Studies On Application Of Bus Technology To Commercial Vehicles

With increasingly use of auto electrical control units and electrical devices, it isa reliable and economical way to employ serial BUS for multi-way transmission andauto electrical network. Meanwhile based on the requirements for safety andreliability, the original mechanical and hydraulic system is more and more likely tobe replaced by electrical system, which will make the vehicle full of networks.This paper introduces the primary research work author participated during thedevelopment of FAW Jiefang commercial vehicle's electrical system network BUS.In the paper, author analyzes the characteristics of auto network in detail; presentsimportant technical standards aimed at the network BUS adopted by this subject;studies the auto network related contents such as network structure, high levelcommunication protocol etc.; raises the implementation plan for the Jiefangcommercial vehicle's electrical system network. As the concrete use, author alsopresents an auto network structure based on CAN/LIN BUS and SAE J1939communication protocol by combining his experience in the Jiefang commercialvehicle CAN/LIN BUS development program. For the confidential reason, authoronly makes a brief introduction for the network's software and hardware design aswell as network test results.The Jiefang truck mentioned in the paper is a brand-new designed andself-developed model, also the leading model among Jiefang brands launched in themarket in 2005. In order to meet users'demands, we added a variety of advancedfunctions in electrical system of the series, since it will make the wire harnessthicker, installation arrangement more difficult and worse reliability due to manynodes if using traditional design method. For the purpose of improving vehicle'scomfort, reliability and its rank, we upgrade our product design concept that fullydemonstrates and adheres to the principle of lightweight design, and fulfill thenetwork communication for partial electrical functions in the series by designingCAN and LIN BUS connections points, interfaces as well as communicationprotocol.Chapter 1 briefly introduces the notion of auto network, summarizes thedevelopment and research status both domestic and abroad, and presents the keystudy purpose, content and achievement for the subject of this paper.Firstly, this subject need study the current status and its development trends offoreign auto network, BUS and communication protocol, make in-depth researchfrom technical side on key auto network technical standard and communicationprotocol. Since there are various technical standards and communication protocols,the comparison between different technical standards and communication protocolsfrom technical and market side is needed. Finally, based on above research, theimplementation plan of application network, BUS and communication protocol israised up.In accordance with the function and composition of Jiefang commercialvehicle's electrical system and SAEJ1939 and LIN1.2 standards, we make the CANcommunication protocol and LIN communication rules for FAW Jiefang commercialvehicle, mainly including constitution of message frame and ID distribution etc., andat last accomplish the electrical system network's communication and messagetransmission function for new Jiefang commercial vehicle.As the theory basis, Chapter2 to Chapter4 introduces the auto network relatedcontents in details, describing a complete auto network and its development processfrom network structure, technical standards and communication protocol sides.Chapter2 discusses the development process of auto network and presents acomprehensive auto network structure. Chapter3 gives priority to the study of 2BUS network standards adopted in Jiefang commercial vehicle. Chapter4 discussesthe auto network's high-level communication protocol by taking SAEJ1939 as anexample.The development of auto network actually is a system project, which goesthrough product position, overall solution design, partial solution design, partialimplementation, partial test, overall integration as well as overall test etc..Furthermore, the development of auto network is a iterative process, a model may behave many iterations during above stages before its launch in the market. The targetof auto maker is to shorten development cycle, reduce development cost as well asrisk to a possible extents, but those targets are inter-restrictive and balanced.Therefore the development of auto network stands at a balanced state in the specifictechnical development period. Chapter2 makes in-depth analysis and study on autonetwork's development process and network structure, also puts up with proposednetwork structure model.On the basis of the analysis of different node communication feature insidevehicle, study and comparison of current auto BUS technology, we propose thefollowing solutions for selective models of Jiefang commercial vehicle's electricalBUS system:1. Employ the BUS technology with LIN as sensor/actuator subnet.2. Employ the BUS technology with CAN as controller network.Chapter3 presents the above2 BUS technologies in a detail and practicalmanner.Different with auto BUS technology, auto makers usually take a conservativeattitude towards the high level communication protocol for the sake of keepingconfidential information. The current situation is almost each auto maker uses theirown special protocol in their own vehicles, therefore the different protocols arenon-compatible, but they can share some information.SAEJ1939 is a high level communication protocol specially for the truck andbus application. SAE expects it can fulfill equipment's combinability andrepeatability on a higher level with the promotion of standard communicationprotocols. In response to the current situation, this process goes forward in a slowway, mainly due to the slow digest of standard protocols, therefore there still isspace for research in this respect.As the applied, chapter 5s of the article described in detail jiefang passenger carelectricity system network structure according to the BUS of CAN/ LIN, and...