Improved model for the capacitance estimation of guarded capacitive sensors

We present a polynomial correction factor to improve the analytical models proposed in literature to estimate the sensing capacitance of guarded capacitive for displacement measurement. The correction factor has been obtained by fitting parametric numerical calculations based on Finite Element Analysis. The proposed heuristic model provides accurate estimations for a wide range of measuring distances. The robustness of the model has been tested by varying the size of the insulator gap g, even considering the sensor mounted in a recess of the fixed grounded plate with different geometries.