| 摘要 |
PURPOSE:To improve the precision of direction data on a vehicle and guides the vehicle accurately by correcting the permissible quantity of direction variation small as the vehicle speed increases, and canceling the output of a terrestrial magnetism sensor when its data deviates from the permissible quantity of direction variation. CONSTITUTION:The run direction of the vehicle is detected by the terrestrial magnetism sensor 6, whose output is sent to a display device 21. Namely, a permissible variation quantity calculating part 18 collates the vehicle speed detected by a vehicle speed sensor 11 with stored data in a permissible direction variation quantity ROM13 to calculates the permissible quantity of direction variation for the vehicle speed. Further, a comparison part 19 compares the permissible quantity of direction variation calculated by the permissible variation quantity calculating part 18 with the quantity of variation detected by the sensor 6. Further, a control part 20 receives the output of the comparison part 19 to cancel the output when the quantity of direction variation obtained by the sensor 6 is larger than the permissible quantity or send the output to a CRT21 when not, thereby displaying the current position of the vehicle on its display screen 21a. |
