CYBER-PHYSICAL SYSTEMS AND MANUFACTURING PARADIGMS SISTEMAS CIBER – FÍSICOS Y PARADIGMAS DE FABRICACIÓN SISTEMAS CIBER – FÍSICOS E PARADIGMAS DE FABRICAÇÃO Oscar D. Quiroga, Universidad Nacional del Litoral (FIQ-UNL)
[email protected] Luis J. Zeballos, INTEC (CONICET-UNL)
[email protected] Abstract In the bibliography, the term Cyber-Physical System (CPS) does not have a single fully accepted definition. The differences in the definitions are mainly related to the perspective adopted. However, in most areas related to engineering, the definition with greater acceptance defines CPS as the integration of computing with the physical processes that allow the connections of the cyber-physical world. Embedded computers and networks monitor and control the physical processes, usually with feedback loops where physical processes affect computations and vice versa. Taking into account the definition given above, the objective of this paper is to relate CPS to some of the manufacturing paradigms that have arisen up to the present, such as Virtual Computer Integrated Manufacturing (VCIM) and Cloud Manufacturing (CM). Resumen En la bibliografía, el término sistema ciber-físico (CPS) no tiene una definición única totalmente aceptada. Las diferencias en las definiciones se relacionan principalmente con la perspectiva adoptada. Sin embargo, en la mayoría de las áreas relacionadas con la ingeniería, la definición con mayor aceptación indica a CPS como la integración de la computación con los procesos físicos que permiten las conexiones del mundo ciber-físico. Las computadoras y redes integradas monitorean y controlan los procesos físicos, generalmente con lazos de realimentación donde los procesos físicos afectan los cálculos y viceversa. Teniendo en cuenta la definición dada anteriormente, el objetivo de este trabajo es relacionar al CPS con algunos de los paradigmas de fabricación que han surgido hasta el presente, tales como Fabricación Integrada por Computadora Virtual (VCIM) y Fabricación en la Nube (CM). Resumo Na bibliografia, o termo sistema ciber-físico (CPS) não possui uma definição única e totalmente aceita. As diferenças nas definições estão relacionadas principalmente com a perspectiva adotada. Entretanto, na maioria das áreas relacionadas à engenharia, a definição com maior aceitação indica ao CPS como a integração da computação com os processos físicos que permitem as conexões do mundo ciber-físico. Computadores e redes integradas
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monitoram e controlam os processos físicos, geralmente com laços de retroalimentação, nos quais os processos físicos afetam os cálculos e vice-versa. Levando em conta a definição dada acima, o objetivo deste artigo é relacionar ao CPS a alguns dos paradigmas de manufatura que emergiram até o presente, como a Fabricação Integrada por Computador Virtual (VCIM) e a Fabricação na Nuvem (CM).
Keywords: INFORMATION SYSTEMS AND TECHNOLOGY; CYBER-PHYSICAL SYSTEMS; VIRTUAL COMPUTER INTEGRATED MANUFACTURING; CLOUD MANUFACTURING. Palabras clave: SISTEMAS DE INFORMACIÓN Y TECNOLOGÍA; SISTEMAS CIBERFÍSICOS; FABRICACIÓN INTEGRADA POR COMPUTADORA VIRTUAL; FABRICACIÓN EN LA NUBE. Palavras - chave: SISTEMAS DE INFORMAÇÃO E TECNOLOGIA; SISTEMAS CIBERFÍSICOS; FABRICAÇÃO INTEGRADA POR COMPUTADOR VIRTUAL; FABRICAÇÃO NA NUVEM. 1. Introduction In the last forty years, the manufacturing environments have suffered important changes mainly due to technological and philosophical improvements connected with the manufacturing processes. The applications of computers in the manufacturing equipment and the developments in information and communication technology (ICT) have led to the emergence of various new manufacturing technologies, which are called as AMTs (Advances Manufacturing Technologies) (Hunt, 1987). AMTs are key technologies for starting to solve the problems of achieving effective and efficient manufacturing strategies, but they are not sufficient. The integration of physical and functional parts of manufacturing organizations gives a relevant competitive advantage by relating, for example, new and existing equipment as well as software, together with database management systems, data communications systems achieving a coordinated and efficiently management process. Furthermore, supplementary improvements can be obtained by considering cross-functional approach and integrating many technologies across all functional units of enterprises. Thus, integration of manufacturing enterprises considers from physical aspects to application integration, and then to business process integration (Vernadat, 1996). In the first part, this paper introduces the concept and characteristics of manufacturing paradigms that allow improving the performance of manufacturing organizations. In the second part, the CPS concept is presented and the main characteristics of CPS are mentioned. Then, the CPS concept is contrasted with the most important manufacturing paradigms. The last part contains the paper conclusions. 2. Manufacturing paradigms One of the most important concepts developed with the objective of integrating the manufacturing environments was CIM. The conceptual bases were initially proposed by Harrington (1973), which considered to CIM as a control and communication structure to integrate a manufacturing system. Nevertheless, the CIM definition has been modified due to the world globalization, the appearance of new AMTs, information technologies and the
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development of different paradigms associated with the business models. Given that the limitations of the CIM concept to fulfill the requirements of globally distributed customers and compete with the capability of other enterprises, more methodologies have been required. Thus, the concept of Distributed CIM (DCIM) has been coined in order to deal with the problems related with the physical interconnection of distributed enterprises, nevertheless a more flexible and comprehensive concept than DCIM was developed, such as Virtual CIM (VCIM) (Zeballos and Quiroga, 2017). VCIM concept merged in order to focus CIM to the dynamic nature of improvements in manufacturing applications, the globalization of the potential markets and production facilities. Practical VCIM implementations comprise subsystems integration using network communications, application of wide-area networks, Internet and intranet based applications, information enhancement by data integration across various system boundaries. The research on VCIM includes models and architectures for enterprise integration, evaluation methodologies for enterprise integration, and international collaboration. Furthermore, topics related to integration of client and server for manufacturing shop-floor automation, application of multimedia and hypermedia for VCIM environment, data management for VCIM systems are to be investigated and integrated. VCIM concept was formalized by the Centre for Advanced Manufacturing Research (CAMR) of University of South Australia and presented by Professor Grier Lin at his keynote speech at the Fourth International Conference of Computer Integrated Manufacturing in Singapore in 1997. VCIM improves the CIM concept developed by the Society of Manufacturing Engineers (SME) in 1992 in order to describe: a) features such as global competition, environmental concerns, mass customization to satisfy the variety of customer requirements, shorter product life cycles of the product, and requirement for innovative products and of faster response, b) concisely the way the systems and concepts can be implemented, c) the finishing expected results of CIM, taking into account the global integrated company through an integrated architecture based on global information and communication links. Finally, it is important to introduce the paradigm called Cloud Manufacturing (CM) that comes from the concept of Cloud Computing (CC), which was defined by the National Institute of Standards and Technology (NIST) as a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computing resources, such as networks, servers, storage, applications and services, that can be rapidly provisioned and released with minimal management effort or service provider interaction (Mell and Grance, 2011). CC has proven to be a disruptive technology that takes advantage of technologies such as Utility Computing, Parallel Computing, and Virtualization. On-demand computing, scalability and elasticity, and self-service provisioning, are some of its most important characteristics (Wu et al., 2014; Foster et al., 2008; Putnik et al., 2013). In CC everything is treated as a service. Implementing CC means a paradigm shift of business and ICT infrastructure, where computing power, data storage and services are outsourced to third parties and made available to enterprises and customers as commodities (Xu, 2012). From the NIST’s definition of CC, many authors have proposed definitions of CM, in which it is considered as a new manufacturing paradigm, as well as a model of computing and service–oriented manufacturing that is developed from existing advanced manufacturing models, such as Agile Manufacturing, Networked Manufacturing, Manufacturing Grid and enterprise information technologies supported by CC (Zhang et al., 2014; Xu, 2012; Wu et al., 2012; Tao et al., 2012).
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CC and IoT (Internet of Things) are technologies that influence the development of CM in a strong and sustained way (Wu and Xu, 2015). CM transforms resources and manufacturing capabilities into manufacturing services that can be managed and operated in an intelligent and unified manner to enable complete exchange and circulation of resources and manufacturing capabilities. CM can provide safe, reliable, high quality, on-demand and cheap manufacturing services for the entire manufacturing lifecycle. The concept of manufacturing includes the entire lifecycle of a product, and according to it, CM is a concept designed to offer on-demand manufacturing services based on network manufacturing resources, and enabled for the cloud, which imitates the CC service paradigm promoting that everything is treated as a service. For example: design, production, assembly, testing and logistics as a service (Li et al., 2010, Zhang et al., 2014, Zang et al., 2011). Since the resources and manufacturing capabilities are shared as services through the Internet; therefore, CM is considered beneficial to small and medium-sized enterprises (SMEs) (Yu et al., 2015). Moreover, CM aims to achieve full shared use and circulation, high utilization and on-demand use of various resources and manufacturing capabilities by providing safe, reliable, and high quality, cheap and on-demand manufacturing services for the entire lifecycle of manufacturing (Tao et al., 2011). 3. Cyber-Physical Systems Advances in communication systems, in computing and in detecting devices, along with the cost reduction of these technologies, have driven the development of powerful systems of monitoring and control based on the Internet of Things paradigm. These new systems provide different types of services associate to improve the transport systems, the weather monitoring, manufacturing activities, etc. Formally, these systems are called CyberPhysical Systems. Nowadays, these systems are still in development and their best versions depend on different problems that the industry and research community are actively trying to solve. The problems are principally connected with availability, security, robustness, performance and resources optimization. Cyber-Physical Systems integrate computing elements with the physical components and processes. The computing elements coordinate and communicate with sensors, which monitor cyber and physical indicators, and actuators, which modify the cyber and physical environment. Cyber-Physical Systems use sensors to link all distributed intelligence in the environment to improve a profounder knowledge of the environment, which permits a more precise actions and tasks. Another important characteristic associated with CPS is the realtime computing where physical systems interact tightly. Therefore, in this work, the concept of CPS is associated with big complex physical systems that interact with a significant amount of distributed computing elements for monitoring, control and management which are able to interchange data among them and human users (operators, managers, customers). It is important to note that while the physical systems involve the exchange of material, energy, the use of shared resources, the components of the control and management system are linked by network of communication that in some cases enforce constraints on the type and amount of information. According to Liu et al. (2017) CPS maintains the following characteristics: a) Physical System is the Most Important Field of CPS due to physical system design that involve the hardware design, energy management, hardware size and connectivity encapsulation and system testing are key elements to achieve the integration of computing elements with physical components and processes.
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b) Information System is the Core of CPS given that information system can transform the information in physical system into the rules and models of software systems. The most basic task in the integration of information is to reach a balance among factors such as real time system, network system, file system, hierarchical storage system, memory management, modular software design, concurrent design and formal verification. c) CPS is the Product of Integration of distributed Heterogeneous Systems where one of the most important aspects is deal with the problem of time synchronization and space location of different components. d) CPS has Requirements of Security, Real-time Capability, and Predictability. Thus, CPS must be able to deal with the problem of credibility, security, effectiveness, real-time, dynamic and predictability. Credibility refers to that senders and receivers must be able to identify the receivers and senders to prevent counterfeiting. Security refers to the encryption and decryption of the interchanged information, while the privacy of information is kept. Validity means the accuracy of processing as well as the validity and integrity of information or instruction set must be guaranteed to prevent the uncertainties and noise in CPS processing from affecting the system processing accuracy. Real-time capability means collected information or instructions must be transmitted timely to meet the temporal requirements of task processing. Dynamic includes the continuous temporal reorganization and reconfiguration, which is to automatically adjust rules and generate guidelines based on the task requirements and changes in external environments to eliminate bias and meet task requirements according to preset rules. 4. Cyber-Physical Systems and the main manufacturing paradigms Cyber-physical systems are enablers for changing business logic and value chains, with the conjunction of cyber-physical systems and the development of new business models facilitating the creation of disruptive innovations (Rauch et al., 2016). In many cases, the concept of CPS is associated itself to a manufacturing paradigm (reference), and it is compared with paradigms such as CIM, VCIM and CM. However, following the definition given above, it can be observed that the concept is more general than the specific one of manufacturing. Moreover, CPS involves work in real time and is based on highly coordinated and communicated physical and computer systems that are associated with different fields of applications (highly credible medical devices and systems, traffic control, environmental control, critical infrastructure, energy consumption and regeneration, future defense systems, distributed robotics, civil infrastructure, etc.). In this sense, the term “Industrie 4.0” is the one that best associates CPS with the manufacturing environments. Industrie 4.0 refers to the fourth industrial revolution and it was originated from a project in the high-tech strategy of the German government, which promotes the computerization of manufacturing and considers the integration of logistics and production (Industrie 4.0 Working Group, 2013). Industrie 4.0’s fundamental idea is to integrate manufacturing systems of different smart factories along a value chain (or a value network) in the form of CPS so that real-time data and information across the entire value chain can be obtained, which enables real-time and accurate decisionmaking (Liu and Xu, 2017). As stated below, comparative analyses among the VCIM, CPS and CM paradigms are described in Table 1. The coincidences and differences are presented in detail in subsection 4.1.
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TABLE 1 – Differences among VCIM, CPS and CM. Parameters
VCIM
CPS
CM
Industrial Revolution
Driving forces of the Fourth Industrial Revolution
Driving forces of the Fourth Industrial Revolution
Driving forces of the Fourth Industrial Revolution
Focus
Integration of all activities in a network of enterprises to share resources and management objectives through information integration, in a cohesive manner to work as a seamless global CIM system.
Integration of computing elements with the physical components and processes. The computing elements coordinate and communicate with sensors.
Integration of shared collection of diversified and distributed manufacturing resources to form temporary, reconfigurable production lines which enhance efficiency, reduce product lifecycle costs, and allow for optimal resource loading in response to variable-demand customer generated tasking.
Integration Time
The integration is achieved after a given period of time.
Real-time integration.
Real-time integration.
Type of organization
World-wide cooperation of enterprises.
World-wide cooperation of computing elements , physical components and processes.
World-wide cooperation of enterprises.
Manufacturing perspective
Manufacturing as an activity of linked enterprises.
The CPS for manufacturing takes the manufacturing as an activity of an organization distributed
Manufacturing as a service of linked enterprises.
Information Technology perspective
Product-centred.
System-centred.
Service-centred.
Origin of the philosophy
Based on the CIM philosophy but including more flexibility and breath to overcome the distance barriers, facility sharing problems and communication obstacles.
Based on the IoT paradigm and the most advanced physical technologies.
Based on the developments of multidisciplinary researches resulting in the evolution and convergence of several computer trends.
Source: based on Authors’ elaboration, and Zeballos and Quiroga (2017).
4.1 Comparative Analysis of VCIM and CM paradigms with CPS In the first row of Table 1, it can be seen that all paradigms belong to the driven forces of the 4th Industrial Revolution. In relation to the next rows of Table 1, for the focus, VCIM integrates all activities in a network of enterprises in order to share resources and management objectives by integration of information. CPS integrates computing elements, coordinated and communicated with sensors, with the physical components and processes. And CM integrates the shared collection of distributed manufacturing resources to form reconfigurable production lines by improving efficiency, reducing product lifecycle costs. For the parameter integration time, CPS and CM have a real-time integration; meanwhile, for VCIM is achieved after a given period of time. In relation to type of organization, VCIM and CM coincide in a world-wide cooperation of enterprises; meanwhile, CPS belongs to a world-wide cooperation of
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computing elements, physical components and processes. In the case of the manufacturing perspective for VCIM is seen as an activity of linked enterprises; for CPS as an activity of an organization distributed; and for CM as a service of linked enterprises. In relation to the information technology perspective, for VCIM it is product-centred; for CPS it is systemcentred; and for CM it is service-centred. As a final point, for the case of the origin of the philosophy, VCIM is based on the CIM philosophy but including more flexibility. CPS is based on the Internet of Things paradigm and the most advanced physical technologies. And CM is based on the developments of multidisciplinary researches resulting in the evolution and convergence of several computer trends. 5. Conclusions This paper had the objective of studying the relation of the Cyber-physical Systems (CPS) to the VCIM and CM manufacturing paradigms. The work shows the main coincidences and differences among them. Thus, it is worth remarking that while all the paradigms analysed (VCIM, CPS and CM) are belonging to the 4th Industrial Revolution, important differenteces can be found taking into account various parameters, such as the focus, the integration time, the type of organization, the manufacturing perspective, the information technology perspective, and the origin of the philosophy. References Foster, I., Zhao, Y., Raicu, I., and Lu, S. (2008). Cloud Computing and Grid Computing 360-Degree Compared. Grid Computing Environments Workshop, Austin. 2008, p. 1–10. Harrington J. (1973). Computer Integrated Manufacturing. Industrial Press Inc., New York. Hunt, V.D. (1987). Dictionary of Advanced Manufacturing Technology. New York: Elsevier. Industrie 4.0 Working Group (2013). Securing the Future of German Manufacturing Industry— Recommendations for Implementing the Strategic Initiative, Munich, Germany, http://www.acatech.de/fileadmin/user_upload/Baumstruktur_nach_Website/Acatech/root/de/Material_fuer_Sond erseiten/Industrie_4.0/Final_report__Industrie_4.0_accessible.pdf Li, B. H., Zhang, L., Wang, S. L., Tao, F., Cao, J. W., Jiang, X. D., Song, X., and Chai, X. D. (2010). Cloud Manufacturing: A New Service-Oriented Networked Manufacturing Model. Computer Integrated Manufacturing Systems, 16(1), 1-7. Liu, Y., Y. Peng, B. Wang, S. Yao, and Z. Liu (2017). Review on Cyber-physical Systems. IEEE/CAA Journal of Automatica Sinica, Vol. 4, Nº 1, 27-40. Liu, Y., and Xu, X. (2017). Industry 4.0 and cloud manufacturing: a comparative analysis. J. Manuf. Sci. Eng. 139 (3), 034701. Mell, P., and Grance, T. (2011). The NIST definition of cloud computing, National Institute of Standards and Technology, U.S. Department of Commerce. Putnik, G., Sluga, A., ElMaraghy, H., Teti, R., Koren, Y., Tolio, T., and Hon, B. (2013). Scalability in manufacturing systems design and operation: State-of-the-art and future developments roadmap. CIRP AnnalsManufacturing Technology. Rauch, E., S. Seidenstricker, P. Dallasega, and R. Hämmerl (2016). Collaborative Cloud Manufacturing: Design of Business Model Innovations Enabled by Cyberphysical Systems in Distributed Manufacturing Systems. Hindawi Publishing Corporation Journal of Engineering. Volume 2016, Article ID 1308639, 12 pages.
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