Timing in cyber-physical systems: The last inch problem

Distributed cyber-physical systems (CPS) are increasingly provided with an accurate and precise common sense of time using a variety of well established time distribution methods such as GNSS, IEEE 1588 and others. Less attention has been paid to the effective use of time in CPS and techniques and components to support such use. This paper reviews these topics and discusses critical components that are needed. If this infrastructure is properly realized recent work suggests that subject to well defined constraints, it will be possible to design CPS where timing is correct-by-construction.