CORRECTION OF GEOMAGNETISM SENSOR IN NAVIGATION SYSTEM

摘要

PURPOSE:To output a correct azimuth even when magnetizing quantity changes, by storing the position of a road crossing, the number of roads at the crossing and a road extending direction along with a map image when map data is preliminarily stored in a system. CONSTITUTION:At first, the initial setting of a revolving circle S0 is performed and the radius and center O of the revolving circle S0 are determined. Next, a vehicle enters a running state and, at the time of straight advance, the distances XA, YA from the origin O of an azimuth index point A and an azimuth angle thetaOA are calculated from a geomagnetism sensor. Subsequently, in such a case that the advance direction of the vehicle is changed, when it is confirmed that the vehicle is advancing straightly after turning, the distances XB, YB on the orthogonal axis of a new azimuth index point B and the azimuth angle thetaOB thereof are taken in from the geomagnetism sensor and, at the same time, a road azimuth angle thetaPB from map data is taken in. Next, operational processing is performed using the taken in data XA, YA, thetaOA, thetaPA, XB, YB, thetaOB, thetaPB and r to calculate the center value P(XP,YP) of the moved revolving circle SP and said center value is set as one hereinafter to be displayed on a display. By this method, a correct azimuth can be outputted and displayed.