Hardware-in-the-loop Simulation Of Vehicle Braking-by-wire System Based On Flexray Bus

Nowadays,consumers put forward higher requirements for the safety and comfort of cars;besides,the automobile electronic technology is developing rapidly,the car manufacturer and the related researchers combine the auto electronic technology,communication technology,automatic control technology with braking system to develop the car Braking-by-Wire system.Braking-by-Wire system has great importance to the lightweight,comfort,braking efficiency,expansibility and environment-friendly of the automobile;however,it has strict requirements for the real-time and reliability of the vehicle network.As the next generation of vehicle network,the FlexRay has been widely used in the actual vehicle and is applicable for the X-by-Wire system,which has a high rate of communication,dual channel redundancy and message sending time determination.In this paper,CANoe and MATLAB are used in the joint modeling and simulation to realize the simulation of vehicle Braking-by-Wire process,and the calculation of the parameters in the braking process.First of all,design communication cluster parameters and schedule by use of the Network Designer of the Vector company,the design content above is imported to CANoe as the Braking-by-Wire system database in the form of an FIBEX file;then design a brake force distribution scheme and programme the node to realize the scheme with CAPL;after that,combined with the braking model designd in MATLAB/Simulink,use the CANoe and MATLAB/Simulink to simulate process of braking-by-wire,exporting the parameters related to the process to automotive display panel which is designed by the Penal Designer.Finally,the braking distance of the systems above is in accordance with relevant regulations of "the vehicle driving safety technical conditions"—the braking distance should be less than 19m when braking speed is 50km/h.This paper developes the FlexRay node and electronic module to replace the braking force distribution node in the network simulation,the braking intention is transmitted to the MC9S12XF512 chip through pedal sensor in forms of analog quantity to calculate the braking force,VN7600 interface card connectes the braking force distribution node to the CANoe to achieve the semi physical simulation of braking-by-wire system.In this paper,an electronic brake pedal module including communication network is designed to replace the braking force distribution node in the simulation network.Electronic brake pedal module is configured the angle and the pressure sensors,which are calibrated in this paper,to express the driver's braking intention,the driver's braking intention is transmitted to the MC9S12XF512 chip through pedal sensors in forms of analog quantity;combined with the current vehicle related the parameters,the calculation of braking force distribution is achieved in ECU;finally braking model is connected with the upper machine through VN7600 network interface card to formate the semi physical simulation of Braking-by-Wire system.