A Variable Stiffness and Damping Control Strategy for Improving Vibration Isolation Performances in Low-Frequency Excitation

Purpose Human body is sensitive to low-frequency excitation, which can not be suppressed effectively by the suspension control strategy that only controls the damper. This paper focuses on improving the vehicles' vibration isolation performances in low-frequency excitation by adjusting the stiffness and damping of suspension simultaneously. Methods By using the designed acceleration-driven-stiffness fuzzy control strategy (ADSFC) and Skyhook based fuzzy control strategy (SHFC), the internal pressure of air spring and the current of magnetorheological damper are controlled separately to realize the adjustment of stiffness and damping. Results The simulation results show that, the performance of the proposed control strategies are better than the passive suspension in up-step excitation and random road excitation. In particular, by using ADS-SHFC, the peak values of the sprung mass acceleration, the suspension dynamic deflection and the tire dynamic deflection are reduced by 59.4%, 48.3% and 59.4% respectively comparing with the passive suspension. Conclusion The proposed control strategies are different from the conventional control methodsthat only controls the damping, this study is one of the first attempts to enhance thelow-frequency vibration isolation by changing the stiffness using control strategies. The simulation results verify the effectiveness of the proposed control strategies to improve the vibration isolation performance under low-frequency excitation.