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- Ghaffari, Ghazaleh, 1985, et al.
(författare)
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Female kinematics and muscle responses in lane change and lane change with braking maneuvers
- 2021
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 22:3, s. 236-241
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The primary aim of this article is to extensively study female occupant kinematics and muscle activations in vehicle maneuvers potentially occurring in precrash situations and with different seat belt configurations. The secondary aim is to provide validation data for active human body models (AHBMs) of female occupants in representative precrash loading situations. Methods: Front seat female passengers wearing a 3-point seat belt, with either standard or pre-pretensioning functionality, were subjected to multiple autonomously carried-out lane change and lane change with braking maneuvers while traveling at 73 km/h. This article quantifies the head center of gravity and T1 vertebra body (T1) linear and rotational displacements. This article also includes surface electromyography (EMG) data collected from 38 muscles in the neck, torso, and upper and lower extremities, all normalized by maximum voluntary contraction (MVC). The raw EMG data were filtered, rectified, and smoothed. Separate Wilcoxon signed-rank tests were performed on EMG onset and amplitude as well as peak displacements of head and T1 considering 2 paired samples with the belt configuration as an independent variable. Results: Significantly smaller lateral and forward displacements for head and T1 were found with the pre-pretensioner belt versus the standard belt (P <.05). Averaged muscle activity, mainly in the neck, lumbar extensor, and abdominal muscles, increased up to 16% MVC immediately after the vehicle accelerated in the lateral direction. Muscles in the right and left sides of the body displayed differences in activation time and amplitude relative to the vehicle’s lateral motion. For specific muscles, lane changes with the pre-pretensioner belt resulted in earlier muscle activation onsets and significantly smaller activation amplitudes compared to the standard belt (P <.05). Conclusions: The presented results from female passengers complement the previously published results from male passengers subjected to the same loading scenarios. The data provided in this article can be used for validation of AHBMs of female occupants in both sagittal and lateral loading scenarios potentially occurring prior to a crash. Additionally, our results show that a pre-pretensioner belt decreases muscle activation onset and amplitude as well as forward and lateral displacements of head and T1 compared to a standard belt, confirming previously published results.
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| 2. |
- Ghaffari, Ghazaleh, 1985
(författare)
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Postural and Muscular Responses of Car Occupants under Pre-Crash Conditions
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Advanced integrated safety technologies in modern cars such as collision avoidance intervention and pre-crash activated restraint systems require comprehensive research on how vehicle occupants respond to these systems. The aim of this thesis is to provide insights into car passengers’ body kinematics and muscle activations in representative pre-crash circumstances with respect to two belt configurations (i.e., standard versus pre-pretensioner). Another objective is to explore the influence of occupants’ individual characteristics — namely age, stature, and sex — on their body kinematics. A complementary objective is to provide validation data for human body models (HBMs). A set of in-vehicle experiments was carried out in which front-row passengers were traveling at 73 km/h and subjected to autonomous lane changes and lane changes combined with braking, each with two belt configurations: standard and reversible pre-pretensioner belts. Volunteer muscle activations were measured by the surface electromyography (EMG) technique. Transformation of coordinates corresponding to several film targets attached to the head and upper torso was used to calculate the kinematics in 3-D. The volunteers’ EMG and kinematics were processed, and the quantified kinematics were statistically explored using principal component analysis and linear mixed model. Compared to the standard belt, pre-tensioning the seat belt prior to the maneuvers reduced lateral and forward displacements of the head and upper torso significantly. Seat belt pre-tensioning was also associated with earlier muscle activation onset and significantly lower activation amplitude for specific muscles. The influence of sex, stature, and their interaction on the head and upper torso kinematics were found statistically significant but accounted for a small amount of variance. A statistical model was developed which can predict head and upper torso kinematics of occupants with different stature and sex. The data provided in this thesis can be used for further enhancement and validation of HBMs. Consequently, the design of integrated safety systems in modern cars can benefit from more biofidelic models representing a wide range of population more accurately. Further statistical investigations for other types of omnidirectional loading scenarios and, preferably with a larger and more diverse sample space, are required to establish more accurate statistical models that can be generalized to the whole population.
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