Research On Hardware-in-loop Of Composite Brake System Based On Flex Ray

With the growing application of X-by-wire technology and intelligent driving assistance system on vehicle controlling field, the quantity of vehicle communication signals are growing fast. To meet the communication need,there are already five to six sets of CAN communication Bus lines and the number is still growing; that indicates that the CAN protocol will soon out of the picture of the future vehicle communication network. Since then, creating and applying a new in-vehicle communication network which has specifications like high throughput, real-time communication, redundancy and flexible topological structure and so on, is urgent. In this paper, I choose the one protocol named Flex Ray,which meets all the specifications above and has a huge possibility to be the next generation of in-vehicle communication network replacing CAN,and appy the network to the Composite Brake System which is electrohydraulic brake system(EHB) for the front axle and electromechanical brake system(EMB)for the rear axle. As two main structures of Brake-by-wire, EHB and EMB both have their own advantages and disadvantages. However as the combination structure above, they can cover the other’s disadvantages with their own advantage, which makes the composite brake system a efficient and stable system,and the application of Flex Ray communication network makes the controlling of the whole system more real-time. To accomplish the composite braking system based on Flex Ray and test its performance with test, I did the following work.At the beginning, based on the controlling need, the controlling factor and the hardware of the EHB and EMB, I created and configured the application layer of the Flex Ray network, which includes the information of the nodes, the signal data base of each nodes, the mapping relation between signals and messages, the schedules of the static segment and the dynamic segment of thecommunication cycle and the configuration of the global parameters and local parameters and so on. Other than the application layer, I also design the physical layer of the network including choosing the hardware of the communication module, the dual 10Mbit/s throughput network channels and the rootless star topological structure and so on. With the combination of the application and physical layer configuration, I make the communication network meet the need of the composite brake system.After that, according to the advantages of the composite brake system and Flex Ray communication network, I choose the antilock brake system(ABS), one of the systems that need the real-time controlling and quick response the most,to be the test module. Combining the driver braking expectation deceleration predicting module, the i curve brake force distribution module, the optimal slip ratio estimation module based on coefficient of road adhesion and the ABS control module based on the Fuzzy logic control and cooperative controlling of them establish the whole ABS control system of the paper.At last, after building the ABS controlling and Flex Ray communication module on Matlab/Simulink platform and combining the Car Sim dynamical model as the controlled vehicle, I started the joint simulation. Using the Simulator and Micro Auto Boxes as the controllers and communication nodes, applying the EHB and EMB platform as actuators, I did the composite braking system hardware-in-loop test based on the different coefficient of road adhesion that configured by Car Sim. According to the test result, the Flex Ray communication network has outstanding performance in real-time communication and reliability, and also a brilliant fault-tolerant ability. The composite brake system based on EHB and EMB can easily follow the brake force expectation and achieve the target brake effect. The ABS system based on fuzzy control can control the test slip rate to optimal slip rate based oncoefficient of road adhesion. The hardware-in-loop test will also provide both theory and test support to the composite braking system integrated control and future real vehicle test.