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Proceedings Paper

Real-time adaptive optimization of track loop controllers in adaptive optics systems as a function of input statistics and sensor gain
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Paper Abstract

The optimal track loop controller in an adaptive optics system is a function of the steering mirror dynamics, the temporal statistics of the input disturbance signal, measurement noise, and the sensor gain. The atmospheric input statistics and the sensor gain of a quadrant detector are slowly time-varying on a scale of minutes. If all parameters are known a prior, the analytical optimal controller is found by augmenting the dynamics of the input disturbance spectra and solving an H2 optimization problem. Near optimal control is achieved by augmenting the mount jitter dynamics and a first order approximation of the atmosphere dynamics and finding the LQG/LTR controller. The optimal bandwidth to compensate for time-varying atmospheric disturbance and noise levels is found by optimizing the loop gain. Recursive least squares is used to estimate the sensor gain and optimize the bandwidth in real time. The only measurements necessary for optimization are the residual track errors from a high frame rate, low noise quad cell algorithm and from a low frame rate dense ccd array using a centroid algorithm. Provided the temporal variations in the sensor gain are slow, closed loop robust stability is guaranteed by constraining the optimization algorithm via projection. Simulation results are presented which verify that the constrained optimal controller is achieved under a variety of conditions.

Paper Details

Date Published: 27 September 1999
PDF: 14 pages
Proc. SPIE 3762, Adaptive Optics Systems and Technology, (27 September 1999); doi: 10.1117/12.363563
Show Author Affiliations
Jeffrey D. Barchers, Air Force Research Lab. (United States)
James M. Brown II, Air Force Research Lab. (United States)

Published in SPIE Proceedings Vol. 3762:
Adaptive Optics Systems and Technology
Robert K. Tyson; Robert Q. Fugate, Editor(s)

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