| 摘要 |
PURPOSE:To improve the reliability of the earth magnetism sensor data regarding a past actual travel by finding an azimuth radius from the distribution of the radius of an azimuth circle based upon the earth magnetism sensor data and a permissible range from the azimuth radius. CONSTITUTION:The time-series output data of the earth magnetism sensor 12 which are gathered in the past are stored in a buffer memory 3. A locator 1 reads the data out to find a distance from the center point of the azimuth circle which is already found by the magnetism quantity correction processing of the earth magnetism sensor 12, further normalizes it to find the mean value of effective data and finds the radius of the azimuth circle, and multiplies the standard deviation of the distribution of the effective data by a constant number to obtain the permissible range of variance of data. Then the ratio that earth magnetism sensor data in a current cycle exceeds the permissible range from the mean value is obtained and evaluates whether or not the earth magnetism sensor is normal or not according to whether the ratio exceeds a specific value or not. Consequently, the reliability of the earth magnetism sensor data, the disorder of the earth magnetic field, or whether the earth magnetism sensor 12 itself is normal or abnormal can be decided. |
