Inertial measurement system for upper limb joints tracking

PEREZ, ELISA; OROSCO, EUGENIO; DOMINGUEZ, MARCOS; LÓPEZ, NATALIA

IFMBE PROCEEDINGS

Springer Verlag

Lugar: Praga; Año: 2018 vol. 68 p. 785 - 789

1680-0737

This work presents a system for tracking and analysis of upper limb movement through the use of inertial sensors. The designed system uses four inertial sensors, which are placed at the midpoint of the corresponding segments, that is, hand, forearm, arm, and the last one is located between the scapulae and the spine, and between vertebrae T5 and T6 (Thoracic 5 and Thoracic 6). This last sensor is used as a reference point. The information of the four sensors is preprocessed by a microcontroller and sent wirelessly to a computer. The data of each sensor is processed in order to calculate the angular position of each joint. In this work the concept of quaternions is used to avoid the singularities that occur when the reference axes are aligned with the Earth?s gravity axis, instead of working directly with the representation through Euler angles. In addition, a descending gradient filter is implemented to merge the accelerometer and gyroscope data in order to compensate drift errors. To visualize the movement, a simple virtual environment is implemented with SimMechanics®. The designed system is evaluated with 10 volunteers, in flexo-extension and abduction-adduction movements, at different velocities and compared with goniometer measures. The system demonstrates good repeatability and the computed error was less than 3°.