| With the continuous increase in the operating years of metro trains,condition monitoring,as a means to ensure traffic safety,can help solve the fault problems of key on-board equipment during operation.Compared with the additional installation of sensor nodes,the condition monitoring method based on the original communication network has the advantages of low cost,low technical difficulty and high feasibility.At present,there is a large-scale communication network for RS485,ARCNET and other trains that do not adopt international standard IEC61375,and the on-board equipment gradually fails under long-term operation.It is necessary to carry out autonomous replacement to make it follow the international standard.At this time,the new and old devices have information interoperability problems due to their compliance with different protocol,and it is impossible to use the original communication network to achieve condition monitoring.In order to solve the problem that the metro train cannot be monitored due to the communication barrier,a universally applicable condition monitoring scheme is proposed.The protocol conversion module is designed to realize the information transmission between devices.On this basis,the software is designed to complete the condition monitoring,thereby realized the stable transmission of devices condition information and achieved the purpose of monitoring the running condition of metro trains.The main research contents are as follows.Taking the Mitsubishi metro train in Shenyang as the research object,according to the High-Level Data Link Control(HDLC)protocol used in it,combined with the actual situation that most of the independent production devices follows the Multifunction Vehicle Bus(MVB)protocol and the actual demand for devices information intercommunication,the conversion scheme between HDLC protocol and MVB protocol is designed.According to the application scenario of replacing traction control unit,the protocol conversion function architecture is determined,and the encoding and decoding modules of HDLC frame and MVB frame are designed by finite state machine.For the frame length mismatch problem caused by different protocols,an adaptive mechanism is designed.For the problem of asynchronous transmission of information caused by data update,dual-port RAM and detection mechanism are added.Through the mutual call between modules,the top-down design of protocol conversion function module is completed.In order to ensure the normal operation of the on-board equipment,a software program for monitoring the operating conditions of metro trains was designed,the overall structure of the condition monitoring software was constructed and the work flow was designed.According to the software architecture,the communication layer,service layer,storage and access layer,and interface layer are respectively designed in detail,and the software of the host computer has been built.Finally,the functional simulation verification of the protocol conversion module was realized.After that,an experimental test environment was built to simulate the working conditions of the metro on-board equipment in the actual operating environment,and a number of functional tests were carried out on the protocol conversion device and the condition monitoring software,the feasibility of the design in this dissertation is verified,and it can effectively respond to the condition monitoring requirements when the on-board equipment is replaced. |
