| 摘要 |
<p>PURPOSE:To prevent erroneous detection of a bearing, by replacing an output data of an earth magnetism sensor with a specified data when it is detected from identifying information that a site subject to a disturbance of earth magnetism exists within a specified distance ahead of the current location. CONSTITUTION:Identifying information is inserted into a map data for a site subjected to a disturbance of earth magnetism such as crossing beforehand. A CPU 7 reads out a data at the subsequent point determined numerically based on the current location from a recording medium 10 to calculate the distance to the subsequent point. If this distance is within a fixed range, it is judged whether a crossing or the like exists near the point or not. When a crossing or the like is determined to exist based on identifying information of the map data, an output data of another sensor, such as angular sensor 2 is used instead of the output data of the earth magnetism sensor 1 until passage through a fixed distance is confirmed after passing the crossing or the like. Otherwise map data may be used or running may be done holding the approaching angle of the vehicle to the point. This can prevent erroneous detection of a bearing as caused by the disturbance of earth magnetism.</p> |
