Research On Control Strategies Of Integrated Novel Electro-hydraulic Brake System

In recent years,as the automobile continues to develop in the direction of intelligence,networking,electrification and sharing,new energy vehicles and intelligent vehicles have become the main offensive direction and technical competition field of the current automotive industry revolution.In order to adapt to this development trend,the automobile braking system is also gradually moving towards to the development of electro-mechanical integration,integration and modularization.The braking system of traditional vacuum booster is limited by its mechanism and working mechanism,which has the disadvantages of coupling human mechanism and slow pressure response during braking.It cannot meet the requirements of electric vehicles and intelligent vehicles.Thus,the braking system should have the functions of decoupling human mechanism,accurate adjustment of wheel cylinder pressure,rapid braking pressure response,and accurate coordinated control of friction braking and motor feedback braking.To solve these problems,this paper proposes a design scheme of an integrated novel electro-hydraulic braking system with high failure backup and functional redundancy structure,and studies its braking control strategy.The main research contents are as follows:(1)In this paper,a highly integrated type of electro-hydraulic braking system is proposed,which is highly integrated,human-mechanism power is decoupled from each other,driver brake force backup can be effectively utilized,and has a dual brake master cylinder/dual motor structure.Based on the design of its component unit structure,the mathematical modeling and parameter matching of the braking system are carried out.By building the AMESim model of the braking system,it is verified that the pressurization rate of the braking system exceeds 24 MPa/s,and the braking pressure can reach 10 MPa in 0.25s.The open-loop performance index meets the design requirements of the electro-hydraulic braking system.(2)Based on the experimental data of a certain class of AO passenger car brake pedal unit,the relevant component parameters of the active brake pedal feeling simulator are matched,and the co-simulation model of AMESim/Simulink is built to verify that the BFI score of the proposed brake pedal feeling simulation strategy reaches more than 80 points,and the change of the system component parameters has little effect on the brake pedal characteristic curve.Meanwhile,the brake pedal characteristic curve can be actively adjusted by changing the control parameters,indicating that the active pedal feeling simulator has the ability to actively adjust the pedal characteristics.(3)In view of the functional requirements of the consistency between the brake pedal travel and the hydraulic pressure of the brake master cylinder,and considering the influence of friction force,PV characteristics,hydraulic pipeline expansion and other interference factors when the master cylinder of the electro-hydraulic braking system is braking pressurization,a sliding mode robust control strategy for the hydraulic pressure of the master cylinder considering the external perturbation is proposed.By building the co-simulation environment of AMESim/Simulink,the proposed hydraulic pressure control strategy is verified to be effective and has high control accuracy under the input of square wave and sine wave expected signals with different parameters.(4)Based on the proposed integrated novel of electro-hydraulic braking system,which can realize the flexible switching between type Ⅱ arrangement and type X arrangement of the braking pipeline,a constant frequency wheel anti-lock control strategy based on type Ⅱ arrangement is proposed,and a CarSim/Simulink co-simulation model is established.The simulation results under low adhesion,open road and high adhesion road conditions show that the braking efficiency and vehicle direction stability are improved,which meets the requirements of wheel anti-lock function.(5)Based on the anti-lock control of Ⅱ hydraulic pipeline layout,an adaptive sliding mode fault tolerant control strategy is proposed.The ability of fault tolerant control to maintain the braking performance of the braking system is studied when the braking system is partially failure.The CarSim/Simulink co-simulation results show that when a fault occurs,the fault-tolerant control can ensure the stability of the braking performance,and the deviation from the expected value is small,so the fault-tolerant control performance is good,which proves the feasibility of the fault-tolerant control strategy.In summary,the open-loop performance index of the proposed integrated novel electro-hydraulic braking system meets the parameter matching requirements of the electro-hydraulic braking system.At the same time,the brake pedal feeling simulator can well simulate the brake pedal feeling,and the hydraulic pressure of the master cylinder can be accurately controlled.The braking anti-lock braking control strategy has certain feasibility.Meanwhile,the fault-tolerant control meets the functional requirements of the electro-hydraulic braking system at the functional redundancy level,which ensures the driving safety of the braking vehicle.Therefore,the proposed braking system preliminarily meets the requirements in terms of scheme design,parameter matching,analysis of braking performance and proposes control strategy.Figure[58]table[10]reference[99]...