COMPARATIVE MEASUREMENTS OF HEAD ANGULAR MOVEMENTS USING A CAMERA SYSTEM AND A GYROSCOPE SYSTEM

Abstract

Assessments of body-segment angular movements are very important in the rehabilitation process. Head angular movements are measured and analyzed for use in studies of stability and posture. However, there is no methodology for assessing angular movements of the head, and it has not been verified whether data measured by fundamentally different MoCap systems will lead to the same results. In this study, we used a camera system and a 3DOF orientation tracker placed on the subject’s head, and measured inclination (roll) and flexion (pitch) during quiet stance. The total length and the mean velocity of the traces of the pitch versus roll plots were used to measure and analyze head orientation. Using these methods, we are able to model the distribution of the measured 2D data, and to evaluate stability and posture. The results show that the total lengths and the mean velocities related to the 3DOF orientation tracker do not differ significantly from the total lengths and the mean velocities of traces related to the IR medical camera. We also found that the systems are not interchangeable, and that the same type of system must be used each time. The designed methods can be used for studies not only of head movements but also of movements of other segments of the human body, and can be used to compare other types of MoCap systems, depending on the requirements for a specific rehabilitation examination.