A blind guidance system for street crossings based on ultrasonic sensors

This paper addresses the technical feasibility of a guidance system based on ultrasonic sensors to aid visually impaired people to cross a road easily and safely. A computer processes ultrasonic signals emitted by a transmitter, which is carried by the impaired user, and provides real-time information on the direction and distance to keep user on the correct track. Instead of time of flight, the system estimates user position by the order of received ultrasonic signals at multiple receivers. Radio transmission is then used to provide guidance information to the user by using of two vibrators that act as tactile feedback. Experimental results are presented to discuss feasibility of this method.