A wireless ranging system as an embedded sensor module for the long cane

This paper presents the design and implementation of a ultrasound-based wireless ranging system that is suited for integration into the shaft of a conventional long cane to serve as a travel aid for the blind. The new cane provides distance and height information on overhanging obstacles in the travel path ahead of the user. The system consists of three ultrasonic sensors, a microcontroller-based RF telemetric data transmitter, and a data receiver. Systematic experiments using four representative objects have confirmed that the system is capable of detecting obstacles within four meters ahead, with the maximum relative error of detection less than 8%