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Discomfort Evaluation of Truck Ingress/Egress Motions Based on Biomechanical Analysis.

Choi NC, Lee SH - Sensors (Basel) (2015)

Bottom Line: Next, the maximum voluntary contraction (MVC) ratios of the muscles were calculated through a biomechanical analysis of the musculoskeletal human model for the captured motion.Finally, the objective discomfort was evaluated using the proposed discomfort model based on the MVC ratios.The validation results showed that the correlation between the objective and subjective discomforts was significant and could be described by a linear regression model.

View Article: PubMed Central - PubMed

Affiliation: Intelligent HMI/CAD Lab, Graduate School of Automotive Engineering, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 136-702, Korea. naamus@dayou.co.kr.

ABSTRACT
This paper presents a quantitative discomfort evaluation method based on biomechanical analysis results for human body movement, as well as its application to an assessment of the discomfort for truck ingress and egress. In this study, the motions of a human subject entering and exiting truck cabins with different types, numbers, and heights of footsteps were first measured using an optical motion capture system and load sensors. Next, the maximum voluntary contraction (MVC) ratios of the muscles were calculated through a biomechanical analysis of the musculoskeletal human model for the captured motion. Finally, the objective discomfort was evaluated using the proposed discomfort model based on the MVC ratios. To validate this new discomfort assessment method, human subject experiments were performed to investigate the subjective discomfort levels through a questionnaire for comparison with the objective discomfort levels. The validation results showed that the correlation between the objective and subjective discomforts was significant and could be described by a linear regression model.

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Related in: MedlinePlus

Modeling the boundary conditions at the contact positions between the human body and the environment: (a) bushing condition between the hand and the handle; (b) contact condition between the foot and the step; and (c) boundary conditions applied to the full body.
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sensors-15-13568-f010: Modeling the boundary conditions at the contact positions between the human body and the environment: (a) bushing condition between the hand and the handle; (b) contact condition between the foot and the step; and (c) boundary conditions applied to the full body.

Mentions: While entering and exiting a truck cabin, the body is in contact with the steps and handles, creating locations for where the reaction forces occur. These external forces were applied to the simulated body by modeling the boundary conditions appropriately. For this purpose, the contact conditions between the foot and the step and between the hand and the handle were modeled as follows. First, as shown in Figure 10b, contact conditions were created between the foot and the step for the generation of the step reaction forces. For the contact conditions, the contact forces in the surface normal directions were calculated using an impact force algorithm for ellipsoid-plane elements. Here, the impact force is modeled as a function of the penetration depth and velocity and the stiffness and damping coefficients. In addition, the contact forces in the tangential direction were calculated from the velocity-based friction force model, which is a function of the static and dynamic friction coefficients that vary with the slip velocity. The attributes of the contact conditions could be adjusted, and in this study, the default values of LifeMOD were applied [22]. Second, in order to generate the contact force between the hand and the handle, a bushing element was adopted and modeled. For this purpose, as shown in Figure 10a, two markers were generated on the palm and the handle at the contact point, and a bushing element was created between them so that a handle reaction force could be generated. The properties of the bushing were adjusted on the basis of the data captured by the force-measuring device in the actual experiments. Figure 10c shows the boundary conditions applied to the full-body model.


Discomfort Evaluation of Truck Ingress/Egress Motions Based on Biomechanical Analysis.

Choi NC, Lee SH - Sensors (Basel) (2015)

Modeling the boundary conditions at the contact positions between the human body and the environment: (a) bushing condition between the hand and the handle; (b) contact condition between the foot and the step; and (c) boundary conditions applied to the full body.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4507608&req=5

sensors-15-13568-f010: Modeling the boundary conditions at the contact positions between the human body and the environment: (a) bushing condition between the hand and the handle; (b) contact condition between the foot and the step; and (c) boundary conditions applied to the full body.
Mentions: While entering and exiting a truck cabin, the body is in contact with the steps and handles, creating locations for where the reaction forces occur. These external forces were applied to the simulated body by modeling the boundary conditions appropriately. For this purpose, the contact conditions between the foot and the step and between the hand and the handle were modeled as follows. First, as shown in Figure 10b, contact conditions were created between the foot and the step for the generation of the step reaction forces. For the contact conditions, the contact forces in the surface normal directions were calculated using an impact force algorithm for ellipsoid-plane elements. Here, the impact force is modeled as a function of the penetration depth and velocity and the stiffness and damping coefficients. In addition, the contact forces in the tangential direction were calculated from the velocity-based friction force model, which is a function of the static and dynamic friction coefficients that vary with the slip velocity. The attributes of the contact conditions could be adjusted, and in this study, the default values of LifeMOD were applied [22]. Second, in order to generate the contact force between the hand and the handle, a bushing element was adopted and modeled. For this purpose, as shown in Figure 10a, two markers were generated on the palm and the handle at the contact point, and a bushing element was created between them so that a handle reaction force could be generated. The properties of the bushing were adjusted on the basis of the data captured by the force-measuring device in the actual experiments. Figure 10c shows the boundary conditions applied to the full-body model.

Bottom Line: Next, the maximum voluntary contraction (MVC) ratios of the muscles were calculated through a biomechanical analysis of the musculoskeletal human model for the captured motion.Finally, the objective discomfort was evaluated using the proposed discomfort model based on the MVC ratios.The validation results showed that the correlation between the objective and subjective discomforts was significant and could be described by a linear regression model.

View Article: PubMed Central - PubMed

Affiliation: Intelligent HMI/CAD Lab, Graduate School of Automotive Engineering, Kookmin University, 77 Jeongneung-ro, Seongbuk-gu, Seoul 136-702, Korea. naamus@dayou.co.kr.

ABSTRACT
This paper presents a quantitative discomfort evaluation method based on biomechanical analysis results for human body movement, as well as its application to an assessment of the discomfort for truck ingress and egress. In this study, the motions of a human subject entering and exiting truck cabins with different types, numbers, and heights of footsteps were first measured using an optical motion capture system and load sensors. Next, the maximum voluntary contraction (MVC) ratios of the muscles were calculated through a biomechanical analysis of the musculoskeletal human model for the captured motion. Finally, the objective discomfort was evaluated using the proposed discomfort model based on the MVC ratios. To validate this new discomfort assessment method, human subject experiments were performed to investigate the subjective discomfort levels through a questionnaire for comparison with the objective discomfort levels. The validation results showed that the correlation between the objective and subjective discomforts was significant and could be described by a linear regression model.

Show MeSH
Related in: MedlinePlus