Integrated map-matching algorithm based on fuzzy logic and dead reckoning

Based on the concept of fuzzy logic, a new map-matching algorithm was proposed to reduce the GPS positioning error by means of position correction in use of the digital map. Firstly, three fuzzy rules are introduced in different aspects which may influent the credibility judgment of the best matching road. And the corresponding membership functions are defined in details separately for sub-evaluations of the direction consistency, the proximity and the track similarity against the original GPS position and its candidate road, where dead reckoning technique is referred. Secondly, the comprehensive evaluation performing as the unique basis for final judgment is made by doing simple addition of the results of these sub-evaluations with certain weights according to their contributions towards the credibility judgment. Finally, the original GPS position is revised by making a vertical projection onto the best matching road. Experimental results demonstrate the effectiveness and applicability of this algorithm in improving the GPS positioning accuracy.