Robust control of an adaptive optics system
07 Nov 2002-pp 293-296
TL;DR: In this paper, a design for an adaptive optics system that utilizes modern H/sub /spl infin// control theory to optimize the robustness of the system is presented for real-time correction of blurred images and have applications in astronomical imaging, freespace optical communications and high-energy laser beam guidance.
Abstract: Adaptive optics systems are concerned with the real-time correction of blurred images and have applications in astronomical imaging, freespace optical communications and high-energy laser beam guidance. This paper outlines the proposed design for an adaptive optics system that utilizes modern H/sub /spl infin// control theory to optimize the robustness of the system.
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TL;DR: By using feedforward control, the dominant dynamics of the membrane can still be controlled allowing for faster settling times and reduced membrane vibrations, and performance enhancements for deformable membrane mirrors based on model-basedFeedforward control are presented.
Abstract: In this paper, performance enhancements for deformable membrane mirrors based on model-based feedforward control are presented. The investigated deformable mirror consists of a flexible membrane and voice coil actuators. Feedback control of the distributed actuators cannot be implemented in these mirrors due to a lack of high speed internal position measurements of the membrane's deformation. However, by using feedforward control, the dominant dynamics of the membrane can still be controlled allowing for faster settling times and reduced membrane vibrations. Experimental results are presented for an ALPAO deformable mirror with 88 distributed actuators on a circular membrane with a pupil of two centimeters in diameter.
33 citations
01 Jan 2013
Abstract: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix Publications and Outcomes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x Acronyms and Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii
12 citations
18 Dec 2012
TL;DR: The use of deformable mirrors (DMs) in adaptive optics (AO) systems allows for compensation of various external and internal optical disturbances during image aquisition as discussed by the authors, which can provide promising examination and treatment opportunities.
Abstract: The use of deformable mirrors (DMs) in adaptive optics (AO) systems allows for compensation of various external and internal optical disturbances during image aquisition. For example, an astronomical telescope equipped with a fast deformable secondary mirror can compensate for atmospheric disturbances and wind shake of the telescope structure resulting in higher image resolution [1–4]. In microscopy, deformable mirrors allow to correct for aberrations caused by local variations of the refractive index of observed specimen. Especially confocal and multi-photon microscopes particularly benefit from the improved resolution for visualization of cellular structures and subcellular processes [5, 6]. In addition, results of applied adaptive optics for detection of eye diseases and in vitro retinal imaging on the cellular level show promising examination and treatment opportunities [7–9].
11 citations
TL;DR: In this paper, the use of adaptive optics for wavefront sensing and surface control of large segmented mirrors is investigated, and an H1 robust control technique is considered for the control of the adaptive optics system with the reduced number of inputs and outputs.
11 citations
03 Apr 2008
TL;DR: In this paper, a wavefront control method for the Naval Postgraduate School adaptive optics testbed is developed to remove structural noise from the flexible optical surface using discrete time proportional integral control with second order filters.
Abstract: Future space based deployable telescopes will be subject to non-atmospheric disturbances. Jitter and optical misalignment on a spacecraft can be caused by mechanical noise of the spacecraft, and settling after maneuvers. The introduction of optical misalignment and jitter can reduce the performance of an optical system resulting in pointing error and contributing to higher order aberrations. Adaptive optics can be used to control jitter and higher order aberrations in an optical system. In this paper, wavefront control methods for the Naval Postgraduate School adaptive optics testbed are developed. The focus is on removing structural noise from the flexible optical surface using discrete time proportional integral control with second order filters. Experiments using the adaptive optics testbed successfully demonstrate wavefront control methods, including a combined iterative feedback and gradient control technique. This control technique results in a three time improvement in RMS wavefront error over the individual controllers correcting from a biased mirror position. Second order discrete time notch filters are also used to remove induced low frequency actuator and sensor noise at 2Hz. Additionally a 2 Hz structural disturbance is simulated on a Micromachined Membrane Deformable Mirror and removed using discrete time notch filters combined with an iterative closed loop feedback controller, showing a 36 time improvement in RMS wavefront error over the iterative closed loop feedback alone.
7 citations
References
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Book•
17 Aug 1995TL;DR: This paper reviewed the history of the relationship between robust control and optimal control and H-infinity theory and concluded that robust control has become thoroughly mainstream, and robust control methods permeate robust control theory.
Abstract: This paper will very briefly review the history of the relationship between modern optimal control and robust control. The latter is commonly viewed as having arisen in reaction to certain perceived inadequacies of the former. More recently, the distinction has effectively disappeared. Once-controversial notions of robust control have become thoroughly mainstream, and optimal control methods permeate robust control theory. This has been especially true in H-infinity theory, the primary focus of this paper.
6,945 citations
Book•
01 Jan 1980
TL;DR: This well-respected, market-leading text discusses the use of digital computers in the real-time control of dynamic systems and thoroughly integrates MATLAB statements and problems to offer readers a complete design picture.
Abstract: From the Publisher:
This well-respected, market-leading text discusses the use of digital computers in the real-time control of dynamic systems The emphasis is on the design of digital controls that achieve good dynamic response and small errors while using signals that are sampled in time and quantized in amplitude Both classical and modern control methods are described and applied to illustrative examples The strengths and limitations of each method are explored to help the reader develop solid designs with the least effort Two new chapters have been added to the third edition offering a review of feedback control systems and an overview of digital control systems Updated to be fully compatible with MATLAB versions 4 and 5, the text thoroughly integrates MATLAB statements and problems to offer readers a complete design picture The new edition contains up-to-date material on state-space design and twice as many end-of-chapter problems to give students more opportunities to practice the material
3,756 citations
1,054 citations