Research On Hybrid Brake System And Its EBD/ABS Control

In order to meet the new requirements of brake system for vehicle safety and intelligence,this paper proposes a hybrid braking system(HBS)which is configured with electro-hydraulic brakes(EHB)on the front wheels and electro-mechanical brakes(EMB)on the rear wheels.The combination of EHB and EMB two different forms of Brake by Wire(BBW)system into a new HBS shows the advantages of BBW of the two different kinds and also make up for their own deficiencies.In this paper,the precise brake force following control strategy of EMB and EHB is studied respectively.Based on the advantage that the wheel braking force can be controlled precisely of the HBS,the method of controlling the wheel slip rate to realize EBD/ABS control of the vehicle is studied by using the HBS.In this paper,the overall structure of the HBS and its control system control architecture are proposed.And then the hardware in loop test bench of HBS was developed based on prototype controller.For the study of brake force control of EMB,an off-line simulation model considering mechanical friction and nonlinear stiffness is established.The simulation parameters of the model are identified through experiments.In order to reduce the influence of the nonlinear friction and non-linear stiffness of the EMB actuator on the brake force control effect,this paper proposes a feedforward friction compensation and system stiffness feedback linearization based on three closed-loop control structure of EMB clamping force.For the EHB wheel cylinder pressure following control,the linear solenoid valve was experimentally tested to determine the working frequency and linear working range.Based on the characteristics of the linear solenoid valve,a double closed loop control strategy of wheel cylinder pressure follow including the solenoid valve current and the wheel cylinder pressure was designed.For the EBD/ABS control of the HBS,the EBD/ABS control architecture based on BBW system is proposed,and the switching logic of EBD and ABS is designed.Finally,all the the control strategy is verificated with different typical experimental conditions on the hardware in loop test bench of HBS.