Integrating GPS/INS/PL for Robust Positioning

Jul 2007 | Comments Off

	The challenging issues and progresses

Concluding Remarks

During the past two decades, GPS has revolutionised surveying, geodesy and other position-sensitive disciplines, such as transportation, personal location and telecommunications. The ever-increasing dependence on the GPS has triggered more and more concerns about the robustness of GPS. However, the recent studies conducted by some leading organizations, such as Volpe National Transportation Systems Centre in the USA, have revealed that GPS cannot perform reliably under weak signal and/or radio interference environments. This critical issue, which may be even a concern of safety-of-life in such positioning applications as aircraft automatic landing or rescue efforts in the high-rise buildings, can be addressed by the ultra-tight integration of GPS/INS/PL.

Fundamentally, radio based positioning systems and inertial sensors have complementary characteristics, offering an ideal integration scenario for a robust positioning and navigation system. In contrast to the existing ultra-tight ‘twin’ integration of GPS/INS, the inclusion of pseudolites into the system will significantly boost the positioning performance as pseudolites can transmit stronger signals than GPS from any desirable locations, ensuring an optimal geometry for positioning operations. In addition, where GPS signals are totally lost/jammed, pseudolites can even replace the GPS as a back-up means of positioning (Wang, 2002). The developments of pseudolites should also address optimal combinations of frequencies and signal structures for a wide range of application environments (Jovancevic, et al., 2007)

This paper has presented an overview of the GPS/INS/PL research and discussed such challenging issues as Modelling INS and GPS/PL measurements; Multiple Access Interference and Near-Far effects; Integration of Pseudolite with GPS/INS; Integration filter, Smart Antenna Array. Finally, the initial results from the real-time experiment demonstrate the robust performance of the ultra-tight integration.

Acknowledgement

This research is supported by the Australian Research Council (ARC) Discovery Project on “Robust Positioning Based on Ultra-tight Integration of GPS, Pseudolite and Inertial Sensors”.

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