Modeling and parameter identification study of automotive MR dampers

Magnetorheological (MR) dampers are semi-active devices that take advantage of the controllable properties of MR fluids. The technology has been most utilized in vibration suppression applications: real-time semi-active controlled automotive chassis systems. Upon exposing the fluid in the control valve to magnetic fields of sufficient magnitude, the dampers generate an additional force. The force generated by such dampers is a complex function of the input velocity or displacement and the current (or magnetic flux), not to mention the fluid’s rheological properties and the solenoid’s performance; the device by design is multidisciplinary. Therefore, developing an accurate and capable MR damper model has been proved to be a challenge. In the paper, the authors present the results of a parameter identification study based on a modified Bouc-Wen model of damper hysteresis applied to three distinct MR damper configurations with realistic force envelopes and tuning range. The obtained results show that the updated model copies the complex relationships of the damper force against the displacement, velocity, and current very well regardless of the input displacement (velocity) frequency or the current magnitude. The comparison is revealed for all three tested damper units in the form of force-displacement, force-velocity loops, respectively, or static force-velocity plots. The study is complemented using the developed HiL (Hardware-in-the-Loop) control system in order to demonstrate the proposed model application for control system studies in a vehicle suspension.