Title :
Self-Tuning Mechanism for the Design of Adaptive Secondary Mirror Position Control
Author :
Battistelli, Giorgio ; Mari, Daniele ; Riccardi, Armando ; Tesi, Pietro
Author_Institution :
Dipt. di Ing. dell´Inf., Univ. of Florence, Florence, Italy
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.
Keywords :
actuators; adaptive control; adaptive optics; astronomical telescopes; control system synthesis; mirrors; optical distortion; position control; self-adjusting systems; 8-m-class large binocular telescope; ASMs; DMs; LBT; adaptive secondary mirror position control design; astronomical imaging resolution; atmospheric turbulence; automatic controller tuning procedure; controller parameter calibration; deformable mirrors; electromechanical devices; force actuators; ground-based telescopes; mirror dynamics modeling; mirror surface; nonrigid wave-front distortions; rigid wave-front distortions; self-tuning mechanism; Actuators; Adaptive optics; Control design; Mirrors; Position control; Telescopes; Adaptive optics (AO); adaptive secondary mirrors (ASMs); decentralized feedback control; reference model design; self-tuning control; unfalsified control; virtual experiment; virtual experiment.;
Journal_Title :
Control Systems Technology, IEEE Transactions on
DOI :
10.1109/TCST.2015.2398822