| Tire mechanical characteristics are the basis of vehicle dynamics. The tire characteristics under cornering have significant effects on the vehicle driving stability and safety. Currently, the Uni Tire model put forward by Professor Guo Konghui in China and the Formula Magic model proposed by Pacejka in Holland are extensively used in engineering project. On the one hand,the team led by Professor Guo Konghui has been devoted to the further research and improvement of the Uni Tire model. This article put forward a new way to describe the combined camber and cornering condition, discussing the mechanism of the lateral force and the aligning torque. On the other hand, Pacejka released the latest version of the Magic Formula Model in 2012.He considered that the aligning torque can now be obtained by multiplying the side force with the pneumatic trail and adding the usually small(except with camber) residual torque,Noting that thisreplacement is more logical. In order to verify the effect of the expression of the new Uni Tire model, this paper carried out a comparative study of the two models of combined camber and cornering condition.1. Simplified brush tire models under combined camber and cornering condition are established. Firstly, the paper introduces the tire coordinate system, the definition of model slip rate, and pure slip brushes simplified theoretical model. Secondly, this paper focuses on combined camber and cornering conditions of brush model, dividing slip angle into two cases such as ?(29)0 and ?(27)0 to study roll and slip theory model, analyzing the mechanism of lateral force and aligning moment in a new way, and introducing the concept of payload. At last, the paper researches the application of the theoretical model taking coefficient of kinetic friction into consideration, providing direct theoretical framework for Uni Tire semi-empirical model.2. Semi-empirical model of the Uni Tire model under combined camber and cornering condition is established. Firstly, the paper introduces the basic framework of Uni Tire. Secondly, guiding the semi-empirical model with simplified theoretical model, and qualitative analyzing some special phenomena in the test. Thirdly, this paper establishes the semi-empirical model under combined camber and cornering condition using with characteristics parameters of lateral curvature factor, cornering stiffness, coefficient of kinetic friction, initial lateral force, aligning arm and initial aligning torque. At last, the precision expression of this model is verified with a large number of experimental data.3. The PAC2012 model is introduced. Firstly, this section introduces the latest version of the Magic Formula- PAC2012 model released by Pacejka, including the model coordinate system, and model ideas. And the influence of the characteristic parameters of model is analyzed. Secondly, PAC2012 specific formula is given. At last, the expression of PAC2012 model under combined camber and cornering condition is analyzed.4. The comparison of Uni Tire and PAC2012 has been made. Firstly, this section carries out the comparison of the latest version of the Uni Tire model and PAC2012 tire model in modeling mechanism, physical meaning of parameters and recognition accuracy of the test data under the combined camber and cornering condition. Secondly, the analysis reveals that Uni Tire has a stronger theoretical foundation due to the former automatically satisfies with the high level boundary conditions in theory. At the same time, the physical meaning of the model parameters is clearer. Thirdly, in terms of identification accuracy, the Uni Tire model is superior to the PAC2012 model in both the lateral force and aligning torque. |
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