Design And Implementation Of Train Broadcast Controller Software Based On Hierarchical State Machine

With the rapid development of domestic and international subway train broadcasting systems,the functional requirements of train broadcasting service systems are increasing,and software design is becoming more and more complex.At present,the train broadcast control system at home and abroad mostly adopts the software structure design based on finite state machine.The software structure design is flat and the state transition process is redundant and complicated.This kind of design is not convenient for the maintenance and expansion of the function in the later stage,and it is easy to cause the program to crash abnormally during the long running of the train.Therefore,how to improve the low stability and low scalability of the existing train broadcast controller system and facilitate the development of the maintenance and secondary development of the developer is still a problem worth exploring.Aiming at the problem that the existing train broadcast controller has many faults and the software design is not fault-tolerant,this thesis optimizes the controller software design and designs a train broadcast controller software system based on the hierarchical state machine.The function control part adopts the design idea of the hierarchical state machine,and transfers the common processing of the sub-state to the top-level state,and realizes the differentiated processing of the event inside the sub-state.Such a tree-like software design architecture can reduce the impact of system changes on the functional substates,thereby improving the system’s scalability and maintainability.At the same time,in order to improve the stability and reliability of the broadcast control system during long-term operation of the train,this thesis carries out a three-level control level division design for the controller.This design can ensure that after the abnormal crash of the program in the main controller,other standby controllers can take over the corresponding functions of the main controller device through reasonable competition to ensure the normal operation of the train broadcast control system.This thesis firstly introduces the characteristics of train broadcast controller and the theory of hierarchical state machine,and expounds the significance of this research.Secondly,this thesis divides the software system module and designs the corresponding communication protocol for the actual project demand of a subway line in Chicago.After that,this thesis designs and implements a software control program for the train broadcast control system,and describes the design content in detail.Finally,this thesis builds a related functional testenvironment and conducts comprehensive tests on various broadcast functions.The test results show that the design can effectively improve the stability and expandability of the system.