Accelerometer
lastmod 2018-08-17created 2014-05-034 edits
An accelerometer is a device that measures the physical quantity of an object's acceleration. It is expressed in units of G, and the range varies by sensor.
It is a sensor that measures the acceleration of a moving object or the strength of an impact. Acceleration refers to the rate of change of velocity for linear motion in a particular direction. What matters here is that it is a linear direction. So an acceleration sensor is a sensor that reports, as a number, the rate of change of velocity per unit time in a linear direction.
iPhone accelerometer
Accelerometer.jpg
The iPhone uses a 3-axis acceleration sensor, with g, meaning gravitational acceleration, as its unit. Since gravity also counts as acceleration, the iPhone constantly senses (gravitational) acceleration downward. Taken into weightless outer space, the iPhone's acceleration sensor would show 0 for all of the X, Y, and Z axes, but on the surface of the Earth it cannot escape the effect of Earth's gravitational acceleration, so the vertical Z-axis sensor will show 지구중력가속도 = -1g = -9.8m/s².
Data can be obtained using the UIAccelerometer or CMMotionManager class.