Vehicle handling performance analysis: a new approach to optimization of Magic Formula tyre model parameters

摘要

In the context of passenger car design, it is essential to be able to determine, through simulation, the values of the different parameters of the vehicle subsystems which help to fit the desired vehicle handling performance. This allows a limitation of the number of vehicle track trials. For objective vehicle handling evaluation, performance indicators are usually determined according to a number of well defined manoeuvres Then the defined vehicle parameter values can be validated by taking a subjective aspect into account. This paper focuses on the optimization of tyre properties in pure cornering conditions. For a given car, this requires the optimization of the parameters of the considered tyre model in simulation. Therefore, a Simplex-based optimization algorithm was developed to optimize the parameters of a standard tyre model: the Magic Formula 5.2 tyre model. It was real-coded in Matlab/Simulink, so that it could be linked to most vehicle dynamics simulation tools in a global optimization process. It was validated in comparison with a standard optimization technique dedicated to the identification of MF tyre models (Levenberg-Marquardt/MF-Tool), from a standard indoor tyre measurement procedure (TIME). Secondly, it was used to optimize MF 5.2 tyre model parameters according to vehicle handling performance indicators which were defined according to a standard steady-state circular test. The principle of the complete optimization process, the Simplex algorithm developed, its validation and first results of its application are presented here.