Research On Coupling And Control Of Active Suspension And Steering System Of Multi-axis Emergency Rescue Vehicle

Emergency rescue vehicles often encounter complex driving terrain during the rescue process.Active suspension is an effective way to improve vehicle ride comfort and handling stability.However,there is a complex coupling relationship between it and multi-axle steering systems.In order to improve the driving performance of multi-axis emergency rescue vehicles,the research on the coupling and control technology of active suspension and steering systems has important theoretical significance and practical application value.This research is based on national key R&D projects "Research on Key Technologies of Chassis and Suspension for High-mobility Emergency Rescue Vehicles(including fire-fighting vehicles)"(number: 2016FYC0802902),This paper analyzes and studies the coupling and control of active suspension and steering systems of multi-axle vehicles,and designs control strategies for vehicles traveling on complex roads to improve the handling stability of multi-axle vehicles.By establishing a linear two-degree-of-freedom maneuvering stability model for a three-axis emergency rescue vehicle,the minimum turning radius is calculated.The zero-center-of-centrifugation angle control theory is used to analyze steady-state and transient response characteristics of the three-axis vehicle steering system.Considering the nonlinear characteristics of tire,the expressions of vertical load,tire yaw angle,and tire lateral force are derived.A three-dimensional model of the single-axle suspension and steering system is established using ADAMS software,and the spatial coupling relationship between these systems is analyzed by kinematics.Based on the eleven-degree-of-freedom mathematical model of the three-axle vehicle suspension and steering coupling system,MATLAB/Simulink is used to analyze the dynamics of the coupling system.Aiming at the nine-degree-of-freedom mathematical model of the active suspension system,a robust controller for each active suspension actuator is designed.Based on the three-degree-of-freedom nonlinear model of steering system,a proportional feedforward and optimal feedback joint controller is designed.Based on the two types of controllers,the upper-layer coordination controller is designed and simulated.Based on the three-axis inertial control suspension system test platform,steering stability of the suspension and steering coupling system is studied.The test results show that compared with the oil-gas suspension mode,the active suspension and multi-axle steering system under coordinated control make the vehicle steer to the left(right),the rms value of the roll angle of vehicle body decreased by 26.31%(27.93%),and the rms value of the pitch angle of vehicle body decreased by 30.72%(23.76%),which effectively improved stability of body attitude,and make up for insufficient turning vectors caused by active suspension and improve handling stability of multi-axle vehicles.