Research On The Modeling And Dynamic Simulation Of The Air Suspension And Its Control System

When the dynamic is analysis for the vehicle used air suspension, generally, the airsprings is substitute by a series of linear air spring in the multi-body vehicle dynamics simulation model,so that it can't describe the impact of nonlinear parameters on vehicle dynamics, the accuracy of vehicle analysis inevitably is poor; on account of the problem that there is a complex "machine-electric-gas-liquid-control coupling" in air suspension system, the dynamic system has strong nonlinearity, external disturbances, time varying parameters and other factors, strongly nonlinear due to air suspension, establish an accurate mathematical model is not easy for control system, the conventional control algorithms application cannot meet the increasing performance requirements of suspension,so the air suspension development and vehicle dynamics is difficult. So the research on the dynamic model that can accurately and effectively reflect the characteristics of sir suspension has important theoretical significance and important practical value in Automotive Engineering.This work is supported by the National "863" High-Tech Development Project of China under the grant No.2003AA001031 and national natural science foundation of China under the grant No.60674067 and 60574053, and the Education Department of Hubei Province Research Project under the grant No D200634002,and Hubei Science and Technology Department Research Project under the grant No 2007AA101C14, and Wuhan Science and Technology Bureau Research Project under the grant No 200710321089, and by "industry- academia-research" cooperation, the low-floor city bus equipped with the independent exploitation air suspension is manufactured by Dongfeng Yangtze Bus (Wuhan) Co., Ltd, and the vehicle performance test is completed in National Automobile Quality Supervision Test Center. Based on the air suspension development, the air springs design theory and method, and the air suspension vehicle characteristics and experimental research are studied in the dissertation, The major work can be summarized as follows:Firstly, in order to provide a more precise air springs analysis model, based on fluid mechanics, thermodynamics and other theories, and the research about air spring at home and abroad, the coupling modular air springs numerical analysis model is presented by Matlab/Simulink, and its characteristics are detailedly discussed in the paper.Secondly, the stiffness and the dynamic characteristics of air spring are analyzed based on the Finite Element Theory, and the influences such as the various of Structural parameters and the contact of rubber and piston is discussed in the paper.Thirdly, in order to improve the performance of the air suspension, the Sliding Fuzzy adaptive Control for active control is proposed in this paper, the hardware-in-the-loop simulation of air suspension based on the dSPACE is designed to demonstrate the performance of the Sliding Fuzzy adaptive Control,the simulation and experimental results show the better performance and better robust and robust stability by adopting the proposed controllers.Finally, in order to analysis the performance of the air suspension, a accurate and effective simulation has been proposed based on ADAMS and Matlab software.the multi-body dynamics simulation model obtained the coupling modular air springs numerical analysis model, through the comparison between combined simulation results and test data under different, the mathematical model is proved to be more accurate and more effective by adopting the proposed air suspension dynamic model.