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Session: Motion
Session starts: Thursday 26 January, 14:30
Presentation starts: 14:45
Room: Room 531

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Junhao Zhang (University of Twente)
Michelle van Mierlo (University of Twente)
Edwin van Asseldonk (University of Twente)
Heike Vallery (TU Delft)
Peter Veltink (University of Twente)

Abstract:
During stable gaits, the whole-body angular momentum (WBAM) appears to be fairly constant through segment-to-segment cancellation and control of joint moments [1, 2]. Yet due to external perturbations or gait impairments, the WBAM can substantially deviate from these stable patterns [3]. Therefore, there is a potential to quantify the state of balance through the variations in the WBAM. To date, video-based motion capture systems are usually used to calculate the WBAM based on a full body model [4]. Our future goal is to use an optimal small set of IMUs to quantify the state of balance, thus it is desirable to assess WBAM from measurements taken from a subset of the body segments. We therefore first investigated segmental contributions to the WBAM under the condition of pure sagittal-plane WBAM perturbations, which aimed to help us choose segments that should be included in simplified body models. We furthermore evaluated the effectiveness of selected simplified body models against the full body model. Based on our previous data reported in [4], two simultaneous forces with the same magnitude were applied in opposite directions to the pelvis and shoulder to perturb only the WBAM, while participants walked on a treadmill. The contribution of each body segment was evaluated against the estimated full-body WBAM both in terms of pattern similarity (correlation coefficients) and magnitude. The results showed that pelvis, torso, thighs, shanks and feet contributed to 1.24%, 30.43%, 5.08%, 33.03% and 36.15%, while the upper limbs only contributed to 2.56% in total. Considering optimal small set of IMUs in future applications, torso and/or thighs and shanks (with one IMU at torso and one IMU at each shank) should be included in simplified models, pelvis and feet could be potentially added if we add more IMUs at these segments. Our next step is to evaluate the effectiveness of these simplified models against the full body model by means of correlation coefficients, root mean square errors, and incremental similarity in variable perturbations. Future application is to use these simplified body models to quantify the state of balance during variable gaits and functional daily tasks, based on IMUs.