Kalman smoother applied to LACE

Abstract

The ability to determine the structural dynamics of space-based platforms from ground-based radar resolved Doppler measurements will aid in the study of control/structure interaction. The Naval Research Laboratory and Lincoln Laboratory conducted an experiment to determine the feasibility of this method. To accomplish this experiment the LACE satellite was equipped with retroreflectors and the ground-based Firepond laser radar facility was employed. Vibrational information is found from the difference between the reflected Doppler frequencies of the retroreflectors. The method of extracting the Doppler separation was to obtain the power spectrum of the heterodyne signal envelope. A pulse-by-pulse processing of the data yields the Doppler separation history over time. Due to a relatively large amount of clutter in the processed data, a filtering mechanism was employed. The histogram technique is the current filtering-based method employed to obtain a Doppler separation history. This thesis addresses the implementation of the Kalman filter algorithm in conjunction with the Rauch-Tung-Striebel fixed-interval optimal smoother algorithm to perform this filtering task. The Kalman smoother filtering based method of processing the data produced superior results when compared t the histogram filtering based method.