accelerometer

An accelerometer is a sensor that measures acceleration along one or more axes. It reports the rate of change of velocity of the device it is attached to, relative to an inertial reference frame. In practical terms, accelerometers measure proper acceleration, which includes non-gravitational forces acting on the sensor. Gravity is felt as a static acceleration when the device is at rest, helping with orientation estimation when combined with other sensors. Accelerometers are core components of inertial measurement units (IMUs) used in navigation, motion tracking, and control systems.

Most modern accelerometers are microelectromechanical systems (MEMS). They typically contain a proof mass attached to a spring and damper on a silicon substrate. When the device accelerates, the mass displaces, and the displacement is converted to an electrical signal by transduction methods such as capacitive, piezoelectric, or piezoresistive sensing.

Other accelerometer types include piezoelectric and piezoresistive devices used in specialized applications, and thermal or optical approaches used in research contexts. MEMS devices often measure acceleration along three orthogonal axes in a compact package, providing tri-axial data within a single chip or stacked configurations. Specifications commonly reported include dynamic range, sensitivity, bandwidth, noise, bias stability, and temperature dependence.

Applications span consumer electronics (smartphones, tablets, wearables, gaming controllers), automotive safety (airbag deployment, stability control), robotics, drones, and structural health monitoring. In smartphones, acceleration data supports screen orientation, motion detection for gestures, and step counting. In navigation and control systems, accelerometers complement gyroscopes to track motion in three dimensions.