| 摘要 |
PURPOSE:To enable displaying of an uninterrupted track by using information from an acceleration sensor and a geomagnetism sensor when there is no signal from a global position measuring system (GPS). CONSTITUTION:If reception signals from a GPS receiver 2 are interrupted, a control portion 3 switches a system to that using an acceleration sensor 4 and a geomagnetism sensor 5 and sends inputs to a display portion 6 or performs control such as reading from and storing into a map storage portion 7. The acceleration sensor 4 samples acceleration by means of a piezoelectric element. The output of the piezoelectric element is integrated by time whereby velocity is found. The velocity is integrated so that distance is found. This output is synthesized with the output of the geomagnetism sensor 5 so that the relative position of an automobile is found. However, the accuracy of control is deteriorated by the double integration performed to find the distance but in the case of short distances the control is sufficient as that for correcting the GPS. Also, the navigation device can be miniaturized and there is no necessity of sampling signals from portions of an automobile such as tyres and so modification of the automobile is unnecessary. |
