Kinematics and Shoulder Belt Position of Child Anthropomorphic Test Devices During Steering Maneuvers

Abstract

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.

Keywords:

• child ATD
• kinematics
• rear seat
• shoulder belt position
• steering maneuver
• child restraint systems

Acknowledgments

We especially acknowledge the driver Thomas Alfredsson at Stora Holm's test track for his repeatability and driving skills. We also thank Anna Johansson and Emelie Gunterberg at Chalmers University for their important contribution in data collection. Håkan Gustafson at Volvo Car Corporation, for providing the vehicle as well as assisting in the data collection process, is, together with Samuel Borgen at Epsilon, sincerely acknowledged. The authors owe special thanks to Jordanka Kovaceva at Volvo Car Corporation for assistance in data preparation and extraction and Benny Nilson at Autoliv Research for software support for the video analysis. The authors also thank everyone in the research group within the Swedish national research project “Safety for Children in the Rear Seat” at SAFER and, in particular, Ola Bostrom at Autoliv Research, Mats Svensson and Laure-Lise Gras at Chalmers University, Maria Wimmerstedt at Volvo Car Corporation, Marianne Andersson and Henrik Svanberg at former Saab Automobile AB, and Kristy Arbogast at The Children's Hospital of Philadelphia.

This study was carried out at SAFER Vehicle and Traffic Safety Centre at Chalmers, Sweden, and partly financed by FFI (Fordonsstrategisk Forsknings och Innovation), Vinnova, Sweden.