MEMS Accelerometer
A MEMS accelerometer is a sensor that capacitively measures the displacement of a tiny spring-mounted mass fabricated on silicon. On a stationary body the only acceleration it measures is gravity; the inclination angle is calculated from the ratio of the axis components. It is the basic measuring element inside levelling sensors.
Inside the chip there is a suspended mass and fixed electrodes next to it. When the mass is displaced under acceleration, the capacitance between the electrodes changes; this change is converted into a voltage and then into a digital value. Since gravity is the only effect while the body is stationary, the ratio of the components read on three axes gives the inclination angle directly.
- Strength: no mechanical wear, low drift, temperature compensation can be done inside the chip.
- Weakness: it cannot distinguish gravity from other accelerations. While the vehicle is rocking, the wind is pushing it or someone is walking inside, the reading fluctuates.
For that reason levelling systems average the measurement over time and base the correction decision on a stable reading. The value is jumping around situation you see in the field is usually not a fault but real movement being measured. If you take the measurement without moving inside the RV, with the doors closed and the wind calm, you will see a far more stable result.
The context in which this term is used: RV automatic levelling guide