# Unwinding The Working Of An Accelerometer

Acceleration is simply the rate of change of velocity with time. It is based on the Newton’s second law of motion, which states that acceleration is the net result of all the forces acting on an object. For any machine which moves, this is an essential parameter to be monitored and controlled for its smooth functioning. A simple and most popular illustration of acceleration is the change of speed of a moving car.

What we observe is not proper acceleration

Taking the above example, a car moves forward or backward or turns circular and the passenger inside it feels the force in three directions every time. This is coordinate acceleration, defined from the perception of the observer. When acceleration is measured as that experienced by the object, it is known as proper or physical acceleration. This is measured by a machine called accelerometer.

The underlying technology

Accelerometer measures g-force, that is, acceleration with respect to free fall experienced by the object. When an accelerometer is kept at rest relative to the Earth’s surface, it indicates a value of approximately 1 g upwards. It is because the machine measures the relative upward acceleration of any point near the surface by keeping a freely falling object near the surface as the local inertial frame, relative to which the accelerator measures. This is gravity offset and it has to be subtracted to obtain the value of acceleration due to motion with respect to the Earth and corrections should be made to remove the effect of the Earth’s rotation.

Applications

An accelerometer is applied in a variety of sectors like production and engineering, life science and medical technology, transport and navigation, electrical, mechanical and other industries, civil construction and structuring etc. It has a futuristic application in all the industries and automobiles; to monitor, analyze and give indications of possible faults in instruments and machines on which it is mounted.

A data collector collects the measured data of the machine vibrations and is fed to analysis software which then signals for probable maintenance by the technician or engineer. This method helps to improve machine performance, production speed, and easy repair and has become a distinguished industrial process.