Experimental validation of massively actuated deformable adaptive mirror numerical models

Manetti, Mauro; Morandini, Marco; Mantegazza, Paolo; Biasi, Roberto; Gallieni, Daniele; Riccardi, Armando

doi:10.1016/j.conengprac.2012.03.018

Cited by 6 publications

(13 citation statements)

References 12 publications

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“…The model in Eq. (6) represents the data generating model. Since we do not have access to an experimental setup, by simulating the data generating model for chosen initial conditions and input sequences, we obtain the identification input-output data.…”

Section: Measurement Equation and Data Generating Modelmentioning

confidence: 99%

“…Our main goal is to estimate a Kalman innovation state-space model [26,57] that approximates the input-output behavior of Eq. (6). The Kalman innovation state-space model has the following form:…”

Section: Subspace Identificationmentioning

confidence: 99%

“…Thus, DMs in AO systems for extremely large telescopes have hundreds or even thousands of spatially distributed actuators [3]. To maximize the correction bandwidth of AO systems it is essential to develop sufficiently accurate models of DMs, WFSs, and possibly of other processes that influence the AO dynamics, such as atmospheric turbulence in the case of telescopes [2,[4][5][6].…”

Section: Introductionmentioning

confidence: 99%

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Modeling and state-space identification of deformable mirrors

Haber

Verhaegen

2020

Opt. Express

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To develop high-performance controllers for adaptive optics (AO) systems, it is essential to first derive sufficiently accurate state-space models of deformable mirrors (DMs). However, it is often challenging to develop realistic large-scale finite element (FE) state-space models that take into account the system damping, actuator dynamics, boundary conditions, and multi-physics phenomena affecting the system dynamics. Furthermore, it is challenging to establish a modeling framework capable of the automated and quick derivation of state-space models for different actuator configurations and system geometries. On the other hand, for accurate model-based control and system monitoring, it is often necessary to estimate state-space models from the experimental data. However, this is a challenging problem since the DM dynamics is inherently infinite-dimensional and it is characterized by a large number of eigenmodes and eigenfrequencies. In this paper, we provide modeling and estimation frameworks that address these challenges. We develop an FE state-space model of a faceplate DM that incorporates damping and actuator dynamics. We investigate the frequency and time domain responses for different model parameters. The state-space modeling process is completely automated using the LiveLink for MATLAB toolbox that is incorporated into the COMSOL Multiphysics software package. The developed state-space model is used to generate the estimation data. This data, together with a subspace identification algorithm, is used to estimate reduced-order DM models. We address the model-order selection and model validation problems. The results of this paper provide essential modeling and estimation tools to broad AO and mechatronics scientific communities. The developed Python, MATLAB, and COMSOL Multiphysics codes are available online.There are various types of DM architectures and design concepts used in AO systems. Depending on how the reflective surface is designed, we can distinguish between segmented, faceplate, and membrane DMs [1,7,8]. Due to their widespread usage, in this manuscript, we consider DMs with continuous faceplates. The results can easily be extended to other mirror concepts. A typical continuous faceplate DMs is composed of a thin faceplate that is deformed by spatially distributed actuators placed on its backside.Modeling and control problems for large-scale DMs have been considered in [5,[9][10][11][12][13][14][15][16][17][18]. Distributed control and estimation problems or problems of efficient implementation of control and estimation algorithms for large-scale DMs and AO systems have been considered in [4,[18][19][20][21][22][23]. Before these methods can be used, it is necessary to develop sufficiently accurate DM models. Furthermore, it is preferable that these models are in a state-space form that can be used for the design of advanced model-based control algorithms. Analytical mirror models that are based on the biharmonic plate equation and its modifications have been developed in [7,10,11,24,25]. Howev...

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Section: Measurement Equation and Data Generating Modelmentioning

confidence: 99%

Section: Subspace Identificationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling and state-space identification of deformable mirrors

Haber

Verhaegen

2020

Opt. Express

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“…The control architecture based on decentralized feedback plus centralized feedforward has been shown to be highly performing and well suited for real-time implementation [20], [23], and is indeed currently adopted for the LBT. However, at the present moment, the design of a control architecture of this kind mainly relies on designers' experience.…”

Section: A Asm Control Designmentioning

confidence: 99%

“…However, at the present moment, the design of a control architecture of this kind mainly relies on designers' experience. Specifically, while many efficient methods are available for computing the centralized feedforward action [23]- [25], few results are available for designing the decentralized feedback action. This is mainly due to the following factors: 1) the decentralized nature of the feedback action for which standard design tools are less available [26] and 2) the difficulty to obtain an accurate model of the shell dynamics.…”

Section: A Asm Control Designmentioning

confidence: 99%

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

Battistelli

Mari²,

Riccardi

et al. 2015

IEEE Trans. Contr. Syst. Technol.

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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.

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