| 摘要 |
PURPOSE:To display the current position precisely by equipping a control means with functions to seek the map information giving the current position out of a memory, which was furnished previously, and to give a corrected indication for the position of itself on a display part. CONSTITUTION:Normally the current position is determined by a control means 50 on the basis of information given by a wheel sped sensor 30 and a terrestrial magnetism sensor 20, and map information on the applicable ordinary road is sought from a CD-ROM 40 and indicated on a CRT display 60 together with the current position. A CPU 51 determines the speed from the information given by the wheel speed sensor 30 and using a timer 54, and it is judged that the car is running on an ordinary road unless speed over a certain level lasts for a specified time. Otherwise it is judged as running on a highway, a search is made into the ROM 40, and the map information on highways and the current position are given on the display 60. While running on a highway, it is checked whether a left winker lamp switch 10 is on. If On and if the car is running at a speed below a certain level for a time exceeding a specified value, a search shall take place to know, among others, if there is any interchange. |
