Accurate Localization of Passive Sensors Using Multiple Impedance Measurements

We consider the problem of locating a sensor in a network of nodes which use inductive coupling as means of interaction. Conventional approaches in this setting require the located node to have a power supply or complex circuitry. By analysis of the circuit model underlying inductive coupling, we develop a localization method which allows for passive nodes with a simple layout. The proposed method reconstructs the unknown position from measurements of the input impedance at a set of reference nodes via the Nelder-Mead simplex algorithm. We show that the accuracy of the localization depends highly on the initialization value used for optimization, and provide a heuristic grid search algorithm to increase the quality of the initial position and thus of the localization process. A lower bound on the performance is provided for a two-dimensional setup; it can be closely met by the proposed localization algorithms in a realistic setup. The results show that the discussed approach can provide very high localization accuracy with a low-complexity node configuration.