Whole body center of mass estimation with portable sensors: using the statically equivalent serial chain and a Kinect

Sensors (Basel). 2014 Sep 11;14(9):16955-71. doi: 10.3390/s140916955.

Abstract

The trajectory of the whole body center of mass (CoM) is useful as a reliable metric of postural stability. If the evaluation of a subject-specific CoM were available outside of the laboratory environment, it would improve the assessment of the effects of physical rehabilitation. This paper develops a method that enables tracking CoM position using low-cost sensors that can be moved around by a therapist or easily installed inside a patient's home. Here, we compare the accuracy of a personalized CoM estimation using the statically equivalent serial chain (SESC) method and measurements obtained with the Kinect to the case of a SESC obtained with high-end equipment (Vicon). We also compare these estimates to literature-based ones for both sensors. The method was validated with seven able-bodied volunteers for whom the SESC was identified using 40 static postures. The literature-based estimation with Vicon measurements had a average error 24.9 ± 3.7 mm; this error was reduced to 12.8 ± 9.1 mm with the SESC identification. When using Kinect measurements, the literature-based estimate had an error of 118.4 ± 50.0 mm, while the SESC error was 26.6 ± 6.0 mm. The subject-specific SESC estimate using low-cost sensors has an equivalent performance as the literature-based one with high-end sensors. The SESC method can improve CoM estimation of elderly and neurologically impaired subjects by considering variations in their mass distribution.

Publication types

  • Comparative Study
  • Evaluation Study

MeSH terms

  • Body Mass Index*
  • Body Water / physiology*
  • Computer Simulation
  • Computers, Handheld*
  • Equipment Design
  • Equipment Failure Analysis
  • Humans
  • Models, Biological*
  • Monitoring, Ambulatory / instrumentation*
  • Monitoring, Ambulatory / methods*
  • Reproducibility of Results
  • Sensitivity and Specificity
  • Transducers*