SPHERE eXtreme AO control scheme: final performance assessment and on sky validation of the first auto-tuned LQG based operational system

C. Petit; J.-F. Sauvage; T. Fusco; A. Sevin; M. Suarez; A. Costille; A. Vigan; C. Soenke; D. Perret; S. Rochat; A. Barrufolo; B. Salasnich; J.-L. Beuzit; K. Dohlen; D. Mouillet; P. Puget; F. Wildi; M. Kasper; J.-M. Conan; C. Kulcsár; H.-F. Raynaud

doi:10.1117/12.2052847

7 August 2014 SPHERE eXtreme AO control scheme: final performance assessment and on sky validation of the first auto-tuned LQG based operational system

C. Petit, J.-F. Sauvage, T. Fusco, A. Sevin, M. Suarez, A. Costille, A. Vigan, C. Soenke, D. Perret, S. Rochat, A. Barrufolo, B. Salasnich, J.-L. Beuzit, K. Dohlen, D. Mouillet, P. Puget, F. Wildi, M. Kasper, J.-M. Conan, C. Kulcsár, H.-F. Raynaud

Author Affiliations +

Proceedings Volume 9148, Adaptive Optics Systems IV; 91480O (2014) https://doi.org/10.1117/12.2052847
Event: SPIE Astronomical Telescopes + Instrumentation, 2014, Montréal, Quebec, Canada

Abstract

The SPHERE (Spectro-Polarimetry High-contrast Exoplanet Research) instrument is an ESO project aiming at the direct detection of extra-solar planets. SPHERE has been successfully integrated and tested in Europe end 2013 and has been re-integrated at Paranal in Chile early 2014 for a first light at the beginning of May. The heart of the SPHERE instrument is its eXtreme Adaptive Optics (XAO) SAXO (SPHERE AO for eXoplanet Observation) subsystem that provides extremely high correction of turbulence and very accurate stabilization of images for coronagraphic purpose. However, SAXO, as well as the overall instrument, must also provide constant operability overnights, ensuring robustness and autonomy. An original control scheme has been developed to satisfy this challenging dichotomy. It includes in particular both an Optimized Modal Gain Integrator (OMGI) to control the Deformable Mirror (DM) and a Linear Quadratic Gaussian (LQG) control law to manage the tip-tilt (TT) mirror. LQG allows optimal estimation and prediction of turbulent angle of arrival but also of possible vibrations. A specific and unprecedented control scheme has been developed to continuously adapt and optimize LQG control ensuring a constant match to turbulence and vibrations characteristics. SPHERE is thus the first operational system implementing LQG, with automatic adjustment of its models. SAXO has demonstrated performance beyond expectations during tests in Europe, in spite of internal limitations. Very first results have been obtained on sky last May. We thus come back to SAXO control scheme, focusing in particular on the LQG based TT control and the various upgrades that have been made to enhance further the performance ensuring constant operability and robustness. We finally propose performance assessment based on in lab performance and first on sky results and discuss further possible improvements.

Citation Download Citation

C. Petit, J.-F. Sauvage, T. Fusco, A. Sevin, M. Suarez, A. Costille, A. Vigan, C. Soenke, D. Perret, S. Rochat, A. Barrufolo, B. Salasnich, J.-L. Beuzit, K. Dohlen, D. Mouillet, P. Puget, F. Wildi, M. Kasper, J.-M. Conan, C. Kulcsár, and H.-F. Raynaud "SPHERE eXtreme AO control scheme: final performance assessment and on sky validation of the first auto-tuned LQG based operational system", Proc. SPIE 9148, Adaptive Optics Systems IV, 91480O (7 August 2014); https://doi.org/10.1117/12.2052847

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available