Early smartphones contained low-power accelerometers and magnetometers to measure device tilt. Tilt tracking allows
users to interact with applications by simply rotating the device. For example, turning the phone on its side will rotate
its interface from portrait to landscape. Modern smartphones include additional micro-electro mechanical gyroscopes.
This combination of sensing hardware can also be found in motion capture systems in the form of inertial measurement units
(IMU). This paper draws a parallel between smartphones and IMUs to answer one question: Is motion capture and activity tracking feasible using smartphone-driven body sensor networks?