An accelerometer is a device used to measure proper acceleration, which is the acceleration it experiences in relation to freefall, and is the acceleration felt by people and objects. Accelerometers are commonly made up of piezoelectric, piezoresistive or capacitive components. Here are some examples of what accelerometers are used for:
- As a component of inertial navigation systems for aircraft and missiles.
- Detecting and monitoring vibration in rotating machinery.
- Making sure images on the screens of phones, tablets and digital cameras are always displayed upright.
- Making the flight of drones more stable.
- Coordinated accelerometers can be used to measure differences in proper acceleration, especially gravity, over their separation in space, such as the gradient of the gravitational field. This gravity gradiometry is useful because absolute gravity is a weak effect and depends on the local density of the Earth, which can constantly change.