Seat Cushion Restraint System

Computer simulation analysis is often the only cost effective way to investigate new ideas and concepts. In 1995 a study was conducted to investigate a device that could mitigate lower extremity injuries.

Although lower extremity injuries are not life threatening, they are often very debilitating and require long periods of rehabilitation. It is believed that bracing the legs against the toeboard, during a vehicle crash, is a major contributor to the injury mechanisms. Another contributor to the lower extremity injuries is leg interaction with the instrument panel.

The Seat Cushion Restraint System (SCRS) comprises 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 instrument panel by limiting the forward travel of the lower torso. It achieves this by inflating an airbag device in the front part of the seat cushion, during the early stages of a vehicle crash. This lifts the legs off the toe board, effectively eliminating the bracing force. It further restrains the lower torso as effective as a lap belt which reduces the interaction of the knees with the instrument panel.

Computer simulations helped to determine design parameters such as timing, raise height and loads. During the analysis phase the initial design concept underwent several changes that were vital to it working the way that was intended. The occupant simulation analysis showed a potential reduction of the lower extremity injury measures by as much as 80% for unbelted occupants. The work is fully described in SAE paper 960503. A world-wide patent application for the device was filed in 1995 and a US patent was issued in 1997 under number 5,695,242.

SCRS Analysis

This image shows the SCRS (on the right) in comparison to a conventional restraint system (on the left). The SCRS effectively lifts the feet off the toeboard and limits the forward travel of the lower torso, reducing the interaction of the knees with the instrument panel.