Develop Of Maglev On-Board Diagnosis System Based On Linux

Maglev train, suspend above track, is a new mean of transport, which is based on non-contact electromagnetic levitation principle. Because of the advantages of maglev train and national conditions, China actively carries out the localization of the advanced technologies, while introducing them in. Through the acquisition of status signal of each components along with part of the analog data, Maglev train diagnosis network is mainly used for on-line electrical and electronic components diagnosis to determine the functional failures and execute relevant command operations, which is the reason why the role it plays in the security of Maglev train is so vital that it is also known as the "nerve center". In this thesis, with an in-depth understanding of the principle and structure of the system, the free and open source RTLinux, a hard real-time, multitasking operating system built by putting patches to the standard Linux kernel, works as the software operating platform, since standard Linux has a poor real-time performance and fails to meet real-time requirements of the system. Real-time performance of the achieved vehicle diagnostic system, based on embedded PC104, is tested.This thesis begins with an analysis of current studies on diagnostic system and the research background, followed by the embedded operating system features, advantages, and some typical real-time operating system. RTLinux is introduced with an analysis of those reasons that lead to the poor real-time performance of Linux. There is a detailed research on the principle of the RTLinux system, mechanism, system features and procedures.,then this thesis discusses the establishment of the RTLinux operating platform based on PC 104Then, based on understandings of functions, working principles and process of vehicle diagnostic network, this thesis proposes a design plan for the realization of Maglev vehicle diagnostic network and divides it into several modules in accordance with their different functions, such as:driver, module, data acquisition module, transmission module for data in different address space, TCP/IP network communications and the graphic user interface of diagnostics system. All the techniques needed in this diagnostics system include process and thread programming, socket network communication and Qt-based GUI development under RTLinux, etc.At last, according to the distinctions between RTLinux and standard Linux, this thesis researches development of device driver under RTLinux and focuses on the realization of CAN device driver registers, register interruption, interrupting program implementation and data structures associated with device operations. Functions implemented include delivery and collection of data from CAN bus, data protocol conversion, sending data to diagnostic PC via Ethernet, data processing and analysis by diagnostic PC, real-time display of relevant information about malfunctioned electrical and electronic components on the screen of diagnostic PC. The diagnostic GUI is friendly, easy to handle and can be used to carry out online diagnosis for electrical and electronic components.Following the implementation of major functions, this thesis performs simulation tests on the diagnostic system. The results from those tests are consistent with the expected analysis, which indicates a stable, simple and highly real-time diagnostic system.