IEEE Access Special Section: Cyber-Physical Systems

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Machine tool digital twin: Modelling methodology and applications

Cyber-Physical Machine Tools (CPMT) represent a new generation of complete Cyber-Physical Systems (CPS)-based machine tools that deeply integrate machine tool and machining processes with computation and networking. CPMT have a higher level of connectivity, intelligence and autonomy compared to current machine tools. Digital Twin is a critical component of any CPS. The core of a CPMT lies in the Machine Tool Digital Twin (MTDT). This paper presents the methodology for modelling the MTDT based on open, unified and platform-independent communication standards such as MTConnect and OPC UA. Two applications of the MTDT are developed to demonstrate the advantages and potential of the proposed approach. The first application is a Web-based machine tool condition monitoring application that allows users to monitor the real-time status as well as the 3D model of the machine tool through web browsers on mobile devices. The second application is an advanced Augmented Reality (AR)-assisted wearable Human-Machine Interface (HMI) that provides users with intuitive and enhanced visualization of the machining processes

Evaluation of (De-)Centralized IT technologies in the fields of Cyber-Physical Production Systems

In the course of the digital transformation, organizations are not only facing increasing volatility of the markets, but also increasing customer requirements and thus an increasing complexity in production and logistics systems. Therefore, production plants need to become more flexible by transforming conventional production systems to Cyber-physical Production Systems (CPPS). CPPS allow organizations to dynamically react to fluctuations in demand and markets and to introduce new product lines quickly and effectively. The challenge in implementing CPPS is to handle and store relevant data streams between Cyber-physical objects in a secure but transparent way. As CPPS involve a high level of decentralization, the data storage can either be combined with centralized IT-solutions like a Cloud or utilize decentralized IT-technologies like Edge Computing or Distributed Ledger Technologies (DLT) like Blockchains. The paper addresses the suitability of centralized and decentralized technologies in terms of dealing with data streams in the fields of CPPS. For this purpose, based on a paper exploration, appropriate evaluation criteria are derived, followed by a comparison of exemplary centralized and decentralized technologies. The outcome is a qualitative evaluation of the supplement of each technology regarding its suitability of dealing with data streams

Machine Tool Communication (MTComm) Method and Its Applications in a Cyber-Physical Manufacturing Cloud

The integration of cyber-physical systems and cloud manufacturing has the potential to revolutionize existing manufacturing systems by enabling better accessibility, agility, and efficiency. To achieve this, it is necessary to establish a communication method of manufacturing services over the Internet to access and manage physical machines from cloud applications. Most of the existing industrial automation protocols utilize Ethernet based Local Area Network (LAN) and are not designed specifically for Internet enabled data transmission. Recently MTConnect has been gaining popularity as a standard for monitoring status of machine tools through RESTful web services and an XML based messaging structure, but it is only designed for data collection and interpretation and lacks remote operation capability. This dissertation presents the design, development, optimization, and applications of a service-oriented Internet-scale communication method named Machine Tool Communication (MTComm) for exchanging manufacturing services in a Cyber-Physical Manufacturing Cloud (CPMC) to enable manufacturing with heterogeneous physically connected machine tools from geographically distributed locations over the Internet. MTComm uses an agent-adapter based architecture and a semantic ontology to provide both remote monitoring and operation capabilities through RESTful services and XML messages. MTComm was successfully used to develop and implement multi-purpose applications in in a CPMC including remote and collaborative manufacturing, active testing-based and edge-based fault diagnosis and maintenance of machine tools, cross-domain interoperability between Internet-of-things (IoT) devices and supply chain robots etc. To improve MTComm’s overall performance, efficiency, and acceptability in cyber manufacturing, the concept of MTComm’s edge-based middleware was introduced and three optimization strategies for data catching, transmission, and operation execution were developed and adopted at the edge. Finally, a hardware prototype of the middleware was implemented on a System-On-Chip based FPGA device to reduce computational and transmission latency. At every stage of its development, MTComm’s performance and feasibility were evaluated with experiments in a CPMC testbed with three different types of manufacturing machine tools. Experimental results demonstrated MTComm’s excellent feasibility for scalable cyber-physical manufacturing and superior performance over other existing approaches

Machine Tool Communication (MTComm) Method and Its Applications in a Cyber-Physical Manufacturing Cloud

The integration of cyber-physical systems and cloud manufacturing has the potential to revolutionize existing manufacturing systems by enabling better accessibility, agility, and efficiency. To achieve this, it is necessary to establish a communication method of manufacturing services over the Internet to access and manage physical machines from cloud applications. Most of the existing industrial automation protocols utilize Ethernet based Local Area Network (LAN) and are not designed specifically for Internet enabled data transmission. Recently MTConnect has been gaining popularity as a standard for monitoring status of machine tools through RESTful web services and an XML based messaging structure, but it is only designed for data collection and interpretation and lacks remote operation capability. This dissertation presents the design, development, optimization, and applications of a service-oriented Internet-scale communication method named Machine Tool Communication (MTComm) for exchanging manufacturing services in a Cyber-Physical Manufacturing Cloud (CPMC) to enable manufacturing with heterogeneous physically connected machine tools from geographically distributed locations over the Internet. MTComm uses an agent-adapter based architecture and a semantic ontology to provide both remote monitoring and operation capabilities through RESTful services and XML messages. MTComm was successfully used to develop and implement multi-purpose applications in in a CPMC including remote and collaborative manufacturing, active testing-based and edge-based fault diagnosis and maintenance of machine tools, cross-domain interoperability between Internet-of-things (IoT) devices and supply chain robots etc. To improve MTComm’s overall performance, efficiency, and acceptability in cyber manufacturing, the concept of MTComm’s edge-based middleware was introduced and three optimization strategies for data catching, transmission, and operation execution were developed and adopted at the edge. Finally, a hardware prototype of the middleware was implemented on a System-On-Chip based FPGA device to reduce computational and transmission latency. At every stage of its development, MTComm’s performance and feasibility were evaluated with experiments in a CPMC testbed with three different types of manufacturing machine tools. Experimental results demonstrated MTComm’s excellent feasibility for scalable cyber-physical manufacturing and superior performance over other existing approaches