title: Determining inertial measurement unit placement for estimating human trunk sway while standing, walking and running.
abstract: Inertial measurement units (IMU) are often used to estimate medial-lateral (M/L) trunk sway for assessing and treating gait disorders, and IMU sensor placement is an important factor effecting estimation accuracy. This study tracked multi-segment spine movements during standing and ambulation tasks to determine optimal IMU placement. Ten young healthy subjects, wearing markers placed along the spine, left/right acromion, and left/right posterior superior iliac spine performed standing and walking trials in a motion capture laboratory. Results showed that movement at the spine location T7-T8 most closely matched the clinical definition of M/L trunk sway for standing trials (0.5 deg error) and at the spine location T9-T10 for walking trials (1.0 deg error), while movement at the lower spine L2-L4 tended to be the least accurate for standing and ambulation tasks (1.5 deg error and 4.0 deg error, respectively). Based on these results, a second study was performed to develop and validate a trunk sway estimation algorithm during walking trials with a single optimally-placed IMU. IMU trunk sway estimation was compared to the clinical definition of trunk sway from motion capture markers and showed root-mean-square errors of 2.5 deg and peak trunk sway errors of 2.0 deg. The results of this study suggest that IMUs should be placed on the mid-back to reduce errors associated with spine movements not matching clinically-defined M/L trunk motion.
authors.lastname: Bo Yu
authors.lastname: Tian Bao
authors.lastname: Dingguo Zhang
authors.forename: Wendy
authors.initials: W
authors.lastname: Carender
authors.forename: Kathleen H
authors.initials: KH
authors.lastname: Sienko
authors.forename: Peter B
authors.initials: PB
authors.lastname: Shull
mesh_terms: D006801:Humans; D011187:Posture; D012420:Running; D060726:Torso; D016138:Walking