Research On Vehicle Active Roll Sliding Mode Control Based On Active Suspension

With the rapid growth of infrastructure and improve the car ownership,vehicle road accidents continue to rise,especially prone to rollover phenomenon of low vehicle roll stability curve at middle and high speed.As an important part of automobile driving system,the performance of suspension system directly affect the roll stability of the vehicle,and the active suspension can according to road conditions and vehicle driving state real-time control,this can not only improve vehicle ride comfort and increase comfort,but also can enhance the lateral stability,increase the safety of vehicle operation.Therefore,active roll control based on active suspension has important theoretical significance and application value.In this paper,when the vehicle is turning,the active suspension control of the vehicle actively tilt to the inside of the turn,making gravity torque generated by the centrifugal force of the torque is reduced or offset,so that the lateral acceleration decreases and vertical load transfer is reduced,which not only improve the vehicle roll stability and ride comfort,but also improves the vehicle curve passing speed and prevent rollover phenomenon.This paper provides a theoretical and methodological guidance for the preliminary research on the active roll based on active suspension.Mainly completed the following aspects of work:(1)A vehicle active roll model with six degrees of freedom based on active suspension is established.The model consists of two degree of freedom steering model and the vehicle roll model with four degrees of freedom.The relationship between the active suspension control model and the vehicle roll characteristics is analyzed,and the desired angle is obtained by theoretical derivation,which is as the target value of the vehicle to roll in turn.Then,sliding mode controller is established in order to realize the control of active suspension system.The simulation results show that the vehicle active inward tilt,which reduces the lateral acceleration of occupant perception and the vertical load transfer,reducing the lateral load transfer rate,and improving handling stability and the vehicle rollover ability.In addition,the active suspension control improves the ride comfort of vehicle.(2)An observer based actively roll sliding mode controller for the vehicle is established.In the actual vehicle,the vehicle lateral velocity is not easy to measure,and the vehicle body roll angle is not accurate due to the slow response of the roll angle sensor.So it is necessary to estimate the vehicle lateral velocity and body roll angle by the observer.This paper designs a reduced dimension observer and solves the state feedback gain matrix.A sliding mode observer is designed based on the reduced order observer design.It overcomes the limitation that the general observeris influenced by external disturbance.The simulation results show that the sliding mode observer can accurately estimate the lateral velocity and the roll angle and sliding mode control based observer compared to passive suspension and lateral acceleration,side-slip and yaw rate are significantly reduced,effectively improve the vehicle rolling stability and running safety,and improve ride comfort.(3)Research on joint simulation of sliding mode control for active roll vehicle based on Car Sim&Matlab/Simulink,the multi-body dynamics model will be established in Car Sim closing to the actual vehicle instead of Simulink in the mathematical model.It is a simulation of vehicles in actual operation conditions and the simulation results are consistent with the mathematical simulation.