Research On Suspension K&C Characteristics Optimization Including Handling Subjective And Objective Evaluation

With more and more HAD(Highly Automated Driving)systems applied to the vehicle,such as ACC and AEB,the controller of vehicle has changed from the driver only to the cooperation of driver and HAD systems.This requires designers can accurately evaluate the impact of HAD systems response on drivers’ subjective feelings during the design phase,so that the vehicle’s objective performance can be quantitatively designed according to consumers’ needs,to ensure that the vehicle has good safety and driving experience.The suspension K&C characteristics have a crucial influence on the handling.How to reasonably optimize the K&C characteristics based on the subjective and objective performance requirements in the virtual design stage is of great significance for realizing the positive development of vehicle.This requires the establishment of an objective evaluation model of handling that can accurately predict subjective performance,that is,the research on the consistency of handling subjective and objective evaluation.The reduction of objective indexes is one key problem,which will directly determine the final accuracy of the evaluation model.However,there are several shortcomings of the existing research on objective indexes reduction as follows: objective indexes chosen less related to the transient handling performance,objective indexes reduction more based on prior knowledge,which leads to miss some important indexes,the lack of detailed description of the correlation between the cross indexes and the subjective indexes and the impact of one test’s objective indexes on the subjective indexes of another test.In view of the above problems,this dissertation aims to establish a set of objective indexes considering the transient handling performance;explore an objective indexes reduction method including subjective performance;propose an objective indexes reconstruction method of handling based on the cross indexes;propose an index selection scheme to find the key indexes;establish a comprehensive objective evaluation model to optimize suspension K&C characteristics.The main contents and conclusions are shown as follows:1.The reduction of handling objective indexes including subjective performance.A set of objective indexes considering the transient handling performance is established.13 key objective indexes of three tests are selected based on Rough Set and correlation analysis.Compared with the reduction results of the ridge regression,the average accuracy of three evaluation models based on above key indexes is increased from 62% to 83%.2.The reconstruction of handling objective indexes.Three regression models between 13 key objective indexes and subjective indexes are established to led to the reconstruction method.10 reconstructed objective indexes are obtained.The result shows,the accuracies of three evaluation models based on the reconstructed objective indexes are all improved by above 12%(absolute difference).A comprehensive objective evaluation model of the handling is established based on the CWAA and multi-linear regression.The result shows,the accuracy of the above model can reach to 72%,demonstrating the model has high precision.3.The extraction of objective indexes and the establishment of handling objective evaluation model considering the interaction indexes.The interaction indexes of three handling tests are selected based on Rough Set.The result shows,the accuracies of three evaluation models including the interaction indexes can all be above 91%.A comprehensive objective evaluation model of handling including the interaction indexes is established,and its accuracy can reach to 90%,showing good consistency.The correlation between the objective indexes of three tests is studied.Under the guarantee of the required accuracy,the 14 key indexes including interaction indexes are simplified to 11,and after simplifying,a comprehensive objective evaluation model is established.The results show,the accuracy of the handling objective evaluation model based on the simplified indexes set can reach to 85%.Finally,the three comprehensive handling objective evaluation models are compared,and the evaluation model considering the interaction indexes which has the best accuracy is used to optimize the suspension K&C characteristics.4.The suspension K&C Characteristics Optimization including vehicle subjective and objective Performance.The suspension K&C characteristics are parameterized,and the optimization objectives are defined based on the comprehensive objective evaluation model of handling.The suspension K&C characteristics are optimized base on the Isight-CarSim-Matlab co-simulation model.The results show,the comprehensive subjective score of the handling can reach to 6.80,which is 13.33% higher than that before the optimization.