Injury protection control of occupant legs by active knee bolster

In this paper an active knee bolster is proposed for the purpose of injury protection of passengers on his/her lower extremity in vehicle collision. Control objectives are not only to reduce the load to femur less than the passive knee bolster but also to suppress the pelvis movement and the pelvis deceleration to the same level as the passive one. The feedback control system is applied to follow a reference signal of the contact force between the knee and the instrument panel. The appropriate reference signal is decided to the step reference signal lowered like the ramp at the latter time of the duration to suppress the pelvis deceleration. It is demonstrated that the proposed active knee bolster can improve the performance of the passive one by carrying out simulations and experiments.