Study On Target Cascading Of Vehicle Handling And Stability Index

Automobile is a very complex system with a variety of performance you need toconsider. It consists of various assemblies and parts. This determines the main idea ofautomobile forward development should be that vehicle performance index is cascaded toassemblies and parts. The achievement of the targets for assemblies and parts ensuresvehicle performance. This process is implemented in the program evaluation stage offoreign V-shape automotive development process. Vehicle performance cascadingcontributes to the control of performance which helps to ensure that the design meets thetarget requirements. And it also facilitates synchronized development of assemblies andparts and improves the efficiency of development and design.But the ability of domestic enterprises in this process is relatively weak. And theyare still in the process of reverse development under the drive of market. Domesticbrands are long struggling to compete with foreign advanced automotive companies. Thedomestic car market has been dominated by joint venture brands. Therefore, vehicleperformance target cascading and assembly matching is not only a major challenge in theforward development process, but also an urgent problem for domestic enterprises. Giventhis purpose, vehicle performance index cascading is studied. And handling and stabilityindex is taken as an example. After investigation, foreign ATC is a theory that fits withthe process of vehicle performance cascaded to assembly characteristics required in earlystage of automobile development. It is suitable for modular-design product such asautomobile. This article focuses on two central issues:1. Analytical Target Cascadingtheory;2. Handling and stability index cascading.Firstly, study on ATC is launched to acquire its basic knowledge, including the basicprinciples, the general process, the mathematical expression and optimization strategies.And two classical mathematical examples are shown to tell how ATC works. The study lays a theoretical foundation for target decomposition. Classic optimization algorithmsand modern optimization algorithms are also presented as optimization theory.Then vehicle handling and stability index cascading is discussed with boththeoretical knowledge and DOE (Design of Experiment). The understeer gradient andbody roll gradient are chosen as target. Their impact factors are theoretically analyzed.The laboratory develops ASCL performance dynamics model. According to thetheoretical factors, the parameters of the2010edition are selected as the factors fororthogonal experiment, and other parameters may have an influence are added as well.ANOVA (Analysis of variance) is applied to distinguish the parameters that havesignificant impact on understeer gradient and body roll gradient. Based on the selectedparameters, ASCL vehicle optimization model is built. In this way, vehicle performanceindex is successfully cascaded to assembly characteristics.Structural parameters can be obtained by further decomposition of assemblycharacteristics. Therefore Adams Macpherson front suspension model is used as anexample. The suspension characteristics from vehicle performance index are the goals ofthis layer. Orthogonal test and ANOVA implemented show the factors which significantlyaffect suspension performance index. And the establishment of a suspension optimizationmodel enables suspension characteristics to be cascaded to structural parameters.However, the result shows that the optimization of the structural parameters may not beable to meet the suspension index cascaded from vehicle model.The top-down and bottom-up optimization strategy of ATC is used to solve thefailure in meeting suspension index. In order to accelerate the coordinating optimizationof vehicle model and suspension model, an examination method is used. Based the resultof every loop, parameters design space and search strategy of the two models are adjusted.The result in the third loop is fine. The vehicle design and the suspension design achieveconsistency, i.e. structural parameters of suspension match assembly characteristicscascaded from vehicle performance index.