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Tire characteristics are the basis of vehicle dynamics. With the development and application of large-scale dynamics software, the tire models have been applied in varying degrees. Tire models are important component used to contact vehicle dynamics model and real vehicle test data, which play a crucial role in vehicle dynamics simulations. An accurate description of steady-state tire behaviors is the basis of vehicle dynamics simulations. Whether the tire models are practical depends on the following:how identification accuracy is, can or not be fitted to test data for all slip conditions, whether parameters are easy to be determined, whether the model has some predication capability. Parameters for tire model have an important role in describing tire characteristics. How to identify precise model parameters has a crucial role in the accurate usage of tire models.Pacejka89, Pacejka94, MF_tyre and UniTire models are fitted test data to determine parameters. The research on parameters identification for Fiala, UA and HSRI tire models is absent. In addition, the research on identification accuracy about steady-state tire models is relatively insufficient.In view of this, Pacejka89, Pacejka94, MF_tyre, UniTire, Fiala, UA and HSRI tire models are fitted, based on Excel Solver, to the same test data at pure and combined slip conditions to identify model parameters and evaluate the merits of each model by analyzing the fitting accuracy. This article main content is as follows:(1) The research on steady-state tire models at pure and combined slip conditionsSome common tire coordinate systems were described briefly and common steady-state tire models, such as Pacejka89, Pacejka94, MF_tyre, UniTire, Fiala, UA and HSRI, were summarized. The solution function of longitudinal force, lateral force and aligning torque at pure slip condition and combined slip condition were respectively described, which provided the theory foundation for the application of steady-state tire models.(2) Parameters identification for steady-state tire models at pure slip conditionThrough the analysis of Pacejka89, Pacejka94, MF_tyre, UniTire, Fiala, UA and HSRI tire models at pure slip condition, the model’s parameters identification scheme, decision variables and constraints were determined. Solving tables of longitudinal force, lateral force and aligning torque were established. Then Pacejka89, Pacejka94, MF_tyre, UniTire, Fiala, UA and HSRI tire models were fitted, based on Excel Solver, to the same test data at pure slip conditions and 246 model parameters were totally identified.The overall identification accuracy of longitudinal force, lateral force and aligning torque were analyzed and the results of 246 model parameters were given out.Because the identification accuracy of Pacejka89 and Pacejka94 had certain dependence on initial values for parameters, a new method was put forward to determine the initial values for peak and stiffness parameters.In addition, UniTire model adopted two solution methods of friction coefficient to analyze the influence of the two methods on identification accuracy for UniTire at pure slip condition.(3) Parameters identification for steady-state tire models at combined slip conditionBy analyzing Pacejka89, Pacejka94, MF_tyre, UniTire, Fiala, UA and the HSRI tire model at combined slip condition, the model parameters identification scheme, objective function and constraints were determined. The solving tables of longitudinal force, lateral force and intermediate variables were described in detail.Pacejka89, Pacejka94, MF_tyre, UniTire, Fiala, UA and HSRI tire models were fitted, based on Excel Solver, to the same test data at combined slip condition and 78 model parameters of combined slip condition were totally identified. The overall identification accuracy of longitudinal and lateral force was analyzed and the results of 78 model parameters were given out.In addition, UniTire model adopted two solution methods of friction coefficient to analyze the influence of the two methods on identification accuracy for UniTire at combined slip condition.
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