The Development Of Electromagnetic Auxiliary Braking System For Automobile Based On DSP

With the rapid growth in vehicle ownership,the traffic security problems that people faced with are becoming more and more severe.The vehicle braking performance is the key factor which affects the safety of driving.Therefore,people are forced to seek braking technique that has higher reliability.The braking device in CR6 light truck of the foreign is regarded as the research object.Combining with the domestic and foreign research results,an electromagnetic auxiliary braking system is designed and developed.The signal acquisition,communication with the principle computer and the control and drive of the auxiliary braking device are completed.In order to reduce the pedal force applied by the driver during the braking process and decrease the braking distance.Thus the braking performance of the vehicle is improved.First of all,the research and development status of electromagnetic braking technology at home and abroad are introduced systematically,which discusses the necessity and significance of developing electromagnetic braking technology.Based on the original vehicle parameters and the structure of the braking pedal assembly,two schemes of auxiliary braking by motor and electromagnetic actuator are designed.And the two schemes' respective strengths and weaknesses are compared and analyzed.The electromagnetic actuator is finally selected as the auxiliary braking device.The structure and performance of the electromagnetic actuator are discussed and the mathematical model is established.A structural basis is provided for the development of the whole system.Secondly,the MC56F8346 digital signal processor is regarded as the main control unit.The hardware design and software development of the electromagnetic auxiliary braking system are completed.In the hardware design part,digital signal processor's minimum system and its basic peripheral circuit,external analog acquisition and conditioning circuit and electromagnetic actuator drive control circuit are mainly included.Schematic diagrams and PCB diagrams are designed based on Altium Designer.The experiment plates of partial circuits are welded according to the schematic diagrams.In the software development part,the programming and debugging of each module program are completed in the CodeWarrior 8.0 development environment according to the module designed thought.The ADC acquisition program of external analog signal,the control program of the driver signal PWM of the electromagnetic actuator and the SCI serial port program of real-time communication with the principle computer are mainly included.And the LabVIEW software is used to monitor the working status of the system.In order to improve the stability of the system,the fuzzy PID control is designed to control the electromagnetic actuator.Finally,the hardware and software that designed are integrated.The functions of each submodule in the system are tested by using the current equipment in laboratory.The AD collection of the signal and real-time display in the principle computer and the real-time adjustable PWM duty cycle are included.The experiment platform of electromagnetic auxiliary braking system is built.And the experimental results verify that effectiveness of electromagnetic auxiliary braking system developed.