Upgrading SPHERE with the second stage AO system SAXO+: first performance results of a data-driven predictive minimum-variance control strategy

In order to address new science objectives in exoplanet imaging, the SAXO+ technical development project has been undertaken for the SPHERE instrument at ESO's VLT. As a part of this, the AO system will be completed by adding a second, faster stage of correction. We present simulation results obtained by implementing an optimal predictive linear quadratic Gaussian controller for the 2nd stage. The prediction relies on a stochastic state-space disturbance model fully identified from closed-loop measurements. In addition, we also investigate a disentangled cascade AO (dCAO) mode whIn order to address new science objectives in exoplanet imaging, the SAXO+ technical development project has been undertaken for the SPHERE instrument at ESO's VLT. As a part of this, the AO system will be completed by adding a second, faster stage of correction. We present simulation results obtained by implementing an optimal predictive linear quadratic Gaussian controller for the 2nd stage. The prediction relies on a stochastic state-space disturbance model fully identified from closed-loop measurements. In addition, we also investigate a disentangled cascade AO (dCAO) mode where the model represents the full incoming disturbance and is identified using in addition the 1st stage commands.ere the model represents the full incoming disturbance and is identified using in addition the 1st stage commands.