Oscillation Suppression Control Of Air Spring Active Suspension

With the increasing demand for people’s travel,the automobile industry has been developed rapidly,and the performance requirements of vehicles have been improved.Among the many structures of the vehicle,suspension is one of the systems that plays a decisive role in the handling stability and comfort of the vehicle Because air spring suspension can significantly improve the performance of the vehicle,adapt to various working conditions during driving,and has the advantages of low noise,light weight,and adjustable stiffness,it has gradually replaced the position of traditional leaf spring suspension.Aiming at the influence of air suspension on vehicle performance,this article mainly studies the charging and discharging control of air suspension:In the beginning,the categories of suspension systems,relevant technologies of air spring modeling and current research status of suspension control at home and abroad are introduced based on the foundation of reading numerous literatures.Also the purpose and structures of this article are explained briefly.Secondly,for the purpose of studying air springs the structures of air spring are described.Based on the principles of thermodynamics an air spring model has been established and the stiffness and frequency characteristics are explored from theoretical.The model of 2-freedom quarter-vehicle active air suspension is derived also the related solenoid valve model is introduced according Newtonian mechanics and hydromechanics.Based on national standards the random road model to simulate various road conditions.For air charge-discharge control,the PWM modulation method is introduced.The source of air spring oscillation is analyzed,and the evaluation index of suspension system performance is put forward.Then,introduced fuzzy and PID control principles.In order to reduce the vibration in the process of vehicle height adjustment the Fuzzy-PID controller is designed for the aim of control the gas quality inside the air spring while using fuzzy control to adjust the PID parameters in real time.The Matlab/Simulink platform is used to build a model for simulation,and the traditional PID is used as a control to prove the effectiveness of the Fuzzy-PID controller.Finally,after introducing sliding mode control theory with the purpose of improve riding comfort of the vehicle on randomly road a Fuzzy-SMC controller has been derived.During the controller the fuzzy is to reduce chattering.The effectiveness of Fuzzy-SMC controller is verified by simulation using Matlab/Simulink.The research results prove that the air spring active suspension have distinctly superiority in enhance vehicle riding comfort and it also increasing vehicle handing ability.The accuracy of vehicle height adjustment can be improved by the designed Fuzzy-PID controller.And the spring-mass vertical acceleration,the vertical displacement of suspension and the dynamic load of tire can be effectively improved by the Fuzzy-PID controller.