ELT M4 system robustness improvement through the addition of active damping

The present work provides analysis of the ELT M4 control system interaction with the deformable mirror supporting structure. The aim is the verification of the system robustness in terms of both stability and performance. The results of the analysis suggested the opportunity to improve the system dynamic behavior through the addition of damping on the system supporting structure. The solution adopted has been the introduction of active damping using six proof mass actuators (PMAs) placed on the ELT M4 reference body (RB). The effectiveness of this solution, which is now part of the ELT M4 final design, is proved through numerical simulations. Moreover, the PMA design together with some experimental tests performed on a pre-series device will be presented.