Hierarchical fuzzy control for engine isolation via magnetorheological fluid mounts

摘要

An engine isolation system via tuneable damping mounts can contribute to enhanced automobile performance. In this study, a magnetorheological fluids (MRF) mount in squeeze mode for engine isolation is proposed and its damping characteristics are analysed. Based on an engine isolation dynamic model with three degrees of freedom, a hierarchical fuzzy control (HFC) system is proposed to decrease the vertical vibration force and roll moment transmitted from an engine to a foundation. On the control level, a fuzzy controller is designed to isolate the engine vertical vibration. On the coordination level, fuzzy reasoning is adopted to realize a coordination strategy for tuning the damping of each MRF mount in order to minimize the transmitted torque. The simulation is developed in MATLAB, and the experimental isolation system for an actual engine is built in the laboratory. With wide excitation frequency inputs under different operation conditions, studies on different engine mount isolation systems are carried out. Simulation results indicate that MRF mounts using the HFC strategy have more advantages than passive elastomeric mounts or hydraulic mounts, especially in the low-frequency range. Laboratory results confirm that the engine HFC system via MRF mounts performs markedly better than the passive mount system. The absolute force transmissibility ratio and torque transmissibility ratio are reduced to lower than 0.3 in actual complex excitation, which is very significant for an improvement in noise, vibration, and harshness.