An inclinometer using movable electrode in a parallel plate capacitive structure

Abstract

We present an inclinometer which incorporates a movable electrode acting as a pendulum inside a parallel plate capacitor. The movable electrode acts as the bottom plate while the top plate is a fixed metal with varying area in the shape of a triangle. When the bottom plate moves under the influence of gravity, the overlapping area of the two plates of the parallel plate capacitor varies corresponding to a change in capacitance. The relation between the angle of tilt, overlapping area, and output capacitance is derived which is used to covert the output capacitance to the tilt angle. The inclinometer has a range of 50° with a resolution of 0.38° and a response time of ∼130 ms. This design has a pronounced advantage over current methods of making inclinometer. Generally, inclinometers incorporate MEMS-based accelerometers which need complex interface circuitry and are expensive to produce while having redundant features that are not required for inclinometers. Other specialized inclinometers use fluids that are prone to environmental changes and complex to manufacture due to the presence of fluids.