In a rear impact, the seatback of many automobile seats is designed to plastically deform or “yield” to absorb energy from the crash to protect the occupant. This yielding provides ride-down of the impact's acceleration as opposed to transferring all energy into the occupant, which is particularly important for out-of-position occupants. Although beneficial to the seated occupant for prevention of injury (particularly in low-speed cases where the occupant is susceptible to whiplash or if the seated occupant is "out-of-position"), this yielding has potential to intrude into the occupant space of anyone sitting behind this seat, especially young children. However, if seats are made to be stiffer to prevent this intrusion, first-row occupant response will suffer as yielding seats offer the best protection in the majority of rear impacts. This has been debated by automotive experts for decades. It is not possible for engineers to develop a single seat design which relies on plastic deformation of the structure that can accommodate a range of occupants in a variety of crash scenarios.

To improve safety across the wide range of rear impact scenarios, an automotive seat is presented with a yielding baseline that is able to mechanically increase the seatback rotational stiffness. The device facilitates the yielding to occur along the entire crash pulse within available space to do so based on the weight of the occupant, the severity of the crash scenario, and the sensed presence of occupants in the row behind the seat. The delta-V input to control this device would be recorded by the vehicle's onboard Airbag Control Unit (ACU). Mass of the occupant and position and the presence of occupants in the row behind can be monitored either via load sensors in the seat base (according to methods described by Vergnano, Designs 8(3) 2024) and Driver Monitoring Systems (DMS).

This contestant has previously published papers describing static and dynamic testing of a proof-of-concept prototype (SAE 2022-01-0585, SAE 2023-01-0648). These publications showed the potential for improved biomechanical response in a range of scenarios. The earlier variant used in these publications is patent-pending and utilized a simple design which provided a step response in the seatback condition (i.e. yielding or stiff). The revised variant proposed in this entry would utilize a semi-active shock absorber internal to the frame of the seat to alter the stiffness based on electronic input; semi-active shock absorbers like this are used in automotive and recreational off-road vehicle industries. This design would best minimize injury to all occupants in a vehicle subjected to a rear impact in varying crash scenarios.