Abstract
With the proliferation of low cost magnetic sensors, magnetic field-based localization systems promise portable and affordable noncontact sensing solutions for tracking the tip of a catheter, such as a NG tube or a ventriculostomy catheter, inside the human's body. Currently, these localization systems are constrained by a short tracking range of up to 150 mm from the sensor center. In this paper, we present a compliant non-invasive system that enables extendable long-range tracking in real time using a permanent magnet-to be embedded to a catheter-and an array of sensors. When the catheter being inserted into the body, the magnet creates a magnetic field which can be detected by proximic sensors. To achieve high accuracy in long-range sensing while keeping the computational requirements reasonable, the sensors are first configured using the best horizontal and vertical offsets identified from numerical simulation. Next, only the magnetic flux densities measured by axial sensing channels of a sensor positioned in close proximity of the magnet, which we refer to as attentive sensing channels, will be considered for localization process. Two threshold schemes for identifying attentive sensing channels are proposed and evaluated. Finally, a novel nonlinear-based localization algorithm is used to estimate the magnet position based on the magnetic flux density detected by attentive axial sensing channels. The results of numerical simulation and real experiments show that our proposed approach warrants long-range localization of magnet position with good localization accuracy, resource conservation and high robustness.