Research On Fault Injection And Health Assessment Method Of Multifunction Vehicle Bus

With the wide application of Train Communication Network(TCN)in high-speed trains,TCN fault Prognostic and Health Management(PHM)has become a hot research topic.In order to obtain the characteristic data sets of TCN under different operation conditions and evaluate the network health status under different working conditions,so as to facilitate the research of fault diagnosis and health management of on-board network,the research of fault injection technology of train network is imminent.At present,the research on fault injection technology of train network mainly focuses on the hard fault research such as cable fault.The designed fault injection equipment has a single function,which can not meet the requirements of the train network PHM research on the function of extracting waveform characteristics under different working conditions of the network.In this paper,through the study of train network fault mechanism,the specific realization of fault injection method is completed,and the network health status under different working conditions is evaluated.The main research contents are as follows:(1)Based on the research object of Multi-function Vehicle Bus(MVB)in train network,the paper analyzes the fault mechanism from three aspects of physical layer,electrical layer and protocol layer combined with the fault cases,and finally determines the fault injection methods such as resistance mismatch,intermittent open circuit,data frame error and electromagnetic interference of MVB bus.(2)According to the method of fault injection,a fault injection board is designed,which includes chip selection,schematic design,PCB drawing,component welding,fault injection board debugging and so on.In the development environment of Quartus II,we use Verilog HDL to complete the development of FPGA software program,including software function design,modular programming,simulation verification and comprehensive optimization.The true random number module realizes the randomness and contingency of fault injection,and the de coding method is used to complete the data frame fault injection.(3)For Self Organizing Maps(SOM)has the advantages of simple network structure,automatic feature mapping and automatic clustering of input modes.This paper proposes a network anomaly detection method based on SOM algorithm,which completes node state quantification by establishing network anomaly detection indicators,and uses weighted method to map node state quantification to network state quantification.(4)Build the MVB bus test platform,complete the function and feasibility test of MVB network fault injection equipment and health assessment method.The test of fault injection equipment includes four functional tests: Board availability,series parallel impedance fault simulation,intermittent open circuit fault simulation and data frame error fault simulation.In the health assessment test,the visualized upper computer software of network health assessment is designed,and the MVB bus node state quantification and network state quantification under different working conditions are completed by combining the test data.The results show that the fault injection device can simulate the communication of MVB bus under different working conditions,and meet the design requirements.The network state quantification under different working conditions can be realized by health assessment method,which is consistent with the actual results.Finally,this paper summarizes the research content and prospects the follow-up work and direction.