Comparison of child and ATD belt fit and posture on belt-positioning boosters during self-selected, holding device, and nominal conditions.

OBJECTIVE: Pediatric anthropomorphic test devices (ATDs) are important tools for the assessment of child occupant protection and should represent realistic child belt fit and posture on belt-positioning boosters. Previous comparisons have been made to children in either self-selected or nominal postural conditions. This study compares belt fit and postural measurements between pediatric ATDs and a single cohort of children assuming different postures on boosters: self-selected, holding a portable electronic device, and nominal. METHODS: A cohort of children (n = 25) were evaluated in a stationary vehicle on five boosters and in three postural conditions: nominal, self-selected, and a representative holding electronic device position. The Hybrid III 6- and 10-year-old and Q-Series 6- and 10-year-old ATDs were evaluated in the same five boosters and in two postural conditions: nominal and a representative holding electronic device position. A 3D coordinate measurement device was used to quantify belt fit (shoulder belt score, lap belt score, maximum gap size, and gap length) and anatomic landmark positions (head, suprasternale, ASIS, and patella). Landmark positions and belt fit were compared between ATDs and children for each booster and postural condition, and Pearson correlations (r) were assessed across boosters. RESULTS: ATDs generally represented Nominal child postures across boosters. In the Device condition, ATDs were seldom able to be positioned to represent both the torso and head position of children, due to limited ATD spinal flexibility. When the torso position was matched, the ATD head was more rear by 63 mm. Correlations between Nominal child and ATD belt fit and belt gap metrics were generally weak and not significant, with the exception of lap belt score (all ATDs p < 0.07, r = 0.8549-0.9857). DISCUSSION: ATDs were generally able to represent realistic child postures and lap belt fit in Nominal and short duration Self-selected postures in a laboratory setting. However, these results display the potential difficulty of utilizing ATDs to represent more naturalistic child postures, especially the more forward head positions and flexed spinal posture associated with utilizing a portable electronic device.

Personalization of human body models and beyond via image registration.

Finite element human body models (HBMs) are becoming increasingly important numerical tools for traffic safety. Developing a validated and reliable HBM from the start requires integrated efforts and continues to be a challenging task. Mesh morphing is an efficient technique to generate personalized HBMs accounting for individual anatomy once a baseline model has been developed. This study presents a new image registration-based mesh morphing method to generate personalized HBMs. The method is demonstrated by morphing four baseline HBMs (SAFER, THUMS, and VIVA+ in both seated and standing postures) into ten subjects with varying heights, body mass indices (BMIs), and sex. The resulting personalized HBMs show comparable element quality to the baseline models. This method enables the comparison of HBMs by morphing them into the same subject, eliminating geometric differences. The method also shows superior geometry correction capabilities, which facilitates converting a seated HBM to a standing one, combined with additional positioning tools. Furthermore, this method can be extended to personalize other models, and the feasibility of morphing vehicle models has been illustrated. In conclusion, this new image registration-based mesh morphing method allows rapid and robust personalization of HBMs, facilitating personalized simulations.

Head injury criteria assessment using head kinematics from crash tests and accident reconstructions.

OBJECTIVE: The aim of this study was to assess head injury criteria based on their correlation to brain strain in a Finite Element (FE) head model (the KTH Royal Institute of Technology model), by simulation of head kinematics data from frontal and side crash tests with Anthropomorphic Test Devices (ATDs), and from Human Body Model (HBM) accident reconstructions. METHODS: Six Degrees of Freedom (DoF) head kinematic data was extracted from 221 crash tests, consisting of frontal impacts with the THOR-50M ATD, near-side and far-side impacts with the WorldSID-50M ATD, and from 19 FE HBM accident reconstructions. The head injury criteria HIC15, HIP, BrIC, UBrIC, DAMAGE and CIBIC were calculated, and FE head model simulations were conducted using the six DoF kinematics data. The 100th, 99th, and 95th percentile Maximum Principal Strains (MPS) of the brain were extracted and linear regression models with respect to the injury criteria were created. The injury criteria were then evaluated based on the coefficient of determination, R2, and the Normalized Root Mean Square Error (NRMSE) of each regression model. RESULTS: For all the data sets combined and for the WorldSID far-side data, CIBIC had the best goodness of fit, with R2 of 0.76 and 0.85. For frontal impacts with THOR and the combined ATD data set, DAMAGE had highest R2, 0.83 and 0.78, respectively. Injury criteria including translational accelerations were ranked lower, and BrIC were among the three lowest ranked for most data sets evaluated. UBrIC generally ranked after DAMAGE and CIBIC with respect to the goodness of fit but had the lowest NRMSE for all data sets. CONCLUSIONS: The two mass-spring-damper brain surrogate model criteria, DAMAGE and CIBIC, were best in capturing the head model MPS response for both the THOR and WorldSID data sets. BrIC had lower correlation to the head model MPS and performed marginally better than the linear acceleration only criteria for all the data sets combined. This study supports the suitability of DAMAGE and CIBIC as brain injury criteria to be used with THOR-50M and WorldSID-50M in vehicle crash test conditions, as they outperform BrIC.

Effects of restraint parameters using PIPER 6y in reclined seating during frontal impact.

OBJECTIVE: This study explores possible challenges for child occupants in reclined seating positions, applying current protection systems. Using PIPER 6 y in frontal impacts, the aim was to investigate the effect of restraint parameters in reclined seating positions, in addition to an upright position, varying booster design, shoulder belt outlet, and pretensioner activation. METHOD: Eighteen full frontal impacts were simulated using the PIPER 6 y human body model restrained on a booster in a front passenger seat. The type of booster, pretensioner activation and shoulder belt outlet were varied with the vehicle seat in 'upright position' (25°) and 'reclined position' (40°). Three booster principles were used: booster seat (BoosterA), booster cushion (BoosterB) and representing properties of a vehicle built-in booster cushion (BoosterC). The two shoulder belt outlets include 'nominal D-ring' and 'rearward D-ring´. RESULTS: Overall, activation of the pretensioner reduced the overall body displacement as well as the head and neck response in both seating positions. Submarining occurred only in the case of BoosterB in 'reclined position' without pretensioner. Some differences were observed for the lap belt interaction with pelvis in the non-submarining simulations. Greater pelvis displacement was observed in 'reclined position' as compared to 'upright position'. In both seating positions, greatest pelvis displacement was observed for BoosterB, due to relatively more forward initial lap belt position. While both provided favorable initial lap belt to pelvis contact, BoosterC offered more efficient lap belt restraint than BoosterA, since the lap belt remained lower on the pelvis and the vertical movement of the pelvis was more limited compared to BoosterA. When in 'reclined position', the 'rearward D-ring' position enabled earlier coupling of the torso due to initial shoulder belt to shoulder contact, resulting in lower head and neck responses as well as shorter head displacement compared to 'nominal D-ring'. CONCLUSIONS: Submarining can be addressed in reclined seating positions using current booster design in combination with a seatbelt pretensioner. Lap belt routing was influenced by booster design and reclined seating, affecting the overall kinematics and responses of the PIPER 6 y. This study highlights the importance of including the whole context of child occupant protection when investigating reclined seating, such as the interaction and compatibility of booster, vehicle seat and seatbelt.

The influence of car passengers' sitting postures in intersection crashes.

Car passengers are frequently sitting in non-nominal postures and are able to perform a wide range of activities since they are not limited by tasks related to vehicle control, contrary to drivers. The anticipated introduction of Autonomous Driven vehicles could allow "drivers" to adopt similar postures and being involved in the same activities as passengers, allowing them a similar set of non-nominal postures. Therefore, the need to investigate the effects of non-nominal occupant sitting postures during relevant car crash events is becoming increasingly important. This study aims to investigate the effect of different postures of passengers in the front seat of a car on kinematic and kinetic responses during intersection crashes. A Human Body Model (HBM) was positioned in a numerical model of the front passenger seat of a midsize Sports Utility Vehicle (SUV) in a total of 35 postures, including variations to the lower and upper extremities, torso, and head postures. Three crash configurations, representative of predicted urban intersection crashes, were assessed in a simulation study; two side impacts, a near-side and a far-side, respectively, and a frontal impact. The occupant kinematics and internal loads were analyzed, and any deviation between the nominal and altered posture responses were quantified using cross-correlation of signals to highlight the most notable variations. Posture changes to the lower extremities had the largest overall influence on the lower extremities, pelvis, and whole-body responses for all crash configurations. In the frontal impact, crossing the legs allowed for the highest pelvis excursions and rotations, which affected the whole-body response the most. In the two side-impacts, leaning the torso in the coronal plane affected the torso and head kinematics by changing the interaction with the vehicle's interior. Additionally, in far-side impacts supporting the upper extremity on the center console resulted in increased torso excursions. Moreover, the response of the upper extremities was consistently sensitive to posture variations of all body regions.

A method for predicting crash configurations using counterfactual simulations and real-world data.

Traffic safety technologies revolve around two principle ideas; crash avoidance and injury mitigation for inevitable crashes. The development of relevant vehicle injury mitigating technologies should consider the interaction of those two technologies, ensuring that the inevitable crashes can be adequately managed by the occupant and vulnerable road user (VRU) protection systems. A step towards that is the accurate description of the expected crashes remaining when crash-avoiding technologies are available in vehicles. With the overall objective of facilitating the assessment of future traffic safety, this study develops a method for predicting crash configurations when introducing crash-avoiding countermeasures. The predicted crash configurations are one important factor for prioritizing the evaluation and development of future occupant and VRU protection systems. By using real-world traffic accident data to form the baseline and performing counterfactual model-in-the-loop (MIL) pre-crash simulations, the change in traffic situations (vehicle crashes) provided by vehicles with crash-avoiding technologies can be predicted. The method is built on a novel crash configuration definition, which supports further analysis of the in-crash phase. By clustering and grouping the remaining crashes, a limited number of crash configurations can be identified, still representing and covering the real-world variation. The developed method was applied using Swedish national- and in-depth accident data related to urban intersections and highway driving, and a conceptual Autonomous Emergency Braking system (AEB) computational model. Based on national crash data analysis, the conflict situations Same-Direction rear-end frontal (SD-ref) representing 53 % of highway vehicle-to-vehicle (v2v) crashes, and Straight Crossing Path (SCP) with 21 % of urban v2v intersection crashes were selected for this study. Pre-crash baselines, for SD-ref (n = 1010) and SCP (n = 4814), were prepared based on in-depth accident data and variations of these. Pre-crash simulations identified the crashes not avoided by the conceptual AEB, and the clustering of these revealed 5 and 52 representative crash configurations for the highway SD-ref and urban intersection SCP conflict situations, respectively, to be used in future crashworthiness studies. The results demonstrated a feasible way of identifying, in a predictive way, relevant crash configurations for in-crash testing of injury prevention capabilities.

Evaluation of users' experience and posture in a rotated swivel seating configuration.

OBJECTIVE: This study aims to evaluate a car passenger's experience and actions in a rotated seat in terms of interaction with an adjacent passenger. METHODS: A static user study was conducted, using a stationary test vehicle with two front row seats facing rearwards. The seats were mounted on a swivel plate which allowed inboard rotation. Thirty-two participants in 16 test pairs were grouped based on stature; short or tall. The participants within each pair knew each other. Three seating configurations were evaluated; 0° and 10° and 20° inboard rotated position of both seats. The participants were seated in each seating configuration for 10 min; 5 min they engaged in a conversation with each other and 5 min they were watching media on an Ipad mounted in front of them. Subjective data from each participant on their experiences and preferences were collected through questionnaires, and objective data on sitting postures and eye gaze were collected through video recording. RESULTS: Ninety-two percent of the short participants preferred to sit in the 20° rotated seating configuration when watching media and 75% preferred the 20° seating configuration when engaged in conversation. Compared to short participants, the tall participants showed a relative larger spread in seating configuration preference; 15% and 30% of them preferred the reference position for media and conversation, respectively. Leg interference was common for tall participants when 20° inboard rotated. They perceived it uncomfortable and used various strategies to avoid contact, including crossing legs or feet. Time spent with mutual eye contact did not vary by seating configuration. CONCLUSIONS: This static user study shows that rotated seats could be a desired seating configuration in future autonomous vehicles for individuals who know each other. It reveals the reasons behind the preferences and the extent of desired seat rotation, showing differences between tall and short individuals. By understanding how occupant position and posture can be influenced by offering various seating configurations, the occupant can choose a comfortable position that is also safe. The leg and feet positions are raised as the body region with most variations and for which an increased understanding of influence in a crash is encouraged.

Booster cushion design effects on child occupant kinematics and loading assessed using the PIPER 6-year-old HBM and the Q10 ATD in frontal impacts.

OBJECTIVE: Our objective was to study the effect on child occupant kinematics and loading by differences in booster cushion designs and attachment in a frontal impact. METHODS: Three different booster cushion designs were exposed to a frontal impact in vehicle rear seat interiors. The boosters were selected based on their difference in shape, stiffness, and guiding loop design. Tests were run varying the shoulder belt routing above or under the guiding loop, in addition to with or without attachment of the booster cushion to the vehicle ISOFIX anchorages. Eighteen simulations with the finite element PIPER 6-year-old human body model (HBM) were run investigating all combinations of parameters, in addition to 3 sled tests with a Q10 anthropomorphic test dummy (ATD). RESULTS: Across 2 different child sizes, using an HBM and an ATD, respectively, consistent sensitivity to the booster design differences were seen. Boosters providing similar initial static belt fit can result in different occupant responses during a crash, due to the design of the boosters and their dynamic performance. Compression of the booster cushion resulted in a delayed pelvis restraint, influencing the upper body kinematics. The guiding loop design as well as the belt routing above or under the guide also influenced the upper body kinematics and shoulder belt interaction. CONCLUSIONS: Early pelvis coupling to initiate torso pitch, and thereby an upper torso motion controlled by the shoulder belt, is the preferred occupant protection for booster-seated children. A stable mid-shoulder belt position centered over the chest initially is a prerequisite. Additionally, it was seen that the design of the guiding loops helps provide favorable interaction with the torso during the crash. The option to allow the shoulder belt to be placed above and under the guiding loops will accommodate a larger span of child sizes and adapt to more vehicle seat belt geometries. This study provides evidence that the design of the booster cushion plays an important role in creating an early pelvis coupling, as well as supporting favorable torso-shoulder belt interaction.

Passenger muscle responses in lane change and lane change with braking maneuvers using two belt configurations: Standard and reversible pre-pretensioner.

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.

Kinematics and shoulder belt engagement of children on belt-positioning boosters during evasive steering maneuvers.

OBJECTIVE: To increase the protection of child passengers in crashes preceded by evasive steering, understanding of how children interact with the seat belt in such situations is essential. This study aims to quantify child kinematics and describe child-to-restraint interaction during evasive steering maneuvers. METHODS: Eighteen child volunteers (aged 5-10) were seated on the rear seat of a passenger vehicle. A professional driver made repeatable sharp turns at 50 km/h. Children were restrained by the seat belt on a booster cushion (BC) and on an integrated booster cushion (IBC). Kinematics of the nasion and upper sternum were analyzed with video tracking software and shoulder belt (SB) engagement and position were evaluated. RESULTS: Children moved laterally inboard, and SB-to-body interaction was influenced by booster and stature. Shorter children displayed initial SB positions closer to the neck with less instances of gap between the SB and the lower torso, resulting in more curved belt paths on the IBC. On the BC, shorter children had less of the SB in contact with the torso and straight belt paths were observed throughout steering. Taller children generally had the SB initially mid-shoulder with less instances of gap, resulting in curved belt paths at initial and maximum displacements on both boosters. Children loaded the shoulder belt by axially rotating their torso into the SB more often on the IBC compared to BC. The SB generally stayed on the shoulder, with 89% of slip-off instances occurring for shorter children on the BC. Shorter children on the BC had the largest average inboard nasion displacement (120 mm). Taller children on the BC had the lowest average inboard displacement of the nasion (100 mm). All children initially displaced on average 90 mm inboard with their upper sternum. CONCLUSIONS: Initial SB position on the shoulder and torso differed with booster and stature, which influenced how children engaged with the seat belt during steering. Children with less SB initially in contact with the torso moved laterally behind the belt, resulting in straighter SB paths and outboard motion of the SB on the shoulder (often ending far out or slipped off). When more of the SB was initially in contact with the torso, children tended to engage the SB more, moving with the belt and causing the SB path to become more curved, resulting in less inboard head displacement and less outboard motion of the SB on the shoulder. Enhanced understanding of how evasive steering affects the kinematic response of children provides valuable data for protection of children in real-world situations.

Seat belt pre-pretensioner effect on child-sized dummies during run-off-road events.

OBJECTIVE: Run-off-road events occur frequently and can result in severe consequences. Several potential injury-causing mechanisms can be observed in the diverse types of run-off-road events. Real-world data show that different types of environments, such as rough terrain, ditch types, and whether multiple events occur, may be important contributing factors to occupant injury. Though countermeasures addressing front seat occupants have been presented, studies on rear seat occupant retention in situations such as run-off-road events are lacking. The aim of this study was to investigate the seat belt pre-pretensioner effect on rear-seated child-sized anthropomorphic test devices (ATDs) during 2 different types of run-off-road events. METHODS: The study was carried out using 2 test setups: a rig test with a vehicle rear seat mounted on a multi-axial robot simulating a road departure event into a side ditch and an in-vehicle test setup with a Volvo XC60 entering a side ditch with a grass slope, driving inside the ditch, and returning back to the road from the ditch. Potential subsequent rollovers or impacts were not included in the test setups. Three different ATDs were used. The Q6 and Q10 were seated on an integrated booster cushion and the Hybrid III (HIII) 5th percentile female was positioned directly on the seat. The seat belt retractor was equipped with a pre-pretensioner (electrical reversible retractor) with 3 force level settings. In addition, reference tests with the pre-pretensioner inactivated were run. Kinematics and the shoulder belt position were analyzed. RESULTS: In rig tests, the left-seated ATD was exposed to rapid inboard lateral loads relative to the vehicle. The displacement for each ATD was reduced when the pre-pretensioner was activated compared to tests when it was inactivated. Maximum inboard displacement occurred earlier in the event for all ATDs when the pre-pretensioner was activated. Shoulder belt slip-off occurred for the Q6 and Q10 in tests where the pre-pretensioner was inactivated. During in-vehicle tests, the left-seated ATD was exposed to an inboard movement when entering the road again after driving in the ditch. The maximum inboard head displacement was reduced in tests where the pre-pretensioner was activated compared to tests in which it was inactivated. CONCLUSIONS: During both test setups, the activation of the pre-pretensioner resulted in reduced lateral excursion of the Q6, Q10, and HIII 5th percentile female due to the shoulder belt remaining on the shoulder and supporting the side of the lower torso. The results provide new insights into the potential benefits of using a pre-pretensioner to reduce kinematic responses during complex run-off-road events through supporting the seat belt to remain on the shoulder. This study addresses potential countermeasures to improve real-world protection of rear-seated children, and it provides a broader perspective including the influence of precrash kinematics.

Kinematics and shoulder belt position of child anthropomorphic test devices during steering maneuvers.

OBJECTIVES: The objective of this study was to quantify and compare the kinematics and shoulder belt position of child anthropomorphic test devices (ATDs) during emergency steering maneuvers. Furthermore, the ATDs were compared to the results from child volunteers aged 4 to 12 in the same test setup (Bohman, Stockman, et al. 2011). METHODS: A driving study was conducted on a test track comprising 4 ATDs: the Q6, Q10, and Hybrid III (HIII) 6- and 10-year-old ATDs restrained in the rear seat of a passenger vehicle. The ATDs were exposed to 2 repeated steering maneuvers in each restraint system. The Q6 and HIII 6-year-old were restrained on booster cushions as well as high-back booster seats. The Q10 and HIII 10-year-old were restrained on booster cushions or restrained by 3-point seat belts directly on the seat. Lateral motion of the forehead and upper sternum was determined, as well as shoulder belt movement on shoulder and torso tilting angle. RESULTS: All ATDs began to move approximately at the same point in time corresponding to a vehicle lateral acceleration of just below 0.2 g. In the later phase of the maneuver, Q10 had moved 26 percent less than the children when restrained by seat belt only and 35 percent less when on a booster cushion. Corresponding numbers for the HIII 10-year-old were 43 and 44 percent higher than for children. Compared to children, the Q6 had moved 34 percent less when restrained on a high-back booster seat and 31 percent less when on a booster cushion. Corresponding numbers for HIII 6-year-old were 7 and 28 percent higher than for children. Due to extensive variety of lateral displacements observed in the children, child performance range covers both ATD families for the evaluated sizes of 6- and 10-year-old ATDs. CONCLUSIONS: Compared to children, the HIII ATDs were closer with regards to mean values in the initial phase of the maneuver and the Q ATDs were closer in the end of the ramping phase of the lateral acceleration. The question regarding which ATD replicates better the behavior of children exposed to steering maneuvers still remains open. As shown in this study, it depends on the focus of the comparison and on what phase of the maneuver is of interest. This study provides valuable knowledge on how representative the current ATDs are for replicating potential precrash postures of children as a result of vehicle emergency steering maneuvers for a variety of restraint systems and ATD sizes.

Kinematics of child volunteers and child anthropomorphic test devices during emergency braking events in real car environment.

OBJECTIVES: The objective of this study was to present, compare, and discuss the kinematic response of children and child anthropomorphic test devices (ATDs) during emergency braking events in different restraint configurations in a passenger vehicle. METHODS: A driving study was conducted on a closed-circuit test track comprising 16 children aged 4 to 12 years old and the Q3, Hybrid III (HIII) 3-year-old, 6-year-old, and 10-year-old ATDs restrained on the right rear seat of a modern passenger vehicle. The children were exposed to one braking event in each of the 2 restraint systems and the ATDs were exposed to 2 braking events in each restraint system. All events had a deceleration of 1.0 g. Short children (stature 107-123 cm) and the Q3, HIII 3-year-old, and 6-year-old were restrained on booster cushions as well as high-back booster seats. Tall children (stature 135-150 cm) and HIII 10-year-old were restrained on booster cushions or restrained by 3-point belts directly on the car seat. Vehicle data were collected and synchronized with video data. Forward trajectories for the forehead and external auditory canal (ear) were determined as well as head rotation and shoulder belt force. RESULTS: A total of 40 trials were analyzed. Child volunteers had greater maximum forward displacement of the head and greater head rotation compared to the ATDs. The average maximum displacement for children ranged from 165 to 210 mm and 155 to 195 mm for the forehead and ear target, respectively. Corresponding values for the ATDs were 55 to 165 mm and 50 to 160 mm. The change in head angle was greater for short children than for tall children. Shoulder belt force was within the same range for short children when restrained on booster cushions or high-back booster seats. For tall children, the shoulder belt force was greater when restrained on booster cushions compared to being restrained by seat belts directly on the car seat. CONCLUSIONS: The forward displacement was within the same range for all children regardless of stature and restraint system. However, the maximum forward position depended on the initial seated posture and shoulder belt position on the shoulder. Differences could also be seen in the curvature of the neck and spine. Short children exhibited a greater flexion motion of the head, whereas a more upright posture at maximum forward position was exhibited by the tall children. The ATDs displayed less forward displacement compared to the children.

Nonresponse analysis and adjustment in a mail survey on car accidents.

Statistical accident data plays an important role for traffic safety development involving the road system, vehicle design, and driver education. Vehicle manufacturers use data from accident mail surveys as an integral part of the product development process. Low response rates has, however, lead to concerns on whether estimates from a mail survey can be trusted as a source for making strategic decisions. The main objective of this paper was to investigate nonresponse bias in a mail survey addressing driver behaviour in accident situations. Insurance data, available for both respondents and nonrespondents were used to analyze, as well as adjust for nonresponse. Response propensity was investigated by using descriptive statistics and logistic regression analyses. The survey data was then weighted by using inverse propensity weights. Two specific examples of survey estimates are addressed, namely driver vigilance and driver's distraction just before the accident. The results from this paper reveal that driver age and accident type were the most influential variables for nonresponse weighting. Driver gender and size of town where the driver resides also had some influence, but not for all survey variables investigated. The main conclusion of this paper is that nonresponse weighting can increase confidence in accident data collected by a mail survey, especially when response rates are low. Weighting has a moderate influence on this survey, but a larger influence may be expected if applied on a more diverse driver population. The development of auxiliary data collection can further improve accident mail survey methodology in future.

Kinematics and shoulder belt position of child rear seat passengers during vehicle maneuvers.

Head impact to the seat back has been identified as one important injury causation scenario for seat belt restrained, head-injured children and previous research highlighted vehicle maneuvers prior to impact as possible contributing factors. The aim was to quantify kinematics of child occupants during swerving maneuvers focusing on the child's lateral movement and seat belt position relative to the child's shoulder. A study was conducted on a closed-circuit test track with 16 children aged 4-12, restrained in the rear seat of a modern passenger vehicle. A professional driving instructor drove at 50 km/h making sharp turns in a repeatable fashion, resulting in inboard motion of the children. The children were exposed to two turns in each of two restraint systems. Shorter children were on a booster or highback booster cushion. The taller children were seated on a booster cushion or with only a lap and shoulder seat belt. Four film cameras were fixed in the vehicle monitoring the child. Vehicle data were also collected. The seat belt slipped off the shoulder in 1 of 5 turns, varying by age and restraint type. Among shorter children, the belt slipped off in a majority of turns when seated on a booster cushion while the belt remained on the shoulder when seated on the highback booster cushion. Among taller children, the shoulder belt moved far laterally on the shoulder in half of the turns. This data provides valuable knowledge on possible pre-impact postures of children as a result of vehicle swerving maneuvers for a variety of restraint systems.

Real World Data Driven Evolution of Volvo Cars' Side Impact Protection Systems and their Effectiveness.

This study analyses the outcome of the continuous improved occupant protection over the last two decades for front seat near side occupants in side impacts based on a real world driven working process. The effectiveness of four generations of improved side impact protection are calculated based on data from Volvo's statistical accident database of Volvo Cars in Sweden. Generation I includes vehicles with a new structural and interior concept (SIPS). Generation II includes vehicles with structural improvements and a new chest airbag (SIPSbag). Generation III includes vehicles with further improved SIPS and SIPSbag as well as the new concept with a head protecting Inflatable Curtain (IC). Generation IV includes the most recent vehicles with further improvements of all the systems plus advanced sensors and seat belt pretensioner activation. Compared to baseline vehicles, vehicles of generation I reduce MAIS2+ injuries by 54%, generation II by 61% and generation III by 72%. For generation IV effectiveness figures cannot be calculated because of the lack of MAIS2+ injuries. A continuous improved performance is also seen when studying the AIS2+ pelvis, abdomen, chest and head injuries separately. By using the same real world driven working process, future improvements and possibly new passive as well as active safety systems, will be developed with the aim of further improved protection to near side occupants in side impacts.

WHIPS (Volvo cars' Whiplash Protection System)-the development and real-world performance.

OBJECTIVES: Present the performance of WHIPS and identify possible next steps of soft tissue neck injury reduction potentials, based on rear-end real-world crash data. METHODS: Front-seat occupants (above 14 years of age) have been analyzed regarding influencing factors on reported incidences of soft tissue neck injuries. The outcome of 1858 occupants in cars equipped with WHIPS and 663 occupants in Volvo cars of model year 1999 without WHIPS are studied with respect to WHIPS injury-reducing effect for different impact severities and injury durations. The occupants in WHIPS are further studied with respect to seating position and sitting posture, such as turned head and head-to-head restraint distance. RESULTS: Soft tissue neck injury risk reductions are seen for occupants in WHIPS as compared to prior Volvo cars; mean values ranging from 21 to 47% depending on impact severity and symptom duration. Sitting posture (turned head and increased backset) increases soft tissue neck injury risks. Based on the self-reported injury data, a significantly lower risk was found for occupants facing straight forward with the head in close proximity to the head restraint as compared to the risk for occupants with rotated head and a larger backset. Even though the highest risk of soft tissue neck injuries is found in higher impact severity, the large amount of soft tissue neck injuries sustained at low impact severity emphasizes the need of focusing measures for crash avoidance. CONCLUSIONS: This study presents the development and real-world performance of WHIPS as well as identifies situations for further focus and challenges for the next generation of soft tissue neck injury protection and prevention, including areas such as occupant posture and crash avoidance.

Synthesis of multi ring-fused 2-pyridones via an acyl-ketene imine cyclocondensation.

Polycyclic ring-fused 2-pyridones (5a-e and 9a-e) have been prepared via a microwave-assisted acyl-ketene imine cyclocondensation. Starting from 3,4-dihydroisoquinolines (4a-b) or 3,4-dihydroharman (8), fused 2-pyridones could be prepared in a one-step procedure. By using either Meldrum's acid derivatives (1a-d) or 1,3-dioxine-4-ones (7a-b) as acyl-ketene sources, mono- or disubstitution of the fused 2-pyridone ring could be accomplished. As an application of the method, a formal synthesis of the indole alkaloid sempervilam was performed.

Evaluation criteria for AIS 1 neck injuries in frontal impacts--a parameter study combining field data and Madymo modeling.

Two situations with an expected higher AIS 1 neck injury rate in frontal impact were compared to a reference situation using a Madymo human body model in three different sitting postures and four different crash pulses. The two situations were reduced occupant weight and occupant with initial forward arm resistance, respectively. Occupant neck motion phases were identified and corresponding possible evaluation criteria were evaluated within the phases. Typical neck kinematics was seen for the two different situations. Occupants of lower weight had a more extended neck in the initial protraction phase and also a generally more pronounced upper neck link angle. Occupants with initial arm resistance had generally greater lower neck link angle at the time when the upper neck link angle was straight. No evaluation criteria reflected the anticipated AIS 1 neck injury rate consistently. In the initial protraction phase, NICmin correlated to expected injury outcome in almost half of the cases. In the protraction-flexion shift phase, Nkm, Nij, upper neck shear force and neck tension force reflected anticipated severity outcome to some extent. In the flexion phase, upper and lower neck extension correlated to anticipated AIS 1 neck injury rate only to a minor extent. The different sitting postures were more influential than the different crash pulses, emphasizing the importance of not only considering the spectra of impact severity but also differences in sitting postures in safety system development and evaluation.