Evaluating the On-Orbit Relative Navigation Performance of Modified Adaptive Kalman Filter with GPS Ambiguity Resolution

Yeji Kim, Pureum Kim, Han-Gyeol Ryu, Sang-Young Park

Abstract:	For real-time relative positioning of formation-flying nanosatellites in free-space optical communication, this study presents an accurate carrier-phase-based differential global positioning system (CDGPS) technique using a modified adaptive Kalman filter (MAKF) with the least-squares ambiguity decorrelation adjustment (LAMBDA) method as an integer ambiguity resolution (IAR) technique. The proposed relative navigation algorithm aims to enhance the real-time positioning performance of two formation-flying satellites in low-Earth orbit (LEO) and long-baseline environments in the very-high-speed intersatellite link system using an infrared optical terminal and nanosatellite (VISION) mission. To overcome the instability and complexity of calculations caused by distance-based noise in LEO satellites, dual-frequency GPS receivers are required to correct ionospheric delay and implement an onboard filter with single-differenced (SD) data. To improve the efficiency and stability of the MAKF algorithm upon the extended or adaptive Kalman filter system in a low-dynamic scenario, a revised estimation of innovation- and residual-based noise covariance was proposed in this study. The proposed algorithm was verified and evaluated in terms of the pointing and positioning accuracy using software- and hardware-based simulations. According to the software-based assessment, the MAKF improved the 3D relative positioning accuracy by 40% and 5% compared to the EKF and AKF models, respectively, in the mission scenario at a 1,000 km baseline with fixed ambiguities. The proposed algorithm can not only improve the relative navigation performance compared to the EKF and AKF, but also decrease the computational complexity with a simplified adaptation method compared to the AKF model in the low-dynamic scenario, for example, near-solar-minimum environments. The hardware-based simulation results also demonstrated that the relative positioning accuracy of the proposed algorithm was improved by 6% compared to the AKF model at a 1,000 km relative distance with a reduced computational burden.
Published in:	Proceedings of the 2024 International Technical Meeting of The Institute of Navigation January 23 - 25, 2024 Hyatt Regency Long Beach Long Beach, California
Pages:	658 - 676
Cite this article:	Kim, Yeji, Kim, Pureum, Ryu, Han-Gyeol, Park, Sang-Young, "Evaluating the On-Orbit Relative Navigation Performance of Modified Adaptive Kalman Filter with GPS Ambiguity Resolution," Proceedings of the 2024 International Technical Meeting of The Institute of Navigation, Long Beach, California, January 2024, pp. 658-676. https://doi.org/10.33012/2024.19484
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