 100 m can be achieved for a low-Earth-orbit (LEO) satellite using the refraction angle, while the positioning accuracy of the traditional method using the apparent height is worse than 500 m under the same conditions. Furthermore, an analysis of the factors that affect navigation accuracy, including the measurement accuracy of the refraction angle, the number of visible refracted stars per orbit and the installation azimuth of star sensor, is presented. This method is highly recommended for small satellites in particular, as no additional hardware besides two star sensors is required.     

电网时间同步技术标准制定

电网时间同步系统对电力工业非常重要,制定电网时间同步技术标准也很重要。介绍了国家电力公司华东公司的企业标准《华东电网时间同步系统技术规范》的制定过程和主要内容,并对编制中问题及其改进加以讨论,指出制定标准货柜繁殖是电力时间同步网建设的第一步,需要各方面的协作努力,尤其是管理、培训等“软件”工作跟上去,才能使电网的时钟等“硬件”设备充分发挥作用。     

北斗/GPS双频载波相位单点定位模型及精度分析

针对海洋工程实时米级绝对定位需求,利用双频伪距、载波相位观测量和同时估计接收机位置、接收机钟差和载波相位模糊度,构建了一种双频载波相位实时单点定位方法.亚太区域14个测站试验结果显示:北斗水平和高程定位RMS分别为1.33m和1.81m,GPS为0.60m和0.85m,北斗/GPS组合为0.56m和0.72m;船载动态...     

Error modeling and compensating of a novel 6-DOF aeroengine rotor docking equipment

In the docking process of aeroengine rotor parts, docking accuracy that indicates the gaps between the end faces is strictly required. A key issue is improving docking accuracy using automated docking equipment. In this paper, a systematic study is carried out on the error modeling and compensation of a novel six-degrees-of-freedom(6-DOF) docking equipment for aeroengine rotors. First, a new model for indicating the main indexes of docking accuracy is proposed. Then, the error model of a special...     

有限元仿真模型V&V技术研究

仿真模型建模过程存在多种误差输入，将引起仿真预测结果的不精确性。采用仿真模型V&V（Verification and Validation,验证与确认）技术，进行仿真模型的建模误差分析与控制。利用物理试验数据进行仿真模型的精度评估，基于模型修正算法进行仿真建模参数的自动修正，提升仿真和试验结果的一致性，帮助设计师基于精确的仿真模型进行产品的虚拟性能预示，提升仿真技术在产品研制流程中的地位和作用。阐述了模型V&V的概念和流程，对模型V&V的关键技术和原理进行了详细论述,以NASA Rotor37转子验模为例进行了V&V案例说明。