Modeling Combined Braking and Cornering Forces Based on Pure Slip Measurements 2012-01-1924
A novel predictable tire model has been proposed for combined braking and cornering forces, which is based on only a few pure baking and pure cornering tests. It avoids elaborate testing of all kinds of combinations of braking and side forces, which are always expensive and time consuming. It is especially important for truck or other large size tires due to the capability constraints of tire testing facilities for combined shear forces tests.
In this paper, the predictive model is based on the concept of slip circle and state stiffness method. The slip circle concept has been used in the COMBINATOR model to obtain the magnitude of the resultant force under combined slip conditions; however the direction assumption used in the COMBINATOR is not suitable for anisotropic tire slip stiffness. The state stiffness method, by which the variation of resultant force direction caused by anisotropy of tire slip stiffness can be described well and then the longitudinal and lateral forces under combined situations can be obtained separately. In addition, the friction ellipse is introduced in state stiffness method to express the anisotropic friction coefficients.
The UniTire pure slip model is introduced firstly in this paper, and then the slip circle concept and state stiffness method are discussed. Finally, the UniTire prediction tire model for combined braking and cornering forces is proposed and the effectiveness of the model is validated by the comparison with the experimental data.