An accelerometer is a device that measures a form acceleration. A multiple axis accelerometer is able to measure acceleration in either two or three axes, which in turn allows it to measure movement in very precise detail. While a single axis accelerometer has uses in medicine and engineering, one of the most common use of a multi-axis accelerometer is in electronic gaming.
The form of acceleration measured by an accelerometer is known as proper acceleration. This is the level of acceleration after taking into account the freefall effects caused by gravity. In effect, an accelerometer measures the acceleration that can be felt by people.
Many types of accelerometer only measure acceleration — and in turn, movement — along a single axis. That is to say, movement in one pair of opposing directions, such as back and forth. There are, of course, three axes for any object, which can be expressed as back and forth, left and right, and up and down. More sophisticated accelerometers can measure in two or all three of these axes.
Both a single or multiple axis accelerometer can be used for engineering purposes. For example, it could measure the way a building vibrates when exposed to forces such as people walking across it, debris falling upon it, high winds, or an earthquake. In turn, these measurements can help assess the best design for withstanding such incidents, as well as achieving a balance between being resilient to such risks without becoming prohibitively expensive.
An accelerometer can also be used for medical purposes. These include creating sensors to help emergency aid staff make chest compressions with a consistent depth. Other medical uses include sports watches that can measure both speed and distance for a runner.
The most high-profile use of multi-axis accelerometers in the 21st century is in video gaming. In some cases, this involves measuring the tilting of a handheld screen, for example in electronic versions of a traditionally wooden maze toy. In other cases, the accelerometers measure the movement of a wireless, handheld controller that can simulate an in-game object, such as a tennis racket or golf club. This allows the player to realistically carry out an on-screen action rather than simply press buttons.
