Multi-objective control of human seat suspension system under hydroplaning conditions

To address the mutual inhibition between the 4-DOF half-car suspension system and the 3-DOF seat-human subsystem (HBS) during vehicle hydroplaning on wet roads, this paper proposes a nonlinear time-delay-improved PID control strategy and an NSGA-II-optimized PID control strategy. A hydroplaning excitation model and the half-vehicle suspension-seat-human coupled system (7-DOF) are established to quantitatively analyze the effects of hydroplaning and vehicle speed on water film thickness (WFT), as well as the influence of WFT and vehicle speed on the road adhesion coefficient. Three control scenarios are designed to enhance driving safety and ride comfort: lower-level nonlinear time-delay PID control for the suspension system only, upper-level fuzzy control for the HBS only, and NSGA-II based coupled control for the full 7-DOF system. Simulation results demonstrate that, compared with the passive 7-DOF system, all evaluation indicators under the three control strategies remain below the safety thresholds. Specifically, the pitch angle differences of the third and fourth neck joints are reduced by 24.5%, 36.93%, and 57.54%, respectively, while the corresponding force limits are reduced by 45.26%, 48.04%, and 61.51%. These reductions significantly lower the risk of soft tissue injury in the human neck, thereby greatly improving ride comfort and driving safety.