Accession Number : ADA613029


Title :   Development of Adaptive Tilt Tracker that Utilizes QUAD-cell Detector to Track Extended Objects


Descriptive Note : Master's thesis


Corporate Author : AIR FORCE INSTITUTE OF TECHNOLOGY WRIGHT-PATTERSON AFB OH GRADUATE SCHOOL OF ENGINEERING AND MANAGEMENT


Personal Author(s) : Thornton, Issac J


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a613029.pdf


Report Date : 17 Mar 2014


Pagination or Media Count : 156


Abstract : Atmospheric turbulence causes tilt distortion that requires telescopes to track and remove image jitter effects. This research develops an adaptive tilt tracking system to measure and compensate for centroid gain volatility while tracking extended objects. The adaptive tracker counteracts deviations in tilt measurement and correction, due to unintended centroid gain changes. Non-adaptive trackers experience sub-optimal bandwidths and possible instabilities. The adaptive tracker utilizes a quadrant (QUAD) cell tilt detector to measure tilt distortion and its centroid gain relates measured intensity imbalances amongst the four cells to tilt distortion. Additionally, this gain becomes a random variable as it is determined by random image spot characteristics. The tracked LEO object and atmospheric seeing govern spot characteristics. This research develops an innovative methodology that rotates the LEO object's image to create a more favorable intensity distribution for the QUAD-cell. Along with image rotation, an adaptive gain term yields significant improvements in QUAD-cell measurement performance, up to 91% for the simulated tilt processes. Using the image rotation and adaptive gain methodology, this research realizes an adaptive tilt tracker model that dithers the fast steering mirror to detect non-optimal centroid gains. Results show the adaptive tracker effectively counteracts centroid-gain deviations.


Descriptors :   *TRACKING , ADAPTIVE SYSTEMS , DETECTORS


Subject Categories : Target Direction, Range and Position Finding


Distribution Statement : APPROVED FOR PUBLIC RELEASE