Vehicle Deceleration Control Based On Electro-mechanical Booster Braking System

In order to reduce environmental pollution and traffic congestion,the smart electric motor has been vigorously developed in recent years.At present,the current automobile intelligence level is still in the R & D stage,so the vehicle brake system should also integrate the basic power braking function of the driver’s participation in addition to the need to match the active braking of intelligent electric vehicles.During the routine braking process of the driver pedal,it is necessary to help the brake system provides a complete basic assistance to provide a sufficient braking force for the vehicle,control the size of the deceleration,thus shortening the brake distance to avoid traffic accidents.During the active braking process without driver participation,by active regulation of the longitudinal force and brake pressure of the whole vehicle,the regulation of the longitudinal kinematic characteristics of the vehicle is achieved,and the safety of the vehicle is reasonably controlled while ensuring driving safety.Therefore,the deceleration control is a key ring in the intelligent car movement control.However,smart electric vehicles have canceled the engine,which is no longer providing vacuum booster boost system to provide vacuum sources,and it is difficult to achieve the core of the brake system core.On the other hand,the traditional vacuum booster power brake system is difficult to integrate active braking function,which is difficult to meet the needs of braking pressure active regulation.In order to adapt to automobile intelligence and electricity demand,high performance motors as a servo power source electronic mechanical boost should be born.First,the electronic mechanical booster can couple the power of the machine and the pedal manpower to push the hydraulic master cylinder construction,and realize the basic power of the vacuum booster.At the time of active braking,the controller automatically adjusts the torque and angle of the internal servo motor,which acts on the brake system to form brake pressure by the drive mechanism to achieve precise control of the vehicle brake deceleration.The above two major characteristics are very good to meet the development of automobile intelligence and electricization.Since the electronic mechanical booster is a complex system integrated with electromechanical fluid,it has strong nonlinear characteristics,which greatly increases its basic boost and active braking control.In addition,in the active braking mode,the vehicle brake deceleration of the driver’s participation is controlled by the slope,the quality of the vehicle,and needs to fully consider the longitudinal dynamics characteristics of the vehicle.Therefore,this paper relies on the school’s corporate cooperation project,with the electronic mechanical booster to control,the vehicle brake reduction control in which the driver’s participation is carried out.In this paper,the vacuum booster is first analyzed and the gantry test is a reasonable pedal input force and hydraulic output force,and realizes a reasonable rendering of the driver’s participation in the decline of the driver’s participation in the relationship between the basic power supply of the electronic machinery boost control.Secondly,the target longitudinal force of the vehicle is planned according to the given target acceleration in the active braking process.In order to obtain a more accurate target longitudinal force,status information including the vehicle quality and the slope is estimated.Building a brake system reverse model transforms the target longitudinal force into a target brake pressure,and acts as an input of the electrical machinery booster active brake pressure control ring,and finally the design control algorithm is closed loop control on the brake pressure.The whole vehicle brake reduction control is involved.The specific research content involved in this article is as follows:(1)Introduction to the characteristics of the vacuum booster and the principle of electronic mechanical assistance.First,the structural principles and work characteristics of the vacuum booster,the electronic machinery booster,respectively.The vacuum booster is tested by means of a vacuum booster to help the vacuum booster test benchmarks.The powerful characteristic curve obtained based on the test is a reasonable pedal input force and hydraulic output force.(2)For the whole vehicle brake deceleration control,the electronic mechanical power control strategy and the active brake control strategy are designed for the electronic mechanical booster.First,in response to the vehicle deceleration control,the push rod displacement is corrected,then analyzes the working principle of the feedback disk and establishes the inverse model,and finally designed the foundation to help adjust the control layer to the electronic mechanical boost.The position of the motor rotor is calculated;the vehicle pressure control loop on brake pressure control is controlled for regulation.Secondly,the mathematical model of the servo motor is established,and the electronic mechanical booster position speed control strategy is designed based on sliding mode variable structure control theory(SMC)and friction model.Finally,the control strategy of the underlying permanent magnet synchronous motor is designed based on PID control theory.(3)Design of vehicle deceleration control strategy based on driver participation.Based on the longitudinal dynamics force,the direct feedforward controller from the target deceleration to the target longitudinal force is designed to design an error feedback controller based on the incremental PID control theory,and the control closed loop of feedforward compensation and feedback correction is formed.The actuator reverse model of the target longitudinal force to the target brake pressure will then be built to obtain the target input of the pressure controller in the electronic mechanical booster.In order to avoid the frequent switching of drivers and braking during the control process,the corresponding buffer layer is designed to complete the ordered switch between the driver and the brake.(4)Hardware-in-the-loop test.First,based on the d SPACE software system and the corresponding hardware actuator,the electronic mechanical booster base assist and active brake control results test bench are completed,and the effectiveness of the electronic mechanical booster control strategy is completed on the basis of this test bench.Designing a variety of typical operating conditions based on the above-mentioned test bench,the Car Sim software is combined to do Hardware-in-the-Loop test,verify the effectiveness of automotive reduction control strategies based on active braking.