Research On Driveability Evaluation And Simulation Method

With the improvement of people’s living standards,consumers not only think of the car as a means of transport,but pay more attention to driving pleasure in the driving process.Driveability reflects the transient quality in the longitudinal dynamics of the vehicle,from the driver’s perspective,it reflects the comprehensive subjective feeling for comfort and controllability in the longitudinal driving process.Good driveability is able to adapt to consumers with different driving styles,and conducive to improving vehicle brand effect.Due to foreign-related technology confidentiality about the driveability research,there are few published literatures that elaborate on driveability evaluation method and process in detail,as well as domestic driveability research started late,resulting in that the driveability evaluation method is still in its infancy.At present,domestic automobile manufacturers still learn foreign development experience,and have not yet formed a unified method and standard.In addition,the domestic still utilize the subjective evaluation method to assess vehicle driveability.As the subjective evaluation method can only rely on the real automotive field test,and depend on the accumulated experience of the engineers in the long-term development process,it is not conducive to enterprises to improve the development efficiency of automotive products.And the real vehicle subjective evaluation method can only be applied to the last tuning period of automotive development,the room for improvement is limited.If the automotive products have some significant problems,it will result in that the final automotive products don’t have enough market competitiveness.Therefore,the domestic and international scholars have been exploring a use of computer simulation technology to implement driveability subjective evaluation to solve these problems.Aiming at the above requirements,the thesis attempts to establish a kind of driveability evaluation method to implement subjective evaluation so ahead of time to the early stage of automotive product development,which can be carried out under the computer simulation environment.The specific research contents are as follows:Firstly,the thesis analyzes the driveability subjective evaluation mechanism.In the open published literatures,the connotation of driveability subjective evaluation is not fully defined.Analyzing the connotation of domestic and foreign scholars and automotive manufacturers about driveability subjective evaluation systematically,the thesis proposes the understanding of driveability subjective evaluation.Summarizing the subjective evaluation items and evaluation phenomenon in worldwide,and communicating with subjective evaluation engineers,the thesis reclassifies subjective evaluation contents,mainly from five aspects to classify that comprise driving comfort,driving controllability,road-feel of driver,driver’s motion sense,sports style expectation deviation.Aiming at some evaluation phenomena,the thesis formulates the test programs,and doing research on the existing subjective scoring methods,formulates the scoring criteria.Secondly,the thesis studies the corresponding characteristic indexes of driveability subjective evaluation phenomena.Through the research group’s driving simulator and automotive dynamics model to carry out the subjective evaluation tests,collecting the corresponding physical quantity,and calculating the selected characteristic indexes that can be able to characterize the size of the evaluation phenomena preliminarly.By using variation coefficient and the related analysis method in statistics,and through the correlation analysis of variation coefficient between the subjective score of the evaluation phenomena and characteristic indexes,the validity of the indexes is verified.So as to prevent the occurrence of redundancy between the characteristic indexes,by calculating the relevance between different indexes,the characteristic indexes system is streamlined finally.Thirdly,in order to predict the subjective evaluation score based on the characteristic indexes,the mathematical model needs to be established between them.The thesis utilizes the multiple linear regression and neural network methods to establish the correlation model between the subjective evaluation score and the characteristic indexes.Then,the thesis determines the relative weight relationship among the levels of driveabiltity subjective evaluation system by fuzzy analytic hierarchy process.The prediction accuracy of the correlation model established by the two methods is compared and analyzed among the various levels.The results show that the prediction accuracy of neural network correlation model is better than that of multiple linear regression correlation model,and through the above model,based on characteristic indexes,it is able to estimate the overall score of driveability subjective evaluation with relative accuracy.Finally,the thesis analyzes the sensitivity of the characteristic indexes about the subjective evaluation results by DOE,which can provide the guidance direction for the optimization of the vehicle transient quality.Finally,the evaluation model of driveability subjective evaluation under the computer simulation environment is constructed by using professional isight optimization analysis software.Based on the configuration parameters of the vehichle,in order to improve the subjective score,the thesis analyzes the sensitivity of chasis design parameters and optimizes the value of chasis design parameters.In this thesis,the vehicle dynamic model simulation,the characteristic indexes calculation program,and the driveability subjective evaluation prediction model are integrated as the driveability evaluation model to conduct the dirveability subjective evaluation method under the computer simulation environment,and the chassis design paremeters are optimized and improved.Finally,the validity of the dirveability eavaluation and simulation method proposed in the thesis is verified.