Kinematics of Child Volunteers and Child Anthropomorphic Test Devices During Emergency Braking Events in Real Car Environment

Abstract

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.

Evaluation of 6 and 10 Year-Old Child Human Body Models in Emergency Events

“…In terms of anthropometry, the Child6YO model has a stature of 116 cm and weighs 21 kg, while the Child10YO is 144 cm tall and weighs 35.5 kg. These values were close to the volunteers’ anthropometry data [26]: children of the short and tall groups were respectively 117±6 cm and 144±5 cm tall and weighed 20 kg and 36 kg in average. Most of the mechanical properties are scaled down from the adult 50 th percentile male model and details can be found in the MADYMO Human Models Manual [20].…”

“…The MADYMO HBMs representing 6 year-old (Child6YO) and 10 year-old (Child10YO) children [20] were used to simulate experiments previously performed with child volunteers in braking [26] and steering events [27]. The MADYMO Release 7.4.1 code was used for all simulations and post processing was done using MATLAB version R2010b (MathWorks, Natick, Massachusetts, U.S.A.).…”

“…Previously published studies have presented child volunteer data for braking [26] and steering [27] events performed on a test track with a Volvo XC70. The study protocol the authors are referring to was reviewed and approved by The Ethics Board of Gothenburg, Sweden [26,27].…”

“…The study protocol the authors are referring to was reviewed and approved by The Ethics Board of Gothenburg, Sweden [26,27]. The driving study was conducted on a closed-circuit test track by a professional driving instructor.…”

“… [26] and Bohman et al [27] with permission of the authors. (A) The braking event was split into three phases.…”