A Quick Map Matching Algorithm for Train Locating Based on Grid Partition

Locating is the basement of train control and onboard detecting. Train position is commonly expressed, as distance relative to a reference start point. For convenience of workers to find the position, the longitude and latitude gotten by GPS receiver should be translated into relative distance. Map matching method is used to do this. The best matching route and segment selection are keys of train locating by map matching method. Traditional methods are ergodic searching and bisearch. But they both have their limitation. This paper proposes a quick map matching algorithm for train location. It partitions the map into grids, builds database of stamp points and grids. The candidate routes and segments are searched in the limited area of adjacent grids around anchor point. The best matching route are determined with the least direction difference. At last, train relative location is calculated by interpolation within two stamp points. Experiment result indicates that the algorithm greatly reduce calculation load, which has nothing to do with complexity of route network. Especially, the algorithm can greatly enhance searching speed in lager database.