Modeling And Simulation Research On Electric Vehicle Chassis System Based On Coordinated Control

With the rapid development of the automobile industry，vehicle chassis system hasbeen supported by the electronic servo which is increasingly complicated. The distributedcontrol of the chassis’ subsystem can’t fulfill our requirement of vehicle’s performance.The integrated control of vehicle chassis has been generally analyzed in the department ofchassis control system. Basis on the conventional vehicle chassis system, the integratedcontrol of electric vehicle utilize the lumped control method to deal with dynamicscoupling chassis, to coordinate the conflict between subsystems, and finally to improve thecombination property of the vehicle.The article was based on the vehicle system dynamics, conceding the coupling of thesubsystem of vehicle’s regenerative braking during the curve for the purpose of analyzingelectric power steering (EPS) system, active suspension system and electric-pneumaticblend braking system. The mathematical model of EPS system which considers tires’influence, lumped ASS system, hub motors and ABS system were established by Newton’slaws of mechanics, and sub controllers were designed for each subsystem. Considering thecoordinating between horizontal and vertical dynamics during the curve, lumped controllerwere designed for EPS system and ASS system. The lumped controller can improve theperformance of each subsystem by lumped global optimization. Based on centralizedcontrol and hierarchical control, cooperative control method of vehicle chassis system wasinvoked after analyzed the coordination between the mentioned three systems. This meansa cooperative controller was designed to manage all of the lower systems, which wereconstituted with subsystem of any structure. The cooperative controller was designed tocooperate with electro-hydraulic blend brake controller, anti-lock brake controller andEPS+ASS lump controller. The steady-state value of the motion state was calculated andthe compensation or amend orders were send to the corresponding lower controller whenthe horizontal and vertical dynamics were coordinating, finally to improve the stability ofelectric-pneumatic blend braking system.The thesis established the simulation model of the electric vehicle chassis controlsystem by amounts of simulating analysis based on MATLAB/Simulink. The results showthat the EPS system which considers tires’ influence can recognize the change of force ontire caused by vehicle attitude, accordingly influence the resistance and the output momentof resistance of the steering system. Compared with passive suspension, the activesuspension with the linear quadratic regulator control method can reach a better performance which shows the designed active suspension controller works well. Theelectric-pneumatic blend braking system can effectively recycle braking energy, and at thesame time can effectively prevent the wheel lock and ensure brake performance. EPSsystem and ASS system lumped controller with linear quadratic Gaussian control theorycan effectively filter the noise of the sensor and has a great engineering value. The lumpedcontrol method can improve the stability and bodywork attitude of the vehicle. Thecooperative control method can coordinate the coupling between subsystems, reduce theconflict between systems and can improve the control stability and braking efficiency.