Self-Tuning Mechanism for the Design of Adaptive Secondary Mirror Position Control

Abstract

Deformable mirrors (DMs) are electromechanical devices used in ground-based telescopes to compensate for the distortions caused by the atmospheric turbulence, the main factor limiting the resolution of astronomical imaging. Adaptive secondary mirrors (ASMs) represent a new type of DMs; two of them have been recently installed on the 8-m-class large binocular telescope (LBT). ASMs are able to jointly correct rigid and nonrigid wave-front distortions thanks to the use of force actuators distributed on the overall mirror surface. As an offset, each actuator needs to be piloted by a dedicated controller, whose parameters must be accurately tuned to obtain the desired mirror shape. At the present time, the calibration of the controller parameters is executed manually. This paper presents a novel automatic controller tuning procedure that does not rely on the modeling of the mirror dynamics. The experimental validation on a prototype reproducing the three innermost rings of the LBT ASM is reported.Index Terms-Adaptive optics (AO), adaptive secondary mirrors (ASMs), decentralized feedback control, reference model design, self-tuning control, unfalsified control, virtual experiment.

Unfalsified adaptive control for manipulators with parameter uncertainties

“…In particular, the authors analyzed performance of specific manipulators with bounded disturbances. Recent works present applications of UAC for fuel cell systems [20], secondary mirror positioning control for ground-based telescopes [21], inertial navigation systems [22], pressure drilling for oil [23] [24], temperature tracking of the Chylla-Haase reactor [25] and inverted pendulum systems [26].…”