Introduction of a Protection System for Rear-Facing Seats in Autonomous Car Crashes

In autonomous cars, occupants will have the option of setting the seat in a rear-facing position. However, sitting on such a seat can introduce higher risk of whiplash when a frontal impact occurs since frontal crashes generally occur at higher severities than rear-end crashes. This study introduces a protection system for rear-facing seats in autonomous cars and evaluates its potential for crash severities up to 64 km/h of delta-V (velocity change) by using seat-occupant simulations. The developed seat system features two rigid torso-plates, energy absorbers at the recliner and beneath the seat-pan whose damping coefficients are varied depending on the severity of the crash. The protection system also incorporates recliner breakaway elements in which higher breakaway forces are required for higher severities. Without the proposed protection system, the human model experiences neck shear forces of above 600 N whereas with the proposed system, neck shear forces are at most 316 N at the highest crash severity of 64 km/h delta-V. Other than neck injury, head, thorax and lumbar injury risk are also monitored. The results indicate that the proposed system protects the occupant successfully by having all injury criteria values well below the injury threshold values.