Automotive MR damper modeling for semi-active vibration control

The magnetorheological (MR) damper is a semi-active device in which varying electric current flow in coils mounted in the piston leads to changes of its dynamical properties. Development of an accurate mathematical model of the MR damper plays a key role in a successful implementation of semi-active vibration attenuation. This paper concerns with the problem of building a model of the MR damper used in a vehicle suspension. This is not a trivial task as the MR damper reveals highly nonlinear, bi-viscous and hysteretic behavior. Furthermore, the model has to be suitable for synthesis of a control algorithm. This means that using the inverse model it should be possible to calculate the input current for a given damping force. The so-called black-box modeling has been proposed with the relative structural simplicity comparing with the phenomenological models. The model structure is not based on a physical description of the MR damper but on the input-output relation that makes the digital controller implementation feasible. This nonlinear model is based on a heuristic approach and is convenient for application in a semi-active suspension system. Parameters of the model were adapted for data obtained during a specially designed experiment performed for the automotive MR damper mounted in the experimental vehicle.