Driver head displacement during (automatic) vehicle braking tests with varying levels of distraction

van Rooij, Lex; Pauwelussen, Jasper; Op den Camp, Olaf; Janssen, Robby

Affiliations

Abstract

Vehicle occupant behavior in emergency driving conditions has a large effect on traffic safety. Distraction is estimated to be the cause of 15-20% of all crashes. Additionally, the posture of the occupants prior to the possibly unavoidable crash is known to have a large effect on the injury reducing performance of the restraint system. In this study it is investigated whether braking settings as well as driver distraction influence the kinematic response of an occupant during braking events, in order to improve the design of crash avoidance or crash and injury mitigation systems.

A mid-size passenger vehicle was instrumented with an automatic brake actuator and a warning light, which could be operated by the test leader, seated on the passenger side. The motion of the driver’s head in six degrees of freedom was recorded via an eye-tracking system, as well as relevant vehicle parameters. A single professional test driver was used, which was driving on a large test track, allowing velocities up to 120 km/h and full braking with 50 km/h velocity reduction in both straights and curves. A total of 61 braking events were generated in a varied order in the following four categories: 1) driver-induced while being attentive, 2) automatic while being attentive, 3) driver-induced after a warning was provided while being distracted and 4) automatic while being distracted. Driver distraction was achieved by asking the driver to type a text message while operating the vehicle.

From 61 braking tests with a single professional test driver, entrance speed, braking deceleration and jerk time histories as well as brake pedal force were plotted in combination with head motion. Head forward displacement varied between 37 and 128 mm, while head forward pitch (relative to vehicle) was in between 4 and 23 degrees. In attentive scenarios, head rearward displacement in anticipation of an oncoming braking event was observed up to 110 mm. Automatic braking for a distracted driver induces on average 123 mm of head forward displacement, which is 67 mm larger than for an attentive driver that applies the brakes himself. Automatic braking for an attentive driver induced substantially higher head motion, which indicates that posture control is dependent on anticipation on the braking pulse.

This study is limited by the fact that tests were performed with one single, professional driver that was aware of the tests to be performed. Wider variation is expected with different drivers and no conclusions could be drawn on habituation. Furthermore, no accurate information is available on timing, such that no information regarding reaction time can be provided.

Sensitivity of driver head kinematic response during emergency braking for various parameters was shown in fairly realistic driving conditions. This information is relevant for the design of safety systems that interface with the occupants, such as a motorized belt pretensioner and autonomous emergency braking systems. Obviously this data can also be used for the validation of human models that are used to support the design and functioning of these systems.

Links

URL: http://www-nrd.nhtsa.dot.gov/pdf/esv/esv23/23ESV-000403.pdf

Cited Works (4)

Year	Entry
2009	Ejima S, Zama Y, Ono K, Kaneoka K, Shiina I, Asada H. Prediction of pre-impact occupant kinematic behavior based on the muscle activity during frontal collision. In: Proceedings of the 21st International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 15-18, 2009; Stuttgart, Germany.
2008	Bose D, Crandall J, Untaroiu C, Maslen E. Influence of pre-impact occupant properties on the injury response during frontal collisions. In: Proceedings of the 2008 International IRCOBI Conference on the Biomechanics of Impact. September 17-19, 2008; Bern, Switzerland.135-147.
2007	Cappon H, Mordaka J, Van Rooij L, Adamec J, Praxl N, Muggenthaler H. A computational human model with stabilizing spine: a step towards active safety. In: Proceedings of the SAE World Congress & Exhibition. April 16-19, 2007; Detroit, MI. Warrendale, PA: Society of Automotive Engineers. SAE 2007-01-1171.
2005	de Lange R, van Rooij L, Mooi H, Wismans J. Objective biofidelity rating of a numerical human occupant model in frontal to lateral impact. Stapp Car Crash J. 2005;49:457-479. SAE 2005-22-0020.

Cited By (6)

Year	Entry
2019	Odate S, Sakamoto N. Research of minimize steering grasping to take over driver from system in advance safety system. In: Proceedings of the 26th International Technical Conference on the Enhanced Safety of Vehicles (ESV). June 10-13, 2019; Eindhoven, Netherlands.
2015	Ghosh P, Andersson M, Vazquez MM, Svensson M, Mayer C, Wismans J. A proposal for integrating pre‐crash vehicle dynamics into occupant injury protection evaluation of small electric vehicles. In: Proceedings of the 2015 International IRCOBI Conference on the Biomechanics of Injury. September 9-11, 2015; Lyon, France.767-782.
2018	Toczyski J, Gepner B, Kerrigan J. ATD head motion relative to the vehicle: the effect of vehicle inertial sensor mounting location. In: Proceedings of the 2018 International IRCOBI Conference on the Biomechanics of Injury. September 12-14, 2018; Athens, Greece.128-129.
2015	Östh J, Brolin K, Bråse D. A human body model with active muscles for simulation of pretensioned restraints in autonomous braking interventions. Traffic Inj Prev. April 3, 2015;16(3):304-313.
2014	Östh J. Muscle Responses of Car Occupants: Numerical Modeling and Volunteer Experiments Under Pre-Crash Braking Conditions [PhD thesis]. Götenburg, Sweden: Chalmers University of Technology; 2014.
2019	Donlon JP. Restraint Biomechanics in Frontal Impacts With Inboard-Leaning Occupants [Master's thesis]. Charlottesville, VA: University of Virginia; August 2019.