Design And Implementation Of Soft-PLC System For Industrial Robots

With the increase of difficulty of industrial application and the scale of control systems,the short of traditional PLC(Programmable Logic Controller)technology in data processing and network communication becomes more and more obvious.Soft PLC technology is based on the PC to realize the PLC control function,which combines advantages of both PLC and PC.In this period of artificial intelligence,robotics,Internet of Things and other technologies booming,soft PLC technology has more application scenarios and better development trend than before.The research of this paper is to design a complete soft PLC system for industrial robot complying with IEC61131-3 international standard.This paper first analyzes the research significance of soft PLC system,and investigates the research status of soft PLC technology at home and abroad.After a brief introduction to the IEC61131-3 standard,the overall design of the soft PLC system is carried out.The soft PLC system consists of three subsystems.(1)Integrated Development Environment(IDE),Compiler and Runner.The IDE is developed based on Web technology,using the RESTful architecture.Use the database to manage users and projects information.Use Ace and MxGraph libraries to implement text language and graphic language editing.Support five programming languages: ST,LD,FBD,SFC and C++.(2)Compiler writes grammar rules file according to IEC61131-3 standard and uses ANTLR to check text in PLC program from the grammatical level.Design domain model for each language element in standard,customizing rules for semantic analysis and translation.After converting PLC program into domain model,check it from semantic level.If no error is found,translate the PLC program into C++ program and finally compile it into a dynamic library using G++.(3)The Runner uses multi-threading and semaphore to schedule the PLC program with the software model specified by the IEC61131-3 standard,supplemented by the reading of I/O devices,to realize the overall function of the soft PLC system application.A variable monitoring WebSocket service will be provided when running.In order to further meet the needs of industrial robot application development,expand the soft PLC system and integrate with the existing robot operating system BAOS.Design and implement the adaptation interface for req-res and pub-sub two kinds of inter-node communication.Support using C++ to write a PLC program,and then support the import of external function libraries to improve the adaptability and flexibility of the soft PLC system.Finally,an object grasping industrial robot application is built,which verifies the effectiveness of the system design.The above soft PLC system realizes the basic functions of PLC program development and running.Improve the support level of IEC61131-3 standard,and explore the combination of soft PLC and industrial robot.It realizes the logic control of complex industrial robot application by expanding the soft PLC system.