Obstacle detection system for use in vehicles

Abstract

An obstacle detection system for vehicles comprises a laser radar mounted on the front end of a vehicle and modulated by drive pulses of high rate. The laser pulses are deflected in two orthogonal directions by paired deflection signals fed from a deflection driver to paired acousto-optic light deflectors to digitally scan a space ahead of the running vehicle. The deflector driver supplies paired deflection information to arithmetic logic means. One deflection signal fed to one deflector has a rate much higher than the other and is synchronized therewith. When receiving a return pulse by a photo-detector, a video pulse of substantially constant level is reproduced by a sensitivity time control function. The distance between a target and the vehicle can be registered in a binary counter. Relevant distance information is supplied to the arithmetic logic means. The latter provides a decision of whether a possibility of collision exists and produces an alarm when the distance approaches a stopping distance. For two facing targets the arithmetic logic means calculates a spacing between them and provides decision that passing-through therebetween is impossible if the spacing is smaller than a predetermined width. For a target above the road the arithmetic logic means calculates its height and provides a decision that passing-through thereunder is impossible if that height is smaller than a predetermined height.