Exploitation Of The Automobile Body Electron Controlling Based On The Field Bus

Electronics in automotive applications have undergone profound changes within the last few years. Increased complexity and cost-reduction efforts will further drive electronic content and semiconductor integration in the cars. Innovation in the automobile sector is almost exclusively driven by intelligent electronics - in many cases this is the only way that new features can be realized. Today, 40 to 50 electronic control units are installed in a well-equipped higher-end car. Top class models have 70 and more. So some modern automobiles contain three miles of cabling for connecting every unit. Because this number is liable to rise as components grow more intelligent, creating problems of increasing numbers of wire harnesses and therefore more weight and cost. We'll need to find ways to reduce the amount of wiring. At the same time traditional control architecture can't satisfy all the needs of real-time control on the automobile. Integrated electronics architecture in the car will create new challenges for the interconnection of components manufactured by different suppliers. Increasingly networked together by various bus communication systems will solve this problem.From the beginning of the eighties last century, every large automobile manufacturer began to devote to the network of automobile electron. In addition, SAE (Society of Automotive Engineers) also began to research it. SAE divides automotive tasks into classes A, B, C according to operating speed level. Among them, the communication's speed of classes B and C are relatively high. CAN provide serial communications that efficiently supports distributed real-time control with a very high level of security and speed. The robustness of the bus in noisyenvironments, and the ability to detect and recover from fault conditions makes the bus suitable for this condition. CAN (Control Area Network), as a transmissions protocol for automobiles is a serial transmission protocol standardized by Robert Bosch in the late 1980s. In most cases, the automobile has multiple CAN bus networks. It can solve the data interchange between the numerous controllers and the equipment within the automobile with data rates up to one MBit/s. Its multi-master architecture allows redundant networks, which are able to operate even if some of their nodes are defect. CAN take a different approach. Every bit transmitted on the bus is defined as recessive or dominant, which maps to 1 or 0. All nodes can listen and transmit at the same time. If more than one node is transmitting, the result will carry a dominant bit if at least one node is transmitting a dominant bit. When a node transmits a dominant bit, it will see a dominant bit on the bus. In this case, the node will not know if anyone else was trying to transmit. If a node transmits a recessive bit, but a dominant bit is seen on the bus, the node knows that someone else is on the bus.In other systems of automobile occasionally use a lower speed bus. Until recently, there was not a low speed robust network that could be implemented for the low peed bus. For this reason the technical specifications of the protocol LIN (Local Interconnect Network) have been developed by a consortium of European automobile producers and other famous companies, including Audi AG, BMW AG, Daimler Chrysler AG, Motorola Inc. Volcano Communications Technologies AB, Volkswagen AG, Volvo Car Corporation and others. It is designated for creating cheap local networks for data exchange at short distances. The European automobile consortium as a cheap additional part to the reliable Controller Area Network (CAN) protocol has affirmed the LIN protocol. These two protocols complement each other and allow the unification of all electronic automobiledevices into a single multifunctional board network. The LIN standard includes the technical specifications both of the protocol and of the transfer medium. As a consecutive link protocol, LIN efficiently supports the operation of electronic nodes and devices in the automobile systems with networks from class A with one master and several slave nodes.In this paper we first discuss the electronic network divide and bus technology. CAN network and LIN network are adopted to construct the automobile body network. On the basis of the original function of Red Flag CA7200E3 car, I design two kinds of networks. According to reality I apply the centralized type as my scheme. In this framework, we use CANoe to release systematic emulation, which can be divided into three phrases. (1) Utilize digital emulation and analysis of the network and design. (2) The node realization and half a physical emulation. (3) The integration of the whole system. With the strong emulation function of CANoe, the whole system model can be constructed under the environment of laboratory easily. In our project, several types 8-bit SCM (single chip micyoco) produced by MOTOROLA Corporation are chosen as ECUs (electronic control units) for their strong function of networks supports. Meanwhile, system energy saving and anti-interference are considered as fully as possible during the hardware design procedure. We have designed door system and light system in CA7200E3 adopting the scheme describe above. The experimental results show that our proposed scheme is efficient and practical.Finally, this paper describes the main factors that influence real-time and accuracy of data transmission and the bit timing method is introduced in details. In order to enhance the reliability while transmitting some important data, TTCAN network technology is adopted. For improving the accuracy of the data transmission, we utilize the Dynamic Priority Assigning Mechanism to deal with...