Electrorheology for Smart Automotive Suspensions

Abstract : The purpose of the work reported was to demonstrate the suitability of electrorheological (ER) technology for adaptive control of suspension forces on tracked and wheeled vehicles. The mechanical shear strength properties of ER fluids change in response to the application of an electric field. The change is very rapid and fully reversible. This property was used to create an automotive suspension damper whose resistive force is readily controlled by an external electrical signal. The device was applied in a semiactive suspension system for the Army's high mobility multipurpose wheeled vehicle (HMMWV). The work reported covers a range of development tasks including definition of the semiactive control algorithm, ER fluid formulation, design and fabrication of an ER damper, design of an electrical control circuit, creation of a quarter-HMMWV test stand for the simulation of ride vibrations, laboratory measurement of the ER-damped performance characteristics over a range of physically simulated operating conditions, and computer simulation of the quarter-HMMWV system. The research demonstrated that an ER damper and appropriate control circuits could out- perform the conventional hydraulic shock absorber, but that various complexities tend to impede broad application of electrorheology in automotive devices.