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Session A8: Space Applications for Cislunar and Beyond

Computationally Efficient Low-Infrastructure Navigation Solutions using Target Localization Algorithms
Bong-Jun Yang, Enkuang Daniel Wang, and Joseph L. Loof, Georgia Tech Research Institute
Location: Ballroom B
Date/Time: Wednesday, Jun. 5, 9:15 a.m.

As future lunar missions to the moon consider exploring and utilizing moon resources, navigation on the moon surface is becoming an important problem for autonomous rover missions. In the literature, a low infrastructure, radiometric navigation system, which uses a minimum number of lunar-orbit satellites with an aid from a reference station, has been proposed for obtaining the position and the velocity of planetary surface users. In solving the position and the velocity of the user, whether the problem is solved in batch processing or in sequential processing, such as the extended Kalman filter, the previous approaches have treated pseudoranges and Doppler frequency measurements as the constraints that must be satisfied, and as a result, numerical procedures for obtaining solutions have been sensitive to initial guesses.
In this study, we show that the low-infrastructure navigation problem can be recast into that of the unknown target localization problem and therefore can be solved by computationally efficient algorithms that do not require initial guesses. The resulting position and the velocity can be fused with onboard sensors, such as Inertial Measurement Units (IMUs), leading to a loosely-coupled Inertial Navigation System/Lunar Navigation Satellite System (INS/LNSS) integration architecture on the moon.
The study addresses the following. A feasibility study for example lunar constellations for navigation and communications architecture is set up, in which the feasibility is defined as the number of visible satellites to a surface user is greater or equal to the minimum number required for solving the position and the velocity. Next, a systematic algorithm, based on the existing target localization literature, is introduced for solving the position and the velocity of lunar dynamic users. Along with the numerical algorithms, underlying implications for communication topologies are analyzed. The robustness of numerical procedure is illustrated in comparison with that of current Newton-Raphson-based algorithms. Finally, the position and the velocity information are fused with an INS on the lunar environment, which constitutes a loosely-coupled INS/LNSS. The navigation performances are evaluated with varying degree of IMU grades and precisions in pseudorange and Doppler frequency measurements.



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