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Of primary importance in Vehicle Navigation systems is the accurate determination of location. Through use of distance sensor, optical-fiber gyroscope, Map-Matching technique, and GPS receiver to reduce accumulated errors, we are improving location accuracy. The model we demonstrated in our March 1991 field test showed good results on three courses of the 10 recommended by the Public Works Research Institute - (10km in an urban area, and 20 and 50km in the suburbs). Additionally, our model displayed two superior strengths: neither the initial location or direction of a vehicle needs to be set; and conventional map data (not 100% accurate) may be utilized. This paper describes the results of our experimental demonstration and how to combine a GPS receiver and inertial sensor.

One of the most important technologies for navigation system is to improve the level of accuracy of vehicle's location. So an autonomous dead reckoning system is effective as a first step, map-matching technique is necessary to eliminate accumulated location errors. For practical use, however the map-matching technique should be evaluated and improved for various driving conditions, because conventional map data are not accurate enough, and there is a wide variety of road conditions. So we have been working to develop a new simulation system to optimize map-matching techniques with a higher degree of efficiency and without so many actual driving tests. This system was designed to make pseudocircumstances of indoor field tests, which allows map-matching techniques to be evaluated more efficiently, and it reduces practical tests to evaluate navigation system. And using this system, we can estimate a goal of specification of sensors.