The apparatus includes a running distance sensor, a heading direction sensor based on terrestrial magnetism, and a map data base for identifying the road on which the vehicle is running. In implementing map matching for collating running data with map data, the difference between the heading direction...http://www.google.com.hk/patents/US5060162?utm_source=gb-gplus-share專利 US5060162 - Vehicle in-situ locating apparatus
