For a distributed embedded system (DES) to operate continuously in a dynamic environment, it must be flexible and highly reliable. This applies in particular to its communication subsystem. The Flexible Time-Triggered...
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ISBN:
(纸本)9781479948451
For a distributed embedded system (DES) to operate continuously in a dynamic environment, it must be flexible and highly reliable. This applies in particular to its communication subsystem. The Flexible Time-Triggered Replicated Star for Ethernet (FTTRS) aims at providing such a subsystem by means of a highly-reliable switched-Ethernet architecture based on the Flexible Time-Triggered paradigm (FTT), a master/slave communication paradigm where the master periodically polls the slaves using so-called trigger messages (TMs). In particular, FTTRS interconnects nodes by redundant communication paths provided by two switches, each embedding an FTT master that manages the communication. This allows FTTRS to tolerate the failure of one switch without interrupting the communication as long as the masters are replica determinate, i.e., provide identical service to the slaves. The master replica determinism entails the masters broadcasting their TMs in a lockstep fashion: when one master broadcasts a TM, the other should do the same quasi-simultaneously. In this paper we present a solution inspired by the Precision Time Protocol (PTP) for achieving this lockstep transmission and preliminary results showing the precision with which we can synchronize the masters on a software prototype.
Service Oriented Programming and Service Oriented Architectures are the basis of one of the most successful technologies of the recent past: Web Services. They support the integration at enterprise level in the global...
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ISBN:
(纸本)0769524524
Service Oriented Programming and Service Oriented Architectures are the basis of one of the most successful technologies of the recent past: Web Services. They support the integration at enterprise level in the global Internet era. However the enterprise level applications are only pall of the spectrum, the other being the ever growing ubiquitous embedded applications. Arguably, the SOA's offer the same advantages at embeddedsystem level. In this article we are evaluating the service oriented paradigm in the context of distributed embedded systems and instantiate the observations on Openwings as a particular service oriented architecture.
A new adaptive thresholding power management (ATPM) scheme is proposed to maximize the data rate of RF circuits in distributed embedded systems powered by renewable energy. Considering time-varying fading channels and...
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ISBN:
(纸本)9781424489350
A new adaptive thresholding power management (ATPM) scheme is proposed to maximize the data rate of RF circuits in distributed embedded systems powered by renewable energy. Considering time-varying fading channels and statistical energy harvesting processes, we propose to turn on RF circuits only when the channel gain is higher than a threshold, and adjust the RF power according to the energy availability to improve the overall data rate. Exploiting the fact that the optimal threshold is a function of variable renewable energy subject to environmental changes, we adaptively adjust the threshold in accordance with renewable energy to improve energy efficiency. Simulation results based on solar energy indicate that the proposed ATPM scheme increases the average data rate by up to 60% compared with the scheme without channel gain thresholding, and achieves over 5X improvement in data rate over the constant power scheme with the same RF power consumption.
Learning programming has positive effect on children's development, and Tangible User Interfaces (TUIs) is a convenient way for teaching young children programming. TanProRobot 2.0 is a tangible system as well as ...
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ISBN:
(纸本)9781450335829
Learning programming has positive effect on children's development, and Tangible User Interfaces (TUIs) is a convenient way for teaching young children programming. TanProRobot 2.0 is a tangible system as well as a small-scale distributed embedded system designed for children at grades 1-2 to learn programming concepts. The system consists of three parts: tangible programming blocks, a robot car and several manipulatives. The input and output of the system are both tangible. Children can program the robot car to act certain actions by arranging the programming blocks. Also, children can interact with the car with manipulatives. TanProRobot 2.0 aims to introduce event handling concept and sensors to children. Through a user study with 11 children, we found that TanProRobot 2.0 is an interesting programming system for children, and it is easy to learn and to use. Furthermore, it could help children get a preliminary understanding of event handling concepts.
Runtime controllers can be used in distributed embedded systems to throttle or stop software components and thus to limit the timing effects that applications have on each other through scheduling dependencies. Such r...
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ISBN:
(纸本)9780769547398
Runtime controllers can be used in distributed embedded systems to throttle or stop software components and thus to limit the timing effects that applications have on each other through scheduling dependencies. Such runtime controllers require bounds on the worst-case admissible resource utilization per task to estimate and to control the worst-case interference between applications. Multi-dimensional sensitivity analysis can be used to derive efficient local controller bounds from global system constraints. In this paper we present a novel distributed algorithm to determine a multi-dimensional sensitivity bound on activation jitter which serves that purpose. Distribution makes it suitable for in-field application in modular designs, a main requirement in many industrial applications. Its properties are formally derived. Extensive experiments evaluate the solution quality and computation time.
Wearable systems are important tools to increase the reach of Computer Science into helping other research fields. In this context, system-on-Chips with embedded low-power processors are useful tools to develop protot...
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ISBN:
(纸本)9781728126074
Wearable systems are important tools to increase the reach of Computer Science into helping other research fields. In this context, system-on-Chips with embedded low-power processors are useful tools to develop prototypes and solutions. Nevertheless, the limited resources of these systems create a limit on the speed and quality of the gathered information. A possible alternative for this problem is to increase the number of embedded computers composing the system, distributing the workload between different nodes. In this study, we analyze the effect of increased distribution on the main wearable constraints using a prototype. In order to investigate the energetic impact of increased distribution, we perform a long-run test. Also, we propose a novel testbed based on the Quality-of-Service (QoS) concepts and use it to analyze the effect of this increased distribution in communication and synchronization performance.
This article presents an efficient technique for placement and routing of sensors/actuators and processing units in a grid network. The driver application that we present is a medical jacket, which requires an extreme...
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This article presents an efficient technique for placement and routing of sensors/actuators and processing units in a grid network. The driver application that we present is a medical jacket, which requires an extremely high level of robustness and fault tolerance. The power consumption of such jacket is another key technological constraint. Our proposed interconnection network is a mesh of wires. A jacket made of fabric and wires would be susceptible to accidental damage via tears. By modeling the tears, we evaluate the probability of having failures on every segment of wires in our mesh interconnection network. Then, we study two problems of placement and routing in the sensor networks such that the fault tolerance is maximized while the power consumption is minimized. We develop efficient integer linear programming (ILP) formulations to address these problems and perform both placement and routing, simultaneously. This ensures that the solution is a lower bound for both problems. We evaluate the effectiveness of our proposed techniques on a variety of benchmarks.
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