PURPOSE: To detect the accurate position of an unmanned car, by delivering the distance signal of an object within a viewfield in the form of the function of an angle signal through a contour detector which is mounted on the unmanned car and then collating the distance signal with a plan of the space through which the unmanned car travels through an electronic computor.

CONSTITUTION: A contour detector 3 measures a distance (d) up to an obstacle X existing in front of an unmanned car 1 by a distance meter 5 within a range of ±θ to the travelling direction of the car 1. The distance signal is written into a memory of an electronic computer 8 mounted on the car 1 in the form of the function of an angle signal of an angle sensor 6 of each time. The computer 8 collates the profile written in the memory with a plan of the travelling space of the car 1 and stored previously. Thus position of the car 1 discriminated in the space, and the result of this discrimination is fed to a monitor center via a ratio transmitter 9 to tell the accurate position of the car 1.