| 1. |
- Larsson, Emma, 1991, et al.
(författare)
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Active Human Body Model Predictions Compared to Volunteer Response in Experiments with Braking, Lane Change, and Combined Manoeuvres
- 2019
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Ingår i: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI. - 2235-3151. ; :S1-9, s. 349-369
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Konferensbidrag (refereegranskat)abstract
- Active human body models are an important tool to study occupant interaction with safety systems in evasive manoeuvres such as braking and/or steering. In this study a finite element human body model with and without closed-loop active muscle control in the neck and lower trunk was compared to volunteer occupants in six different load cases with lane change, braking, and combined manoeuvres using standard and prepretensioned seat belts. Seven different muscle controllers, using two different muscle activation strategies based either on head and torso displacements or muscle length, and one with the controller turned off have been compared to volunteer kinematics. Cross-correlation analysis with CORA was used to evaluate the model biofidelity. The results show an improvement in CORA scores when using active muscles, compared to the model with muscle activity turned off, for one load case and similar CORA scores between the models for five load cases. CORA scores ranged from 0.78 to 0.88 for the active models and 0.70 to 0.82 from the model with muscles turned off. The active model gave a kinematic response with good biofidelity in lane change with braking, pure braking, and lane change with pre-pretensioned seat belt, but the biofidelity of the model was rated as fair in lane change with standard seat belt.
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| 2. |
- Leledakis, Alexandros, 1991, et al.
(författare)
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Influence of an Individualised Shoulder Belt Position for Diverse Occupant Anthropometries on Seatbelt Interaction in Frontal and Side Impacts
- 2023
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Ingår i: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI. - 2235-3151. ; , s. 639-664
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Konferensbidrag (refereegranskat)abstract
- This simulation study investigated the influence of individualised shoulder belt position on seatbelt interaction and occupant kinematics in two frontal and one far side impact, considering the variability of occupant anthropometry and sitting postures. Morphed Human Body Models, positioned as front passengers, were simulated in 132 setups. For every occupant, an individualised shoulder belt position configuration was created by changing the D-ring mounting location, aiming for a mid-shoulder belt fit. A “traditional belt” configuration was also tested, with the D-ring mounted on the B-pillar. The initial belt's placement over the occupant's shoulder was influential; however, it may not necessarily lead to an overall improved seatbelt interaction as a single parameter. Different occupants were associated with different seatbelt interaction challenges. Tall occupants with low Body Mass Index (BMI) were more likely to slide out of the shoulder belt, while short low-BMI occupants were more likely to submarine. The early torso to pelvis retention balance and the torso’s axial rotations were identified as the main mechanisms behind those observations. The study identified seatbelt interaction challenges for different occupant groups and could facilitate the analysis of additional changes in belt characteristics towards individualised occupant restraint systems.
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| 3. |
- Leledakis, Alexandros, 1991, et al.
(författare)
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The Influence of Occupant's Size, Shape and Seat Adjustment in Frontal and Side Impacts
- 2022
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Ingår i: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI. - 2235-3151. ; 2022-September, s. 549-584
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Konferensbidrag (refereegranskat)abstract
- The sensitivity of occupant kinematic and kinetic crash responses to anthropometric and seat adjustment variation was investigated by performing frontal- and side-impact simulations with a family of morphed Human Body Models (HBMs). The HBM family included variations of shape and size, accounting for stature, Body Mass Index (BMI) and sex. A global sensitivity analysis method was developed and applied. Increased BMI was associated with increased spinal and extremity loading in the HBM for all evaluated impacts. Increasing the stature resulted in a consistent increase in lower extremity loading. The fore-aft seat position influenced the head and torso speed relative to the vehicle interior. Furthermore, in high-severity frontal impacts, adjusting the seat position rearwards altered the load path, increasing the HBM pelvic and lumbar spine loading in favour of reducing the lower extremity forces, and vice versa when the seat was positioned forward. The results from this study highlight potential occupant protection challenges and trade-offs, and can be used to enhance protection, considering occupant anthropometric diversity and seat adjustment variation.
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| 4. |
- Brolin, Karin, 1974, et al.
(författare)
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Towards omni-directional active human body models
- 2016
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Ingår i: 6th International Symposium on Human Modeling and Simulation in Automotive Engineering, Heidelberg, GERMANY, October 20-21.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Brynskog, Erik, 1989, et al.
(författare)
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Population Variance in Pelvic Response to Lateral Impacts - A Global Sensitivity Analysis
- 2022
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Ingår i: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI. - 2235-3151. ; 2022-September, s. 173-196
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Konferensbidrag (refereegranskat)abstract
- Pelvic fracture remains the third most common moderate to severe injury in motor vehicle crashes, and the dominating lower extremity injury in lateral impacts. An essential tool for analysis of injury, and real-world occupant protection, are finite element human body models. However, today's state-of-the-art pelvis models do not adequately consider the variability in shape and size naturally occurring in human populations. In this study, we developed a new detailed pelvis finite element model, morphable to enable representation of the population shape variance. The model was validated using force-displacement data from post-mortem human subjects, in lateral loading of the denuded pelvis, followed by a global sensitivity analysis. The results suggests that in lateral impacts to the pelvis, pelvic shape contributes to the model response variance by the same magnitude as pelvic bone material stiffness, and that each of these contributions are approximately twice that of the cortical bone thickness. Hence, to model pelvic response for a general population accurately, future studies must consider both pelvic shape and the material properties in the analysis. Increased knowledge about population variability, and inclusion in safety evaluations, can result in more robust systems that reduce the risk of pelvic injuries in real-world accidents.
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| 6. |
- Brynskog, Erik, 1989, et al.
(författare)
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Predicting pelvis geometry using a morphometric model with overall anthropometric variables
- 2021
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Ingår i: Journal of Biomechanics. - : Elsevier BV. - 1873-2380 .- 0021-9290. ; 126
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Tidskriftsartikel (refereegranskat)abstract
- Pelvic fractures have been identified as the second most common AIS2+ injury in motor vehicle crashes, with the highest early mortality rate compared to other orthopaedic injuries. Further, the risk is associated with occupant sex, age, stature and body mass index (BMI). In this study, clinical pelvic CT scans from 132 adults (75 females, 57 males) were extracted from a patient database. The population shape variance in pelvis bone geometry was studied by Sparse Principal Component Analysis (SPCA) and a morphometric model was developed by multi- variate linear regression using overall anthropometric variables (sex, age, stature, BMI). In the analysis, SPCA identified 15 principal components (PCs) describing 83.6% of the shape variations. Eight of these were signifi- cantly captured (α < 0.05) by the morphometric model, which predicted 29% of the total variance in pelvis geometry. The overall anthropometric variables were significantly related to geometrical features primarily in the inferior-anterior regions while being unable to significantly capture local sacrum features, shape and position of ASIS and lateral tilt of the iliac wings. In conclusion, a new detailed morphometric model of the pelvis bone demonstrated that overall anthropometric variables account for only 29% of the variance in pelvis geometry. Furthermore, variations in the superior-anterior region of the pelvis, with which the lap belt is intended to interact, were not captured. Depending on the scenario, shape variations not captured by overall anthropometry could have important implications for injury prediction in traffic safety analysis.
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| 7. |
- Carlsson, Stina, 1967, et al.
(författare)
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Volunteer occupant kinematics during driver initiated and autonomous braking when driving in real traffic environments
- 2011
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Ingår i: 2011 IRCOBI Conference Proceedings - International Research Council on the Biomechanics of Injury IRCOBI, 14 - 16 September 2011, Krakow, Polen. ; 2011, s. 125-136
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Konferensbidrag (refereegranskat)abstract
- When a vehicle is braking, the occupants are subjected to longitudinal forces which may influence their positions. The aim of this paper is to quantify the driver and passenger kinematics during medium harsh braking while driving in real traffic and to identify the influencing parameters.The overall motions were relatively small during braking and the effect of seat belt locking was obvious. Mean forward motions were 55 ±26 mm for the chest and 97 ±47 mm for the head. This study indicates that several properties influence forward motion. Taller volunteers had a larger forward motion; females had a larger forward motion than males of the same sitting height. Passengers exhibited larger motions than drivers for most of the volunteers.The result provides a deeper understanding of pre-impact conditions and adds knowledge to further improve the interaction of active and passive safety systems. It also provides valuable validation data for low-g occupant models, which can be used in studies of the effect of pre-impact braking on restraint interaction.
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| 8. |
- Ghaffari, Ghazaleh, 1985, et al.
(författare)
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Passenger muscle responses in lane change and lane change with braking maneuvers using two belt configurations: Standard and reversible pre-pretensioner
- 2019
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Ingår i: Traffic Injury Prevention. - : Informa UK Limited. - 1538-957X .- 1538-9588. ; 20:sup1, s. S43-S51
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Tidskriftsartikel (refereegranskat)abstract
- Objective : The introduction of integrated safety technologies in new car models calls for an improved understanding of the human occupant response in precrash situations. The aim of this article is to extensively study occupant muscle activation in vehicle maneuvers potentially occurring in precrash situations with different seat belt configurations. Methods : Front seat male passengers wearing a 3-point seat belt with either standard or pre-pretensioning functionality were exposed to multiple autonomously carried out lane change and lane change with braking maneuvers while traveling at 73 km/h. This article focuses on muscle activation data (surface electromyography [EMG] normalized using maximum voluntary contraction [MVC] data) obtained from 38 muscles in the neck, upper extremities, the torso, and lower extremities. The raw EMG data were filtered, rectified, and smoothed. All muscle activations were presented in corridors of mean ± one standard deviation. Separate Wilcoxon signed ranks tests were performed on volunteers’ muscle activation onset and amplitude considering 2 paired samples with the belt configuration as an independent factor. Results : In normal driving conditions prior to any of the evasive maneuvers, activity levels were low (<2% MVC) in all muscles except for the lumbar extensors (3–5.5% MVC). During the lane change maneuver, selective muscles were activated and these activations restricted the sideway motions due to inertial loading. Averaged muscle activity, predominantly in the neck, lumbar extensor, and abdominal muscles, increased up to 24% MVC soon after the vehicle accelerated in lateral direction for all volunteers. Differences in activation time and amplitude between muscles in the right and left sides of the body were observed relative to the vehicle’s lateral motion. For specific muscles, lane changes with the pre-pretensioner belt were associated with earlier muscle activation onsets and significantly smaller activation amplitudes than for the standard belt (P <.05). Conclusions : Applying a pre-pretensioner belt affected muscle activations; that is, amplitude and onset time. The present muscle activation data complement the results in a preceding publication, the volunteers’ kinematics and the boundary conditions from the same data set. An effect of belt configuration was also seen on previously published volunteers’ kinematics with lower lateral and forward displacements for head and upper torso using the pre-pretensioner belt versus the standard belt. The data provided in this article can be used for validation and further improvement of active human body models with active musculature in both sagittal and lateral loading scenarios intended for simulation of some evasive maneuvers that potentially occur prior to a crash.
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| 9. |
- Iraeus, Johan, 1973, et al.
(författare)
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A new open-source finite element lumbar spine model, its tuning and validation, and development of a tissue-based injury risk function for compression fractures
- 2023
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Ingår i: Conference proceedings International Research Council on the Biomechanics of Injury, IRCOBI. - 2235-3151. ; , s. 1048-1072
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Konferensbidrag (refereegranskat)abstract
- Lumbar spine fractures have been identified as a problem in motor vehicle crashes, and it is expected that this problem might increase with the introduction of reclined postures in autonomous vehicles. Human body models provide a means to address this issue and develop countermeasures. In this study a new open-source finite element lumbar spine model and an associated tissue-based injury risk function were developed and validated. The injury risk function was based on trabecular bone compressive strain in the superior-inferior direction. The kinematic and kinetic validation showed that the model compared reasonably to experimental data, with axial compression and flexion predictions being closest to experimental results. The new risk function was found to have a good quality index. Even though the model evaluations indicated that the fracture risk was somewhat overpredicted, it was judged that the current model, together with the associated injury risk function, can be used to estimate the risk for compressive fractures in the lumbar spine, with the knowledge that these estimates are most likely somewhat conservative.
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| 10. |
- Larsson, Emma, 1991, et al.
(författare)
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Investigating sources for variability in volunteer kinematics in a braking maneuver, a sensitivity analysis with an active human body model
- 2023
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Ingår i: Frontiers in Bioengineering and Biotechnology. - 2296-4185. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Occupant kinematics during evasive maneuvers, such as crash avoidance braking or steering, varies within the population. Studies have tried to correlate the response to occupant characteristics such as sex, stature, age, and BMI, but these characteristics explain no or very little of the variation. Therefore, hypothesis have been made that the difference in occupant response stems from voluntary behavior. The aim of this study was to investigate the effect from other sources of variability: in neural delay, in passive stiffness of fat, muscle tissues and skin, in muscle size and in spinal alignment, as a first step towards explaining the variability seen among occupants in evasive maneuvers. A sensitivity analysis with simulations of the SAFER Human Body Model in braking was performed, and the displacements from the simulations were compared to those of volunteers. The results suggest that the head and torso kinematics were most sensitive to spinal alignment, followed by muscle size. For head and torso vertical displacements, the range in model kinematics was comparable to the range in volunteer kinematics. However, for forward displacements, the included parameters only explain some of the variability seen in the volunteer experiment. To conclude, the results indicate that the variation in volunteer vertical kinematics could be partly attributed to the variability in human characteristics analyzed in this study, while these cannot alone explain the variability in forward kinematics. The results can be used in future tuning of HBMs, and in future volunteer studies, when further investigating the potential causes of the large variability seen in occupant kinematics in evasive maneuvers.
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