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Citation
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Zander O, Dausse I, Martin PG, Park JS. 27th International Technical Conference on the Enhanced Safety of Vehicles (ESV); April 3-6, 2023; Abstract #: 23-0144, pp. 21p. Washington, DC USA: US National Highway Traffic Safety Administration, 2023. |
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Abstract
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27th International Technical Conference on the Enhanced Safety of Vehicles (ESV): Enhanced and Equitable Vehicle Safety for All: Toward the Next 50 Years
https://www-esv.nhtsa.dot.gov/Proceedings/27/27ESV-000144.pdf
World-wide test and assessment procedures for passive pedestrian protection have been in place for many years. Passive safety requirements within global technical regulation no. 9 (UN-GTR9) are prescribed through tests to the front ends of stationary vehicles with instrumented impactors representing the pedestrian's head, pelvis and lower extremities. However, no specific requirements are included for vehicles equipped with active bonnets and other deployable pedestrian protection systems (DPPS). This paper describes the work of the UN informal working group (IWG) to develop procedures on DPPS that are intended to be incorporated into UN-GTR9 and UN-R127 as amendments. DPPS must work as intended during actual vehicle-to-pedestrian accidents. Therefore, test methods and conditions need to reflect the challenges DPPS are facing during actual and representative accident scenarios, but without being design restrictive. Several prerequisites need to be met in order to assure that DPPS operate properly and offer at least the same level of pedestrian protection as conventional passive pedestrian protection systems. These prerequisites include system requirements providing pedestrian detection and the timely and safe DPPS deployment. Also, headform tests are run at impact speeds below the DPPS deployment threshold on the undeployed system to confirm the undeployed bonnet is sufficiently safe. Draft amendments intended for UN-GTR9 and UN-R127 are being finalized by the IWG on DPPS to harmonize testing under the agreements of 1958 and 1998 while preserving contracting parties' options for domestic standards. Results reported herein include IWG investigations of: (1) An appropriate impactor to assure a pedestrian is detected by the front-end sensing system; (2) Real world pedestrian accidents to determine the needed width of the detection test area; (3) Qualification procedures for Human Body Models (HBM) for use in simulations to determine head impact times (HIT) and impact locations; (4) An empirical formula to determine HIT in lieu of HBM computer simulations; (5) Experimental determination of the total response time of the DPPS. Altogether, the amendments provide for headform impact test conditions on deployable systems against established performance requirements to reduce head injury risk. A DPPS is expected to offer a sufficient level of pedestrian protection while preserving vehicle design freedom. Several shortcomings of the developed procedure are discussed and limitations are identified which could reduce the actual pedestrian protection during a crash: The FlexPLI does not mimic the hardest to detect pedestrian. The detection test area does not fully account for all pedestrian impact trajectories. The bonnet clearance afforded by a DPPS could be compromised by the upper body load. The deployment height and the oncoming speed of the Zander 2 deploying bonnet could differ between testing and real-world scenarios. A valid HIT determination using a HBM simulation on a given vehicle model requires good CAE correlation with the actual vehicle. The alternatives, experimental testing or an empirical formulation to determine HIT, could increase objectivity. The draft procedures are being developed by the IWG for consideration as amendment to UN-GTR9 and UN-R127. It will offer an approach for compliance testing of vehicles equipped with DPPS. Since UN-R127 and the European New Car Assessment Programme (Euro NCAP) have extended their scopes to the head protection of bicyclists, the DPPS head protection potential should be investigated accordingly in future studies.
Language: en |