Design And Implementation Of Vehicle Bus Network And Its Interface With In-vehicle Gateway

With the development of electronic technique and its wider use on the automobile, there are more and more electronic equipments, and these electronic devices usually centralized controlled by the electronic control system. Traditional electronic control system can improve a vehicle's dynamics, economy and comfort, but some problems also have come up, such as the body wiring complexity, space constraints and some reliability issues. In order to solve these problems, in the integration of computer networks and modern control technology, the vehicle network technology has been generated. Vehicle network has many advantages, such as a significant reduction of wiring harness, reducing body weight and costs, improving the efficiency of fault diagnosis and enhancing the level of intelligent control. At present, some vehicle buses have been already put into used, such as CAN bus, LIN bus, MOST, and Flexray. Different applicants can select proper one to achieve their purposes. Because of the good network transmission characteristics and low cost, CAN bus is considered as the most popular solution for vehicle network.Network is the largest hot spot of automobile electronics. Various kinds of buses can improve the vehicle performance, and the market scope will continue growing. However, in a short period of time, there can not have a uniform solving method of automotive network to satisfy all the requirements. Vehicle bus network will maintain the competition situation for a long time, and now for different applications, a model uses two or more kinds of buses to connect different application-level electronic control systems. Although the automobile network has realized information transmission and data exchange between electronic control systems in the same network, exchange of information between different buses, and automotive electronic control system information interaction with the outside world are beyond its ability.Future automobile will become a terminal of internet, and in-vehicle information system will be an indispensable part of automobile. The complex information need to be accessed and acquired in automobile, and these are basic information for the various services of future Network vehicles. The application interface between vehicle network and in-vehicle gateway is the key part of development. The interface provides great facilitation for the follow-up development. Without knowing what's the data communication form in vehicle bus and how the vehicle electronic control module have implemented, application layer software developers can complete the development works based on corresponding interface protocols only.The study of in-vehicle gateway in this paper is based on the National Development and Reform Commission (NDRC) project"IPv6-based in-vehicle information system research and industrialization". The purpose of the project is to support the next generation of in-vehicle information systems. The work in this article is the key technique of IPv6-based in-vehicle information system, and has practical significance to future networke automobile. The major work is divided into two parts: first part, the design and implementation of vehicle network are completed, mainly about CAN, LIN bus network within vehicle environment; another part, the interface between vehicle bus and gateway is constructed. At the aspect of hardware, A CAN and a LIN bus which have the basic functions are constructed. In-vehicle gateway used SAMSUNG's S3C2410 processor, and hardware development environment makes from the core board and bottom board (peripherals board or basic board). The core board integrates the SAMSUNG's S3C2410 processor, the 16M and 64M FLASH SDRAM, and backplane provides the mainly peripheral interfaces. The hardware system has small size, low power consumption and other characteristics, also can load and run the embedded Linux operating system. At the aspect of software, the corresponding codes are programmed to support the protocol transmit, including the design and implementation of CAN Bus and LIN bus interface with In-vehicle gateway, and a part of application programs. The interface can be used by user applications to exchange the in-vehicle informations. In the in-vehicle information system project, such informations are transmitted through wireless communications to the monitor center server by other applications of in-vehicle gateway. This provides a large number of timely and effective informations which are used for automobile online monitoring and fault diagnosis.Based on these thoughts mentioned above, this paper implements the CAN, LIN bus application interface with in-vehicle gateway and the corresponding vehicle CAN, LIN bus network. After summarized the former works, the development is improved, and some new methods and techniques are adopted. In the article, the overall structure, functions and requirement definition of gateway interface are presented.The main contents of this paper are as follows:(1) The paper has introducted the research background on the in-vehicle information systems, and analyzed the necessity and feasibility of implementation of the vehicle bus and its interface with the in-vehicle gateway.(2) Through analysis of in-vehicle information system project, and combined with the past development experiences, the paper presents a overall structure, functions and protocols of vehicle bus network and its interface with in-vehicle gateway. The paper also analyses the implementaion Technology for various parts: hardware and software architecture, and designs the protocols between different parts.(3) Based on analysis of functional demands, the paper completes the part of vehicle Bus Network Design and Implementation, including CAN, LIN bus structure definition, functional requirement analysis and protocol definition, as well as the hardware design and software implementation of the nodes in the network.(4) In this article, we particularly present the design and implementation of vehicle bus interface with in-vehicle gateway. First, a brief introduction of gateway hardware platform, software platform, and embedded Linux system device driver development are given. On this basis, we focused on the hardware design about the CAN, LIN interface with the in-vehicle gateway, as well as the device drivers and some application programs.(5) After completion of works above, a prototype system is installed in a automobile and tested. The works include the choice of models, vehicle wiring installation, distribution of nodes, etc. And cooperating with other applications, we carry out the tests of integrated system, including system hardware and system software testing. Finally, test results and recommendations of the next step development are given.The research described in this paper is based on the analysis on the trend of in-vehicle information system. The innovation points are shown as follow:(1) Construction of in-vehicle gateway hardware and software design. Various vehicle bus networks can seamlessly connect to esch other, and information can be exchanged through intercommunication.(2) Adoption of the concept of mid-ware research and development. The equipments developed by this way have a strong expansibility and compatibility, and will have good market prospects.(3) ARM-Linux development platform provides a standard interface for all kinds of equipments, and that will facilitate the service provider.