The accelerometer is also the base of any inertial navigation system
such as some aircraft autopilot
s, or ship nav systems. A set of accelerometers continually measures acceleration in all three dimensions
; the second integral
!) of these values will give you the distance traveled in each direction from the starting point (well, not that simply, but using that method).
Many accelerometers utilize gyros of some sort, from mechanical gyroscopes to ring laser gyros.