| 摘要 |
PURPOSE:To certainly judge whether an earth magnetism sensor receives the effect of disturbance and to make the correspondence thereof proper by comparing the output signal of a sensor for detecting the change quantity of a moving body in the advance direction thereof with that of the earth magnetism sensor. CONSTITUTION:A direction detector 1 using an earth magnetism sensor detects the advance direction of a moving body and a direction detector 2 using a sensor such as a left-and-right wheel number-of-rotation difference detector detects the change quantity of the moving body in the advance direction thereof. A distance detector 3 outputs, for example, the pulse train signal proportional to the number of rotations of a tire. A signal processor 4 measures the running distance of the moving body from the number of pulses from the detector 3 and operates the present position of the moving body on two-dimensional coordinates according to the advance direction of the moving body detected by the detector 1 and also judges whether the earth magnetism sensor receives the effect of disturbance through the comparison based on the output signal of the detector 2 and that of the detector 1 using the sensor. When it is judged that the earth magnetism sensor receives the effect of disturbance, the output correction of the detector 1 is performed to display the present position of a display device 5. |
