Optimisation of Occupant Restraint Systems for Autonomous Vehicles in Reclined Postures

Occupant restraint systems (ORS) play an integral and critical role in protecting occupant safety. However, research on optimising ORS in reclined postures in autonomous vehicles is still insufficient. This study aimed to conduct multiobjective optimisation of the ORS to explore potential occupant injury reduction capability. Firstly, the MADYMO simulation method quantitatively correlates the relevant parameters of the ORS with occupant injuries. Then, parameters that significantly impact the safety performance of the ORS (pretensioning time, pretensioning force, webbing stiffness, seatbelt limiter force, and explosive pretensioning time) were selected as design variables. The occupant's comprehensive injury evaluation criterion, WIC, was used as the optimisation criteria. The ORS parameters were optimised by combining the Latin hypercube experimental design, the Kriging surrogate model, and the NSGA-II optimisation algorithm. The results show that after optimisation, the occupant's head injury criteria (Chead) decreased by 10.87%, neck injury criteria (Cneck) decreased by 14.18%, chest injury criteria (Cchest) decreased by 8.43%, lumbar spine injury criteria (Clumbar) decreased by 2.37%, and the comprehensive weighted injury criterion (WIC) decreased by 8.14%. This study significantly reduced injuries to various parts of the occupant, thereby improving the safety of occupants in reclined postures.