Ultra-Low Power and Non-intrusive Wireless Monitoring for Smart Buildings

Wireless Sensor Networks (WSNs) offer a new solution for distributed monitoring, processing and communication. First of all, the stringent energy constraints to which sensing nodes are typically subjected. WSNs are often battery powered and placed where it is not possible to recharge or replace batteries. Energy can be harvested from the external environment but it is a limited resource that must be used efficiently. Energy efficiency is a key requirement for a credible WSNs design. From the power source's perspective, aggressive energy management techniques remain the most effective way to prolong the lifetime of a WSN. A new adaptive algorithm will be presented, which minimizes the consumption of wireless sensor nodes in sleep mode, when the power source has to be regulated using DC-DC converters. Another important aspect addressed is the time synchronisation in WSNs. WSNs are used for real-world applications where physical time plays an important role. An innovative low-overhead synchronisation approach will be presented, based on a Temperature Compensation Algorithm (TCA). The last aspect addressed is related to self-powered WSNs with Energy Harvesting (EH) solutions. Wireless sensor nodes with EH require some form of energy storage, which enables systems to continue operating during periods of insufficient environmental energy. However, the size of the energy storage strongly restricts the use of WSNs with EH in real-world applications. A new approach will be presented, which enables computation to be sustained during intermittent power supply. The discussed approaches will be used for real-world WSN applications. The first presented scenario is related to the experience gathered during an European Project (3ENCULT Project), regarding the design and implementation of an innovative network for monitoring heritage buildings. The second scenario is related to the experience with Telecom Italia, regarding the design of smart energy meters for monitoring the usage of household's appliances

Sensores passivos para aplicações espaciais

Mestrado em Engenharia Eletrónica e TelecomunicaçõesUma das áreas, se não a principal área, com maior desenvolvimento nos últimos anos e a exploração espacial. A entrada de empresas privadas no negocio aliadas aos novos meios de comunicação reacenderam a curiosidade sobre o espaço. Esta dissertação surge com o intuito de desenvolver um sistema de comunicação passivo, com capacidades de monitorização e de processamento para aplicações espaciais. Para tal quer-se utilizar conceitos tais como: antenas, projecto de formas de onda, transmissão de energia sem os, circuitos de RF-DC, radio retrodifusão , modulação e desmodulação de sinais. Para se chegar a um sistema funcional, pretende-se analisar e testar diferentes soluções para cada uma das partes do sistema. Quer-se que o trabalho seja o mais abrangente possível, e que aborde todos as partes necessárias para o desenvolvimento do sistema. No entanto e devido a complexidade do mesmo, este trabalho e focado em quatro pontos: antenas, circuitos de RFDC, circuitos de retrodifusão e microcontroladores. Os restantes aspectos são abordados mas superficialmente. Para alem de toda a parte hardware do sistema, também se pretende desenvolver uma solução otimizada a nível do software, de modo a que a solução nal tenha o melhor rendimento possível. Inicialmente o sistema ser a projectado para aplicações espaciais, no entanto espara-se que o mesmo possa ser usado em outras áreas.One of the areas, if not the principal area, with higher development in recent year is space exploration. The entry of more private companies in the business allied with new ways of communication reignited the curiosity about the space. This dissertation, appears with the intention of developing a passive communication system for spatial applications. The system should have sensing and processing capabilities. To achieve this, some concepts are important: antennas, waveform design, wireless power transmission, circuit RF-DC, radio backscatter, wave modulation and demodulation. In order to design a functional system, each part of the system will be analysisd and tested. The work is designed to be the more embracing possible, however due to its complexity it is more focused in four points: antennas, circuit RF-DC, radio backscatter and microcontrollers. The other aspects are approached but with less details. Beyond all the hardware aspects, it is also intended to develop a optimized solution for software, trying to achieve a better general system e ciency. The system is designed for spatial applications, however it is expected that it could be a solution for other areas

Application specific instruction set processor design for embedded application using the coware tool

An Application Specific Instruction Set Processor (ASIP) is widely used as a System on a Chip(SoC) Component. ASIPs possess an instruction set which is tai-lored to benefit a specific application. Such specialization allows ASIPs to serve as an intermediate between two dominant processor design styles- ASICs which has high processing abilities at the cost of limited programmability and Programmable solu-tions such as FPGAs that provide programming exibility at the cost of less energy eficiency. In this dissertation the goal is to design ASIP, keeping in mind a temper-ature sensor system. The platform used for processor design is LISA 2.0 description language and processor designing environment from CoWare. Coware processor de-signer allows processor architecture to be defined at an abstract level and automatic generation of chain of software tools like assembler, linker and simulator for functional verification followed by RTL level description. RTL level description is used to gen-erate synthesized report of the design using RTL compiler and finally the layout is created using Cadence encounter

Development of a customised, self powered data logger for monitoring farm fence energizers

For gathering information on the performance of energizer products in the field, Gallagher Group Limited had a well out-dated data-logger which periodically monitored the voltage of the fence and transmitted the data back to base over a GSM network. However the existing data-logger had very limited capability and a new one was needed that could monitor the environment inside and around the energizer, and hopefully provide some information on why an energiser might be failing. The ideal data-logger was self powered, could last years in the field without needing to be serviced, and could collect data on the energizer without affecting it in any way. It would also collect data on as many environmental parameters as possible, such as temperature, humidity, ambient light level, lightening strikes and pressure. Ideally it would also be able to monitor the energizer voltage using a contactless measuring system. The data-logger was designed for Gallagher Animal Management Systems, the part of Gallagher Group Limited that specialises in farming equipment. The design project arose from the need for a data-logger that could monitor both the fence voltage and the environment around the fence, so that a critical explanation of why an energizer failed in the field could be found, leading to better product design in the future. It was jointly funded by Gallagher Group Limited and the Foundation of Research Science and Technology (FoRST)

Runtime Hardware Reconfiguration in Wireless Sensor Networks for Condition Monitoring

The integration of miniaturized heterogeneous electronic components has enabled the deployment of tiny sensing platforms empowered by wireless connectivity known as wireless sensor networks. Thanks to an optimized duty-cycled activity, the energy consumption of these battery-powered devices can be reduced to a level where several years of operation is possible. However, the processing capability of currently available wireless sensor nodes does not scale well with the observation of phenomena requiring a high sampling resolution. The large amount of data generated by the sensors cannot be handled efficiently by low-power wireless communication protocols without a preliminary filtering of the information relevant for the application. For this purpose, energy-efficient, flexible, fast and accurate processing units are required to extract important features from the sensor data and relieve the operating system from computationally demanding tasks. Reconfigurable hardware is identified as a suitable technology to fulfill these requirements, balancing implementation flexibility with performance and energy-efficiency. While both static and dynamic power consumption of field programmable gate arrays has often been pointed out as prohibitive for very-low-power applications, recent programmable logic chips based on non-volatile memory appear as a potential solution overcoming this constraint. This thesis first verifies this assumption with the help of a modular sensor node built around a field programmable gate array based on Flash technology. Short and autonomous duty-cycled operation combined with hardware acceleration efficiently drop the energy consumption of the device in the considered context. However, Flash-based devices suffer from restrictions such as long configuration times and limited resources, which reduce their suitability for complex processing tasks. A template of a dynamically reconfigurable architecture built around coarse-grained reconfigurable function units is proposed in a second part of this work to overcome these issues. The module is conceived as an overlay of the sensor node FPGA increasing the implementation flexibility and introducing a standardized programming model. Mechanisms for virtual reconfiguration tailored for resource-constrained systems are introduced to minimize the overhead induced by this genericity. The definition of this template architecture leaves room for design space exploration and application- specific customization. Nevertheless, this aspect must be supported by appropriate design tools which facilitate and automate the generation of low-level design files. For this purpose, a software tool is introduced to graphically configure the architecture and operation of the hardware accelerator. A middleware service is further integrated into the wireless sensor network operating system to bridge the gap between the hardware and the design tools, enabling remote reprogramming and scheduling of the hardware functionality at runtime. At last, this hardware and software toolchain is applied to real-world wireless sensor network deployments in the domain of condition monitoring. This category of applications often require the complex analysis of signals in the considered range of sampling frequencies such as vibrations or electrical currents, making the proposed system ideally suited for the implementation. The flexibility of the approach is demonstrated by taking examples with heterogeneous algorithmic specifications. Different data processing tasks executed by the sensor node hardware accelerator are modified at runtime according to application requests

A two-layer energy-efficient wireless sensor network for precision agriculture applications

Thesis (M.S.) University of Alaska Fairbanks, 2018The agriculture industry has benefited from the recent technological evolution; for example, farmers now use satellite images to monitor large fields. The use of technology in agriculture, generally referred to as Precision Agriculture, has attracted a lot of research interest from electrical engineers. One particular area of Precision Agriculture is the application of embedded systems in monitoring large crop fields. Sensor nodes are placed at various locations in the field where they measure different parameters, such as temperature and soil moisture. The collected measurements are sent to a central hub outside of the field where they can be further processed and displayed for the farmers to make appropriate decisions. From the farmers' perspective, this kind of wireless sensor network (WSN) is a cost-effective solution that allows them to gather accurate information about their crops in real time and significantly improve production. To scientists, it provides invaluable information that can help them improve farming processes or even develop new crop varieties. From the embedded systems stand-point however, such a network poses several challenges, mainly battery life and network lifetime. Battery life is a serious challenge because nodes are scattered in the field and it would be labor intensive and expensive to replace their batteries. It is important to keep nodes alive because dead nodes not only fail to collect data but they also fail to relay packets from other active nodes. Radio communication draws most of the node's battery in WSN, so most energy saving techniques revolve around careful management of the radio. In this study, we focus on routing protocols that maximize the lifetime of the network. Most researchers have suggested various routing schemes to minimize battery consumption by finding the shortest path to a hub; however, when looking at the network as a whole, this approach may not be ideal. We present a lifetime-maximizing routing scheme that uses a cost function to distribute the traffic load among all nodes and to spare those with low remaining energy. The cost function being essential to our algorithm, we evaluate the impact of different types of cost function on the network lifetime. Lastly, we evaluate the impact of link quality in the cost function. Simulation results show that the power cost function has the best performance and that link quality can improve network lifetime. Another major contribution of this research is the design of a test framework that can be used to evaluate other routing protocols. In order to evaluate our routing protocol, we created a WSN simulation in Castalia. The simulation and the routing protocol are highly parametric and with minor modifications, users can experiment with new protocols or variations of ours. Using our platform can save users a lot of time and trouble, especially those unfamiliar with simulation tools, hence allowing them to focus their efforts on their protocol

A Heterogeneous System Architecture for Low-Power Wireless Sensor Nodes in Compute-Intensive Distributed Applications

Wireless Sensor Networks (WSNs) combine embedded sensing and processing capabilities with a wireless communication infrastructure, thus supporting distributed monitoring applications. WSNs have been investigated for more than three decades, and recent social and industrial developments such as home automation, or the Internet of Things, have increased the commercial relevance of this key technology. The communication bandwidth of the sensor nodes is limited by the transportation media and the restricted energy budget of the nodes. To still keep up with the ever increasing sensor count and sampling rates, the basic data acquisition and collection capabilities of WSNs have been extended with decentralized smart feature extraction and data aggregation algorithms. Energy-efficient processing elements are thus required to meet the ever-growing compute demands of the WSN motes within the available energy budget. The Hardware-Accelerated Low Power Mote (HaLoMote) is proposed and evaluated in this thesis to address the requirements of compute-intensive WSN applications. It is a heterogeneous system architecture, that combines a Field Programmable Gate Array (FPGA) for hardware-accelerated data aggregation with an IEEE 802.15.4 based Radio Frequency System-on-Chip for the network management and the top-level control of the applications. To properly support Dynamic Power Management (DPM) on the HaLoMote, a Microsemi IGLOO FPGA with a non-volatile configuration storage was chosen for a prototype implementation, called Hardware-Accelerated Low Energy Wireless Embedded Sensor Node (HaLOEWEn). As for every multi-processor architecture, the inter-processor communication and coordination strongly influences the efficiency of the HaLoMote. Therefore, a generic communication framework is proposed in this thesis. It is tightly coupled with the DPM strategy of the HaLoMote, that supports fast transitions between active and idle modes. Low-power sleep periods can thus be scheduled within every sampling cycle, even for sampling rates of hundreds of hertz. In addition to the development of the heterogeneous system architecture, this thesis focuses on the energy consumption trade-off between wireless data transmission and in-sensor data aggregation. The HaLOEWEn is compared with typical software processors in terms of runtime and energy efficiency in the context of three monitoring applications. The building blocks of these applications comprise hardware-accelerated digital signal processing primitives, lossless data compression, a precise wireless time synchronization protocol, and a transceiver scheduling for contention free information flooding from multiple sources to all network nodes. Most of these concepts are applicable to similar distributed monitoring applications with in-sensor data aggregation. A Structural Health Monitoring (SHM) application is used for the system level evaluation of the HaLoMote concept. The Random Decrement Technique (RDT) is a particular SHM data aggregation algorithm, which determines the free-decay response of the monitored structure for subsequent modal identification. The hardware-accelerated RDT executed on a HaLOEWEn mote requires only 43 % of the energy that a recent ARM Cortex-M based microcontroller consumes for this algorithm. The functionality of the overall WSN-based SHM system is shown with a laboratory-scale demonstrator. Compared to reference data acquired by a wire-bound laboratory measurement system, the HaLOEWEn network can capture the structural information relevant for the SHM application with less than 1 % deviation

Pile de protocoles pour des réseaux des capteurs avec récupération d'énergie

This thesis concerns energy efficient protocols for harvested wireless sensor networks. It is a part of an industrial Internet of Things project. STMicroelectronics started the GreenNet project with the objective to develop and design a new generation of harvesting smart objects to be integrated in the Internet of Things. The GreenNet platform is novel with respect to the existing solutions due to its small size that implies a small energy buffer and small harvesting capabilities. This aspect makes the standard protocols and precedent solutions not directly applicable on this extremely low power platform. In this dissertation, we analyse standard protocols and existing solutions to identify their issues in the gn platform. Then, we provide protocol and algorithm adaptations to make feasible the concept of auto configurable and sustainable networks of GreenNet nodes. We proposed MCBT, an energy efficient protocol for the bootstrap procedure. It enables low power nodes to be enrolled in mh mc wireless sensor networks thanks to the network support for enrolling new nodes. It represents an energy efficient solution that extends the standard protocol. We proposed STADA, a sustainable algorithm to adapt the node activity according to the available energy and traffic conditions. STADA is based on a weighted function that takes into account the energy present in the battery, the energy harvesting rate, and network traffic. In this way, the algorithm takes into account all main parameters to adapt the energy consumption and improve the node performance. To make the harvested network more efficient according to light variations, we proposed a novel metric that makes the path choice a simple process. With the Expected Delay, we synthesize all network parameters in a single monotonic variable that facilitates the path choice in mh harvesting wireless sensor networks. All proposed solutions are designed to work with standard beacon-enabled IEEE 802.15.4 protocols and are easily portable on the future version of IEEE 802.15.4e. We validated the proposed protocols with emulations and simulations. The evaluation results shown better performance in terms of energy consumption and quality of service.Cette thèse vise à améliorer la pile de protocoles pour réseaux de capteurs sans fil à récupération d'énergie afin de les rendre autonomes dans un contexte multi-saut. Elle s'inscrit dans le projet GreenNet de STMicroelectronics qui a pour objectif de concevoir et développer une nouvelle génération d'objets intelligent basés sur la récupération d'énergie ambiente en vue de l'intégration dans l'Internet des Objets. L'originalité de la plateforme GreenNet repose sur sa petite taille qui implique une faible capacité de stockage d'énergie ainsi qu'une faible capacité de récupération d'énergie. Avec un si faible budget d'énergie, les protocoles standards ou les solutions proposées par les communautés académique/industrielle ne permettant pas d'assurer un fonctionnement autonome de ces réseaux. Dans cette thèse, nous analysons les protocoles standards et les solutions existantes pour identifier leurs limites avec la plateforme GreenNet. Ensuite, nous proposons 3 contributions afin de permettre cette autonomie. La première contribution est MCBT, un protocole permettant d'accélérer la découverte et le rattachement de nouveaux noeuds à un réseau multi saut et multi-canaux en formation ou existent. Ce protocole réduit efficacement l'énergie dépensée dans cette phase fortement consommatrice. La deuxième contribution est STADA, un algorithme adaptant l'activité des capteurs en fonction des conditions locales de trafic et d'énergie disponible. STADA est basé sur une fonction de pondération qui tient compte de l'énergie présente dans la batterie, du taux de récupération d'énergie et du trafic local. Enfin, notre troisième contribution propose une nouvelle métrique de routage basée sur Expected Delay synthétisant en une seule variable monotone des facteurs tels que l'éloignement au puits, les chemins bénéficiant d'un ordonnancement de relayage de paquet privilégié et de périodes cumulées d'activité des radios sur le chemin favorable. Toutes les solutions proposées sont conçues pour fonctionner avec la norme IEEE 802.15.4 slotté et sont facilement transposables à son évolution définie par la norme IEEE 802.15.4e. Nous avons validé les protocoles proposés grâce à un simulateur émulant des noeuds réels (Cooja) et au simulateur WSNet. Les résultats ont montré de meilleures performances en termes de consommation d'énergie et de qualité de service par rapport à l'existant

Progetto di reti Sensori Wireless e tecniche di Fusione Sensoriale

Ambient Intelligence (AmI) envisions a world where smart, electronic environments are aware and responsive to their context. People moving into these settings engage many computational devices and systems simultaneously even if they are not aware of their presence. AmI stems from the convergence of three key technologies: ubiquitous computing, ubiquitous communication and natural interfaces. The dependence on a large amount of fixed and mobile sensors embedded into the environment makes of Wireless Sensor Networks one of the most relevant enabling technologies for AmI. WSN are complex systems made up of a number of sensor nodes, simple devices that typically embed a low power computational unit (microcontrollers, FPGAs etc.), a wireless communication unit, one or more sensors and a some form of energy supply (either batteries or energy scavenger modules). Low-cost, low-computational power, low energy consumption and small size are characteristics that must be taken into consideration when designing and dealing with WSNs. In order to handle the large amount of data generated by a WSN several multi sensor data fusion techniques have been developed. The aim of multisensor data fusion is to combine data to achieve better accuracy and inferences than could be achieved by the use of a single sensor alone. In this dissertation we present our results in building several AmI applications suitable for a WSN implementation. The work can be divided into two main areas: Multimodal Surveillance and Activity Recognition. Novel techniques to handle data from a network of low-cost, low-power Pyroelectric InfraRed (PIR) sensors are presented. Such techniques allow the detection of the number of people moving in the environment, their direction of movement and their position. We discuss how a mesh of PIR sensors can be integrated with a video surveillance system to increase its performance in people tracking. Furthermore we embed a PIR sensor within the design of a Wireless Video Sensor Node (WVSN) to extend its lifetime. Activity recognition is a fundamental block in natural interfaces. A challenging objective is to design an activity recognition system that is able to exploit a redundant but unreliable WSN. We present our activity in building a novel activity recognition architecture for such a dynamic system. The architecture has a hierarchical structure where simple nodes performs gesture classification and a high level meta classifiers fuses a changing number of classifier outputs. We demonstrate the benefit of such architecture in terms of increased recognition performance, and fault and noise robustness. Furthermore we show how we can extend network lifetime by performing a performance-power trade-off. Smart objects can enhance user experience within smart environments. We present our work in extending the capabilities of the Smart Micrel Cube (SMCube), a smart object used as tangible interface within a tangible computing framework, through the development of a gesture recognition algorithm suitable for this limited computational power device. Finally the development of activity recognition techniques can greatly benefit from the availability of shared dataset. We report our experience in building a dataset for activity recognition. Such dataset is freely available to the scientific community for research purposes and can be used as a testbench for developing, testing and comparing different activity recognition techniques

Design of a launch system for a scientific fix wing UAV without undercarriage

The general objective is to design the electric system of a vehicle (‘dolly’ type) for take-off of scientific fix wing UAV without undercarriage. The system shall ensure stability of the dolly/aircraft during rolling-take-off while maintaining a fix heading. The dolly would be able to provide additional propulsion/trust for a fast take-off. Specific objectives Determination of the dolly’s movement specifications in order to determine the heading control system and propulsion specifications. Design of the heading automatic control system. Design of the propulsion control system. Design of the breaking control system. Construction and validation. Tasks -Review of the current designs of take-off dollys. -Numerical simulation of the dolly including the movement, propulsion system, heading system and breaking system. -Definition of the safety and redundancy requirements. -Conceptual specification of the electrical system (heading, propulsion and breaking) of the dolly indicating and weighting alternatives. -Detailed definition of the dolly. -Detail specification of the electrical control system of the dolly. -Design, construction and validation of the heading system. -Design, construction and validation of the propulsions system. -Design, construction and validation of the breaking system. -Integration of the heading, propulsion and breaking system to the dolly. -Field tests of the dolly. -Review and improvement of the design. -Final tests