Research On Cnc System Of Microservice Architecture For Cluster Deployment

Intelligent CNC machine tools can reduce manual intervention and reduce the professional ability requirement of operators while ensuring machining accuracy and improving processing efficiency.It is a necessary condition for realizing intelligent workshops and unmanned factories,and provides an effective way to solve social problems such as aging population and reduction of the working population.At present,the numerical control system in the mainstream market still adopts a closed architecture.Due to the poor access capability of multi-source information,CNC system cannot generate intelligent decisions effectively and it can only act as a passive exection role in the manufacturing system.It is unable to satisfy more and more flexible,agile,customized production requirements.Therefore,this dissertation aims to realize intelligent CNC machining workshop through designing and developing an open CNC system based on microservice architecture.In order to meet the low-latency transmission and processing requirements of industrial big data,a clould computing platform is deployed in the workshop layer using the concept of edge computing,providing large-scale parallel computing capabilities for the intelligent workshop.Based on the concept of CSaa S(Control System as a Service),the equipment control systems are integrated into the edge cloud computing platform,forming a clustered workshop control system.Then an open CNC system architecture based on microservice is proposed.The CNC system is divided into a series of loosely coupled and independently deployed microservices by adopting the domain-driven design pattern.In addition,colored Petri-net is used as a formal method to model and simulate the microservice architecture of CNC system,which verifies the feasibility of the system architecture.As microservice is the basic unit of microservice architecture CNC system,the development group is organized according to the microservice division.In order to coordinate the development work of different teams,the CDC(Consumer Driven Contract)pattern is adopted in the development of NC microservices.A microservice interface contract with standard semantics is formulated.An hierarchical structure model of NC microservice is established.Serval NC microservices are developed using the proposed microservice interface and software structure model,including NCK microservice,Gcode microservice,RTE microservice and HMI microservice.In order to guarantee the realtime requirements of CNC systems in the cluster environment,the scheduling strategies of different types of tasks are studied.A feedback scheduling strategy is proposed for the data flow task with producer/consumer relationship in the CNC system.By monitoring the data consumption speed in real time and adjusting the execution cycle of the producer task,the data volume in the buffer is dynamically balanced to avoid data flow interruption.For hard real-time tasks,the effects of task schedulability,execution cycle,and delay on the stability and quality of the control system are studied.In order to guarantee the schedulability of real-time tasks which are assigned to the same set of CPU cores,a real-time task period assignment method based on response time is proposed,as well as a heuristic period optimization method based on processor utilization.The reconfigurable configuration strategy of the micro-service architecture CNC system based on container technology is proposed,which lays a foundation for the flexible expansion of intelligent functions.The clustered workshop control system runs in an industrial server cluster.The cluster consists four kinds of nodes,including data nodes,NC nodes,Web service nodes and GPU nodes.Each type of nodes are dedicated in specific functions.Using Kafka,docker,kubernetes and other technologies,the microservice architecture CNC systems are deployed in the NC nodes.The network of the clustered workshop control system consists of 10 Gbps cluster network,1Gbps management network,realtime Ethernet and wireless network.The real-time Ethernet topology and reliability and fault tolerance techniques in the workshop are studied.An experimental platform of microservice architecture CNC systems is built using an industrial server and two machine tools.Performance tests and actual processing experiments has shown the feasibility of the overall system.