| 摘要 |
PURPOSE:To improve the accuracy of detection of an estimated position, by providing information showing whether the estimated position is within an extraordinary magnetic field area, a map storage means outputting azimuth variation amount data at the time of an extraordinary state when said position is within the extraordinary magnetic field area, etc. CONSTITUTION:An azimuth angle of the direction of advance is determined from an output value of a geomagnetism detecting means 11, a distance of advance is determined from an output of a running distance detecting means 10, and a supposed position is computed from these values by a supposed navigation computing means 14, at every prescribed time. However, the estimated position deviates from an actual position when a vehicle runs in a place wherein geomagnetism is disturbed by various environmental conditions. Accordingly, data on positions in an extraordinary magnetic field area and data on the amount of variation of azimuth due to an extraordinary magnetic field are stored beforehand in a map storage means 13; when the storage means 13 outputs an information on the presence of the vehicle in the extraordinary magnetic field area, which is obtained from the estimated position, the data from the geomagnetism detecting means 11 are corrected with an angle of deviation and also corrected 12 with the data on the amount of variation of azimuth, so as to compute a new estimated position. An estimated position of high accuracy can be determined in this way. |
