Magnetic field localization method for guiding visually impaired applications

This paper presents a method to assist visually impaired persons to locate magnetic objects along a path when performing daily arm-reaching and way-finding tasks. To avoid the effect of geo-magnetics, gradient of an object from measured magnetic flux densities has been developed, which characterize the two properties; the relative location and magnetic moment vectors of a magnetic object in the presence of geomagnetic fields. Based on the object motion relative to the sensor along a path, this method overcomes the difficulty of measuring the magnetic anomalies directly. Using dipole models, the magnetic moment and position vectors of the object are measured by a multi-sensor system; and these properties along a path graphically are represented by a magnetic tensor based ellipsoids. The effectiveness and accuracy of the magnetic field localization has been numerically demonstrated and validated by comparing results against exact solutions. For one object condition, the location and moment can be calculated accurately. Results also show that the tensor based ellipsoids are path dependent and can be used to identify the presence of a second object.