High Sensitivity GPS Velocity Updates for Personal Indoor Navigation Using Inertial Navigation Systems

M.G. Petovello, O. Mezentsev, G. Lachapelle, M.E. Cannon

Abstract:	Previous work on indoor navigation has typically focused on using high sensitivity (HS) GPS receivers augmented with other dead-reckoning sensors. To this end, these approaches use the pseudorange measurements from the HSGPS receiver as the means to update the dead-reckoning sensors. Unfortunately, these pseudorange measurements are noisy under degraded signal environments and suffer from systematic errors from multipath and echo-only signals. These errors combine with degraded satellite geometry to produce largely erroneous position estimates. To help circumvent this problem, this paper investigates the possibility of using Doppler measurements from a HSGPS receiver to update a tactical-grade inertial navigation system. The advantage of this approach is that Doppler multipath effects are a function of receiver velocity, and for the indoor environment should remain at a reasonable level. The paper begins by assessing the variability of the HSGPS Doppler measurements as a function of received signal power. This assessment is performed using data collected on a hardware simulator, as well as data collected in a wood barn and inside a residential garage. Results show that Doppler accuracies of better than 2 m/s are possible, even with signals that are attenuated by approximately 25 dB relative to nominal GPS environments. Unfortunately, the Doppler measurements are also shown to be biased, thus producing biased velocity estimates. Once the above assessment is complete, the results are used to conduct a series of covariance simulations to assess the potential performance of an integrated HSGPS/INS system. Simulation parameters were selected to approximate the use of a tactical-grade IMU. Overall, the horizontal positioning accuracy was found to be dependent on the frequency of zero velocity updates, especially as the Doppler accuracy decreases. In contrast, the vertical channel accuracy remains relatively unaffected by the accuracy of the Doppler measurements.
Published in:	Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003) September 9 - 12, 2003 Oregon Convention Center Portland, OR
Pages:	2886 - 2896
Cite this article:	Petovello, M.G., Mezentsev, O., Lachapelle, G., Cannon, M.E., "High Sensitivity GPS Velocity Updates for Personal Indoor Navigation Using Inertial Navigation Systems," Proceedings of the 16th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GPS/GNSS 2003), Portland, OR, September 2003, pp. 2886-2896.
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