Synchronizing sampling and actuation in the absence of global time in Networked Control Systems

The successful operation of Networked Control Systems (NCS) requires employing appropriate approaches for dealing with network induced time delays, i.e. time intervals elapsed from consecutive sampling and actuation operations. Effective approaches often require to impose periodic execution for the sampling and/or actuation operations, enforcing synchronized constant time delays. And considering that sampling and actuation is performed in different nodes, global time between nodes achieved by clock synchronization is the standard assumption or strategy that enables such synchronized operations. This paper presents a technique that permits to implement these synchronized operations in NCS in the absence of global time. Experimental results corroborate the effectiveness of the presented approach.