Research And Development Of Time Sharing CBTC Simulation System Based On Cloud Platform

Communication based train control(CBTC)system is an important technology widely used in the field of signal control of urban rail transit.The establishment of CBTC simulation experiment system with complete functions plays an important role in improving the quality of personnel training and promoting the development of the industry.Therefore,a CBTC simulation control system based on time sharing of cloud platform is proposed and developed in this thesis.The system combines intelligent control,network communication,video media and other technologies,and realizes the sharing of experimental equipment resources in the form of time sharing with the help of public cloud platform.The main work includes the following four parts:(1)A general large capacity digital input-output system is designed and developed.The system includes four parts: decoding control module,output driver module,input acquisition module and bus backplane module.Based on the embedded ARM platform,the driver control and information acquisition are realized through the external interface module(EIM)bus interface of i.MX6 UL.The system circuit board adopts 4U standard,and can expand up to six 19 inch standard cages by decoding.Each cage decodes 16 driving or acquisition modules,each module has 32 channels of driving and acquisition points,and the maximum number of driving and acquisition points can reach 3072.The system is based on Linux operating system,realizes 100 m network communication through UDP protocol,and realizes interconnection with Web ATS system in the cloud through the external network interface.(2)An intelligent control decision simulation vehicle subsystem is manufactured and prepared.The system uses the STM32 microcontroller whose core is Cortex?-M3 and constructs three-layer functional structure for the peripheral modules of the core configuration: the sensor layer,the control communication layer and the executive layer.According to the demand analysis,the video,radio frequency,current and voltage detection and speed measurement modules of the sensor layer are proposed to collect the information data such as ground reality,transponder,current and voltage,and vehicle speed,which are processed by the main controller of the control communication layer and generated UDP protocol to send data frames.The Wi Fi module is connected to the cloud communication channel to form a socket transmission bitstream,and thedecision results are sent to the executive layer to drive motor to complete the function.(3)The software of digital input-output system and on-board system is provided.The software of the system is developed based on the Ubuntu system,and the preparatory work involves the construction of cross compiling environment and Linux porting.On this basis,the EIM bus driver of the modular kernel layer is written,and the application programming interface for hardware function of the application layer is built.Four sub thread function modules of application layer are completed about design communication,heartbeat package,EIM reading and EIM writing.Vehicle subsystem software based on keil5/?Vision5 IDE software platform which is equipped with CMSIS and the corresponding STM32F103 device support package for development.According to the functional requirements,the data decision-making processing,communication,control and other structured codes are analyzed and completed,and the onboard transmission and reception data frame communication protocol is constructed.(4)Information security and encryption of cloud control interaction system is addressed.The cloud platform sharing laboratory system needs to ensure the security and accuracy of user information and communication data transmission.In this thesis,the one-way hash MD5 algorithm is embedded in the modular code segment of the upper computer and the lower computer in the cloud.In the background of the website,the user's information and password are converted into MD5 value storage,and the transmitted data are encrypted and verified by MD5.Using the irreversibility and simplicity of this algorithm,the system can quickly effectively protect the privacy rights and interests of users and improve the stability of system functions.The full text includes 67 pictures,8 tables,and 51 references.