Abstract: A system, having: a first sensor module having an inertial measurement unit and configured to be attached to a forearm of a user and to generate first motion data identifying an orientation of the forearm connected between a hand of the user and an upper arm of the user; a second sensor module having an inertial measurement unit and configured to be attached to the hand of the user and to generate second motion data identifying an orientation of the hand; and a computing device communicatively coupled to the first sensor module and the second sensor module through communication links, the computing device configured to calculate, based on the orientation of the forearm, a position of the forearm, and the orientation of the hand, an orientation of the upper arm.

Abstract: A method including receiving, in a computing device, periodic measurements of accelerations from a plurality of sensor modules. The computing device determines whether each respective sensor module of the sensor modules is attached to a respective part of a user from the periodic measurements of accelerations from the plurality of sensor modules as received. In response to the determination that each respective sensor module of the sensor modules is attached to the respective part of the user, the method includes initiating, by the computing device, a calibration operation to calibrate orientation measurements of the sensor modules relative to a common reference system defined based on an orientation of the user.