Motion Analysis of the Upper-limb Based on Inertial Sensors: Part 3 – Assessment of Instrumental Accuracy for a New Protocol

INTRODUCTION Inertial Sensors Systems (ISS) are a new generation of low cost, portable, fully wearable motion analysis systems recently become available on the market [1]. ISS sensing units (SU) are lightweight boxes integrating accelerometers, gyroscopes and magnetometers. For each SU a local system of reference (SoR) is defined, and its relative orientation with respect to a global, earth-based SoR is computed by the ISS in real-time. Based on this property, in [2] a protocol has been presented which allows the estimation of elbow, humero-thoracic and scapulo-thoracic 3D kinematics. In [3] it was proved that the protocol, once used in combination with the Xsens MT9B ISS (Xsens Technologies, NL), is based on bone-embedded SoRs representative of the joints functional anatomy. As a further step, the aim of this third abstract was to assess the limits of the Xsens dynamic accuracy during the execution of the protocol [2]. It was proved in fact that the Xsens accuracy is sensitive to direction and velocity of rotation [4] and that it generally depends on the type of motion (Xsens Technical Manual).