| Intelligent new energy vehicles have become a strategic highland for the global auto industry,and the chassis brake-by-wire execution system is its core component.my country has long faced the blockade and monopoly of foreign core technologies,which restricts the independent,controllable and sustainable development of the auto industry.At present,the key technical problems of brake-by-wire mainly focus on braking force control,including active braking force control and braking force control in the process of braking energy recovery.Strategy Research.First,mathematical modeling and bench testing of the brake-by-wire system and key components are carried out.Twobox semi-decoupled brake-bywire system using e Booster(electric brake booster)+ ESC(Electronic Stability Controller)A co-simulation model of AMESim and Simulink was established,and a bench test was carried out to verify the accuracy of the model.Secondly,the estimation and control of master cylinder pressure based on friction compensation is studied.The factors affecting the control-by-wire effect are analyzed: nonlinear friction will reduce the control accuracy of the braking system,the pressure feedback signal of the master cylinder is at risk of being lost due to sensor or line faults,resulting in uncontrolled braking,and the motor control effect is directly Affects braking response time.To this end,a Lu Gre friction model was established to quantitatively analyze the friction phenomenon,and a master cylinder pressure observer based on unscented Kalman filtering was designed to form signal redundancy with the master cylinder pressure sensor.Motor speed.Furthermore,a cascaded adaptive backstepping sliding mode controller is designed to follow the target pr essure,cope with nonlinear,disturbance and uncertain factors,and improve the robustness of the controller.Thirdly,the boost control strategy of the electric brake booster is studied,and the bench test is carried out.The working characteristics of th e vacuum booster are analyzed,and the displacement states of the main and auxiliary surfaces of the feedback disc in each working stage are obtained.Taking the relative displacement between the input push rod and the sub-surface of the feedback disc as the controlled quantity,the assist curve is designed.The bench experiment was carried out,and the same effect as the vacuum booster was obtained,which verifies the effectiveness of the booster control strategy.Finally,the coordinated control strategy of braking force in the process of cooperative braking energy recovery is studied.The vehicle longitudinal dynamics model is established,the braking force distribution strategy in the braking energy recovery process is formulated,and the action logic of e Booster and ESC is studied for three situations of hydraulic braking force and regenerative braking force in the braking process.Simulation experiments are carried out under three braking strengths to verify the effectiveness of the control strategy. |
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