The reflector of FAST (Five-hundred-meter Aperture Sphere Telescope) is a net mesh structure and can be considered as a flexible parallel motion mechanism array which can form the varying paraboloid surface by controlling the motion of the net mesh nodes. As a parallel mechanism, the motion of the nodes are coupled together. In order to release the coupling, or to estimate the surface error of the reflector, the motion of FAST 30m Model was simulated combined with ADAMS and SIMULINK. The net mesh mechanism was modeled as springs and spheres with mass in ADAMS software. To control the large amount of actuators, and to analyze the motion of the net mesh motion mechanism, a control model in SIMULINK has been built, which includes astronomical plan, actuator controlling and surface analysis. The model can be used as the test tool of the actuator control strategy and optimization for the net mesh structure. With the combined simulation, the amount of the couple phenomenon is estimated precisely. The paraboloid shape forming and moving in the observing course is simulated, and the variation of the surface error of the reflector and the forces of each cable are given. By the simulation, it can be concluded that the couple effect is small in the FAST 30m Model, and such a method can be applied to the FAST prototype.

Date Published: 23 July 2008
PDF: 8 pages
Proc. SPIE 7018, Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation, 701849 (23 July 2008); doi: 10.1117/12.790541

Published in SPIE Proceedings Vol. 7018:
Advanced Optical and Mechanical Technologies in Telescopes and Instrumentation
Eli Atad-Ettedgui; Dietrich Lemke, Editor(s)