Minimization of sensor activation in discrete-event systems with control delays and observation delays

Abstract

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 activation 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 minimise sensor activation 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 decentralised observation setting.

Keywords:

• Discrete-event systems
• sensor activation
• control delays
• observation delays

Disclosure statement

No potential conflict of interest was reported by the author(s).

Notes

1 To fulfill the sensor activation task, we may activate an event that is not active at the current state due to observation delays and control delays. Thus, the SAP Δ is defined over the whole $Q\times {\mathrm{\Sigma }}_o$ instead of $\{(q,\sigma )\in Q\times {\mathrm{\Sigma }}_o:\delta (q,\sigma )!\}$.

2 The definition of ${\theta }^{\hat{\mathrm{\Delta }}}$ for a transition-based SAP $\hat{\mathrm{\Delta }}$ can be obtained in a similar way as that of ${\theta }^{\mathrm{\Omega }}$ for a language-based SAP Ω, as stated in Wang, Lafortune, Lin, et al. (2010).