A portable mid-range localization system using infrared LEDs for visually impaired people

• A portable sized guidance system for the visually impaired was developed.
• An ultrasound time-of-flight method and a differential infrared intensity method were realized.
• It is possible to use the infrared intensity method to generate a uniform signal field that exceeded 30 m.
• The measurement was independent of external conditions within a certain range.
• We made it possible to use this receiver in portable devices such as smartphones.

A versatile indoor/outdoor pedestrian guidance system with good mobility is necessary in order to aid visually impaired pedestrians in indoor and outdoor environments. In this paper, distance estimation methods for portable wireless localization systems are verified. Two systems of a fixed active beacon and a receiver using an ultrasound time-of-flight method and a differential infrared intensity method are proposed. The infrared localization system was appropriate for the goal of this study. It was possible to use the infrared intensity method to generate a uniform signal field that exceeded 30 m. Valid distance estimations which were within 30 m of coverage indoors and within 20 m of coverage outdoors were made. Also, a pocket-sized receiver which can be adapted to a smartphone was found to be suitable for use as a portable device.