Improving INS/GPS Positioning Accuracy During GPS Outages Using Fuzzy Logic

M.M.R. Taha, A. Noureldin, N. El-Sheimy

Abstract:	Most integrated INS/GPS positioning systems have been implemented using Kalman filtering technique. Although of being widely used, Kalman filtering has some drawbacks related to computation load, immunity to noise effects and observability. In addition, Kalman filter only works well under certain predefined error models and it provides accurate estimation of INS errors only during the availability of GPS signal. Upon losing the GPS signal, if the inertial sensor errors do not have an accurate stochastic model, Kalman filter delivers poor prediction of INS errors, and thus a considerable increase in position errors may be observed. This paper introduces an alternative INS/GPS integration method using fuzzy logic. A new adaptive neuro-fuzzy system (ANFIS) model based on Tagaki-Sugeno-Kang (TSK) fuzzy inference system is developed to estimate INS errors during GPS outages. The advantage of the fuzzy system over other classical filtering algorithms is its ability to deal with imprecision and vagueness in the input data in dynamic environments. The ANFIS model divides the input space into fuzzy sub-spaces and maps the output using a set of linear functions. During the availability of GPS signal, the ANFIS system will be trained to map the error between the GPS and the INS. The fuzzy system will then be employed to predict the error of the INS position components during GPS signal blockage. The proposed architecture was tested in a land vehicle using two Ashtech Z12 GPS receivers (for DGPS) and a navigation-grade INS (Honeywell LRF-III). GPS signal outages of a time period between 60 to 120 seconds were simulated during 3200 seconds of land vehicle navigation. The experimental results demonstrated the advantages of the new approach in terms of performance and computational efficiency.
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:	499 - 508
Cite this article:	Taha, M.M.R., Noureldin, A., El-Sheimy, N., "Improving INS/GPS Positioning Accuracy During GPS Outages Using Fuzzy Logic," 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. 499-508.
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