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A new vehicle suspension control system that enhances vehicle stability and handling in fast evasive maneuvers performed close to the limit of adhesion is evaluated. The central idea is to use continuously variable magneto-rheological (MR) dampers to distribute the damping forces between front and rear axles in order to bring the vehicle yaw rate as close as possible to the desired yaw rate. This mitigates the vehicle oversteer or understeer tendencies during quick transient maneuvers. The basic principle of system operation is explained using known dynamic properties of MR dampers, vehicles and tires. The available control authority and the effect of MR damper settings on vehicle yaw response is then evaluated using computer simulations. The results of vehicle tests are presented. They demonstrate the benefits of the proposed control method in terms of improved vehicle response and reduced driver steering effort.

In this paper a simple yet insightful model to predict vehicle propensity to rollover is proposed, which includes the effects of suspension and tire compliance. The model uses only a few parameters, usually known at the design stage. The lateral accelerations at the rollover threshold predicted by the model are compared to the results of simulations, in which vehicles with the same static stability factor, but different suspension characteristics and payloads are subjected to roll-inducing handling maneuvers. The results of simulations correlate well with the predictions based on the proposed model. Design recommendations for passive suspensions, which would increase rollover stability are discussed.