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Active Bonnet System: The Effect of Partial Occlusion on Driver Performance and Safety

Funding Organisation: Jaguar Cars


European Law dictates that production cars are pedestrian "crashworthy" at low speeds and forms part of the Euro NCAP testing regime. To achieve this, Jaguar has developed the Active Bonnet System (ABS). During a frontal pedestrian collision, ABS deploys a vehicle's bonnet by a small amount, allowing a space underneath the bonnet in which to absorb the energy of the impact.

One of the characteristics of ABS is that when deployed, it partially occludes the driver's visual field. The amount of occlusion is affected by the eye-height of the driver, such that shorter drivers experience more occlusion. This study attempted to quantify the amount of disruption to the normal driving task, when the system is deployed.

The system was animated in the LADS for different driver populations by projecting an image from three different eye-heights. When occluded, drivers tended to decelerate (engine braking); as occlusion time increased, so did this deceleration. This effect was only significant for the shortest drivers (5th percentile). Across occlusion times, the effect only became significant at 3s and above for straight sections, and 2s for curves. Jaguar used these results to determine suppliers of the ABS mechanics.