Electromagnetic Navigation Linear Displacement Transducer Based on Magnetic Field Gradient Technique

A linear displacement transducer (LDT) for electromagnetic navigation is developed based on the sensing of magnetic field gradients in a pair of counterwound coils. The operation and linear response conditions of the LDT are theoretically described by electromagnetic formulations, numerically analyzed by COMSOL Multiphysics finite-element analysis, and experimentally verified in a 1/10-scaled inspection vehicle-overhead cable model. A high sensitivity of 51 mu V/cm and a small nonlinearity of 3.7% are achieved in the LDT prototype by setting an optimal height-to-baseline h/L ratio of 1/root 8 in a practical linear response condition with the transverse displacement d constraint of +/- 50% of L. The proposed LDT can overcome the discontinuous response and nonlinearity problems intrinsic in traditional magnetic field-based LDTs, thereby providing a continuous displacement (movement) feedback with an accuracy of within several millimeters.