A novel wearable measurement system for ambulatory assessment of joint loading in the occupational setting

Authors: Faber GS^1,2, Chang CC², Kingma I³, Dennerlein JT¹

1 Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA
2 Liberty Mutual Research Institute for Safety, Hopkinton, MA, USA
3 Research Institute MOVE, Faculty of Human Movement Sciences, VU University Amsterdam, The Netherlands

Why a wearable measurement system?

Biomechanical overexposure is a risk factor for occupational injuries. Therefore, it is important to evaluate the biomechanical exposure in the workplace. Methods currently used, such as video analysis, are time-consuming and therefore not frequently used.

This poster presents a less laborious wearable measurement system for automatic and continuous ambulatory assessment of joint loading in the occupational setting.

The wearable measurement system

The wearable measurement system (Xsens Technologies, Netherlands) consists of: 1) a full body inertial sensor motion capture system (measuring segment orientation) which can be worn under the clothes and 2) shoes instrumented with 3D force sensors. Using this system you are able to assess not only joint loading due to body postures, but also joint loading due to external loads (using the forces measured by the shoes), occurring during manual materials handling, for example.

Research carried out to date

In recent studies we have successfully validated separate components of the proposed measurement system:

• Measuring trunk inclination using a single inertial sensor [1,2]
• Measuring 3D ground reaction forces using instrumented ForceShoes [3,4]
• Using orientation sensors (e.g. inertial sensors) instead of position sensors for analysis of joint loading [5]
• Estimating hand forces based on ground reaction forces and segment accelerations [6]

Current and future research

Currently we are validating the combined measurement system in the laboratory by comparing the assessed joint loading to that of a conventional state-of-the-art lab-based method. If the proposed system proves to be a valid measurement system, we will use it in future field studies.

References

1. Faber GS, Kingma I, Bruijn SM & van Dieën JH. Optimal inertial sensor location for ambulatory measurement of trunk inclination. Journal of Biomechanics, 2009, 42(14): 2406-2409.
2. Faber GS, Chang CC, Kingma I & Dennerlein JT. Gender and lifting style do not affect optimal inertial sensor location for ambulatory assessment of trunk inclination. In preparation.
3. Faber GS, Chang CC, Kingma I, Herber S, Schepers HM, Veltink PH & Dennerlein JT. A force plate based method for the calibration of Force/Torque sensors. Journal of Biomechanics, In press.
4. Faber GS, Kingma I, Martin Schepers H, Veltink PH & van Dieen JH. Determination of joint moments with instrumented force shoes in a variety of tasks. Journal of Biomechanics, 2009, 43(14): 2848-54.
5. Faber GS, Kingma I & van Dieën JH. Bottom-up estimation of joint moments during manual lifting using orientation sensors instead of position sensors. Journal of Biomechanics, 2010, 43(7): 1432-6.
6. Faber GS, Chang CC, Kingma I & Dennerlein JT. Estimating dynamic external hand forces during manual lifting based on ground reaction forces and body segment accelerations. In preparation.

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