Title:
Performance of a low infrastructure navigation system for planetary surface users
Performance of a low infrastructure navigation system for planetary surface users
Author(s)
Jun, William W.
Advisor(s)
Lightsey, E. Glenn
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Abstract
With the plan to return to the Moon, there is great interest in a sustained lunar presence by both autonomous vehicles and humans. Establishing a lunar presence necessitates an accurate lunar navigation service that is scalable in user quantity. Future lunar users will require onboard, real-time position, velocity, and timing (PVT) estimation. This research proposes a low infrastructure, radiometric navigation system to fulfill this need.
This thesis first introduces a set of Doppler-based navigation methods to enable positioning of lunar surface users with a low infrastructure navigation architecture. Combined with range measurements and a well-known reference station, these methods create Joint Doppler and Ranging (JDR) navigation. JDR reduces errors in Doppler measurements through geometric constraints between the user, reference station, and orbiter. This provides effective position estimation using Doppler measurements.
Then, to mitigate biases in frequency measurements, this research introduces measurement differencing with JDR. To evaluate the performance of JDR with realistic Doppler measurements, this thesis develops a comprehensive Doppler shift measurement simulation that generates frequency biases, drifts, and noise based on a high-fidelity oscillator model. This oscillator model develops integrated frequency errors from commercial oscillator phase noise data. Case studies establish performance of JDR with various grades of local oscillators onboard the users and the navigation orbiters.
Finally, this thesis generalizes JDR for dynamic users, enabling real-time PVT estimation. The generalized JDR method with measurement differencing effectively navigates a user along a challenging trajectory on the lunar surface. A case study demonstrates orbit determination of a low lunar orbiter with JDR. The use of one-way radiometric measurements results in a scalable navigation architecture that can service any user in the reference station's region.
This research advances the navigation capabilities of future lunar missions. With its low infrastructure navigation architecture, JDR is applicable as navigation service for other target planets, such as Earth and Mars.
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Date Issued
2023-07-25
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Dissertation