37 research outputs found

    A Survey of Fault-Tolerance Techniques for Embedded Systems from the Perspective of Power, Energy, and Thermal Issues

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    The relentless technology scaling has provided a significant increase in processor performance, but on the other hand, it has led to adverse impacts on system reliability. In particular, technology scaling increases the processor susceptibility to radiation-induced transient faults. Moreover, technology scaling with the discontinuation of Dennard scaling increases the power densities, thereby temperatures, on the chip. High temperature, in turn, accelerates transistor aging mechanisms, which may ultimately lead to permanent faults on the chip. To assure a reliable system operation, despite these potential reliability concerns, fault-tolerance techniques have emerged. Specifically, fault-tolerance techniques employ some kind of redundancies to satisfy specific reliability requirements. However, the integration of fault-tolerance techniques into real-time embedded systems complicates preserving timing constraints. As a remedy, many task mapping/scheduling policies have been proposed to consider the integration of fault-tolerance techniques and enforce both timing and reliability guarantees for real-time embedded systems. More advanced techniques aim additionally at minimizing power and energy while at the same time satisfying timing and reliability constraints. Recently, some scheduling techniques have started to tackle a new challenge, which is the temperature increase induced by employing fault-tolerance techniques. These emerging techniques aim at satisfying temperature constraints besides timing and reliability constraints. This paper provides an in-depth survey of the emerging research efforts that exploit fault-tolerance techniques while considering timing, power/energy, and temperature from the real-time embedded systems’ design perspective. In particular, the task mapping/scheduling policies for fault-tolerance real-time embedded systems are reviewed and classified according to their considered goals and constraints. Moreover, the employed fault-tolerance techniques, application models, and hardware models are considered as additional dimensions of the presented classification. Lastly, this survey gives deep insights into the main achievements and shortcomings of the existing approaches and highlights the most promising ones

    Biometrics

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    Biometrics-Unique and Diverse Applications in Nature, Science, and Technology provides a unique sampling of the diverse ways in which biometrics is integrated into our lives and our technology. From time immemorial, we as humans have been intrigued by, perplexed by, and entertained by observing and analyzing ourselves and the natural world around us. Science and technology have evolved to a point where we can empirically record a measure of a biological or behavioral feature and use it for recognizing patterns, trends, and or discrete phenomena, such as individuals' and this is what biometrics is all about. Understanding some of the ways in which we use biometrics and for what specific purposes is what this book is all about

    Smart Wireless Sensor Networks

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    The recent development of communication and sensor technology results in the growth of a new attractive and challenging area - wireless sensor networks (WSNs). A wireless sensor network which consists of a large number of sensor nodes is deployed in environmental fields to serve various applications. Facilitated with the ability of wireless communication and intelligent computation, these nodes become smart sensors which do not only perceive ambient physical parameters but also be able to process information, cooperate with each other and self-organize into the network. These new features assist the sensor nodes as well as the network to operate more efficiently in terms of both data acquisition and energy consumption. Special purposes of the applications require design and operation of WSNs different from conventional networks such as the internet. The network design must take into account of the objectives of specific applications. The nature of deployed environment must be considered. The limited of sensor nodes� resources such as memory, computational ability, communication bandwidth and energy source are the challenges in network design. A smart wireless sensor network must be able to deal with these constraints as well as to guarantee the connectivity, coverage, reliability and security of network's operation for a maximized lifetime. This book discusses various aspects of designing such smart wireless sensor networks. Main topics includes: design methodologies, network protocols and algorithms, quality of service management, coverage optimization, time synchronization and security techniques for sensor networks

    Mobile Robots

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    The objective of this book is to cover advances of mobile robotics and related technologies applied for multi robot systems' design and development. Design of control system is a complex issue, requiring the application of information technologies to link the robots into a single network. Human robot interface becomes a demanding task, especially when we try to use sophisticated methods for brain signal processing. Generated electrophysiological signals can be used to command different devices, such as cars, wheelchair or even video games. A number of developments in navigation and path planning, including parallel programming, can be observed. Cooperative path planning, formation control of multi robotic agents, communication and distance measurement between agents are shown. Training of the mobile robot operators is very difficult task also because of several factors related to different task execution. The presented improvement is related to environment model generation based on autonomous mobile robot observations

    Towards the efficient use of LoRa for wireless sensor networks

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    Since their inception in 1998 with the Smart Dust Project from University of Berkeley, Wireless Sensor Networks (WSNs) had a tremendous impact on both science and society, influencing many (new) research fields, like Cyber-physical System (CPS), Machine to Machine (M2M), and Internet of Things (IoT). In over two decades, WSN researchers have delivered a wide-range of hardware, communication protocols, operating systems, and applications, to deal with the now classic problems of resourceconstrained devices, limited energy sources, and harsh communication environments. However, WSN research happened mostly on the same kind of hardware. With wireless communication and embedded hardware evolving, there are new opportunities to resolve the long standing issues of scaling, deploying, and maintaining a WSN. To this end, we explore in this work the most recent advances in low-power, longrange wireless communication, and the new challenges these new wireless communication techniques introduce. Specifically, we focus on the most promising such technology: LoRa. LoRa is a novel low-power, long-range communication technology, which promises a single-hop network with millions of sensor nodes. Using practical experiments, we evaluate the unique properties of LoRa, like orthogonal spreading factors, nondestructive concurrent transmissions, and carrier activity detection. Utilising these unique properties, we build a novel TDMA-style multi-hop Medium Access Control (MAC) protocol called LoRaBlink. Based on empirical results, we develop a communication model and simulator called LoRaSim to explore the scalability of a LoRa network. We conclude that, in its current deployment, LoRa cannot support the scale it is envisioned to operate at. One way to improve this scalability issue is Adaptive Data Rate (ADR). We develop two ADR protocols, Probing and Optimistic Probing, and compare them with the de facto standard ADR protocol used in the crowdsourced TTN LoRaWAN network. We demonstrate that our algorithms are much more responsive, energy efficient, and able to reach a more efficient configuration quicker, though reaching a suboptimal configuration for poor links, which is offset by the savings caused by the convergence speed. Overall, this work provides theoretical and empirical proofs that LoRa can tackle some of the long standing problems within WSN. We envision that future work, in particular on ADR and MAC protocols for LoRa and other low-power, long-range communication technologies, will help push these new communication technologies to main-stream status in WSNs

    Classification and Management of Computational Resources of Robotic Swarms and the Overcoming of their Constraints

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    Swarm robotics is a relatively new and multidisciplinary research field with many potential applications (e.g., collective exploration or precision agriculture). Nevertheless, it has not been able to transition from the academic environment to the real world. While there are many potential reasons, one reason is that many robots are designed to be relatively simple, which often results in reduced communication and computation capabilities. However, the investigation of such limitations has largely been overlooked. This thesis looks into one such constraint, the computational constraint of swarm robots (i.e., swarm robotics platform). To achieve this, this work first proposes a computational index that quantifies computational resources. Based on the computational index, a quantitative study of 5273 devices shows that swarm robots provide fewer resources than many other robots or devices. In the next step, an operating system with a novel dual-execution model is proposed, and it has been shown that it outperforms the two other robotic system software. Moreover, results show that the choice of system software determines the computational overhead and, therefore, how many resources are available to robotic software. As communication can be a key aspect of a robot's behaviour, this work demonstrates the modelling, implementing, and studying of an optical communication system with a novel dynamic detector. Its detector improves the quality of service by orders of magnitude (i.e., makes the communication more reliable). In addition, this work investigates general communication properties, such as scalability or the effects of mobility, and provides recommendations for the use of such optical communication systems for swarm robotics. Finally, an approach is shown by which computational constraints of individual robots can be overcome by distributing data and processing across multiple robots

    Flexi-WVSNP-DASH: A Wireless Video Sensor Network Platform for the Internet of Things

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    abstract: Video capture, storage, and distribution in wireless video sensor networks (WVSNs) critically depends on the resources of the nodes forming the sensor networks. In the era of big data, Internet of Things (IoT), and distributed demand and solutions, there is a need for multi-dimensional data to be part of the Sensor Network data that is easily accessible and consumable by humanity as well as machinery. Images and video are expected to become as ubiquitous as is the scalar data in traditional sensor networks. The inception of video-streaming over the Internet, heralded a relentless research for effective ways of distributing video in a scalable and cost effective way. There has been novel implementation attempts across several network layers. Due to the inherent complications of backward compatibility and need for standardization across network layers, there has been a refocused attention to address most of the video distribution over the application layer. As a result, a few video streaming solutions over the Hypertext Transfer Protocol (HTTP) have been proposed. Most notable are Apple’s HTTP Live Streaming (HLS) and the Motion Picture Experts Groups Dynamic Adaptive Streaming over HTTP (MPEG-DASH). These frameworks, do not address the typical and future WVSN use cases. A highly flexible Wireless Video Sensor Network Platform and compatible DASH (WVSNP-DASH) are introduced. The platform's goal is to usher video as a data element that can be integrated into traditional and non-Internet networks. A low cost, scalable node is built from the ground up to be fully compatible with the Internet of Things Machine to Machine (M2M) concept, as well as the ability to be easily re-targeted to new applications in a short time. Flexi-WVSNP design includes a multi-radio node, a middle-ware for sensor operation and communication, a cross platform client facing data retriever/player framework, scalable security as well as a cohesive but decoupled hardware and software design.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201

    A sensor node soC architecture for extremely autonomous wireless sensor networks

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    Tese de Doutoramento em Engenharia Eletrónica e de Computadores (PDEEC) (especialidade em Informática Industrial e Sistemas Embebidos)The Internet of Things (IoT) is revolutionizing the Internet of the future and the way new smart objects and people are being connected into the world. Its pervasive computing and communication technologies connect myriads of smart devices, presented at our everyday things and surrounding objects. Big players in the industry forecast, by 2020, around 50 billion of smart devices connected in a multitude of scenarios and heterogeneous applications, sharing data over a true worldwide network. This will represent a trillion dollar market that everyone wants to take a share. In a world where everything is being connected, device security and device interoperability are a paramount. From the sensor to the cloud, this triggers several technological issues towards connectivity, interoperability and security requirements on IoT devices. However, fulfilling such requirements is not straightforward. While the connectivity exposes the device to the Internet, which also raises several security issues, deploying a standardized communication stack on the endpoint device in the network edge, highly increases the data exchanged over the network. Moreover, handling such ever-growing amount of data on resource-constrained devices, truly affects the performance and the energy consumption. Addressing such issues requires new technological and architectural approaches to help find solutions to leverage an accelerated, secure and energy-aware IoT end-device communication. Throughout this thesis, the developed artifacts triggered the achievement of important findings that demonstrate: (1) how heterogeneous architectures are nowadays a perfect solution to deploy endpoint devices in scenarios where not only (heavy processing) application-specific operations are required, but also network-related capabilities are major concerns; (2) how accelerating network-related tasks result in a more efficient device resources utilization, which combining better performance and increased availability, contributed to an improved overall energy utilization; (3) how device and data security can benefit from modern heterogeneous architectures that rely on secure hardware platforms, which are also able to provide security-related acceleration hardware; (4) how a domain-specific language eases the co-design and customization of a secure and accelerated IoT endpoint device at the network edge.Internet of Things (IoT) é o conceito que está a revolucionar a Internet do futuro e a forma como coisas, processos e pessoas se conectam e se relacionam numa infraestrutura de rede global que interligará, num futuro próximo, um vasto número de dispositivos inteligentes e de utilização diária. Com uma grande aposta no mercado IoT por parte dos grandes líderes na industria, algumas visões otimistas preveem para 2020 mais de 50 mil milhões de dispositivos ligados na periferia da rede, partilhando grandes volumes de dados importantes através da Internet, representando um mercado multimilionário com imensas oportunidades de negócio. Num mundo interligado de dispositivos, a interoperabilidade e a segurança é uma preocupação crescente. Tal preocupação exige inúmeros esforços na exploração de novas soluções, quer a nível tecnológico quer a nível arquitetural, que visem impulsionar o desenvolvimento de dispositivos embebidos com maiores capacidades de desempenho, segurança e eficiência energética, não só apenas do dispositivo em si, mas também das camadas e protocolos de rede associados. Apesar da integração de pilhas de comunicação e de protocolos standard das camadas de rede solucionar problemas associados à conectividade e a interoperabilidade, adiciona a sobrecarga inerente dos protocolos de comunicação e do crescente volume de dados partilhados entre os dispositivos e a Internet, afetando severamente o desempenho e a disponibilidade do mesmo, refletindo-se num maior consumo energético global. As soluções apresentadas nesta tese permitiram obter resultados que demonstram: (1) a viabilidade de soluções heterogéneas no desenvolvimento de dispositivos IoT, onde não só tarefas inerentes à aplicação podem ser aceleradas, mas também tarefas relacionadas com a comunicação do dispositivo; (2) os benefícios da aceleração de tarefas e protocolos da pilha de rede, que se traduz num melhor desempenho do dispositivo e aumento da disponibilidade do mesmo, contribuindo para uma melhor eficiência energética; (3) que plataformas de hardware modernas oferecem mecanismos de segurança que podem ser utilizados não apenas em prol da segurança do dispositivo, mas também nas capacidades de comunicação do mesmo; (4) que o desenvolvimento de uma linguagem de domínio específico permite de forma mais eficaz e eficiente o desenvolvimento e configuração de dispositivos IoT inteligentes.This thesis was supported by a PhD scholarship from Fundação para a Ciência e Tecnologia, SFRH/BD/90162/201

    Easy Peripherals for the Internet of Things

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    The project aims to develop a communication protocol, using a Bluetooth Low Energy profile as a carrier, to enable easy access to the functionalities offered by the Pandlet platform. The Pandlet features a Nordic Semmiconductor microcontroller (with integrated BLE radio) as well as a large number of on-board sensors (e.g. IMU, EMU). The supported functionalities will include GPIO operations, as well as I2C and UART communication. A companion API will also be developed as a way to seamlessly integrate an Android gateway device and the Pandlet platform

    ARM microprocessor software based emulator

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    With the recent explosion of devices driving “smart technologies” such as tablets, phones, in-vehicle infotainment systems, and many such devices, ARM has taken center stage in being the core of choice for many such device vendors. Thus the appreciation and workings of the ARM core has become more relevant than ever. In light of that fact, over the years, many emulators have been designed with the intent of emulating the ARM core on a software paradigm. Software based emulation lends itself to many uses, from early application validation to an educational tool for the masses. Hence, this work has emulated the ARM instruction set based on the ARM 7 core. With the objective to enable an extensible and modular design, the framework was developed by designing classes for certain core components which can be replicated as objects and encapsulating execution based entities into functions. The final result of this project is the development of a mechanism for updating the CPSR for each instruction, alongside 16 Data Processing instructions with rotational and register shifting support, all aspects of single data transfer load and store, positive and negative branching with and without link alongside 16 conditional code evaluation, and all User Mode visible registers. The ARM emulator also supports both normal assembler instruction and conditional code instructions in both 2 and 3 operand format. The emulator was verified using single instructions and the GCD conditional code instruction as a program
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