Digital inclinometer for joint angles measurements with a real-time 3D-animation

Range of motion measurement using wearable sensors is an inexpensive, convenient, and efficient manner of providing useful information for joint disorder. Classical digital inclinometers can only measure joint angles in a vertical plane. This paper describes an embedded system that measures joint angles simultaneously in vertical and horizontal planes. It is based on gravitational acceleration and magnetic field sensors measurements. The method used in order to measure the correct angles for a given position of the device is described. A Graphical User Interface has been developed to display simultaneously the flexion-extension, abduction-adduction and internal-external rotations of the upper limb joint angles during a movement performed by a subject. This movement is reconstructed in a 3D real-time animation.