Biodynamic Response Mitigation to Shock Loads Using Magnetorheological Seat Suspensions

This study investigates biodynamic response mitigation of both sinusoidal vibration and shock loads using a magnetorheological (MR) seat suspension. In doing so, an MR seat suspension model for helicopters, with a detailed lumped parameter model of the human body, was developed. The lumped parameter model of the human body consists of four parts: pelvis, upper torso, viscera and head. From the model, the governing equation of motion of the MR seat suspension considering the human body was derived. Based on this equation, a semi-active nonlinear optimal control algorithm appropriate for the MR seat suspension was developed. The simulated control performance of the MR seat suspension was evaluated under both sinusoidal vibration and shock loads due to a vertical crash landing of a helicopter. In addition, the mitigation of injuries to humans due to such shock loads was also evaluated and compared with the passive seat suspension using a passive hydraulic damper.