Dynamic modeling and adjustable damping layered control of air suspension hybrid system

Abstract

ABSTRACT Due to the coupling of continuous variables and discrete events, the vehicle height adjustment and damping force control system of air suspension can be described as a typical hybrid system, which poses theoretical challenges for researchers in recent years. Therefore, this paper focuses on the modelling and control of the air suspension hybrid system, realising the coordination control between the solenoid valve on-off status and the magneto-rheological damper current. A highly nonlinear hybrid dynamical mechanism model of vehicle height and damping force adjustment is established to describe the continuous dynamic behaviour and the discrete events of air suspension. Based on some assumptions and piecewise linear approximation for nonlinear components of air suspension, the mixed logical dynamical model compiled by the hybrid systems description language is constructed by introducing the auxiliary logical variables and the continuous logical variables. Using this model, a novel layered control strategy is designed and the efficient is verified by test results.The simulation results show that the proposed control method can not only adjust the vehicle height without switching the solenoid valve frequently,but also improve the ride comfort without deteriorating the handling stability, which leads to the closed-loop system with a favourable dynamical property.