Evaluation of a diverse population of morphed human body models for prediction of vehicle occupant crash kinematics

Larsson, Karl-Johan; Pipkorn, Bengt; Iraeus, Johan; Forman, Jason; Hu, Jingwen

doi:10.1080/10255842.2021.2003790

Cited by 10 publications

(28 citation statements)

References 16 publications

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“…Moreover, the SAFER HBM v9 has been validated to predict the kinematics and rib fracture risk of an upright seated occupant (Pipkorn et al, 2019) and the kinematics of a reclined seated occupant (Mroz et al, 2020). The parametric morphed versions of the SAFER HBM v9 include females and males of various anthropometries (including a large male), which were validated by means of PMHS tests in both frontal and lateral impact conditions (Larsson et al, 2021).…”

Section: Occupant Surrogatesmentioning

confidence: 99%

Reducing Lumbar Spine Vertebra Fracture Risk With an Adaptive Seat Track Load Limiter

Östling

Lundgren²,

Lübbe³

et al. 2022

Front. Future Transp.

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In future fully automated vehicles, sleeping or resting will be desirable during a drive. While a horizontal position currently appears infeasible, a relaxed seating position with a reclined seatback and an inclined seat pan which enables a safe, comfortable position for sleeping or resting is possible. However, the inclined seat pan increases the forces and moments acting on the lumbar spine of the occupant and thereby the risk of lumbar vertebra fractures in a frontal crash. An energy management system integrated into the longitudinal seat adjustment (a seat track load limiter: STLL) that can reduce this risk should be investigated. When evaluating the injury reduction potential of a new restraint system such as a STLL it is important to include variations in both occupant size and crash severity. Otherwise, there is a risk of sub-optimizing, that is, the restraint system is only working for a limited number of situations. The restraint systems addressing these variations are normally referred to as adaptive restraint systems. The first objective of the study is to develop an activation strategy (adaptive release time of the STLL) for different crash severities and occupant sizes, making full use of the available stroke distance without bottoming out the STLL. The second objective is to evaluate the potential of the adaptive STLL to reduce the risk of lumbar vertebra fractures by comparing it to 1) a fixed seat and 2) a passive version of the STLL. Simulated frontal impacts were performed with two male SAFER human body models (HBMs) as occupant surrogates: mid-sized (80 kg and 1.8 m) and large (130 kg and 1.9 m). Three crash pulse severity levels were evaluated: low (40 km/h), medium (50 km/h), and high (56 km/h) impact speeds. The fracture risk was evaluated for the five lumbar vertebrae (L1–L5) in three different seat conditions: 1) a seat fixed to the sled, 2) a passive STLL that moves when a given force is exceeded, and 3) an adaptive STLL which moves at a time that depends on the occupant mass and crash pulse severity. The risk for lumbar vertebra fracture increased with crash pulse severity, while HBM size had no effect on risk. For all conditions, the passive STLL reduced injury risks compared to the fixed seat, and the adaptive STLL reduced risk even further.

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Section: Occupant Surrogatesmentioning

confidence: 99%

Reducing Lumbar Spine Vertebra Fracture Risk With an Adaptive Seat Track Load Limiter

Östling

Lundgren²,

Lübbe³

et al. 2022

Front. Future Transp.

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show abstract

“…An exception is probabilistic rib fracture risk prediction, which can produce multiple age-adjusted risk predictions from the same, fixed, HBM rib strain predictions. In recent years, morphing (re-shaping) the geometry of HBMs based on statistical human shape models has been used to create several HBMs that geometrically represent male and female occupants of varying age, height, and weight ( Hu et al, 2019 ; von Kleeck et al, 2022 ; Larsson et al, 2022b ). However, these HBMs still represent geometrically average individuals, with an average ribcage shape, for the subpopulation described by each choice of sex, age, height, and weight.…”

Section: Introductionmentioning

confidence: 99%

Influences of human thorax variability on population rib fracture risk prediction using human body models

Larsson

Iraeus

Holcombe

et al. 2023

Front. Bioeng. Biotechnol.

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Rib fractures remain a common injury for vehicle occupants in crashes. The risk of a human sustaining rib fractures from thorax loading is highly variable, potentially due to a variability in individual factors such as material properties and geometry of the ribs and ribcage. Human body models (HBMs) with a detailed ribcage can be used as occupant substitutes to aid in the prediction of rib injury risk at the tissue level in crash analysis. To improve this capability, model parametrization can be used to represent human variability in simulation studies. The aim of this study was to identify the variations in the physical properties of the human thorax that have the most influence on rib fracture risk for the population of vehicle occupants. A total of 15 different geometrical and material factors, sourced from published literature, were varied in a parametrized SAFER HBM. Parametric sensitivity analyses were conducted for two crash configurations, frontal and near-side impacts. The results show that variability in rib cortical bone thickness, rib cortical bone material properties, and rib cross-sectional width had the greatest influence on the risk for an occupant to sustain two or more fractured ribs in both impacts. Therefore, it is recommended that these three parameters be included in rib fracture risk analysis with HBMs for the population of vehicle occupants.

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“…Some of these models have been further developed by adding models of musculature with controlled activation, hereafter referred to active HBMs. With active musculature, the models can be used to predict kinematic response in evasive maneuvers ( Kato et al, 2018 ; Devane et al, 2019 ; Larsson et al, 2019 ; Martynenko et al, 2019 ).…”

Section: Introductionmentioning

confidence: 99%

“…Another THUMS version, THUMS-D activates the individual muscles in response to the individual muscle lengthening ( Martynenko et al, 2019 ; Wochner et al, 2022 ). The SAFER HBM, when modelling a passenger, activates the neck muscles based on change in a link angle between head and T1 vertebral body, from reference posture to current posture, and lumbar muscles in the same manner for a link angle between sacrum and T10 vertebral body ( Larsson et al, 2019 ). These active HBMs have been validated using volunteer responses in evasive maneuvers ( Kato et al, 2018 ; Devane et al, 2019 ; Larsson et al, 2019 ; Martynenko et al, 2019 ; Wochner et al, 2022 ).…”

Section: Introductionmentioning

confidence: 99%

Investigating sources for variability in volunteer kinematics in a braking maneuver, a sensitivity analysis with an active human body model

Larsson,

Iraeus,

Davidsson

2023

Front. Bioeng. Biotechnol.

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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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Evaluation of a diverse population of morphed human body models for prediction of vehicle occupant crash kinematics

Cited by 10 publications

References 16 publications

Reducing Lumbar Spine Vertebra Fracture Risk With an Adaptive Seat Track Load Limiter

Reducing Lumbar Spine Vertebra Fracture Risk With an Adaptive Seat Track Load Limiter

Influences of human thorax variability on population rib fracture risk prediction using human body models

Investigating sources for variability in volunteer kinematics in a braking maneuver, a sensitivity analysis with an active human body model

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