Accession Number : ADA505330


Title :   Application of the Backward-Smoothing Extended Kalman Filter to Attitude Estimation and Prediction using Radar Observations


Descriptive Note : Master's thesis


Corporate Author : MASSACHUSETTS INST OF TECH CAMBRIDGE


Personal Author(s) : Volpe, Kyle C


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a505330.pdf


Report Date : Jun 2009


Pagination or Media Count : 323


Abstract : The Lincoln Attitude Estimation System (LAES), a new tool being developed for the Space Situational Awareness Group (SSAG) at MIT Lincoln Laboratory, integrates several existing hardware and software systems, with a backward-smoothing extended Kalman filter (BSEKF). LAES is intended to determine the rotational motion of a freely tumbling spacecraft from a sequence of discrete-time radar images. The raw range-Doppler returns are collected using a ground-based sensor, which is owned and operated by the SSAG, and processed into a set of range/cross-range images. A three-dimensional geometric model is, through computer graphics procedures, displayed on top of the two-dimensional radar images, enabling an analyst to rotate (and scale in cross-range) the model in order to align it to the object's image. Therefore, the orthographic projection matrix that the computer graphics procedures computed to display the computer model, simultaneously describes the projection of the object onto the radar image plane. These measurements are essentially corrections to a nominal or baseline motion which had to be assumed in order to generate the images in the first place. Combining the reference motion, which describes the orientation of the image plane in inertial space, with the sequence of rotations describing the attitude of the spacecraft within the image plane, yields the final set of attitude measurements which are then passed to the BSEKF for processing. The existing free motion software currently in use within the Space Situational Awareness Group makes two critical assumptions: 1) that the spacecraft is a symmetric rigid body and 2) that there are no disturbance torques acting on the spacecraft during the imaging period.


Descriptors :   *SPACECRAFT , *SMOOTHING(MATHEMATICS) , *RADAR IMAGES , *KALMAN FILTERING , MODELS , MEASUREMENT , OBSERVATION , DOPPLER RADAR , MOTION , ORTHOGONALITY , THESES , SITUATIONAL AWARENESS , THREE DIMENSIONAL , COMPUTER GRAPHICS , GROUND BASED , ROTATION , PREDICTIONS , SPACE SYSTEMS , SOFTWARE TOOLS , TWO DIMENSIONAL


Subject Categories : Numerical Mathematics
      Statistics and Probability
      Active & Passive Radar Detection & Equipment
      Unmanned Spacecraft


Distribution Statement : APPROVED FOR PUBLIC RELEASE