The development and test of a device for the reconstruction of 3-D position and orientation by means of a kinematic sensor assembly with rate gyroscopes and accelerometers

In this paper, we propose a device for the Position and Orientation (P&O) reconstruction of human segmental locomotion tasks. It is based on three mono-axial accelerometers and three angular velocity sensors, geometrically arranged to form two orthogonal terns. The device was bench tested using step-by-step motor-based equipment. The characteristics of the six channels under bench test conditions were: crosstalk absent, non linearity <= +/- 0, 1% fs, hysteresis < 0, 1% fs, accuracy 0, 3% fs, overall resolution better than 0, 04 deg/s, 2 * g * 10(-4). The device was validated with the stereophotogrammetric body motion analyzer during the execution of three different locomotion tasks: stand-to-sit, sit-to-stand, gait-initiation. Results obtained comparing the trajectories of the two methods showed that the errors were lower than 3 *10(-2) M and 2 deg during a 4s of acquisition and lower than 6 *10(-3) m. and 0.2 deg during the effective duration of a locomotory task; showing that the wearable device hereby presented permits the 3-D reconstruction of the movement of the body segment to which it is affixed for time-limited clinical applications.