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Control challenges for extremely large telescopes

MacMartin, Douglas G. (2003) Control challenges for extremely large telescopes. In: Smart Structures and Materials 2003: Industrial and Commercial Applications of Smart Structures Technologies. Proceedings of SPIE. No.5054. Society of Photo-Optical Instrumentation Engineers , Bellingham, WA, pp. 275-286. ISBN 9780819448590.

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The next generation of large ground-based optical telescopes are likely to involve a highly segmented primary mirror that must be controlled in the presence of wind and other disturbances, resulting in a new set of challenges for control. The current design concept for the California Extremely Large Telescope (CELT) includes 1080 segments in the primary mirror, with the out-of-plane degrees of freedom actively controlled. In addition to the 3240 primary mirror actuators,the secondary mirror of the telescope will also require at least 5 degree of freedom control. The bandwidth of both control systems will be limited by coupling to structural modes. I discuss three control issues for extremely large telescopes in the context of the CELT design, describing both the status and remaining challenges. First, with many actuators and sensors, the cost and reliability of the control hardware is critical; the hardware requirements and current actuator design are discussed. Second, wind buffeting due to turbulence inside the telescope enclosure is likely to drive the control bandwidth higher, and hence limitations resulting from control-structure-interaction must be understood. Finally, the impact on the control architecture is briefly discussed.

Item Type:Book Section
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MacMartin, Douglas G.0000-0003-1987-9417
Additional Information:© 2003 Society of Photo-Optical Instrumentation Engineers. Many of the results discussed herein were developed with the entire CELT project team, led by Jerry Nelson at the University of California, Santa Cruz. Jerry Nelson and Terry Mast (UCSC) led the effort on actuator hardware, and the voice-coil design presented was developed by Ken Lorell and Jean-Noel Aubrun. Discussions on control architecture involved Steve Padin (California Institute of Technology), and also George Angeli (AURA New Initiatives Office)and Mark Whorton (NASA Marshall Space Flight Center), both working on GSMT. The Gemini South Wind data from which the analysis in Figures 6 and 7 was developed was made available by the New Initiatives Office of AURA Inc. Discussions on wind modeling have involved both AURA and individuals working on CELT.
Subject Keywords:Extremely Large Telescopes, CELT, Segmented Mirror Control
Series Name:Proceedings of SPIE
Issue or Number:5054
Record Number:CaltechAUTHORS:20181219-085238234
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Official Citation:Douglas G. MacMartin, "Control challenges for extremely large telescopes," Proc. SPIE 5054, Smart Structures and Materials 2003: Industrial and Commercial Applications of Smart Structures Technologies, (14 August 2003); doi: 10.1117/12.484661
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:91907
Deposited By: Tony Diaz
Deposited On:19 Dec 2018 17:38
Last Modified:16 Nov 2021 03:45

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