What Is a 3-Axis Accelerometer?

Ray Hawk

A 3-axis accelerometer is a device that is designed to measure acceleration along three axes in space — the forward and back X-axis, the left and right Y-axis, and the up and down Z-axis. Since an accelerometer measures acceleration as related to a state of free fall, where no forces are acting on it except for gravity, 3D acceleration is considered at a default state of zero or in a weightless state, even though the accelerometer itself has mass. The properties of a 3-axis accelerometer, therefore, make it a key component of inertial guidance systems, such as on missiles or aircraft, that measure changes in acceleration that affect the net inertial state of the vehicle.

Complex acceleration forces in amusement parks rides can be studied with a 3-axis accelerometer.
Complex acceleration forces in amusement parks rides can be studied with a 3-axis accelerometer.

As micro-electromechanical system (MEMs) sensors for measuring acceleration have become more commonplace and affordable, the 3-axis accelerometer has been incorporated into several consumer devices. It can be used to study complex acceleration forces in amusement park rides, video game controllers, and to enable humanoid-like robots to simulate the way that people walk. The technology of the 3-axis accelerometer has also been incorporated into roll-over safety and vibration systems on automobiles, navigational controls in mass transportation, and for stability in industrial equipment.

Accelerometer technology is often compared to the 3D gyroscope that also operates along three axes, and has been used in ships and planes as a mechanical device for many decades. A modern version of computer accelerometer in these applications is based on a microchip sensor that measures differential capacitance that occurs as acceleration takes place. This signal is transformed into a voltage that feeds into control systems. Most 3-axis accelerometer devices are built in technologies that help vehicles, control systems, and industrial machinery, such as pumps and compressors operate at peak efficiency, while measuring the motion of the object relative to the effect of gravity.

The idea behind how a 3-axis accelerometer functions has also led to it being incorporated into a variety of modern technology. Portable electronic display devices where the screen display rotates itself into an upright position opposite gravity as the device is moved about are one example. Animated accelerometer readouts can be used along with motion capture technology for more than just game and phone screen displays, however. The same data can also be analyzed to determine human body movement for how clothing wears out as it is used, for optimal biokinetics for runners and other athletes, and in medical applications such as cardiopulmonary resuscitation (CPR) techniques.

Virtual accelerometer software is also now available for defensive and military training. The software measures 3-axis accelerometer impact forces such as power, speed, and direction against a dummy used in boxing, martial arts, and combat training. The feedback gives direct access to weaknesses in technique upon which need to be improved.

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