We propose a new algorithm for an adaptive optics system control law which
allows to reduce the computational burden in the case of an Extremely Large
Telescope (ELT) and to deal with non-stationary behaviors of the turbulence.
This approach, using Ensemble Transform Kalman Filter and localizations by
domain decomposition is called the local ETKF: the pupil of the telescope is
split up into various local domains and calculations for the update estimate of
the turbulent phase on each domain are performed independently. This data
assimilation scheme enables parallel computation of markedly less data during
this update step. This adapts the Kalman Filter to large scale systems with a
non-stationary turbulence model when the explicit storage and manipulation of
extremely large covariance matrices are impossible. First simulation results
are given in order to assess the theoretical analysis and to demonstrate the
potentiality of this new control law for complex adaptive optics systems on
ELTs.Comment: Proceedings of the AO4ELT3 conference; 8 pages, 3 figure