A heuristic reliable model for guarded capacitive sensors to measure displacements

In this paper we analyze and compare different analytical models proposed in literature to estimate the sensing capacitance of guarded capacitive sensors for displacement measurement. The analysis is carried out by means of parametric numerical calculations based on Finite Element Analysis. Adopting an heuristic approach, we propose to modify one of the presented models with a polynomial correcting factor to obtain a better accurate estimation of the sensing capacitance, for a wide range of distances. The robustness of the presented model has been validated by means of parametric numerical perturbations.