Figure 4

System sensitivity to IMU malposition. Top, superimposition of the kinematic trajectories [deg] from three pairs of IMU for a hip flexion/extension exercise in one subject. The three pairs of IMU were worn simultaneously on the subject’s leg and thorax, each in one of the three positions of -7 cm, 0 cm, and +7 cm with respect to the correct medio-lateral position. Bottom, superimposition of the kinematic trajectories [deg] from three pairs of IMU for a hip abduction exercise in one subject. The three pairs of IMU were worn simultaneously on the subject’s leg and thorax, each in one of the three orientations of -15°, 0° and 15° with respect to the correct frontal-plane orientation.