Wireless Routing and Control: A Cyber-Physical Case Study

Abstract

Wireless sensor-actuator networks (WSANs) are being adopted in process industries because of their advantages in lowering deployment and maintenance costs. While there has been significant theoretical advancement in networked control design, only limited empirical results that combine control design with realistic WSAN standards exist. This paper presents a cyberphysical case study on a wireless process control system that integrates state-of-the-art network control design and a WSAN based on the WirelessHART standard. The case study systematically explores the interactions between wireless routing and control design in the process control plant. The network supports alternative routing strategies, including single-path source routing and multi-path graph routing. To mitigate the effect of data loss in the WSAN, the control design integrates an observer based on an Extended Kalman Filter with a model predictive controller and an actuator buffer of recent control inputs. We observe that sensing and actuation can have different levels of resilience to packet loss under this network control design. We then propose a flexible routing approach where the routing strategy for sensing and actuation can be configured separately. Finally, we show that an asymmetric routing configuration with different routing strategies for sensing and actuation can effectively improve control performance under significant packet loss. Our results highlight the importance of co-joining the design of wireless network protocols and control in wireless control systems. * The first two authors contributed equally to this work.

Age-of-information vs. value-of-information scheduling for cellular networked control systems

“…In order to compensate for packet drops or delays caused by the network, each controller C i employs a Kalman-like state estimator as in [11,22]. The state estimation is based on the following assumptions: Assumption 1 is motivated by the time-invariant nature of the sub-systems' dynamics.…”

Fast Feedback Control over Multi-hop Wireless Networks with Mode Changes and Stability Guarantees

“…The control community has investigated design and stability analysis for wireless (and wired) networks based on different system architectures, delay models, and message loss processes; recent surveys provide an overview of this large body of fundamental research [31,71]. However, the majority of those works focuses on theoretical analyses or validates new wireless CPS designs (e.g., based on WirelessHART [39,48]) only in simulation, thereby ignoring many fundamental challenges that may complicate or prevent a real implementation [42]. One of the challenges, as detailed in Section 3, is that even slight variations in the quality of a wireless link can trigger drastic changes in the routing topology [15]and this can happen several times per minute [26].…”

Industrial wireless sensor and actuator networks in industry 4.0: Exploring requirements, protocols, and challenges—A MAC survey

“…Reliability can be characterized in terms of packet reception rate, ie, packet reception rate should be above a certain threshold to guarantee a certain level of reliability in which processes and systems work without further degradation. Packet priority and heterogeneity. Industrial domain is heterogeneous, different types of packets are generated like sensing measurements, controlling commands, actuation tasks, etc. Each of the traffic has a different priority to be treated.…”

“…• Packet priority and heterogeneity. Industrial domain is heterogeneous, different types of packets are generated like sensing measurements, controlling commands, actuation tasks, 74 etc. Each of the traffic has a different priority to be treated.…”