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Design For Practice |
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Northern Arizona University |
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Adaptive Algorythm |
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In additional research, we found pre-existing solutions to vibration problems cause by random environmental effects. At a different optical interferometer site, located in Chile, researchers experienced similar problems in there multiple telescope array dealing with environmental effects causing vibrations. The Chile Very Large Telescope (VLT) uses an adaptive algorithm in addition to their current feed forward algorithm (Figure 2) that uses a complex grid network of accelerometers to correct the vibrations at a downstream delay line. The adaptive algorithm was successful in correcting vibrations and allowed for a longer fringe lock in more challenging weather conditions. The algorithm does not need any human interaction and thus is a closed loop. The benefits arising from use of this algorithm is that once in place, the algorithm essential constantly is fixing the problem. However, to implement at NPOI, a sensory grid will have to be added in addition to actuators to cancel the vibrations. Another problem that might arise will be from the difference in site structures. NPOI might need a more complex network and algorithm due to NPOI’s use of a beam compressors configuration being different from the telescopes beam compressor configuration.
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Simplified diagram of the fringe tracking system, with adaptive vibration cancellation bounded by the dashed box (Lieto)
Lieto, Nicola Di, et al. “Adaptive Vibration Cancellation on Large Telescopes for Stellar Interferometry.” Proceedings of SPIE- The International Society for Optical Engineering 7013 (June 2008): n. pag. Compendex. Web. 17 Nov. 2009. |