Abstract: The active control retractor (ACR) is beneficial to the reduction of occupant's out-of-position displacement and the minimization of secondary impact risk. In order to investigate the effect of ACR on occupants in braking conditions, a volunteer real vehicle road test is conducted with occupant kinematics responses analyzed based on test data, and a simulation model including active human model is built. After the verification of simulation model, a Kriging approximation model is set up and an optimization on ACR parameters is conducted using NSGA-II algorithm. The results show that the out-of-position displacements of head mass center and the 1st thoracic spine (T1) are reduced by 55% and 73.44% respectively, the accelerations of all parts are lowered significantly during rebound phase, the pretension force and the occupant's out-of-position displacement shows a tendency of negative correlation, and compared with triggering before braking, the pretensioning time in triggering ACR after braking has a larger effect on the out-of-position displacement of occupant

Key words: active control retractor, real vehicle test, active human model, pretension parameters