Rejecting the low-frequency noise in the 10m diameter primary mirror of the GRANTECAN telescope

The goal of this paper is to provide an overview of the studies that have been done with the aim of finding a controller that solves the noise rejection problem in the 10m diameter primary mirror of the Grantecan Telescope. In the first place, a method for decoupling the dynamics of this large-scale MIMO system is presented. A change of basis makes the decoupling possible, becoming an important result for control purposes. In addition to this, the possibility of making tests with a scale model of the mirror is specially interesting thanks to the decoupling. Secondly, this scale model is described and its dynamic identified using an ARMAX model. Finally, a discussion about the design of a controller for low-frequency noise rejection in the scale model's segments and the results obtained are presented.