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Abstract In this study, a hybrid predictive model is used to predict 3D asymmetric lifting motion and assess potential musculoskeletal lower back injuries for asymmetric lifting tasks. The hybrid model has two modules: a skeletal module and an OpenSim musculoskeletal module. The skeletal module consists of a dynamic joint strength based 40 degrees of freedom spatial skeletal model. The skeletal module can predict the lifting motion, ground reaction forces (GRFs), and center of pressure (COP) trajectory using an inverse dynamics based optimization method. The equations of motion are built by recursive Lagrangian dynamics. The musculoskeletal module consists of a 324-muscle-actuated full-body lumbar spine model. Based on the generated kinematics, GRFs and COP data from the skeletal module, the musculoskeletal module estimates muscle activations using static optimization and joint reaction forces through the joint reaction analysis tool. Muscle activation results between simulated and experimental EMG are compared to validate the model. Finally, potential lower back injuries are evaluated for a specific-weight asymmetric lifting task. The shear and compression spine loads are compared to NIOSH recommended limits. At the beginning of the dynamic lifting process, the simulated compressive spine load beyond the NIOSH action limit but less than the permissible limit. This is due to the fatigue factors considered in NIOSH lifting equation.
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Differences in kinematics and resulting lumbar spinal forces during repetitive lifting tasks: Simulation versus estimation of the effects of wearing a back-support exoskeleton
We explored the feasibility of using biomechanical simulations to predict altered spinal forces resulting from wearing a back-support exoskeleton (BSE) during repetitive lifting tasks. Twenty (10M, 10F) young, healthy participants completed repetitive lifting task, while wearing a BSE (‘with EXO’) and without wearing a BSE (‘without EXO’). Spinal forces were estimated by applying the BSE torque profile to body kinematics measured in ‘with EXO’ condition, while spinal forces were simulated by applying the same torque profile to body kinematics measured in ‘without EXO’ condition. Simulated compression force was higher than estimated compression force, probably due to lower trunk flexion angle in ‘without EXO’ condition. Such differences were larger among women than among men. However, simulated shear force was comparable with estimated shear force. Future works further need to compare simulated and estimated spinal forces for different BSEs (e.g., soft BSE), asymmetric lifting tasks, and different age group.
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- Award ID(s):
- 2242610
- PAR ID:
- 10469984
- Publisher / Repository:
- SAGE Publications
- Date Published:
- Journal Name:
- Proceedings of the Human Factors and Ergonomics Society Annual Meeting
- Volume:
- 67
- Issue:
- 1
- ISSN:
- 1071-1813
- Format(s):
- Medium: X Size: p. 842-844
- Size(s):
- p. 842-844
- Sponsoring Org:
- National Science Foundation
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In this study, a 3D asymmetric lifting motion is predicted by using a hybrid predictive model to prevent potential musculoskeletal lower back injuries for asymmetric lifting tasks. The hybrid model has two modules: a skeletal module and an OpenSim musculoskeletal module. The skeletal module consists of a dynamic joint strength based 40 degrees of freedom spatial skeletal model. The skeletal module can predict the lifting motion, ground reaction forces (GRFs), and center of pressure (COP) trajectory using an inverse dynamics-based motion optimization method. The musculoskeletal module consists of a 324-muscle-actuated full-body lumbar spine model. Based on the predicted kinematics, GRFs and COP data from the skeletal module, the musculoskeletal module estimates muscle activations using static optimization and joint reaction forces through the joint reaction analysis tool in OpenSim. The predicted asymmetric motion and GRFs are validated with experimental data. Muscle activation results between the simulated and experimental EMG are also compared to validate the model. Finally, the shear and compression spine loads are compared to NIOSH recommended limits. The differences between asymmetric and symmetric liftings are also compared.more » « less
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