Magnetic Tensor Sensor and Way-Finding Method Based on Geomagnetic Field Effects With Applications for Visually Impaired Users

This paper presents a method utilizing geomagnetic field effects commonly found in nature to help the visually impaired persons (VIPs) navigate safely and efficiently; both indoor and outdoor applications are considered. Magnetic information indicating special locations can be incorporated as waypoints on a map to provide a basis to help the user follow a map that amalgamates the waypoints into spatial information. Along with a magnetic tensor sensor (MTS), a navigation system for helping VIPs more effectively comprehend their surroundings is presented. With the waypoint-enhanced map and an improved dynamic-time-warping algorithm, this system estimates the user's locations from real-time measured magnetic data. Methods using image data to enhance waypoints at dangerous locations are discussed. The MTS-enhanced method can be integrated into existing personal mobile devices (with built-in sound, image, video, and vibration alert capabilities) to take advantages of the rapidly developing internet, global positioning systems, and computing technologies to overcome several shortcomings of blind-assistive devices. A prototype MTS-enhanced system for indoor/outdoor navigation has been developed and demonstrated experimentally. Although the MTS and algorithm are presented in the context of way-finding for a VIP, the findings presented here provide a basis for a wide range of applications where geomagnetic field effects offer an advantage.