Research On Vehicle Body Stability And Ride Comfort Of Hydraulic Active Suspension

As land rescue equipment,emergency rescue vehicles often drive on uneven and unstructured roads.The traditional passive suspension can not meet the requirements of mobility,ride comfort,safety and handling stability of emergency rescue vehicles.The active suspension system can adjust the suspension attitude and reduce the vibration amplitude through the real-time control of the controller,which can significantly improve the ride comfort,trafficability and handling stability of the emergency rescue vehicle.Combined with the national key R&D project "Research on Key Technologies of Chassis and suspension for high-mobility emergency rescue vehicles(including firefighting vehicles)"(project number: 2016FYC0802902),this paper studies the control method of nonlinear vehicle hydraulic active suspension,considering the nonlinear characteristics of stiffness and damping in suspension system and vehicle body motion coupling factors,aiming at improving vehicle body stability and ride comfort.The main work of the paper is as follows:(1)The model of hydraulic active suspension system is established.Aiming at the twoaxle prototype vehicle,the nonlinear two degree of freedom and seven degree of freedom suspension system dynamics models are established.In order to study the control algorithm of electro-hydraulic servo control and active suspension,the valve controlled asymmetric cylinder model of hydraulic actuator and the four-wheel road input model are established respectively.(2)The linear feedback controller of active suspension system is designed.In order to solve the control torque of heave,pitch and roll motion,the dynamic equation is generalized as a second-order nonlinear system,and linear feedback controllers are designed respectively.The extended state observer is used to estimate the coupling factors of road disturbance and motion torque in the second-order system,and the feedback variables of the controller are obtained.The parameters of the controller are adjusted by genetic algorithm to meet the suspension travel constraints and tire grounding constraints.After decoupling the control torque,the vehicle state is adjusted by the electro-hydraulic servo controller of each actuator.(3)The physical model of simscape is built and the simulation analysis of hydraulic active suspension control is carried out.The consistency between the simulation results of Simscape and the state-space model is compared.The force tracking performance of the electro-hydraulic servo control is verified in the simscape model,and the linear feedback control simulation of the vehicle active suspension system is carried out.The results show that the optimized controller can improve the performance of the hydraulic active suspension system under the given constraint conditions,and make the vehicle have a good performance on body stability and ride comfort.(4)Two-axle prototype vehicle test is carried out.The parameters of the electric control system are adjusted and calibrated,and the VB program of the upper computer is designed.The double side bridge is used as the experimental road.The results show that,compared with the passive suspension,the linear feedback control hydraulic active suspension reduces22.69%、24.23% and 18.84% in the RMS vertical acceleration of the center of mass,the acceleration of the pitch angle and the acceleration of the roll angle respectively,and the RMS value and the peak stability value of the pitch angle and the roll angle are significantly reduced.