Objective: To provide a common technical and conceptual foundation for CPS that enables conceptualization, realization and assurance of cyber-physical systems across all domains, including a comprehensive and traceable methodology for meeting all stakeholder concerns throughout any systems engineering process.
What is the technical idea? Cyber Physical Systems (CPS) integrate computation, communication, sensing and actuation with physical systems and humans to fulfill time-sensitive functions with varying degrees of interaction with the environment. These attributes provide the basis for a shared technical definition of CPS across all domains, all levels of functional-technical expertise and illustrate how progress in any one domain – for example new methods for CPS co-design – can fuel progress toward meeting common stakeholder concerns in many domains if developed through a common reference architecture.
The basic elements of a general CPS architecture include multiple layers from physical components and their associated sensors and actuators, through control systems and analytics, to the overall optimization and user functionality, with assurance that requirements have been satisfied. As described in the CPS Framework, work on CPS analysis methodology has led to the development of the organizational concepts of facets (modes of thinking: conceptualization, realization and assurance) and aspects (collections of concerns: functional, business, human, trustworthiness, timing, data, composition, boundaries, and lifecycle) to support system engineering analysis, design, development, operation, and validation and assurance of CPS. Though most CPS today have a domain-specific focus, the future of CPS will undoubtedly include massive communication and interoperation between domains. This CPS framework methodology provides a solid foundation for the development of a consensus technical architectures with common vocabulary and use cases that are, in turn, the basis for cooperation and collaboration for progress in all applications of cyber-physical systems. An example of the applicability of the CPS Framework as an analysis tool is in the Internet-of-Things-Enabled Smart City Framework (IES-City Framework) International Working Group, launched by NIST and its international partners. In this activity, the CPS Framework methodology is being applied to analyze existing deployed smart cities architectures and identify pivotal points of interoperability (PPI), in which common decisions have been made in different deployed architectures and can be leveraged to promote cross-domain (and multiple-architectural) applications.
What is the research plan? Building on the work of the NIST and its CPS PWG to develop and publish the CPS Framework Release 1.0 and the successful launch of the NIST-led IES-City Framework International Working Group, the research plan for this project now includes the following efforts: (1) progression of select components of the CPS Framework by NIST, such as in the areas of trustworthiness and assurance formal methods; (2) guiding working groups to identify pivotal points of interoperability in smart cities CPS/IOT deployed architectures, and finalizing the IES-City Framework Release 1.0 including addressing public comments; (3) tailoring of the CPS Framework for use in selected vertical domains, including the transportation industry through a collaboration with SAE; (4) development of UML and XML modeling and tools that effectively combining the functionality of the CPS Framework with use cases development modeling to support technology transfer to industry, including the transportation industry; and (5) continued introduction of technical contributions to and engagement with relevant national and international standards efforts.
Following the upcoming publication of Release 1.0 as a NIST Special Publication, the CPS Framework activity is focusing on more targeted work to improve key components of the Framework, such as trustworthiness (safety, security, privacy, resilience and reliability) and formal methods for assurance. As part of this activity, additional expertise in areas such as safety and reliability will be identified to further develop the aspect of trustworthiness of the CPS Framework, with the goal of developing and publishing an expanded CPS Framework component (aspect) of Trustworthiness.
After the IES-City Framework is completed, public comments will be solicited, reviewed and addressed to mature it to a final consensus form. After review and final publication of the IES-City Framework, it will be made available (like other work products) to relevant national and international standards efforts.
Through a NIST-SAE collaboration, a tailoring of the CPS Framework to the transportation domain is being produced, with special attention to trustworthiness for autonomous/connected vehicles. In addition, an application of the CPS test bed concept UCEF (universal CPS experimental facility) will be demonstrated for the transportation domain, as described in the CPS testbed project.
The UML/XML modeling tools activity is developing an XMLSchema that is derived from a composite UML model of a use case (IEC 62599-3) and a model of the CPS Framework. In conjunction with this XMLSchema, an example is being constructed of a CPS design from conceptualization to realization to assurance with all design artifacts populated in the model. By this means, a versatile data structure can be defined that is aligned with the CPS Framework and will enable tool integration during the systems engineering process of designing, building and testing a CPS. Outreach to system engineering tool builders to join a NIST-initiated open source project will occur in September 2017, and continue in FY18 to encourage uptake of the CPS Framework and its technology by industry through incorporation of these tools into their own development tool suites. An additional activity involves collaboration with the transportation sector on scoping an autonomous vehicle testbed as an application of the NIST federated testbed model. The NIST-SAE collaborators will work with transportation original equipment manufacturers and suppliers to represent the component systems of an autonomous, connected vehicle system as hardware or emulated hardware or simulated software components for purposes of configuring an autonomous vehicle test bed. ‘Federated’ into a testbed, these collaborators will pilot test and virtual assessment the system’s performance. Based on this work, a publication is planned to summarize the use of this pilot and test bed technology for transportation systems and developing the new measurement science needed for future autonomous systems.