A Batch Filter for Baseline Estimation Using On-Orbit GPS and Gyro Data

Dolan Highsmith, Penina Axelrad

Abstract:	The GPS Attitude and Navigation Experiment (GANE) flown on STS-77 simulated the environment of the GPS antenna array and inertial instrument suite planned for the International Space Station (1SS). This paper describes a methodology for batch estimation of initial attitude and GPS baselines intended for use with the 1SS and presents results for the GANE. The results are compared to reference data from ground tests and on-orbit from the Orbiter high-accuracy in-ertial navigation system (HAINS). Initial attitude errors for the GPS/IRU solution as compared to the Orbiter reference are within 0.14 deg for one data set, and 1.5 deg for a second data set, with the largest errors occurring in the pitch axis. Base-line vector estimates differ from pre-~lght values by as much as 5 cm, with the magnitudes of the base-line vectors differing by as much as 6 mm. However, the baseline vector estimates agree with the Orbiter-derived reference to within 4 mm; with the maximum difference in magnitudes being less than 1 mm. Line bias estimates differ from pre-flight values by as much as O.O5cycles for one data set, and 0.03 cy for another data set. For both data sets, the difference is less than 0.006 cycles when compared to the line biases derived from the Orbiter reference data. The results illustrate the importance of baseline calibration on-orbit due to changes in the antennas and baaelines between ground and flight operations. Furthermore, consistency between the operational IRU and the reference Orbiter INS provides confidence in the accuracy of the batch estimation procedure and results.
Published in:	Proceedings of the 54th Annual Meeting of The Institute of Navigation (1998) June 1 - 3, 1998 The Adams Mark Hotel Denver, CO
Pages:	133 - 143
Cite this article:	Highsmith, Dolan, Axelrad, Penina, "A Batch Filter for Baseline Estimation Using On-Orbit GPS and Gyro Data," Proceedings of the 54th Annual Meeting of The Institute of Navigation (1998), Denver, CO, June 1998, pp. 133-143.
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