Magnetorheological Damper Model Is Compared With The Control Study

The intelligent vehicle suspension design applying the magneto-rheological fluids damper (MRD) has become one of international forefront subjects. The damping force of MRD shows heavy hysteresis and saturation nonlinearities and has strong dependences on both applied direct magnetic field and exciting frequency and magnitude, it is thus a challenge task to accurately model characteristics of MRD and synthesis a hybrid semi-active controller to meet the multi-objective performances of vehicle suspension and compensate the hysteresis nonlinearity.The dissertation focuses on reviewing the proposed different hysteretic damping force versus velocity models of the MRD, and further proposes a generalized model which decouples the current control dependence on magnetic field and the hysteron dependence on exciting nature and is easy to derive the inverse model. The proposed current control gain with Sigmoid function is employed to modify the proposed Nonlinear hysteresis bi-viscous model, Phenomenal hysteresis model, S hysteresis model and Generalized hysteresis model, and identify parameters of these models on basis of the measuring data of a candidate MRD. Furthermore, the operation properties of these modified models are systematically compared by combining these models with the quarter-vehicle dynamic model and the classic "Skyhook" control policy, under harmonic, rounded pulse and random road excitations. The results show that these modified models can accurately describe the current control property and better match the measured data, under different drive currents and excitations.A new inverse model based hybrid semi-active controller is further developed, by employing the proposed generalized hysteresis model and the modified "on-off" damping law, as well as the control algorithm for generating asymmetric damping property from the symmetric damping MRD design. The controller is integrated with generalized hysteresis model and the quarter-vehicle dynamic model, so as to systematically evaluate the controller robust and suspension performances under varying vehicle operation speed and load, and varying road surface excitation, the results show that the proposed inverse model based hybrid semi-active controller has enhanced robustness on vehicle operating uncertainties, and can better suppress the hysteresis and switching transient effects of the MRD. The dissertation study plays an important role in improving the MRD intelligent vehicle suspension design to realize the multi-objective suspension performances such as oscillation suppression, vibration isolation, suspension space, road-holding, etc..