Delay Compensation for Real Time Disturbance Estimation at Extremely Large Telescopes

Michael Bohm, Jorg Uwe Pott, Martin Kurster, Oliver Sawodny, Denis Defrere, Philip M Hinz

Research output: Contribution to journalArticle

13 Scopus citations

Abstract

In ground-based astronomy, aberrations due to structural vibrations, such as piston, limit the achievable resolution and cannot be corrected using adaptive optics (AO) for large telescopes. We present a model-free strategy to estimate and compensate piston aberrations due to the vibrations of optical components using accelerometer disturbance feed forward, eventually allowing the use of fainter guide stars both for the fringe detector and in the AO loop. Because the correction performance is very sensitive to signal delays, we present a strategy to add a delay compensation to the developed disturbance estimator, which can, in principle, be applied to many other applications outside of astronomy that lack observer performance due to a measurement delay or need a prediction to compensate for input delays. The ability to estimate vibration disturbances in the critical frequency range of 8-60 Hz is demonstrated with on sky data from the Large Binocular Telescope (LBT) Interferometer, an interferometer at the LBT. The experimental results are promising, indicating the ability to suppress differential piston induced by telescope vibrations by a factor of about 3 (rms), which is significantly better than any currently commissioned system.

Original languageEnglish (US)
Pages (from-to)1384-1393
Number of pages10
JournalIEEE Transactions on Control Systems Technology
Volume25
Issue number4
DOIs
Publication statusPublished - Jul 1 2017

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Keywords

  • Acceleration
  • delay
  • disturbance
  • estimation
  • optics
  • prediction
  • sensor networks
  • telescope

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Electrical and Electronic Engineering

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