Inertial Motion Capture-Based Whole-Body Inverse Dynamics.

Mohsen M Diraneyya,Carl T Haas,Juhyeong Ryu,Eihab Abdel-Rahman

doi:10.3390/s21217353

Mohsen M Diraneyya, Carl T Haas + Show 2 more

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https://doi.org/10.3390/s21217353

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Abstract

Inertial Motion Capture (IMC) systems enable in situ studies of human motion free of the severe constraints imposed by Optical Motion Capture systems. Inverse dynamics can use those motions to estimate forces and moments developing within muscles and joints. We developed an inverse dynamic whole-body model that eliminates the usage of force plates (FPs) and uses motion patterns captured by an IMC system to predict the net forces and moments in 14 major joints. We validated the model by comparing its estimates of Ground Reaction Forces (GRFs) to the ground truth obtained from FPs and comparing predictions of the static model’s net joint moments to those predicted by 3D Static Strength Prediction Program (3DSSPP). The relative root-mean-square error (rRMSE) in the predicted GRF was 6% and the intraclass correlation of the peak values was 0.95, where both values were averaged over the subject population. The rRMSE of the differences between our model’s and 3DSSPP predictions of net L5/S1 and right and left shoulder joints moments were 9.5%, 3.3%, and 5.2%, respectively. We also compared the static and dynamic versions of the model and found that failing to account for body motions can underestimate net joint moments by 90% to 560% of the static estimates.

Highlights

Inverse dynamic analysis is used in biomechanics to predict the forces and moments developing in muscles and joints during body motions
This study aims to develop a whole-body inverse dynamics model that is applicable to arbitrary motion patterns captured by an Inertial motion capture (IMC) system without a need for force plates (FPs) or other specialized equipment
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Summary

Introduction

Inverse dynamic analysis is used in biomechanics to predict the forces and moments developing in muscles and joints during body motions. Optical tracking requires a line-of-sight between the cameras and body markers [3,4] or body segments, which complicates the experimental set-up and constrains their use to confined laboratories [2]. These constraints render OMC systems impractical for on-site studies and other tasks that are performed in open space. IMC systems continuously capture whole-body motions using measured acceleration, angular rate, and magnetic field orientation [5,6] They are portable and eliminate the need to maintain line-of-sight between the camera and markers or body segments. Using the suit and a custom-made algorithm, they analyzed real-time joint angles to evaluate performance during aquatic exercise

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