This NIST Special Publication describes the relationship between the phrases cyber-physical systems and Internet of Things. CPS and IoT both refer to trends in integrating digital capabilities, including network connectivity, with physical devices and systems. This document describes the origins of these terms, analyzes the range of definitions over time, describes a unified perspective, and explores implications of this perspective. Four categories of overlap were identified in publications comparing and contrasting CPS and IoT. The distinctions hinge on three issues: control, internet, and human interactions. The lack of consistent distinguishing metrics and the convergence of definitions indicate an emerging consensus around the equivalence of CPS and IoT concepts. This convergence creates opportunities for progress through integrating the research, innovation, and standards efforts of the respective communities. Two models provide the bases for a unified CPS/IoT perspective. A unified components model provides 4 categories for CPS and IoT systems components: logical, physical, transducing, and human. A unified interactions model provides a formal basis for describing the performance of CPS and IoT systems. The unified perspective can be expressed as follows: Internet of Things and Cyber-Physical Systems comprise interacting logical, physical, and human components engineered for function through integrated logic and physics. Three criteria based on a characteristic set of components, capabilities, and functions are proposed for interchangeably labeling a system CPS or IoT. Implications of a unified CPS and IoT perspective include the need for new hybrid discrete and continuous methods as science and engineering foundations for CPS/IoT design, operation, and assurance; and the importance of tight logical-physical linkage as the basis for the transformational nature of CPS/IoT systems.
Special Publication (NIST SP) - 1900-202
CPS, Cyber-Physical Systems, IoT, Internet of Things, Definition, Standards