  In discrete-event systems, to save sensor resources, the agent continuously
adjusts sensor activation decisions according to a sensor activation policy
based on the changing observations. However, new challenges arise for sensor
activations in networked discrete-event systems, where observation delays and
control delays exist between the sensor systems and the agent. In this paper, a
new framework for activating sensors in networked discrete-event systems is
established. In this framework, we construct a communication automaton that
explicitly expresses the interaction process between the agent and the sensor
systems over the observation channel and the control channel. Based on the
communication automaton, we can define dynamic observations of a communicated
string. To guarantee that a sensor activation policy is physically
implementable and insensitive to non-deterministic control delays and
observation delays, we further introduce the definition of delay feasibility.
We show that a delay feasible sensor activation policy can be used to
dynamically activate sensors even if control delays and observation delays
exist. A set of algorithms are developed to minimize sensor activations in a
transition-based domain while ensuring a given specification condition is
satisfied. A practical example is also provided to show the application of the
proposed framework. Finally, we briefly discuss how to extend the proposed
framework to a decentralized observation setting.
