Using Shoulder Bolster and Knee Bolster to Achieve Protection Effect Comparable to Seatbelt and Airbag

Seatbelt and airbags provide effective occupant restraint, but are also potential to induce intrusive deformation and submarining injuries in motor vehicle crashes. To address these issues, this study puts forward a new restraint concept that applies restraint loads on shoulders and knees/femurs, i.e., the sturdiest regions of human body, via a combined use of shoulder bolster and knee bolster based on biomechanical computational analysis. The load characteristics of the two bolsters were optimized to obtain protection effectiveness superior to conventional use of seatbelt and airbag. Occupant kinematics and kinetics were taken into account, including the excursions of head, shoulders and knees, the accelerations of head and chest, and the compressions of thorax on several locations on the ribcage. The injury risk of rib fractures was monitored based on the strain levels of ribcage. Results show that applying adaptive restraint loads on the sturdy regions of human body using shoulder bolster and knee bolster can ensure reasonable kinematical motion and acceptable injury levels of occupant, and can also avoid intrusive deformations in thorax and abdomen as well as airbag hazards. The protection effect of shoulder bolster and knee bolster is comparable or superior to that of using seatbelt and airbag. To achieve a balance of comfort and safety in autonomous driving environment, the system will be activated only when collision is sensed unavoidable.