Time is central to predicting, measuring and controlling properties of the physical world, and is one of the most important constraints distinguishing Cyber-Physical Systems from distributed computing in general. However mixing the cyber and the physical has a fundamental challenge, since computers and communications systems have abstracted away the physical layer and timing is fundamentally a physical signal. CPS used in industry today achieve time-awareness by making use of time-aware fieldbuses and devices with specialized proprietary software. However, this approach has proven restrictive in both the topologies achievable, and the scalability of networks beyond a certain size. This is curbing improvements in efficiency, and is constraining innovation. The new era of the Internet-of-Things and the Industrial Internet is paving the way for convergence, where time is an integral part of the cyber, making integration of cyber and physical seamless. However, this requires successful research in a number of different areas. We discuss the current status of the research, and the potential future of how CPSs may be built on these new converged networks (with integrated time).
Proceedings of the IEEE
Cyber-physical systems, Internet of Things, time-sensitive networks, time-stamp