Title :
Control characteristics of the ALMA Nutator
Author :
Jiang, Homin ; Chen, Ming-Tang ; Han, Johnson C.
Author_Institution :
Acad. Sinica Inst. of Astron. & Astrophys., Taipei, Taiwan
Abstract :
The control of a 75 centimeter diameter Atacama Large Millimeter/submillimeter Array (ALMA) nutating subreflector, or Nutator, to meet the specifications of 10 millisecond (ms) settle time and 1.3 arc-second pointing error involves tremendous challenges. The ALMA Nutator has been under development since 2003, and we have improved its dynamic characteristics through robust PID control algorithm, increasing the open loop bandwidth to beyond 200Hz and shortening the settle time to 20 ms. A mode switching associate with model following control scheme is also presented, and expected to improve the settle time and pointing error.
Keywords :
radiotelescopes; robust control; three-term control; ALMA nutator; Atacama large millimeter-submillimeter array; model following control scheme; nutating subreflector; open loop bandwidth; robust PID control algorithm; Field programmable gate arrays; Mathematical model; Mirrors; Switches; Transfer functions; Voltage control;
Conference_Titel :
Control Applications (CCA), 2010 IEEE International Conference on
Conference_Location :
Yokohama
Print_ISBN :
978-1-4244-5362-7
Electronic_ISBN :
978-1-4244-5363-4
DOI :
10.1109/CCA.2010.5611324
