Research On Land Vehicle's Ride Comfort Based On Suspension Control

Ride comfort is one of vehicle's major features and a key subject area in vehicle's riding dynamics. On one hand, road roughness is the main excitation of vehicle vibration, which affects vehicle's ride comfort; on the other, vehicle's suspension control restrains vehicle vibration and thus improves ride comfort. This thesis studies vehicle's ride comfort and vehicle suspension control.Firstly, this thesis studies road roughness model in frequency domain and time domain. Through harmonic superposition and AR model, two time domain road models are developed. Based on this model, a single track road excitation model is developed. This road excitation model is the basis of vehicle vibration studies.Secondly, in order to study vibration's effect upon ride comfort, vehicle's dynamics are analyzed and a four degree-of-freedom's one half vehicle model developed. Using the vibration model along with road excitation model, a vehicle system ride comfort analysis model is derived. Based on this model, the vehicle ride comfort simulation platform is constructed. Simulation of vehicle vibration caused by road excitation under two conditions are carried out and the results are analyzed.Thirdly, this thesis studies vehicle's semi active suspension and active suspension system's control. This part is carried out on a one fourth vehicle simplified model. For semi active suspension, a sliding model controller is designed and refined by RBF network. For active suspension, a LQG controller is designed and the thesis uses analytic hierarchy process (AHP) to determine the weights in the performance measure. Both semi active suspension and active suspension controller are simulated.