Active Optics of Large Segmented Mirrors: Dynamics and Control

This paper examines the active optics of future large segmented telescopes from the point of view of dynamic simulation and control. The first part of the paper is devoted to the modeling of the mirror. The model has a moderated size and separates the quasi-static behavior of the mirror (primary response) from the dynamic response (secondary or residual response). The second part of the paper is devoted to control. The control strategy considers explicitly the primary response ofthe telescope through a singular value controller. The control-structure interaction is addressed with the general robustness theory of multivariable feedback systems, where the secondary response is considered as uncertainty. This approach is very fast and allows extensive parametric studies. The study is illustrated with an example involving 90 segments, 270 inputs, and 654 outputs.

[1]  B. Sedghi,et al.  E-ELT primary mirror control system , 2008, Astronomical Telescopes + Instrumentation.

[2]  P. Bely.  The Design and Construction of Large Optical Telescopes , 2010 .

[3]  Jerry Nelson,et al.  The status of the Thirty Meter Telescope project , 2008, Astronomical Telescopes + Instrumentation.

[4]  George Z. Angeli,et al.  Active optics challenges of a thirty-meter segmented mirror telescopy , 2004, Extremely Large Telescopes.

[5]  M. Bampton,et al.  Coupling of substructures for dynamic analyses. , 1968 .

[6]  G. Stein,et al.  Multivariable feedback design: Concepts for a classical/modern synthesis , 1981 .

[7]  Jean-Noel Aubrun,et al.  Performance analysis of the segment alignment control system for the ten-meter telescope , 1988, Autom..

[8]  Petros G. Voulgaris,et al.  H2 Control of Large Segmented Telescopes , 2009 .

[9]  Robert L. Kosut,et al.  Robust Control of Flexible Spacecraft , 1983 .

[10]  R. Guyan.  Reduction of stiffness and mass matrices , 1965 .

[11]  Roberto Gilmozzi,et al.  The 42m European ELT: status , 2008, Astronomical Telescopes + Instrumentation.

[12]  George Z. Angeli,et al.  Active optics and control architecture for a giant segmented mirror telescope , 2003, SPIE Astronomical Telescopes + Instrumentation.

[13]  Maciejowsk.  Multivariable Feedback Design , 1989 .

[14]  Thomas R. Yechout,et al.  Classical Feedback Control , 2003 .

[15]  Mark J. Sirota,et al.  Analysis of TMT primary mirror control-structure interaction , 2008, Astronomical Telescopes + Instrumentation.

[16]  Gary Chanan,et al.  Control and alignment of segmented-mirror telescopes: matrices, modes, and error propagation. , 2004, Applied optics.

[17]  Gene F. Franklin,et al.  Feedback Control of Dynamic Systems , 1986 .

[18]  J. Aubrun,et al.  Dynamic analysis of the activley controlled segmented mirror of the W. M. Keck ten-meter telescope , 1987, IEEE Control Systems Magazine.

[19]  G. Rodrigues,et al.  Active Optics for Large Segmented Mirrors : Scale Effects , 2009 .

[20]  Mark J. Sirota,et al.  Control of many coupled oscillators and application to segmented-mirror telescopes , 2008 .