Efficacy of predictive wavefront control for compensating aero-optical aberrations

Goorskey, David; Schmidt, Jason D.; Whiteley, Matthew R.

doi:10.1117/1.oe.52.7.071418

Cited by 19 publications

(11 citation statements)

References 19 publications

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“…This latency problem has previously been addressed using various prediction methods such as dynamic mode decomposition 19 , receding-horizon adaptive control 20 , and simple "frozen-flow" advection prediction 21 . We recently developed a method 7 for overcoming this latency problem using a predictive neural network controller in conjunction with a conventional feedback loop as shown in Figure 6.…”

Section: American Institute Of Aeronautics and Astronauticsmentioning

confidence: 99%

A Robust Modification of a Predictive Adaptive-Optic Control Method for Aero-Optics

Burns

Jumper

Gordeyev

2016

47th AIAA Plasmadynamics and Lasers Conference

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A modification of a previous predictive adaptive-optic controller is presented in this paper. Conventional adaptive-optic controllers suffer from bandwidth limitations caused by latency in their control loops. This latency severely limits their capabilities in aero-optic applications that cannot be overcome with conventional feedback techniques. Our method uses prior knowledge of flow behavior to predict future behavior, and thus overcome deadtime. We have modified our previous neural network controller to use a linearized predictor, which we demonstrate to be more accurate, more robust to noise and flow disturbances, and less computationally expensive. Our previous neural network method showed disturbance rejection in the range of 35-55% in simulation over our test conditions in the most optically-active regions, while the improved method shows disturbance rejection between 45-75% over the same range. Additionally, we demonstrate that the predictive control method is stable, even in the presence of latency uncertainty.

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Section: American Institute Of Aeronautics and Astronauticsmentioning

confidence: 99%

A Robust Modification of a Predictive Adaptive-Optic Control Method for Aero-Optics

Burns

Jumper

Gordeyev

2016

47th AIAA Plasmadynamics and Lasers Conference

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“…Several methods have been suggested to take advantage of temporal coherence, [13][14][15] including frozen flow characteristics, for improved wave-front control in AO systems. Here, the FFM allows us essentially to know the atmospheric aberration just outside the beacon light cone even when we cannot directly see it.…”

Section: Resultsmentioning

confidence: 99%

Tomographic wave-front sensing with a single guide star

2016

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Adaptive optics or numerical restoration algorithms that restore high resolution imaging through atmospheric turbulence are subject to isoplanatic wave-front errors. Mitigating those errors requires that the wave-front aberrations be estimated within the 3D volume of the atmosphere. Present techniques rely on multiple beacons, either natural stars or laser guide stars, to probe the atmospheric aberration along different lines of sight, followed by tomographic projection of the measurements onto layers at defined ranges. In this paper we show that a three-dimensional estimate of the wave-front aberration can be recovered from measurements by a single guide star in the case where the aberration is stratified, provided that the telescope tracks across the sky with non-uniform angular velocity. This is generally the case for observations of artificial earth-orbiting satellites, and the new method is likely to find application in ground-based telescopes used for space situational awareness.

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“…Faghihi et al 16 have developed a state-space model and filter for the prediction of POD mode coefficients that could also be used in a predictive controller. Goorskey et al 17 have proposed a promising controller based on the Dynamic Mode Decomposition of Schmid 18 that is capable of compensating for one timestep of delay. Their algorithm was demonstrated to show a significant improvement (approximately 25% on average, and in many cases more) in controller performance.…”

Section: Figure 3: Effect Of Wavefront Mitigation On Strehl Ratiomentioning

confidence: 99%

“…A potentially more robust approach is to reduce the dimensionality of the problem using modal decomposition 21 . Additionally, Goorksey et al 17 have used Dynamic Mode Decomposition 18 to estimate a low-rank approximation of A to improve real-time feasibility.…”

Section: Theoretical Backgroundmentioning

confidence: 99%

A Latency-Tolerant Architecture for Airborne Adaptive Optic Systems

Burns

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Gordeyev

2015

53rd AIAA Aerospace Sciences Meeting

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A new data-driven method for latency compensation in adaptive optics sytems is developed and evaluated in this paper. Conventional adaptive optic controllers typically assume a single timestep of latency in the feedback loop, which is an appropriate assumption for low-frequency applications such as atmospheric optics compensation. However, the controller frequencies needed for aero-optic applications can approach the tens of kilohertz. Cumulative latency in the feedback loop originating from digital communication links, sensors, processing, etc. can exceed one timestep and thus significantly reduce the performance of adaptive optic controllers, even though open-loop frequencies of individual components are sufficiently fast for the application. Our method uses proper orthogonal decomposition as a basis for wavefront model reduction and an artificial neural network to predict the evolution of the associated modal coefficients over a short temporal horizon equivalent to the amount of latency present in the feedback loop. The method is capable of significantly augmenting the performance of conventional adaptive optics controllers. This algorithm has been evaluated in closed-loop simulation with disturbance data gathered from the Airborne Aero-Optics Laboratory. Over a 5-step prediction window, the new controller could reduce OPD rms in the worst cases by over 35%. Over a single timestep window, mitigations of greater than 55% are realized.

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Efficacy of predictive wavefront control for compensating aero-optical aberrations

Cited by 19 publications

References 19 publications

A Robust Modification of a Predictive Adaptive-Optic Control Method for Aero-Optics

A Robust Modification of a Predictive Adaptive-Optic Control Method for Aero-Optics

Tomographic wave-front sensing with a single guide star

A Latency-Tolerant Architecture for Airborne Adaptive Optic Systems

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