Wireless Sensor And Actuator Networks Research Articles

Distributed multi-agent architecture for real-time wireless control networks of multiple plants

This paper describes an interesting model architecture based on the tree topology, as well as its analysis through an associated validation method for control networks designed for low-rate wireless sensor and actuator networks (WSAN), consisting of multiple control loops closed over a wireless communication network, taking advantage of the flexible communications features of IEEE 802.15.4 protocol. The main problem to be addressed is the control of multiple or parallel plants, which should have an intelligent and flexible architecture based on multi-agent systems (MAS), that allows to add or remove new plants or nodes online, without the need of reconfiguring the system, while maintaining temporal and functional restrictions in the system. Important issues to consider in the research are tackled herein like topology, optimal static routing, end-to-end test analysis of the real-time flows on the WSAN, real-time kernel with Earliest Deadline First (EDF) scheduler, periodic and aperiodic tasking models for the nodes, lightweight and flexible compensation-based control algorithms for WSAN that exhibit packet dropouts, and an event-triggered sampling scheme. Additionally, as example of an application in a simulation environment is presented, in which is intended to guarantee an optimal parallel fed-batch bioreactor operations model controlled over a WSAN, using a master–slave synchronization system as control strategy, obtaining an accurate end-to-end communication analysis of the proposed plant with Wireless Sensor and Actuator Networks.

SensoTube: A Scalable Hardware Design Architecture for Wireless Sensors and Actuators Networks Nodes in the Agricultural Domain.

Wireless Sensor and Actuators Networks (WSANs) constitute one of the most challenging technologies with tremendous socio-economic impact for the next decade. Functionally and energy optimized hardware systems and development tools maybe is the most critical facet of this technology for the achievement of such prospects. Especially, in the area of agriculture, where the hostile operating environment comes to add to the general technological and technical issues, reliable and robust WSAN systems are mandatory. This paper focuses on the hardware design architectures of the WSANs for real-world agricultural applications. It presents the available alternatives in hardware design and identifies their difficulties and problems for real-life implementations. The paper introduces SensoTube, a new WSAN hardware architecture, which is proposed as a solution to the various existing design constraints of WSANs. The establishment of the proposed architecture is based, firstly on an abstraction approach in the functional requirements context, and secondly, on the standardization of the subsystems connectivity, in order to allow for an open, expandable, flexible, reconfigurable, energy optimized, reliable and robust hardware system. The SensoTube implementation reference model together with its encapsulation design and installation are analyzed and presented in details. Furthermore, as a proof of concept, certain use cases have been studied in order to demonstrate the benefits of migrating existing designs based on the available open-source hardware platforms to SensoTube architecture.

Communication Range Dynamics and Performance Analysis for a Self-Adaptive Transmission Power Controller.

The deployment of the nodes in a Wireless Sensor and Actuator Network (WSAN) is typically restricted by the sensing and acting coverage. This implies that the locations of the nodes may be, and usually are, not optimal from the point of view of the radio communication. Additionally, when the transmission power is tuned for those locations, there are other unpredictable factors that can cause connectivity failures, like interferences, signal fading due to passing objects and, of course, radio irregularities. A control-based self-adaptive system is a typical solution to improve the energy consumption while keeping good connectivity. In this paper, we explore how the communication range for each node evolves along the iterations of an energy saving self-adaptive transmission power controller when using different parameter sets in an outdoor scenario, providing a WSAN that automatically adapts to surrounding changes keeping good connectivity. The results obtained in this paper show how the parameters with the best performance keep a k-connected network, where k is in the range of the desired node degree plus or minus a specified tolerance value.

A Decentralized Damage Detection System for Wireless Sensor and Actuator Networks

The unprecedented capabilities of monitoring and responding to stimuli in the physical world of wireless sensor and actuator networks (WSAN) enable these networks to provide the underpinning for several Smart City applications, such as structural health monitoring (SHM). In such applications, civil structures, endowed with wireless smart devices, are able to self-monitor and autonomously respond to situations using computational intelligence. This work presents a decentralized algorithm for detecting damage in structures by using a WSAN. As key characteristics, beyond presenting a fully decentralized (in-network) and collaborative approach for detecting damage in structures, our algorithm makes use of cooperative information fusion for calculating a damage coefficient. We conducted experiments for evaluating the algorithm in terms of its accuracy and efficient use of the constrained WSAN resources. We found that our collaborative and information fusion-based approach ensures the accuracy of our algorithm and that it can answer promptly to stimuli (1.091 s), triggering actuators. Moreover, for 100 nodes or less in the WSAN, the communication overhead of our algorithm is tolerable and the WSAN running our algorithm, operating system and protocols can last as long as 468 days.

Node/Proxy portability: Designing for the two lives of your next WSAN middleware

Middleware for wireless sensor and actuator networks (WSANs) provides powerful programming abstractions which simplify application development. While it is highly desirable to reuse WSAN middleware across a wide range of hardware platforms, in practice, complex middleware may not fit in nodes with limited resources. As one possible solution, we propose the so-called proxy approach: the middleware is ported on a general purpose computer, from where the sensors and actuators of the resource-constrained nodes are accessed remotely yet in a way that is transparent to the application, which runs unmodified, as if it resided on the physical nodes. We provide design guidelines and a middleware transformation process for implementing the proxy approach in a structured way. We also present a concrete implementation of the proxy approach for our own middleware, along with a performance evaluation of the proxy software environment in a wired testbed with almost 200 sensor nodes.

Active structures integrated with wireless sensor and actuator networks: a bio-inspired control framework

One of the main problems in controlling the shape of active structures (AS) is to determine the actuations that drive the structure from the current state to the target state. Model-based methods such as stochastic search require a known type of load and relatively long computational time, which limits the practical use of AS in civil engineering. Moreover, additive errors may be produced because of the discrepancy between analytic models and real structures. To overcome these limitations, this paper presents a compound system called WAS, which combines AS with a wireless sensor and actuator network (WSAN). A bio-inspired control framework imitating the activity of the nervous systems of animals is proposed for WAS. A typical example is tested for verification. In the example, a triangular tensegrity prism that aims to maintain its original height is integrated with a WSAN that consists of a central controller, three actuators, and three sensors. The result demonstrates the feasibility of the proposed concept and control framework in cases of unknown loads that include different types, distributions, magnitudes, and directions. The proposed control framework can also act as a supplementary means to improve the efficiency and accuracy of control frameworks based on a common stochastic search.

Stochastic optimal linear control of wireless networked control systems with delays and packet losses

In this study, the design of the optimal decentralised state-feedback controllers is considered for a wireless sensor and actuator network (WSAN) with stochastic network-induced delays and packet losses. In particular, taking advantage of multiple controllers, the authors model the WSAN as a wireless networked control system with decentralised controllers, and then formulate the stochastic optimal state-feedback control problem as a non-cooperative linear quadratic game. The optimal control law of each controller is obtained that is a function of the current plant state and past control signals. The performance of the proposed algorithm is investigated by an unstable linearised inverted pendulum and an application of the load frequency control system in power grid.

Smart Control of Multiple Evaporator Systems with Wireless Sensor and Actuator Networks

This paper describes the complete integration of a fuzzy control of multiple evaporator systems with the IEEE 802.15.4 standard, in which we study several important aspects for this kind of system, like a detailed analysis of the end-to-end real-time flows over wireless sensor and actuator networks (WSAN), a real-time kernel with an earliest deadline first (EDF) scheduler, periodic and aperiodic tasking models for the nodes, lightweight and flexible compensation-based control algorithms for WSAN that exhibit packet dropouts, an event-triggered sampling scheme and design methodologies. We address the control problem of the multi-evaporators with the presence of uncertainties, which was tackled through a wireless fuzzy control approach, showing the advantages of this concept where it can easily perform the optimization for a set of multiple evaporators controlled by the same smart controller, which should have an intelligent and flexible architecture based on multi-agent systems (MAS) that allows one to add or remove new evaporators online, without the need for reconfiguring, while maintaining temporal and functional restrictions in the system. We show clearly how we can get a greater scalability, the self-configuration of the network and the least overhead with a non-beacon or unslotted mode of the IEEE 802.15.4 protocol, as well as wireless communications and distributed architectures, which could be extremely helpful in the development process of networked control systems in large spatially-distributed plants, which involve many sensors and actuators. For this purpose, a fuzzy scheme is used to control a set of parallel evaporator air-conditioning systems, with temperature and relative humidity control as a multi-input and multi-output closed loop system; in addition, a general architecture is presented, which implements multiple control loops closed over a communication network, integrating the analysis and validation method for multi-loop control networks designed for multi-evaporator systems.

Application of Wireless Sensor and Actuator Networks to Achieve Intelligent Microgrids: A Promising Approach towards a Global Smart Grid Deployment

Smart Grids (SGs) constitute the evolution of the traditional electrical grid towards a new paradigm, which should increase the reliability, the security and, at the same time, reduce the costs of energy generation, distribution and consumption. Electrical microgrids (MGs) can be considered the first stage of this evolution of the grid, because of the intelligent management techniques that must be applied to assure their correct operation. To accomplish this task, sensors and actuators will be necessary, along with wireless communication technologies to transmit the measured data and the command messages. Wireless Sensor and Actuator Networks (WSANs) are therefore a promising solution to achieve an intelligent management of MGs and, by extension, the SG. In this frame, this paper surveys several aspects concerning the application of WSANs to manage MGs and the electrical grid, as well as the communication protocols that could be applied. The main concerns regarding the SG deployment are also presented, including future scenarios where the interoperability of different generation technologies must be assured.

Network functions virtualization architecture for gateways for virtualized wireless sensor and actuator networks

Virtualization enables multiple applications to share the same wireless sensor and actuator network (WSAN). However, in heterogeneous environments, virtualized wireless sensor and actuator networks (VWSAN) raise new challenges, such as the need for on-the-fly, dynamic, elastic, and scalable provisioning of gateways. Network Functions Virtualization (NFV) is a paradigm emerging to help tackle these new challenges. It leverages standard virtualization technology to consolidate special-purpose network elements on commodity hardware. This article presents NFV architecture for VWSAN gateways, in which software instances of gateway modules are hosted in NFV infrastructure operated and managed by a VWSAN gateway provider. We consider several VWSAN providers, each with its own brand or combination of brands of sensors and actuators/robots. These sensors and actuators can be accessed by a variety of applications, each may have different interface and QoS (i.e., latency, throughput, etc.) requirements. The NFV infrastructure allows dynamic, elastic, and scalable deployment of gateway modules in this heterogeneous VWSAN environment. Furthermore, the proposed architecture is flexible enough to easily allow new sensors and actuators integration and new application domains accommodation. We present a prototype that is built using the OpenStack platform. Besides, the performance results are discussed

A Kautz-Based Wireless Sensor and Actuator Network for Real-Time, Fault-Tolerant and Energy-Efficient Transmission

Wireless sensor and actuator networks (WSANs) are composed of sensors and actuators to perform distributed sensing and actuating tasks. Most WSAN applications (e.g., fire detection) demand that actuators rapidly respond to observed events. Therefore, real-time (i.e., fast) and fault-tolerant transmission is a critical requirement in WSANs to enable sensed data to reach actuators reliably and quickly. Due to limited power resources, energy-efficiency is another crucial requirement. Such requirements become formidably challenging in large-scale WSANs. However, existing WSANs fall short in meeting these requirements. To this end, we first theoretically study the Kautz graph for its applicability in WSANs to meet these requirements. We then propose a Kautz-based REal-time, Fault-tolerant and EneRgy-efficient WSAN (REFER). REFER embeds Kautz graphs into the physical topology of a WSAN for real-time communication and connects the Kautz graphs using distributed hash table (DHT) for high scalability. We also theoretically study routing paths in the Kautz graph, based on which we develop an efficient fault-tolerant routing protocol. It enables a relay node to quickly and efficiently identify the next shortest path from itself to the destination based only on node IDs upon routing failure, rather than relying on retransmission from the source. REFER is advantageous over previous Kautz graph based works in that it does not need an energy-consuming protocol to find the next shortest path and it preserves the consistency between the overlay and physical topology. We further improve routing in REFER by multi-path based routing and energy-efficient multicasting within and between Kautz graph cells, respectively. Extensive experimental results demonstrate the superior performance of REFER in comparison with existing WSAN systems in terms of real-time communication, energy-efficiency, fault-tolerance and scalability.

Performance comparison between simulated and real case scenario of RSSI-Based localization algorithms on a WSAN

Abstract: A wide set of applications have been designed for Wireless Sensor and Actuator Networks (WSAN). Localization algorithms implemented over a wireless link such as WSAN, are recently reaching high interest due the low recourses and precision challenge involved. Received Signal Strength (RSS) is considered the simplest way to compute position location on WSAN, even though it is highly affected by multipath channels and other interferences, which are not included on simulator software. The main contribution of this proposal lays on a comparative analysis between simulated WSAN's RSS-Based algorithms and its implementation on real WSAN nodes. In this way we were able to determine how some factors affect the localization environment. This implementation took advantage of an experimentally measured RSS, using XBee Series 1 transceivers, on a fixed grid topology.

Precision Irrigation using Wireless Sensor Networks for Indian Agriculture -A Survey

Wireless sensor Networks (WSNs) are wide utilized in motoring and collecting interests of environment information. Besides the challenging environmental conditions, India needs efficient and cost effective Wireless sensor and actuator Network (WSAN) to assist the farmers and improve the crop production. This paper surveyed varied international automated irrigation approach and compared it with the Indian scenarios to adopt the most effective irrigation technique. Existing approaches requires an efficient decision support system that can work well with Indian conditions.

DYSSS: A Dynamic and Context-Aware Security System for Shared Sensor Networks

In recent years, we have witnessed the emergence of Shared Sensor Networks (SSNs) as a core component of cyber-physical systems for diverse applications. As Wireless Sensor and Actuator Networks (WSANs) design starts shifting from application-specific platforms to shared system infrastructures, a pressing research challenge is security. In scenarios involving unprotected hostile outdoor areas, SSNs are prone to different types of attacks that can compromise reliability, integrity, and availability of the sensor data traffic and sensor lifetime as well. In this work we propose a Dynamic Security System to be applied in the shared sensor network context. Its basic feature is the nodes neighborhood monitoring and collaboration (through the use of the Byzantine algorithm) to identify an attack and enhance security. The proposed security system is dynamic since it is able to manage the availability, integrity, and confidentiality of multiple applications according to the current execution context. It is also resilient, since it is able to support the continuous network operation even in the presence of malicious or faulty nodes. Its resilience is achieved for the capacity of gathering information from several nodes, thus inferring the countermeasures using context information.

Clustering algorithm of hierarchical structures in large-scale wireless sensor and actuator networks

In this study, we propose a clustering algorithm to enhance the performance of wireless sensor and actuator networks (WSANs). In each cluster, a multi-level hierarchical structure can be applied to reduce energy consumption. In addition to the cluster head, some nodes can be selected as intermediate nodes (INs). Each IN manages a subcluster that includes its neighbors. INs aggregate data from members in its subcluster, then send them to the cluster head. The selection of intermediate nodes aiming to optimize energy consumption can be considered high computational complexity mixed-integer linear programming. Therefore, a heuristic lowest energy path searching algorithm is proposed to reduce computational time. Moreover, a channel assignment scheme for sub-clusters is proposed to minimize interference between neighboring subclusters, thereby increasing aggregated throughput. Simulation results confirm that the proposed scheme can prolong network lifetime in WSANs.

An approach based on the domain perspective to develop WSAN applications

As wireless sensor and actuator networks (WSANs) can be used in many different domains, WSAN applications have to be built from two viewpoints: domain and network. These different viewpoints create a gap between the abstractions handled by the application developers, namely the domain and network experts. Furthermore, there is a coupling between the application logic and the underlying sensor platform, which results in platform-dependent projects and source codes difficult to maintain, modify, and reuse. Consequently, the process of developing an application becomes cumbersome. In this paper, we propose a model-driven architecture (MDA) approach for WSAN application development. Our approach aims to facilitate the task of the developers by: (1) enabling application design through high abstraction level models; (2) providing a specific methodology for developing WSAN applications; and (3) offering an MDA infrastructure composed of PIM, PSM, and transformation programs to support this process. Our approach allows the direct contribution of domain experts in the development of WSAN applications, without requiring specific knowledge of programming WSAN platforms. In addition, it allows network experts to focus on the specific characteristics of their area of expertise without the need of knowing each specific application domain.

Controlling the fluid factors of an environment by sensor and actuator networks

Recently, wireless sensor and actuator networks (WSANs) have been widely discussed. An important application of WSANs is the control of environmental fluid factors, such as temperatures, in an environment. In this paper, we study the control of temperatures in an indoor environment with energy saving in mind. Temperature sensors are deployed in a regular grid or a random manner. Actuators are controllable air conditioners with multiple outlets. Users may be located in any places in the environment. We consider two user satisfaction models: binary and continuous. Based on these assumptions, we present models and control mechanisms to adjust air conditioners to meet users’ requirements. Simulation results show that our mechanisms can indeed achieve our goals in an efficient way.

Plataforma autoconfigurable de monitoreo remoto para aplicaciones móviles en WSAN

Wireless networks have been evolving toward higher complexity applications. It makes sense not to expect an one-fits-all application framework. These applications require a particular framework profile in order to solve particular issues. In this paper we propose a Wireless Sensor and Actuator Network (WSAN) framework profile, which solves the particular issue of writing and reading memory slots on the sensor node's microcontroller. As simple as it sounds this application opens the framework to a wide set of possibilities, which could be reading a sensed data, or even switching the purpose of the whole node just by changing a pointer value on the remote microcontroller memory. This framework is suitable for a star topology amidst an IEEE802.15.4 standard. It is also able to control, process and communicate successfully among the network nodes.

Efficient Rule Engine for Smart Building Systems

In smart building systems, the automatic control of devices relies on matching the sensed environment information to customized rules. With the development of wireless sensor and actuator networks (WSANs), low-cost and self-organized wireless sensors and actuators can enhance smart building systems, but produce abundant sensing data. Therefore, a rule engine with ability of efficient rule matching is the foundation of WSANs based smart building systems. However, traditional rule engines mainly focus on the complex processing mechanism and omit the amount of sensing data, which are not suitable for large scale WSANs based smart building systems. To address these issues, we build an efficient rule engine. Specifically, we design an atomic event extraction module for extracting atomic event from data messages, and then build a β-network to acquire the atomic conditions for parsing the atomic trigger events. Taking the atomic trigger events as the key set of MPHF, we construct the minimal perfect hash table which can filter the majority of the unused atomic event with O(1) time overhead. Moreover, a rule engine adaption scheme is proposed to minimize the rule matching overhead. We implement the proposed rule engine in a practical smart building system. The experimental results show that the rule engine can perform efficiently and flexibly with high data throughput and large rule set.

ISO/IEC/IEEE 21451 Compliant Sensor Nodes for Energy-Aware Wireless Sensor Networks

Much attention is focused nowadays on the developing of energy-aware wireless sensor and actuator network (WSAN) and in particular on implementing network control algorithms by exploiting the ability of a sensor to reliably estimate and report its energy status at network level where energy-saving strategies can be implemented. This poses the attention on how a sensor may transfer information regarding its energy resources at network level in a standardized way. In this paper, we face the problem concerning the realization of energy-aware WSAN by using ISO/IEC/IEEE 21451 compliant sensor nodes. To this end, some guidelines on how exploiting the capability of the current version of the ISO/IEC/IEEE 21451 standard to obtain information about the energy-status of network nodes will be reported and, furthermore, some extensions for overcoming the existing shortcomings will finally be proposed.