Evaluation of Kinematics and Restraint Interaction when Repositioning a Driver from a Reclined to an Upright Position Prior to Frontal Impact using Active Human Body Model Simulations

Paper in proceeding, 2020

A user expectation for future cars is being able to ride in a reclined position, which creates new challenges for how to protect the occupant in a frontal impact. Existing vehicles are designed for an upright seat position and their protection measures are likely not optimal for reclined seat positions. The present study evaluates the effect on occupant kinematics and restraint interaction using a protection strategy in which the occupant is repositioned back to an upright position prior to a frontal impact, through simulations with an Active Human Body Model. The seat-back repositioning was beneficial in that it achieved similar head kinematics during crash as in an upright initial position. Submarining of the occupant pelvis under the lap-belt was not avoided as the pelvis did not return fully to upright due to the flexibility of the lumbar spine of the HBM. The study also revealed that repositioning could be achieved by the occupant's own torso inertia during pre-crash braking as well as by moving the seat-back. Comparison of simulations with both active and passive HBM showed that the active muscles could potentially influence the crash consequence predictions from the HBM.