Reasearh On Isolation Performance Of The Dualchamber Hydro-pneumatic Suspenison

Handling stability and ride comfort are two important indicators of modern vehicles,and the design and optimization of the suspension system is the key way of improving these indicators.The adaptive suspension have the ability of adjusting its own stiffness and damping coefficient according to the excitation frequency from road profile.The paper proposed a dual-chamber hydro-pneumatic suspension,a modified version of the traditional hydro-pneumatic suspension,can provide enhanced suspension performance.According to the working principle of the adaptive suspension,a certain number of springs and dampers are combined into a mechanical network with the specific series-parallel logic.The performances of the passive and intelligent version of the dual-chamber hydro-pneumatic suspension are discussed deeply and in detail.The systematic structure and working principle of the dual-chamber hydropneumatic suspension were introduced,and the mathematical model is established based on the polytropic equation of state and the fluid dynamics theory.We use two very different theories,nonlinear vibration theory and fractional calculus theory,to analyze the characteristics of a dual-chamber hydro-pneumatic suspension.We find that both the storage stiffness and damping coefficient show a strong dependency on the excitation frequency.The effect of various suspension parameters on storage stiffness and damping coefficient are discussed in detail using numerical simulation.We also performed experiments that confirm the validity of the mathematical expressions for both the storage stiffness and the damping coefficient.The multiobjectives optimization problems of the traditional passive suspension and the passive dual-chamber hydro-pneumatic suspension are solved by genetic algorithm.Furtherly,qualitative analyses are carried out according to the Pareto solution.The effect on control strategies of intelligent suspension of the road excitation level classification is discussed in detail as well as the adjustment strategy that should be followed.The method is proposed to classify road excitation levels based on the vibration responses of the suspension system.Measurement signals is deal with wavelet packet and empirical mode decomposition(EMD)in order,then improved distance evaluation technique(IDET)helps to select effective features in amplitude domain,the result acts as training set of road classifier based on the support vector machine(SVM).The classify result of weights of optimization objectives.To keep high level of ride comfort and handling stability in various road conditions,three different suspension control algorithm,optimal control,an integral sliding mode control based on the back-stepping technique and skyhook stiffness ON-OFF control,for the intelligent dual-chamber hydro-pneumatic suspension are developed in this research.The control law of the actuator force of those control strategies are derived based on the lyapunov stability theory.The closed loop stability and asymptotic convergence performance of the controller have been proved.The control effect in improving suspension performance have been experimentally confirmed on a quartercar test rig.