Capacitance mismatch correction for a fluidic inclinometer

Capacitive fluidic inclinometers provide an interesting alternative to pendulum based sensor principles for inclination measurement in harsh industrial environments, as mechanical problems due to the large pendulum are avoided. However, the performance of these sensors is strongly dictated by fluid properties. A common means to cope with the non ideal effects of the fluid in order to achieve high accuracy is calibration of the sensor after fabrication. This work presents a method based on a detailed model of the sensor front-end and the interface circuitry to provide an absolute measurement error of less than 0.25° over full turn measurement range and the industrial temperature range without the need of calibration.