Design And Research On Electronic Parking Brake System For Automobile Based On CAN Bus

At present, with the increase of car ownership in the cities, vehicle road safety graduallybecomes the focus of attention, and it also has higher requirements for vehicle security.Although general traditional automobile brake system has been developed and improved for along time，it still has some serious shortcomings, such as low brake efficiency、slow brakeresponse、complex control actuators、poor reliability and so on. Along with continuousdevelopment and popularization of computer and electronic technology，especially theprogress of auto technology more embodied in the field of automotive electronics, X-by-wiretechnology application in the field of automotive brake is gradually become the futuredevelopment direction of automobile brake system. Brake-by-wire uses wire instead of someor all of the brake hydraulic line in traditional brake system，adopts the electric brake insteadof the previous mechanical brake, assigns the size of braking force on the axle and wheelsappropriately by means of electronic control unit based on MCU, and accurately control theprocess of automobile brake. Compared with the traditional brake system, brake-by-wiresystem can satisfy the huge equipment, complex control strategy, and multiple connectionmode of automobile brake. The basic working principle of the system is：firstly，a variety ofsensor collect the information of driving conditions、 automobile transient state and roadcondition；secondly， the information are converted into electrical signals，and analyzed byelectronic control unit (ECU), the analysis results are transferred to the central control unit；thirdly，with the help of CAN bus，MCU give an instruction to the brake actuator, completethe car brake operation.As a kind of brake-by-wire system, the electronic parking brake system (EPB)，throughmanual operation electronic key, realize the parking brake. DC motors is controlled by theelectronic control unit. It can only play a role when vehicle speed is less than a certainthreshold or almost zero. EPB reacts quickly, has high braking reliability and simple structure,is easy to implement intelligent control. The system not only has the function which thetraditional parking system has, but also be able to have the function of Hill Starting Aid (HSA).When the car which parked on the hillside carries on the parking brake, clutch isseparated, the accelerator pedal is pulled, raising hand brake and parking brake has not yetbeen cancelled at this time. When the clutch pedal is combined together，the ECU of rearbrake wheels，based on the signal of the clutch pedal sensor and the throttle opening sensor，will make logical analysis and judgment，selects the appropriate time to cancel the parkingbrake of motor，avoids some accidents such as vehicle skid and flameout，reduces the driver，s operation complexity， and improves the comfort and convenience. This study focuses onthe structure design of the hardware and software design of the EPB.This paper designs a electronic parking brake system based on MCU control, It is mainlystudied hardware and software design of EPB. Through x-by-wire technology, the system isbased on CAN bus network as the medium of communication, and the Philips80C592microcontroller as the foundation, analyses the hardware composition and structure ofelectronic parking brake system, designs and researches hardware and software of electronicparking brake system.This paper first introduces x-by-wire technology and research background and thedevelopment status at home and abroad of electronic parking brake system, and thensummarizes the related content of CAN bus which is involved in the project study, and isbased on CAN bus network to design of EPB system working principle. According to theprinciple, hardware and software of electronic parking brake system is designed.According to the specific hardware requirements to analyze the hardware structure andcomposition，the main control unit, power monitoring and processing module, motor drivepart H bridge, CAN communication module and the peripheral interface circuit is designed.On the basis of the CAN communication protocol for designing program of the relevant nodes,it includes the main control program part of the node and the parking brake design.、theinitialization of Philips80C592and SJA1000(CAN bus controller). Finally, the study designsprogramming of the rear parking brake microcontrollers、interrupt execution、sending andreceiving message.