Time Synchronization

Coordinating clocks in multiple devices to function simultaneously.

Visible to the public  NIST CPS PWG
Jun 30, 2014 1:00 pm - 2:30 pm EDT

NIST Cyber-Physical Systems Public Working Group

What are Cyber-Physical Systems or CPS?

  • Is a CPS any engineered system with a microprocessor?
  • Do all CPS need to be connected to the internet?
  • Are there a set of basic functions and architectural elements common to all CPS?

You are invited to join us in answering these questions and charting the path to the future.


Visible to the public CPS: Breakthrough: Robust Team-Triggered Coordination for Real-Time Control of Networked Cyber-Physical Systems

The overarching project goal is to advance the design of opportunistic state-triggered aperiodic controllers for networked cyber-physical systems. This poster considers the problem of opportunistic human-robot collaboration to solve multi-objective optimization problems. We consider scenarios where a human decision maker works with a robot in a supervisory manner in order to find the best Pareto solution to a given optimization problem. The human has a time-invariant function that represents the value she gives to the different outcomes.


Visible to the public Safe Collaborative driving Systems

The objective of this project has been to apply the techniques developed for communications networks to collaborative, intelligent vehicles. The techniques are applied to a lane merge protocol that assists a driver who is merging between two vehicles in an adjacent lane.

The previous work that has been reported on this project includes: a multiple stack, layered architecture; a strategy for using synchronized clocks; and the probabilistic verification of protocols.


Visible to the public ROSELINE: Enabling Robust, Secure and Efficient Knowledge of Time Across the System Stack

Having a shared and accurate sense of time is critical to distributed Cyber-Physical Systems (CPS)
and the Internet of Things (IoT). Thanks to decades of research in clock technologies and
synchronization protocols, it is now possible to measure and synchronize time across distributed
systems with unprecedented accuracy. However, applications have not benefited to the same
extent due to limitations of the system services that help manage time, and hardware-OS and


Visible to the public Event-triggered Control for Nonlinear Systems with Time-Varying Input Delay poster.pdf

The overarching project goal is to advance the design of opportunistic state-triggered aperiodic controllers for networked cyber-physical systems. This poster considers the problem of event-triggered control design for cyberphysical systems with nonlinear dynamics under time-varying input delays.


Visible to the public The impact of QoT on feedback control systems Poster

It's common in controller design to assume that the controller reads the sensors and writes to the actuators at the same time instant. This assumption is often violated in practice because the controller executes its code sequentially on a microprocessor. If the microprocessor is "fast enough," often the controller will still work. However, if the sensing and control are done by two different devices that must communicate across a network, the resulting timing uncertainty due to network delays and clock offsets will often destabilize the controller.


Visible to the public Pulsar- Wireless Propagation-Aware Clock Synchronization

This poster presents the Pulsar platform, which can achieve better than 5 nanosecond clock synchronization in an indoor environment combining wireless ultra-wideband communication with a chip-scale atomic clock. We discuss the various challenges in synchronization at nanosecond scales then propose and evaluate a proof-of-concept protocol for the same.


Visible to the public Foundations Of Resilient CybEr-physical Systems (FORCES)

The FORCES group

FORCES is designed to help protect the nation's critical infrastructure from attack and to ensure its robust, secure and efficient operation. Specifically, FORCES aims to increase the resilience of large-scale networked cyber-physical systems (CPS) in the key areas of energy delivery, transportation, and energy management in buildings.