Identification of a magnetorheological damper for semi-active vibration control

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 successful implementation of semi-active vibration attenuation. The paper deals with the problem of a model building for MR damper relating damping force with piston velocity and supplied voltage. This is not a trivial task as the MR damper reveals highly nonlinear, bi-viscous and hysteretic behaviour. Furthermore, the model has to be suitable for synthesis of a control algorithm. This means that using the reverse model it should be possible to calculate the input voltage for the set damping force. The so-called black box modelling has been proposed with relative structural simplicity comparing with phenomenological models. The model structure is not based on physical description of the MR damper but on the functional input-output relation that makes digital controller implementation feasible. This nonlinear model is based on a heuristic approach and it is convenient for application in semi-active suspension system. Parameters of the model were adopted for data obtained during a specially designed experiment performed for the automotive MR damper used in the experimental all-terrain-vehicle.