Wireless routing and control: a cyber-physical case study (original) (raw)

Distributed Control for Cyber-Physical Systems

| Networked Cyber-Physical Systems (CPS) are fundamentally constrained by the tight coupling and closed-loop control and actuation of physical processes. To address actuation in such closed-loop wireless control systems there is a strong need to re-think the communication architectures and protocols for maintaining stability and performance in the presence of disturbances to the network, environment and overall system objectives. We review the current state of network control efforts for CPS and present two complementary approaches for robust, optimal and composable control over networks. We first introduce a computer systems approach with Embedded Virtual Machines (EVM), a programming abstraction where controller tasks, with their control and timing properties, are maintained across physical node boundaries. Controller functionality is decoupled from the physical substrate and is capable of runtime migration to the most competent set of physical controllers to maintain stability in the presence of changes to nodes, links and network topology.

Design Considerations for Wireless Networked Control Systems

IEEE Transactions on Industrial Electronics, 2016

In traditional networked control systems, wired communication networks are used for the transmission of information between the communicating systems. With the increasing demand for distributed systems and the growth in the scale of the applications, the use of wireless communication networks offers significant advantages over their wired counterparts. To facilitate the deployment of a fully automated closed-loop Wireless Networked Control System (WNCS), this paper addresses several design considerations for a proposed topology for potential use as a closed-loop WNCS. The topology consists of a plant system having sensor and actuator nodes, a controller system having input and output nodes, an intermediate network system having interconnected nodes, and wireless communication links for the information transfer between the different nodes of the plant, controller and network systems. More specifically, the design considerations addressed in the paper are: the condition requirements needed to facilitate the design of optimal controller and network systems, the joint design of optimal controller and network systems to control the plant system, and the structured model reduction of the closed-loop WNCS to reduce its scale. Finally, simulation examples are provided to demonstrate the applicability of discussed design considerations. Index Terms-Cyber-physical systems, distributed systems, industrial control, networked control systems, wireless automation. I. INTRODUCTION A traditional networked control system uses wired communication networks to transfer the information between the communicating systems in the closed-loop control system. This technique can introduce limitations, such as in the distribution of the systems and in the increase of the scale of the applications. Thus, wireless communication networks can become suitable replacements for their wired counterparts. This control system architecture is referred to as a Wireless Networked Control System (WNCS), and has been studied in different perspectives; for example, the construction of decentralized event-triggered implementations over wireless sensor

An Architecture for Wireless Sensor Actor Networks for Industry Control

International Journal on Advances in Networks and Services

A robust and reliable architecture for wireless sensor actor networks for industry control (WASANIC) is discussed and described in this paper. The stringent physical constraints in an industry environment are taken into consideration. We proposed an architecture that allows efficient cross-layering between a semi-scheduled medium access control (MAC) protocol called the Neighbor Turn Taking MAC (NTT-MAC) and a routing protocol based on the Multi-Meshed Tree (MMT) routing algorithm that is suited to the WSANIC topology encountered in an industry. The proposed architecture also addresses survivability and security. The cross-layered approach, named NTT-MMT, supports reliable and robust transportation of data. Through simulations, the performance of NTT-MMT was compared with carrier sense multiple access with collision avoidance (CSMA/CA) MAC and dynamic source routing (DSR) protocol.

Robust Wireless Sensor and Actuator Networks for Networked Control Systems

Sensors

The stability guarantee of wireless networked control systems is still challenging due to the complex interaction among the layers and the vulnerability to network faults, such as link and node failures. In this paper, we propose a robust wireless sensor and actuator network (R-WSAN) to maintain the control stability of multiple plants over the spatial-temporal changes of wireless networks. The proposed joint design protocol combines the distributed controller of control systems and the clustering, resource scheduling, and control task sharing scheme of wireless networks over a hierarchical cluster-based network. In particular, R-WSAN decouples the tasks from the inherently unreliable nodes and allows control tasks to share between nodes of wireless networks. Our simulations demonstrate that R-WSAN provides the enhanced resilience to the network faults for sensing and actuation without significantly disrupting the control performance.

Industrial control over wireless networks

International Journal of Robust and Nonlinear Control, 2000

Traditionally, industrial control systems have relied on hardwired information flows among sensor, actuator and control nodes over rather simple network architectures. Over the last decades, distributed control systems have seen a transition to communication buses, such as fieldbus and Ethernet. At present, there is a major interest in taking a further step in this evolution by incorporating wireless connectivity with a concrete perspective of achieving increased efficiency, flexibility, mobility and easier installation. As a matter of fact, wireless technology is already present in several manufacturing and process industries. Wireless links have already been installed for long-range (100-1000 m) monitoring applications, wireless LANs have been used for applications with non-stringent communication requirements (e.g. logistics) and wireless communication has been even used for instrumentation setups (e.g. temperature and pressure measurements).

Wireless Sensor Actor Networks For Industry Control

A robust and reliable architecture for wireless sensor actor networks for industry control is discussed and described in this paper. The stringent physical constraints in an industry environment are taken into consideration. A combination of MAC and routing protocol to support reliable and robust transportation of data is described.

Challenges of Wireless Control in Process Industry

There has been tremendous interest in the research and development of wireless technology. In general wireless for the control industry is not a new topic, either. Many industry organizations; such as, WINA, ZigBee, and ISA have been pushing wireless technology for years. There is a set of well-known and agreed upon challenges that we have to overcome to apply wireless to industry control; such as, security, robustness, delay, and power. After touching on those concerns briefly, we will analyze the challenges in applying control over process sensor networks. While using sensor network for process monitoring has been studied extensively and we already see products on the market, doing control over a sensor network is still considered impractical. While people agree this will eventually happen, a continued long term effort from both academia and industry is required. This paper lists several areas to collaborate on.

Novel wireless sensors network routing approach for industrial process control

10th International Multi-Conferences on Systems, Signals & Devices 2013 (SSD13), 2013

The present work treats the problem of routing data within a wireless sensors network (WSN) for industrial process control. Our application interests British Gas to monitor the level of propane in a tank. The considered methodology is based on the algorithm CSMA / CA Slotted to access the medium, the processing algorithm measures the volume of propane to exploit failing sensors and intelligent routing algorithm transmission value through the base station while ensuring minimizing energy consumption and maximizing the life time of nodes. The combination of these mechanisms gives birth to a new approach which has been applied to a WSN installed in the industry in order to analyze the performance of the techniques developed for the quality of service Qos, the energy conservation and extension of life.

Robust architectures for embedded wireless network control and actuation

ACM Transactions on Embedded Computing Systems, 2012

Networked Cyber-Physical Systems are fundamentally constrained by the tight coupling and closed-loop control of physical processes. To address actuation in such closed-loop wireless control systems there is a strong need to re-think the communication architectures and protocols for reliability, coordination and control. We introduce the Embedded Virtual Machine (EVM), a programming abstraction where controller tasks with their control and timing properties are maintained across physical node boundaries and functionality is capable of migrating to the most competent set of physical controllers. In the context of process and discrete control, an EVM is the distributed runtime system that dynamically selects primarybackup sets of controllers given spatial and temporal constraints of the underlying wireless network. EVMbased algorithms allow network control algorithms to operate seamlessly over less reliable wireless networks with topological changes. They introduce new capabilities such as predictable outcomes during sensor/ actuator failure, adaptation to mode changes and runtime optimization of resource consumption. An automated design flow from Simulink to platform-independent domain specific languages, and subsequently, to platform-dependent code generation is presented. Through case studies in discrete and process control we demonstrate the capabilities of EVM-based wireless network control systems.

Architecture for a fully distributed Wireless Control Network

Information Processing in Sensor Networks, 2011

We demonstrate a distributed scheme for control over wireless networks. In our previous work, we introduced the concept of a Wireless Control Network (WCN), where the network itself, with no centralized node, acts as the controller. In this demonstration, we show how the WCN can be utilized for distillation column control, a well-known process control problem. To illustrate the use of a WCN, we have utilized a process-inthe-loop simulation, where the behavior of a distillation column was simulated in Simulink and interfaced with an actual, physical network (used as the control network), which consists of several wireless nodes, sensors and actuators. The goal of this demonstration is to show the benefits of a fully-distributed robust wireless control/actuator network, which include simple scheduling, scalability and compositionality.