Research On Dynamics And Control Of Hydro-pneumatic Suspension System With Vehicle-road Environment Adaptability

With the continuous development of hydro pneumatic suspension technology,hydro pneumatic suspension is widely used in off-road vehicles,heavy mining vehicles,tanks and other special vehicles.The hydro pneumatic suspension has the characteristics of non-linear and increasing stiffness.Its reasonable design can achieve good buffer effect on the rolling road,improve the driving performance of the vehicle,and effectively protect the road surface.Firstly,taking the two-stage pressure type hydro pneumatic suspension as the research object,the composition and working principle of the two-stage pressure type hydro pneumatic suspension are analyzed in detail,and the relationship between the elastic force and displacement,damping force and speed of the two-stage pressure type hydro pneumatic spring is deduced through the relevant theory,and then the change rule of the main parameters'influence on its performance is obtained by changing the key parameters.Then,according to the performance of the two-stage pressure hydro pneumatic spring and the vehicle dynamics theory,the nine degree of freedom hydro pneumatic suspension system model and the four-wheel road environment input model of the whole vehicle are established.At the same time,the factors such as vehicle,seat and people are considered,and the motion equation is derived.The nine degree of freedom model of the whole vehicle is established,which reflects the vertical direction,pitch,roll and other changes of the vehicle.The absorbed power of the human body is deduced by the formula,and the comprehensive evaluation of ride performance is increased.According to PID control theory,variable universe fuzzy control theory and fractional calculus principle,this paper designs PID controller,fuzzy adaptive PID controller,Fuzzy Adaptive Fractional Order PI~?D~?controller,Variable Universe Fuzzy Adaptive Fractional Order PI~?D~?controller,and establishes the simulation model of active control nonlinear hydro pneumatic suspension system.Finally,under the condition of level C and level D uneven road surface input,the active control analysis of the system's no-load,full load,two-stage pressure hydro pneumatic suspension state and single air chamber hydro pneumatic suspension state is carried out,and the four-wheel suspension's dynamic deflection and load,the vertical acceleration of the body,the human body and the seat,the body pitch angle acceleration,the vehicle body's vertical acceleration are obtained by using MATLAB/Simulink software Simulation results of body roll acceleration,body absorbed power,suspension breakdown probability,etc.The simulation results show that the two-stage pressure hydro pneumatic suspension is superior to the single chamber hydro pneumatic suspension in vehicle ride comfort.The controller designed in this paper can not only effectively realize the active control of the nonlinear hydro pneumatic suspension,but also improve the ride comfort and handling stability of the vehicle.The variable universe fuzzy adaptive fractional order PI~?D~?controller has the best effect.