A method for lower back motion assessment using wearable 6D inertial sensors

A method for lower back motion assessment using wearable 6D inertial sensors

Molnar, Marco (Technical University of Berlin)
Kok, M. (TU Delft Team Jan-Willem van Wingerden)
Engel, Tilman (University of Potsdam)
Kaplick, Hannes (University of Potsdam)
Mayer, Frank (University of Potsdam)
Seel, Thomas (Technical University of Berlin)

2018

Low back pain (LBP) is a leading cause of activity limitation. Objective assessment of the spinal motion plays a key role in diagnosis and treatment of LBP. We propose a method that facilitates clinical assessment of lower back motions by means of a wireless inertial sensor network. The sensor units are attached to the right and left side of the lumbar region, the pelvis and the thighs, respectively. Since magnetometers are known to be unreliable in indoor environments, we use only 3D accelerometer and 3D gyroscope readings. Compensation of integration drift in the horizontal plane is achieved by estimating the gyroscope biases from automatically detected initial rest phases. For the estimation of sensor orientations, both a smoothing algorithm and a filtering algorithm are presented. From these orientations, we determine three-dimensional joint angles between the thighs and the pelvis and between the pelvis and the lumbar region. We compare the orientations and joint angles to measurements of an optical motion tracking system that tracks each skin-mounted sensor by means of reflective markers. Eight subjects perform a neutral initial pose, then flexion/extension, lateral flexion, and rotation of the trunk. The root mean square deviation between inertial and optical angles is about one degree for angles in the frontal and sagittal plane and about two degrees for angles in the transverse plane (both values averaged over all trials). We choose five features that characterize the initial pose and the three motions. Interindividual differences of all features are found to be clearly larger than the observed measurement deviations. These results indicate that the proposed inertial sensor-based method is a promising tool for lower back motion assessment.

avoid magnetometers
back motion assessment
drift correction
human motion analysis
Inertial measurement units
joint angle estimation
low back pain
validation against optical motion capture

http://resolver.tudelft.nl/uuid:37089a57-34c7-4790-abd6-04655284bc86

https://doi.org/10.23919/ICIF.2018.8455828

IEEE, Piscataway, NJ, USA

2019-03-06

978-0-9964527-6-2

Proceedings of the 21st International Conference on Information Fusion 2018 (FUSION 2018)

21st International Conference on Information Fusion, FUSION 2018, 2018-07-10 → 2018-07-13, Cambridge, United Kingdom

Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.

Institutional Repository

conference paper

© 2018 Marco Molnar, M. Kok, Tilman Engel, Hannes Kaplick, Frank Mayer, Thomas Seel