0
Research Papers

Optimization of Inertial Sensor-Based Motion Capturing for Magnetically Distorted Field Applications

[+] Author and Article Information
Christoph Schiefer

Institute of Occupational and Social Medicine,
Medical Faculty,
RWTH Aachen University,
Aachen 52074, Germany
Institute for Occupational Safety
and Health of the German Social
Accident Insurance (DGUV),
Sankt Augustin 53757, Germany
e-mail: christoph.schiefer@dguv.de

Rolf P. Ellegast

Institute for Occupational Safety
and Health of the German Social
Accident Insurance (DGUV),
Sankt Augustin 53757, Germany
e-mail: rolf.ellegast@dguv.de

Ingo Hermanns

Institute for Occupational Safety
and Health of the German Social
Accident Insurance (DGUV),
Sankt Augustin 53757, Germany
e-mail: ingo.hermanns@dguv.de

Thomas Kraus

Institute of Occupational and Social Medicine,
Medical Faculty,
RWTH Aachen University,
Aachen 52074, Germany
e-mail: tkraus@ukaachen.de

Elke Ochsmann

Institute of Occupational and Social Medicine,
Medical Faculty,
RWTH Aachen University,
Aachen 52074, Germany
West Saxon University of Applied Sciences,
Zwickau 08056, Germany
e-mail: elke.ochsmann@fh-zwickau.de

Christian Larue

Institut de recherche Robert Sauvé
en santé et en sécurité travail (IRSST),
Montréal, QC H3A 3C2, Canada
e-mail: christian.larue@irsst.qc.ca

André Plamondon

Institut de recherche Robert Sauvé
en santé et en sécurité travail (IRSST),
Montréal, QC H3A 3C2, Canada
e-mail: andre.plamondon@irsst.qc.ca

Manuscript received May 8, 2014; final manuscript received September 10, 2014; accepted manuscript posted October 16, 2014; published online November 3, 2014. Assoc. Editor: Brian D. Stemper.

J Biomech Eng 136(12), 121008 (Nov 03, 2014) (8 pages) Paper No: BIO-14-1200; doi: 10.1115/1.4028822 History: Received May 08, 2014; Revised September 10, 2014; Accepted October 16, 2014

Inertial measurement units (IMU) are gaining increasing importance for human motion tracking in a large variety of applications. IMUs consist of gyroscopes, accelerometers, and magnetometers which provide angular rate, acceleration, and magnetic field information, respectively. In scenarios with a permanently distorted magnetic field, orientation estimation algorithms revert to using only angular rate and acceleration information. The result is an increasing drift error of the heading information. This article describes a method to compensate the orientation drift of IMUs using angular rate and acceleration readings in a quaternion-based algorithm. Zero points (ZP) were introduced, which provide additional heading and gyroscope bias information and were combined with bidirectional orientation computation. The necessary frequency of ZPs to achieve an acceptable error level is derived in this article. In a laboratory environment the method and the effect of varying interval length between ZPs was evaluated. Eight subjects were equipped with seven IMUs at trunk, head and upper extremities. They performed a predefined course of box handling for 40 min at different motion speeds and ranges of motion. The orientation estimation was compared to an optical motion tracking system. The resulting mean root mean squared error (RMSE) of all measurements ranged from 1.7 deg to 7.6 deg (roll and pitch) and from 3.5 deg to 15.0 deg (heading) depending on the measured segment, at a mean interval-length of 1.1 min between two ZPs without magnetometer usage. The 95% limits of agreement (LOA) ranged in best case from −2.9 deg to 3.6 deg at the hip roll angle and in worst case from −19.3 deg to 18.9 deg at the forearm heading angle. This study demonstrates that combining ZPs and bidirectional computation can reduce orientation error of IMUs in environments with magnetic field distortion.

FIGURES IN THIS ARTICLE
<>
Copyright © 2014 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

Flowchart of unidirectional orientation estimation

Grahic Jump Location
Fig. 2

Laboratory setup of the platform, the initial subject’s position and orientation. A pile of five boxes was moved between positions 1–4 in varying order. Lights at each position indicated where to place the boxes next while a sound indicated the speed for lifting and lowering the boxes.

Grahic Jump Location
Fig. 3

Moving boxes from position 2 (second layer of boxes at shoulder height) to position 4 (ground layer)

Grahic Jump Location
Fig. 4

Mean RMSEe by varying number of ZPs for all segments. Error bars indicate SD. For readability reasons the SD is only drawn for the top and bottom curve, representing worst- and best-case scenario.

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In