AO4ELT5 Proceedings

Disturbance Feedforward Control for Vibration Suppression in Adaptive Optics of Large Telescopes

Glück, Martin (University of Stuttgart / Institute for System Dynamics)

With increasing the telescope size the effects of structural vibrations become more dominant and therefore its suppression in Adaptive Optics system is a big challenge. For that reason new control concepts as the observer-based disturbance compensation (LQG control) were developed. Nevertheless, under different environmental conditions these concepts are not sufficient to suppress the vibrations in an acceptable range. When observing with faint natural guide stars the integration time of the wavefront sensor is increased to obtain a better Signal-to-Noise ratio. However by reducing the loop speed the bandwidth of the AO system cannot mitigate high frequency vibrations (> 5 Hz). In this paper an additional accelerometer-based disturbance feedforward (DFF) control is proposed to improve the performance for high frequency vibrations. In an AO end-to-end simulation the DFF control is compared with the common concepts. Thereby, it is shown that the Strehl ratio can be increased for faint natural guide stars (> 13 mag) by a factor two up to four.

DOI: 10.26698/AO4ELT5.0064- Proceeding PDF

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