Semantics- and Task-Oriented Scheduling for Networked Control Systems in Practice

Abstract

Networked control systems (NCSs) are feedback control loops closed over a communication network. Emerging applications, such as telerobotics, drones, and autonomous driving, are the most prominent examples of such systems. Regular and timely information sharing between the components of NCSs is essential to fulfilling the desired control tasks, as stale information can lead to performance degradation or even physical damage. In this work, we consider multiple heterogeneous NCSs that transmit their system state over a shared physical wireless channel to a gateway node. We conduct a comprehensive experimental study on selected MAC protocols using software-defined radios with state-of-the-art (SotA) solutions designed to increase information freshness and control performance. As a significant improvement over the SotA, we propose a novel contention-free algorithm that is able to outperform the existing solutions by combining their strengths in one protocol. In addition, we propose a new metric called normalized mean squared error that maps the age of information to a dimensionless quantity that captures the expected value of a control system's next transmission. We demonstrate its adoption and effectiveness for wireless resource scheduling in a case study involving multiple inverted pendulums. From our experimental study and results, we observe that value-aware prioritization of the sub-systems contributes to minimizing the adverse effects of information staleness on control performance. In particular, as the number of devices increases, the benefit of control awareness to the quality of control stands out when compared to protocols that focus solely on maximizing information freshness.INDEX TERMS Age of information, networked control systems, semantics of information, task-oriented communications

Optimal Finite Horizon Scheduling of Wireless Networked Control Systems

“…One of the possible extensions of this work would be the implementation of the FH scheduling algorithm on real hardware, e.g., using software-defined radios as in [47]. Moreover, the proposed theoretical framework can be employed to capture alternative task-criticalities, contexts, and semantics through the replacement of the utilized scheduling metric, i.e., nMSE, with a different age-penalty function.…”

“…To name an example, in a different work involving real-life measurements, we have shown that simple contention-free protocols outperform the random access protocols mentioned above w.r.t. information freshness and control performance [47]. Therefore, we do not consider contention-based protocols in the remainder of this work.…”

Large Population Games with Timely Scheduling over Constrained Networks

“…the paper [48] discusses the potential energy savings resulting from semantic interaction in connected autonomous vehicles; and the paper [49] demonstrates the effectiveness of semantics powered sampling for remote real-time source reconstruction. We refer the interested reader to [50], [51], and the references therein for additional details. In this work, we capture the semantics of information using the value of information (VoI) metric [26].…”

Goal-Oriented Transport Layer Protocols for Wireless Control

“…The sampling periodicity is set to 10 ms. The selection of the parameters defines the state-space representation (1) of IP, the details of which can be found in [9]. III.…”