Autonomous undersea systems require resilient navigation solutions capable of maintaining accurate positioning over extended durations without access to external navigation updates. While inertial navigation systems provide self-contained navigation capability, position errors inevitably accumulate over time, creating a requirement for complementary navigation technologies capable of operating in the undersea domain. Recent advances in quantum sensing, particularly diamond-based vector magnetometers, have renewed interest in magnetic navigation as a practical aiding technology for long-endurance autonomous operations.
Magnetic navigation operates by comparing onboard magnetic measurements with geo-referenced magnetic field maps. Compared with conventional scalar magnetometers, vector magnetometers provide significantly richer information about the local magnetic field and therefore have the potential to substantially improve map-matching localisation performance. However, vector magnetic navigation is highly sensitive to platform attitude uncertainty. Even small orientation errors can introduce magnetic field errors comparable to or larger than the magnetic anomalies used for navigation, significantly degrading localisation performance and limiting the operational utility of vector map matching.
Our work addresses this challenge through an attitude-aware magnetic navigation framework based on scalar–vector map-matching fusion. The approach combines the robustness of scalar magnetic navigation with the enhanced observability provided by vector magnetic measurements. By using scalar magnetic map matching to constrain navigation uncertainty before applying vector map matching, the method reduces sensitivity to attitude errors while preserving many of the localisation advantages offered by vector sensing.
The approach has been evaluated using long-duration simulated trajectories exceeding 1,000 km and 100 hours of operation across both global magnetic field models and regional magnetic anomaly maps. Our results demonstrate that scalar–vector fusion consistently outperforms conventional scalar magnetic navigation, while offering improved resilience relative to vector-only approaches under realistic platform attitude uncertainties for the modelled trajectories. The resulting navigation performance smoothly transitions between scalar and vector limits depending on the quality of the platform attitude estimate, providing a practical pathway for operational deployment.
These results demonstrate how quantum-enabled magnetic navigation may contribute to future resilient navigation architectures for autonomous maritime systems operating in contested, remote, and GNSS-denied environments. The work also highlights the growing role that diamond-based quantum sensing technologies may play in next-generation navigation, autonomy, and maritime domain awareness capabilities.