Seat and Airbag Design to Mitigate Frontal Crash Lower Limb Injuries

Although lower extremity injuries are not life threatening (AIS less than 4), they are very debilitating and require long periods of rehabilitation. A possible cause of the ankle/foot injury in frontal crashes is the foot dorsiflexion resulting from intrusion of the toeboard. Ankle injury on the driver side in the same type of crashes may also be caused by the foot eversion or inversion as it slides off the pedals. In both cases, it is believed that bracing the leg is a major contributor to the injury mechanism. Another contributor to lower extremity injuries is leg interaction with the instrument panel (IP).

This paper describes an activated seat design that acts to eliminate the interaction between the lower extremities and the vehicle interior. It also reduces the interaction between the legs and the IP by limiting the forward travel of the lower torso. Three different design approaches are presented in the paper. These approaches use either an airbag, pyrotechnic, or mechanical device, which acts in the seat cushion to then free the leg and foot from the intruding or reactive structure, and to minimize the travel of the lower torso into the IP.