Coordinated Control Of Semi-Active Suspension And Anti-Lock Braking System Based On Magneto-Rheological Damper

In the braking process of vehicle, the dynamic load will created for the existing of braking deceleration,the vertical direction of vibration of the automobile suspension system will produce the Vertical dynamic load of tyres, which effects the normal force between ground and tire, and longitudinal pitching motion will cause the change of tire vertical load,which effect the control of the braking process and the adjust of ABS.Because of the existence of brake inertia, which makes the vehicle have longitudinal pitching motion and then effect and control of vehicle suspension system.In the braking process of vehicle, the above two systems interact and influence each other.In order to simplify the analysis, person usually makes the suspension system and the brake system be independent. Therefore,through the analysis of the coupling movement, this thesis established the module of coordinated control and the corresponding algorithm and the corresponding strategy between the braking system and suspension system. The research mainly includes the following aspects:Firstly established the mathematical model of ABS braking system, including the conventional brake model and Pacejka tire model which can reflect Tire nonlinear characteristics and tire rotation motion model and a single wheel braking model.Secondly, this thesis designed the bang-bang controller and PID controller and fuzzy-PID controller of ABS based on the above model.The results show that the braking system with fuzzy-PID controller can brake with least amount of time and the shortest distance compared with then model of conventional brake.Thirdly, this thesis analyzed the working model and the hysteresis characteristics of magneto-rheological damper, the state of art of the magneto-rheological damper, and compared the widely-used forward and inverse models of magneto-rheological damper. Then this thesis determined to take the commonly-used modified Bouc-Wen model, established and simulated its mechanics model, which lay the foundation for the follow-up study.it may cause some problems. Further using the Lagrangian method, this thesis established the two degree of freedom (DOF) quarter car mathematic model of the semi-active suspension, and discussed the mutual restriction relations among the main performance index for the vehicle suspension system.This thesis designed a PID controller and another fuzzy PID controller for suspension system, then completed a comparison with passive suspension. The simulation results show that, for the semi-active suspension system,and each performance index of PID control and fuzzy PID control has obvious increasing, and the effect of fuzzy PID controller is the best one among all the controllers.Finally, on the basis of the two subsystems separate control, this thesis established a relation model between these two subsystem models, and created a coordinated controller, which combine ABS controlled by fuzzy PID control with the magnetorheological semi-active suspension based on fuzzy control. Through the coordinated controller, the effective adjusting to the ABS control process is realized. The simulation results show that coordinated control can not only effectively eliminate the negative influence of suspension control on the braking system, obtain the best braking performance of the car, but also improve the performance of the suspension system.