Study On Optimization Of Vehicle Minimum Time Handling And Stability

According to relevant investigations,overspeed is the second major cause of accidents following the puncture in highway traffic accidents.The probability of traffic accidents in vehicles increases as the driving speed increases.Vehicle minimum time handling and stability that mainly reflect the steering stability performance of high-speed vehicles is closely related to the safety of high-speed vehicles.Increasing vehicle minimum time handling and stability will help to reduce the accident rate of high-speed vehicles,which has important practical significance.In this paper,the virtual simulation model of the whole vehicle was established in ADAMS/Car.The minimum time handling and stability of the vehicle model was evaluated by objective comprehensive evaluation index through a double lane change simulation experiment.Based on the response surface method,the vehicle minimum time handling and stability was further improved.During this process,the optimization design parameters were the stiffness and damping of the suspension system and the optimization goal was the comprehensive evaluation index of vehicle minimum time handling and stability.(1)The vehicle multi-body dynamics simulation model was assembled from six sub-models.According to the Mitsubishi Lancer vehicle parameters,the sub-models were built in the ADAMS/Car module.The sub-models include a double wishbone front suspension model,a multi-link rear suspension model,a steering system model,a powertrain model,a body model and tire models.The objective evaluation indexes of vehicle minimum time handling and stability and the threshold value and weighting value of the vehicle motion characteristic parameters required by this paper were expounded,which laid the foundation for the later optimization.(2)According to the double lane change vehicle test international standard ISO-3888,the simulation test was carried out in the simulation environment,and the minimum time handling and stability of the vehicle model was evaluated in combination with the objective evaluation indexes of vehicle minimum time handling and stability.By analyzing the influencing factors of the vehicle minimum time handling and stability,the spring stiffness and damper damping of the front and rear suspension were determined to optimization design variables.(3)Based on the response surface method,thirteen characteristic parameters such as the steering wheel angle velocity were used as the objective function.The front and rear suspension spring stiffness scaling factors,the front and rear suspension damper compression and the tensile stroke damping coefficient scale factor were used as design variables.According to the DOE table obtained by simulation,the response surface quadratic regression models of each objective function with respect to the design variables were established by the least squares method,and the models were evaluated for fitness.The values of the optimization design variables were obtained in Insight and verified in ADAMS/Car.The results before and after optimization showed that the driver's burden reduced by 10.27% after optimization;the evaluation index of vehicle rollover risk decreased by 11.92%;the slip risk evaluation index decreased by 19.1%;the tire grip ability evaluation index decreased by 17.57%;the minimum time handling and stability evaluation index decreased by 8.75%.In other words,vehicle minimum time handling and stability has been improved to some extent.(4)According to the 50 response surface design points data of the thirteen characteristic parameters obtained by the response surface method center composite design simulation test,the response surface design points data of the vehicle minimum time handling and stability comprehensive evaluation index was obtained.The second-order response surface model was obtained by the least squares parameter identification method.The optimal solution of the response surface model was obtained based on the quadratic programming method,and the vehicle time handling and stability was optimized.It could be seen from the simulation test results that the optimal design variables were obtained by the quadratic programming method,driver's burden further decreased by 7.17%;rollover risk further decreased by 7.718%;slip risk further decreased by 14.161%;the tire grip capacity further increased by 14.34%;the final value of the minimum time handling and stability evaluation index further decreased by 4.532%.Therefore,the vehicle minimum time handling and stability was further improved.