Design Of Vehicle Initiative Safety System Based On Electronic Mechanical Brake

With the rapid development of automobile technologies,people are paying more attention to the safety of their cars.Because the traditional braking system adopts a hybrid braking mode of pneumatic,hydraulic,and/or mechanical technology,there are too many components in the entire system,the braking time is somewhat slow,and the braking distance is somewhat long.Also,because of the rules of logical control used in the braking process,the problems of ergonomics are critical,and it is not very safe.Due to aforementioned features and practical situations,Electro-Mechanical Braking(EMB)system has became increasingly popular,which has a simpler structure,a more reliable function,and a faster response time.In its braking process,it can adjust its braking torque continuously;it also could be synchronized with other electronic control devices for information sharing by CAN bus.Firstly,this paper introduces the concept of Electro-Mechanical Braking(EMB)system,its research actuality both domestically and internationally,and the trend of its development.According to the demand of the basic function of Active Safety,the overall structure of Electro-Mechanical Braking(EMB)system of an entire vehicle is designed.Additionally,according to the different characteristics between EMB and the traditional braking device,this paper details the structure and principles of EMB actuator.Then,in accordance with the characteristics,the overall structure of its driving circuit is designed,and the program through which the speed and modulation of Brushless DC Motor is controlled and confirmed.Secondly,in the design of the hardware,according to the functional requirements of EMB system,the overall structure of the system of the hardware is designed,the hardware's design of the master-slave node is finished by selecting an appropriate chip based on STM32F103 embedded micro-controller.And,the hardware's design includes a STM32F103 core circuit,an A/D interface circuit,a CAN interface circuit,a motor circuit,a feedback current circuit,etc.Then,it details how the quarantine of high-speed signal is solved and the switching circuit between different electrical levels is finished.Thirdly,in the software's design,the software's process of the master/slave node is designed.Then,according to the functions of EMB system,the control strategy is built,the node address is assigned,the communication protocol is written,the moduleprogram and simulation are designed about the CAN bus of master node.At last,on the basis of influence factors of braking force,the combination of fuzzy control and PID control algorithm is more beneficial,and the servo control system could solve the problem that brake actuator of EMB is unstable.Lastly,the system has passed the standard test,which verifies the feasibility of the system.Furthermore,through the debugging process of software and hardware,the master node could capture the wheel speed precisely,and it also could receive the signal of pedal sensor and send the message of the result of the calculation to the slave node via CAN bus.Thus,the entire control system has achieved the anticipated effect.