GB1300299A - System for preventing collision of vehicles - Google Patents

Abstract

1300299 Laser radar MITSUBISHI DENKI KK 14 Oct 1970 48893/70 Heading H4D A pulsed laser radar is carried by a motor vehicle and is used to detect the distance to an obstacle and cause automatic actuation of the braking system if the distance is too small in relation to the vehicle's speed. The return from a transmitted pulse is gated to the detector by a gate pulse delayed from the transmitted pulse by a period proportional to the vehicle's speed. Three gates may be used each delayed by successively greater amounts and giving corresponding warnings of decreasing danger when an obstacle reflection is gated therethrough. In the single gate embodiment, Figs. 1, 3, an astable multivibrator triggering generator 10 feeds pulses (a) Fig. 3, to a thyrister/capacitor pulser 12 which causes a laser diode to emit pulses (b) of coherent light towards the obstacle. The reflections (c) are detected by photo transistors 20 and the video signal fed, after amplifying, to gate 28. The gating generator 24 produces gating pulses (d) delayed under the control of the output of a vehicle speed detector 26. When the obstacle is at a dangerous distance commensurate with the vehicles speed, its reflection is gated by 28 (e) and fed to an F.E.T./diode/ capacitor pulse height holding circuit 30, reset by each trigger pulse by a discharge generator 32, to give an output (f) successively recording the heights of the gated reflections. An integrator 34 smoothes the height output and actuates an alarm 36 and the braking system, when its output rises to indicate an actual obstacle rather than just noise. In the three gate embodiment (Fig. 4, not shown), the three alarms are green, orange and red lights respectively. The invention is stated to be applicable to radio and acoustic energy.