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The primary goal of this work is to provide an easy and systematic way of developing safe soft real-time systems. To achieve this goal, we propose a method of generating real-time programs from formally verified models written as systems of timed automata. The models are verified using UPPAAL model checker prior to be processed by our code generators. A characteristic of our code generator is that...
Designing and verifying distributed protocols in a multi-rate asynchronous system is, in general, extremely difficult when the distributed computations require consistent input views, consistent actions and synchronized state transitions. In this paper, we address this problem and introduce a formal, complexity-reducing architectural pattern, called Multi-Rate PALS system, to support virtual synchronization...
In this paper we present an approach to efficiently mix Java with asynchronous and synchronous concurrency and execute it on a specialized Java processor extended with capabilities for concurrency and reactivity. A new processor, which uses JOP (Java Optimized Processor) as its base, executes concurrent programs that comply with Globally Asynchronous Locally Synchronous (GALS) formal model of computation...
This paper presents a self-stabilizing distributed clock synchronization protocol in the absence of faults in the system. It is focused on the distributed clock synchronization of an arbitrary, non-partitioned digraph ranging from fully connected to 1-connected networks of nodes while allowing for differences in the network elements. This protocol does not rely on assumptions about the initial state...
Fault-tolerant clock synchronization is the foundation of synchronous architectures such as the Time-Triggered Architecture (TTA) for dependable cyber-physical systems. Clocks are typically local counters that are increased with a given rate according to real time, and clock synchronization algorithms ensure that any two clocks in the system read about the same value at about the same point in real...
In uniprocessor real-time systems, resource sharing is usually done using protocols such as Stack Resource Policy, Priority Ceiling Protocol and Priority Inheritance Protocol. Unfortunately these protocols did not work as expected on real-time multiprocessor systems. Such problem must be addressed with different approaches like Multiprocessor Priority Ceiling Protocol (MPCP) and Multiprocessor Stack...
Avionics systems in modern and next-generation airborne vehicles combine and integrate various realtime applications to efficiently share the physical resources on board. Many of these real-time applications also need to fulfill fault-tolerance requirements — i.e., the applications have to provide a sufficient level of service even in presence of failures — and this combination of real-time and fault-tolerance...
The IEEE 1588 standard could synchronizes independent clocks running on separate nodes of a distributed measurement and control system to a high degree of accuracy and precision. But the standard did not present the method to implement the protocol in detail. An implementation of the IEEE 1588 based on an FPGA is presented in this paper. And the result of the experiment shows this method could achieve...
Maintaining a common notion of time among communicating nodes in mobile multihop networks is crucial to the correctness of many distributed real-time applications such as target tracking, data fusion, and environmental monitoring. Achieving both synchronization accuracy and efficiency (in terms of communication and energy overheads) are important goals of a time synchronization mechanism. While these...
The proposed technique integrates IEC61850 and PMU for extent of wide area measurement system (WAMS) with a new Synchronized Measurement Technology. This new Electronic Devices comprise three main technologies: a LM3S8962 microcontroller for PTP slave, a Single-Board-RIO for acquisition and synchronization and an IPC@CHIP based system for communications with IEC61850. For Master task a PCI_1588 card...
The ubiquitous presence of powerful low-power wireless systems on chip (SoC) able to operate in the Industrial, Scientific and Medical (ISM) band has brought a new enhanced operational choice for real-time Radio Control (RC) applications such as aircrafts and cars in the hobby grade category. Frequency Hopping Spread Spectrum (FHSS) has become the dominant transmission technique for the previously...
In safety-critical applications, the real-time behavior is crucial for the correctness of the overall system and must be tested thoroughly. However, the generation of test traces that cover most or all of the desired behavior of a real-time system is a difficult challenge. In this paper, we present an evolutionary algorithm that generates timed test traces, which achieve a given transition coverage...
A simple, highly-effective, DSP-free, optical OFDM(OOFDM) synchronous clock recovery technique preserving system performance and enhancing stability is proposed and experimentally demonstrated, for the first time, in real-time end-to-end, 11.25Gb/s 64-QAM OOFDM, directly-modulated-DFB-based, 25km IMDD systems.
Verification of real-time systems - e.g. communication protocols or embedded controllers - is an important task. One method to detect errors is called bounded model checking (BMC). In BMC the system is iteratively unfolded and then transformed into a satisfiability problem. If an appropriate solver finds the $k$-th instance to be satisfiable a counterexample for a given safety property has been found...
A lot of research is done in the field of wireless sensor networks, particularly in the field of ad-hoc networks. Large-scale real-time wireless networks for factory automation are hardly covered by existing research. Such networks usually have thousands of nodes, which makes simulation a necessity for system validation. Discrete Event Simulators (DES) are efficient tools to do so, but their event...
Many distributed and multiprocessor real-time applications consist of pipelines of tasks that must complete before their end-to-end deadlines. Different schedulability analyses have been proposed for both Fixed Priority and Earliest Deadline First scheduling. All the schedulability analyses proposed so far assume that a global clock synchronization protocol is used to synchronize the deadlines of...
At present, an increasing number of distributed control systems are based on platforms made up of conventional PCs running open-source real-time operating systems. Often, the need arises in these systems to have networked devices supporting synchronized operations. In this paper, an inexpensive solution is introduced, described, implemented and evaluated that relies on standard software and protocols...
A new generation of distributed real-time systems (DRTS) is based on heterogeneous models of computation and communication and is associated with flexible real-time constraints. Classical design flows based on realtime scheduling theory display important limitations related to the restrictive assumption on the system model. On the other hand, formal verification of timed automata is far more general,...
One very interesting trend in factory automation is the introduction of wireless networks to the factory floor. This requires investigation of problems which are not present with wired technology. Tracking of mobile nodes, as well as seamless handover are such problems. Precise clock synchronization is needed to solve these new issues. For large-scale systems it is economically unreasonable to implement...
This paper presents a low power ultra-wide band digital receiver baseband architecture for handling IEEE 802.15.4a packets in real-time. Real-time processing allows duty cycling of the analog frontend, which is key to achieve low power consumption. The architecture consists of a programmable application specific instruction set processor and a set of application specific integrated circuits. The design...
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