On the analysis of active reflector supporting manipulator for the large spherical radio telescope

Mechatronics ◽  
2004 ◽  
Vol 14 (9) ◽  
pp. 1037-1053 ◽  
Author(s):  
Xiaoqiang Tang ◽  
Jinsong Wang ◽  
Hui Zhang ◽  
Qiming Wang
Author(s):  
Y X Su ◽  
B Y Duan ◽  
R D Nan ◽  
B Peng

An optomechatronics design project for the pilot of an Arecibo-type large spherical radio telescope for the square kilometre array (SKA) is proposed, concentrating on the feed-supporting system with large-span cables. The feed-supporting system consists of two parallel manipulators: the parallel cable manipulator, which provides a large workspace for the trajectory tracking and realizes the coarse tracking control, and the fine-tuning Stewart platform, which connects the parallel cable manipulator to the cabin structure and implements the high-accuracy requirement of tracking. In order to improve the real-time controllability, an approximate kinematics model of the parallel cable manipulator is developed using straight links to approximate the cables based on static equilibrium at low tracking velocity. A control strategy for the feed-supporting system is proposed using the independent control method, and the corresponding tracking accuracy of the coarse control and fine tuning is presented. The simulation results have supported the rationale of this approximate model of the parallel cable manipulator and the feasibility of this mechatronics design project for the SKA.


2016 ◽  
Vol 24 (7) ◽  
pp. -1
Author(s):  
李爱华 LI Ai-hua ◽  
周国华 ZHOU Guo-hua ◽  
李国平 LI Guo-ping ◽  
张 勇 ZHANG Yong ◽  
张振超 ZHANG Zhen-chao

Author(s):  
Jian-Ling Li ◽  
Bo Peng ◽  
Cheng-Jin Jin ◽  
Hui Li ◽  
Richard G Strom ◽  
...  

Abstract The Five-hundred-meter Aperture Spherical radio Telescope (FAST), the largest single dish radio telescope in the world, has implemented an innovative technology for its huge reflector, which changes the shape of the primary reflector from spherical to that of a paraboloid of 300 m aperture. Here we explore how the current FAST sensitivity can potentially be further improved by increasing the illuminated area (i.e., the aperture of the paraboloid embedded in the spherical surface). Alternatively, the maximum zenith angle can be increased to give greater sky coverage by decreasing the illuminated aperture.Different parabolic apertures within the FAST capability are analyzed in terms of how far the spherical surface would have to move to approximate a paraboloid. The sensitivity of FAST can be improved by approximately 10% if the aperture of the paraboloid is increased from 300 m to 315 m. The parabolic aperture lies within the main spherical surface and does not extend beyond its edge. The maximum zenith angle can be increased to approximately 35 degrees from 26.4 degrees, if we decrease the aperture of the paraboloid to 220 m. This would still give a sensitivity similar to the Arecibo 305 m radio telescope. Radial deviations between paraboloids of different apertures and the spherical surfaces of differing radii are also investigated. Maximum zenith angles corresponding to different apertures of the paraboloid are further derived. A spherical surface with a different radius can provide a reference baseline for shape-changing applied through active reflector technology to FAST-like telescopes.


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