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浏览/检索结果: 共3条，第1-3条 帮助 限定条件 内容类型：会议论文     已选(0)清除 条数/页：5101520253035404550556065707580859095100   排序方式：请选择作者升序作者降序题名升序题名降序发表日期升序发表日期降序提交时间升序提交时间降序 United steering of control moment gyros for small satellite with limited gimbal rate (EI CONFERENCE) 会议论文 2010 IEEE International Conference on Information and Automation, ICIA 2010, June 20, 2010 - June 23, 2010, Harbin, Heilongjiang, China Xu K.; Jin G.; Chen C. 收藏  |  浏览/下载：15/0  |  提交时间：2013/03/25 Single Gimbal Control Moment Gyroscopes (SGCMG) can could provide large control torque and quick attitude maneuver rate to small satellites without any increase in power  volume and mass  which will help small satellites become more powerful. Singularity avoidance and failure steering are two important problems to SGCMGs and also the main focus in this field. A new united steering law for SGCMGs with capabilities of singularity avoidance and quick transition of singularity surfaces is developed in this paper. To ensuring the existence of null motion  the commanded output of controller was changed real-timely as the variation of singularity measurement of SGCMGs  which can avoid the gimbal angle rate saturation. This developed steering law could help the SGCMGs provide real-time control toques in spite of limitation of gimbal angle rate. Simulation analysis is conducted for a certain 4-SGCMG system mounted on a small satellite. Simulation results indicate that the steering law is very effective in singularity avoidance. 2010 IEEE.   Design and tolerance analysis of compensator for high order aspheric surface testing (EI CONFERENCE) 会议论文 2009 International Conference on Optical Instruments and Technology - Optoelectronic Measurement Technology and Systems, October 19, 2009 - October 22, 2009, Shanghai, China Chen X.; Liu W.; Kang Y.; Wei Z. 收藏  |  浏览/下载：18/0  |  提交时间：2013/03/25 High accuracy is required in surface testing of 90nm nodal point lithography projecting lens. By comparing various aspheric surface testing methods  the structure layout of the compensator is a meniscus positive lens combined with a Plano-convex positive lens. The design results indicate that: primary and high order aberrations are balanced well  we adopt Offner null compensator to test the aspheric surface in the point diffraction interferometer at last. In this paper  MTF exceeds diffraction limit  an Offner compensator is presented on the base of the third order aberration theory to test concave aspheric surface  root-mean-square (RMS) of wave front error /167. The F-number of the system can achieve F/1.64. By the analysis of the process of aspheric surface testing with the designed system  the optical construction parameters of which is determined by introducing equal-quantities spherical aberration to compensate all orders of aspheric coefficients. The field of view of the system is 0.02  a loosen distribution of the tolerance was presented based on the accuracy of measuring apparatus. 2009 SPIE.   A Novel RFID Transceiver Architecture with Enhanced Readability (CPCI-S收录) 会议论文 2007 INTERNATIONAL CONFERENCE ON WIRELESS COMMUNICATIONS, NETWORKING AND MOBILE COMPUTING, VOLS 1-15 作者:  Zheng, Shipu[1,2];  Yu, Fengqi[1];  Zhu, Yuesheng[2] 收藏  |  浏览/下载：5/0  |  提交时间：2019/04/17 readability  field null  multipath  dead zoned  RFID