| With the development of automobile industry and highway construction in China, increasing the vehicle comfort, handling stability and road holding ability at high speed become one of key problems of China automobile industry. The commercial vehicle with ECAS (electroni-controlled air suspension) has better performance in ride comfort, road holding ability, handling stability, and road prolension from damaging than those with leaf spring suspension. So it has great significance to study the control of air suspension. The paper aimed at air suspension and researched on system control and air spring air inflation /deflation characters.Firstly,three performance evaluation indicators of air suspension were introduced,and then a random road input model and 1/4 vehicle model with two freedom degrees were developed by Newton. Which made the base for air suspension system developmenet.Secondly,air spring air inflation and deflation characters were analyzed,and then the relation curves were obtained between stiffness,height of air spring and on/off time of electro-magnetic valve by test. The relation function between them were fit out. Which made the base for air suspension based on Fuzzy-PID control system.Thirdly,Fuzzy-PID controller was designed and the air suspension control system based on Fuzzy-PID control system was established, one performance indicator of air suspension-vertical vibration acceleration of quality-on-spring could be found loss through analysis to simulating model under control system, so vehicle ride-comfort was proved better under Fuzzy-PID control system.Lastly,air suspension passive test and imposed Fuzzy-PID control test were put respectively on the ECAS experimental stage. The test results show the control target-vertical vibration acceleration of quality-on-spring RMS had been decreased. the conclusion could be drew that Fuzzy-PID control tactic took on an excellent control effect. |
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