Discussion on the Research Focus and Key Technology of Automobile Bus

The research and development of automobile bus system can be divided into three stages: the first stage is to study the basic control system of the car (also called comfort bus system), such as lighting, power windows and centralized control locks. The second stage is to study the main control system (also known as the power bus system) of the car, such as the electronic injection ECU control system, ABS system, automatic transmission, etc. The third stage is to study the integration, real-time control and information feedback between various electronic control systems of the vehicle. According to my country's automotive electronic technology development plan, after entering the 21st century, automotive electronic technology can reach the level of foreign cars in the 1990 s. In order to shorten the gap with foreign automobile technology and improve their competitiveness, relying solely on the introduction of technology is not conducive to development. Research and development of autonomous vehicle bus and network application systems is on the rise. At present, the research and application of automobile and bus in China is still in its infancy, and the application trend of automobile and bus is obvious. Now is a good time to get involved in this research. The research focus of automobile passenger car. Since my country's models are mainly European and American models, and European and American models are mainly CAN buses, almost all domestic models using bus technology use CAN buses. Therefore, the research and development of automobile and bus should be selected according to the actual situation at home and abroad. CAN bus. CAN conforms to the ISO/OSI reference model, but only specifies the protocols of the physical layer and the data link layer, and the protocols of the application layer need to be defined by the user. There are many chips that support the CAN low-level protocol, including on-chip MCUs and off-chip CAN controllers. Users have also developed many application layer protocols. For example, the DEVICENET protocol defined by AB is an application layer protocol based on the CAN protocol. Honeywell's SDS bus also defines its own application layer on the basis of CAN. It can be seen that the research focus of the car can bus is to develop ECU hardware and application layer software for specific models, and form an in-vehicle network. Key technology uses can bus to construct vehicle network. The key technical problems to be solved are: 1) technical problems such as the rate, capacity, priority and node capacity of bus transmission information; 2) reliable data transmission in a high electromagnetic interference environment; 3) determining the maximum transmission delay time; 4) network fault tolerance technology; 5) network monitoring and fault diagnosis functions; overview of bus network system With the improvement of the performance of automotive electronic control systems, in particular, the performance of the controller chip and software is improved. With the improvement of automobile bus network system, it can not only share information and save wiring harness, but also provide richer software functions, improve the value and competitiveness of products, and meet the needs of automobile reliability and comfort. Bus technologies corresponding to these functions include: network management: the controller monitors the running state of the network through network management, and immediately performs fault handling once a communication fault is found. The sleep and wake functions of network management can coordinate the power management of each controller, thereby reducing battery power consumption when the vehicle is parked. Diagnosis: The diagnosis can not only read the fault code, but also realize two important functions of offline configuration and detection and program download. The automatic offline configuration and detection function can quickly and comprehensively configure and detect the functions of the controller (such as window zero configuration and anti-pinch detection), so as to ensure the quality of the car and speed up the production line. Through the program download function, automakers can refresh the controller's software in 4S stores, thereby reducing the cost of recalls due to software defects. Measurement and calibration: In the development process of the new model, the rapid control prototype controller using measurement and calibration technology can easily adjust the control parameters and algorithms in real time through the computer and network system, which greatly shortens the development cycle and cost. The technology has been widely used in the development of new energy vehicles in Europe, the United States and Japan. Foreign automakers such as General Motors, Ford, and Volkswagen, as well as domestic automakers such as FAW, Dongfeng, SAIC, Changan, GAC, and Chery, have integrated bus technology into the general network platform for high, medium and low-end models. In this way, the change of the network system is reduced, the software reuse is increased, and the development cost is reduced. The vehicle manufacturer's network platform consists of network standards, test specifications and protocol stacks (network-related embedded software). The commercial vehicle network platform meets the SAEJ1939; the passenger vehicle network platform has its own characteristics for the original equipment manufacturers, but more and more original equipment manufacturers adopt international standards to share supplier resources. At the same time, more and more vendors choose to develop protocol stacks by professional companies, thereby reducing development manpower and cycles. The development process of bus network system network platform construction and network system development adopt V mode development process, as shown in the following figure. The V model defines a clear and effective development process: the OEM completes the formulation of system requirements and component requirements from system requirements to component requirements, and releases the component requirements to the supplier; after the supplier completes the component development, from component testing to System testing, the original equipment manufacturer has completed the integration and verification of multi-wheel prototypes and prototype vehicles.