Long range, high sensitivity, low noise capacitive sensor for tagless indoor human localization

Capacitive sensors have important advantages and are widely used, but typically up to sensing distances comparable to sensor size. We present the design and experimental results of a self-contained long range capacitive sensor that is suitable for indoor human localization. We make differential measurements of the reactance effects of sensor plate capacitance using a constant excitation frequency, which is both less prone to noise and easier to filter. The experimental results show good sensor sensitivity up to 200 cm for a 16 cm square sensor plate, low noise and good measurement stability.