Five hundred meter aperture spherical radio telescope (FAST) will be the largest radio telescope in the world. The innovative engineering concept and design pave a new road to realizing a huge single dish in the most ...Five hundred meter aperture spherical radio telescope (FAST) will be the largest radio telescope in the world. The innovative engineering concept and design pave a new road to realizing a huge single dish in the most effective way. Three outstanding features of the telescope are the unique karst depressions as the sites, the active main reflector which corrects spherical aberration on the ground to achieve full polarization and a wide band without involving a complex feed system, and the light focus cabin driven by cables and servomechanism plus a parallel robot as secondary adjustable system to carry the most precise parts of the receivers. Being the most sensitive radio telescope, FAST will enable astronomers to jumpstart many of the science goals, for example, the neutral hydrogen line surveying in distant galaxies out to very large redshifts, looking for the first shining star, detecting thousands of new pulsars, etc. Extremely interesting and exotic objects may yet await discovery by FAST. As a multi-science platform, the telescope will provide treasures to astronomers, as well as bring prosperity to other research, e.g. space weather study, deep space exploration and national security. The construction of FAST itself is expected to promote the development in high technology of relevant fields.展开更多
A Stewart platform is introduced in thc 500 m aperture spherical radio telescope（FAST） as an accuracy adjustable mechanism for teed receivers. Accuracy analysis is the basis of accuracy design. However, a rapid and ...A Stewart platform is introduced in thc 500 m aperture spherical radio telescope（FAST） as an accuracy adjustable mechanism for teed receivers. Accuracy analysis is the basis of accuracy design. However, a rapid and effective accuracy analysis method for parallel manipulator is still needed. In order to enhance solution efficiency, an interval analysis method（lA method） is introduced to solve the terminal error bound of the Stewart platform with detailed solution path. Taking a terminal pose of the Stewart platform in FAST as an example, the terminal error is solved by the Monte Carlo method（MC method） by 4 980 s, the stochastic mathematical method（SM method） by 0.078 s, and the IA method by 2.203 s. Compared with MC method, the terminal error by SM method leads a 20% underestimate while the IA method can envelop the real error bound of the Stewart platform. This indicates that the IA method outperforms the other two methods by providing quick calculations and enveloping the real error bound of the Stewart platform. According to the given structural error of the dimension parameters of the Stewart platform, the IA method gives a maximum position error of 19.91 mm and maximum orientation error of 0.534°, which suggests that the IA method can be used for accuracy design of the Stewart platfbnn in FAST. The 1A method presented is a rapid and effective accuracy analysis method for Stewart platform.展开更多
500 m口径球面射电望远镜(Five-hundred meter aperture spherical radio telescope,FAST)馈源舱主要用于实现馈源的精调定位,馈源舱的精度控制机构即其内部的Stewart平台,根据控制方案可将馈源舱的精度分析研究简化为该Stewart平台的...500 m口径球面射电望远镜(Five-hundred meter aperture spherical radio telescope,FAST)馈源舱主要用于实现馈源的精调定位,馈源舱的精度控制机构即其内部的Stewart平台,根据控制方案可将馈源舱的精度分析研究简化为该Stewart平台的精度分析研究。根据馈源舱实际工况及控制方案,提出三类馈源舱定位精度主要影响因素,基于索驱动控制误差分析及舱索耦合情况,分析得到为避免舱索耦合而形成的馈源舱控制残差;考虑馈源舱的低刚度性,基于Stewart平台控制方案及结构变形分析参数,采用蒙特卡洛与区间分析方法得到结构变形造成的馈源舱定位误差;分析馈源舱实际测量手段得到测量误差,最终得到三类影响因素下馈源舱定位精度综合评估值。通过建立半物理仿真模型,使用仿真软件模拟实际工况及舱索耦合特性,以实际的馈源舱内机构为试验对象,试验验证了馈源舱精度分析的准确性,并为馈源舱后续调试及应用提供了必要的控制参数和参考。展开更多
射电天文的发展需要更宽的观测频率,但是随着通讯的不断发展,射频无线电干扰(Radio Frequency Interference,RFI)对射电观测的影响日益加重,射电望远镜需要选择电磁环境优良的站址并进行保护.文中描述了目前国内在建和预研阶段的望远镜...射电天文的发展需要更宽的观测频率,但是随着通讯的不断发展,射频无线电干扰(Radio Frequency Interference,RFI)对射电观测的影响日益加重,射电望远镜需要选择电磁环境优良的站址并进行保护.文中描述了目前国内在建和预研阶段的望远镜的电磁环境的测试过程,阐述了数据分析和处理方法.通过对我国射电望远镜台址选择和保护进行的电磁环境测试,优选出适合建立大型射电望远镜的台址.展开更多
基金the Chinese Academy of Sciences and the National Natural Science Foundation of China (Grant No. 10433020).
文摘Five hundred meter aperture spherical radio telescope (FAST) will be the largest radio telescope in the world. The innovative engineering concept and design pave a new road to realizing a huge single dish in the most effective way. Three outstanding features of the telescope are the unique karst depressions as the sites, the active main reflector which corrects spherical aberration on the ground to achieve full polarization and a wide band without involving a complex feed system, and the light focus cabin driven by cables and servomechanism plus a parallel robot as secondary adjustable system to carry the most precise parts of the receivers. Being the most sensitive radio telescope, FAST will enable astronomers to jumpstart many of the science goals, for example, the neutral hydrogen line surveying in distant galaxies out to very large redshifts, looking for the first shining star, detecting thousands of new pulsars, etc. Extremely interesting and exotic objects may yet await discovery by FAST. As a multi-science platform, the telescope will provide treasures to astronomers, as well as bring prosperity to other research, e.g. space weather study, deep space exploration and national security. The construction of FAST itself is expected to promote the development in high technology of relevant fields.
基金supported by National Natural Science Foundation of China (Grant Nos. 10973023,11103046,11203048)
文摘A Stewart platform is introduced in thc 500 m aperture spherical radio telescope（FAST） as an accuracy adjustable mechanism for teed receivers. Accuracy analysis is the basis of accuracy design. However, a rapid and effective accuracy analysis method for parallel manipulator is still needed. In order to enhance solution efficiency, an interval analysis method（lA method） is introduced to solve the terminal error bound of the Stewart platform with detailed solution path. Taking a terminal pose of the Stewart platform in FAST as an example, the terminal error is solved by the Monte Carlo method（MC method） by 4 980 s, the stochastic mathematical method（SM method） by 0.078 s, and the IA method by 2.203 s. Compared with MC method, the terminal error by SM method leads a 20% underestimate while the IA method can envelop the real error bound of the Stewart platform. This indicates that the IA method outperforms the other two methods by providing quick calculations and enveloping the real error bound of the Stewart platform. According to the given structural error of the dimension parameters of the Stewart platform, the IA method gives a maximum position error of 19.91 mm and maximum orientation error of 0.534°, which suggests that the IA method can be used for accuracy design of the Stewart platfbnn in FAST. The 1A method presented is a rapid and effective accuracy analysis method for Stewart platform.
文摘500 m口径球面射电望远镜(Five-hundred meter aperture spherical radio telescope,FAST)馈源舱主要用于实现馈源的精调定位,馈源舱的精度控制机构即其内部的Stewart平台,根据控制方案可将馈源舱的精度分析研究简化为该Stewart平台的精度分析研究。根据馈源舱实际工况及控制方案,提出三类馈源舱定位精度主要影响因素,基于索驱动控制误差分析及舱索耦合情况,分析得到为避免舱索耦合而形成的馈源舱控制残差;考虑馈源舱的低刚度性,基于Stewart平台控制方案及结构变形分析参数,采用蒙特卡洛与区间分析方法得到结构变形造成的馈源舱定位误差;分析馈源舱实际测量手段得到测量误差,最终得到三类影响因素下馈源舱定位精度综合评估值。通过建立半物理仿真模型,使用仿真软件模拟实际工况及舱索耦合特性,以实际的馈源舱内机构为试验对象,试验验证了馈源舱精度分析的准确性,并为馈源舱后续调试及应用提供了必要的控制参数和参考。
文摘射电天文的发展需要更宽的观测频率,但是随着通讯的不断发展,射频无线电干扰(Radio Frequency Interference,RFI)对射电观测的影响日益加重,射电望远镜需要选择电磁环境优良的站址并进行保护.文中描述了目前国内在建和预研阶段的望远镜的电磁环境的测试过程,阐述了数据分析和处理方法.通过对我国射电望远镜台址选择和保护进行的电磁环境测试,优选出适合建立大型射电望远镜的台址.
