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The redundancy regeneration (sparing or rebuild) algorithms in disk arrays face the problem of balancing between the data recovery activity within the array and the user workload acting upon the array at the same time [1]. If the algorithm favors the user workload so the user requests can always preempt the internal data recovery, then the data sparing can stall in the presence of a sustained workload...
In this paper the problem of the temporal characteristics preservation of a sampled trajectory when it is transmitted on a digital network from a master node to a slave node, that has to rebuilt it, is faced. An event-triggered philosophy is adopted for the communication without any kind of data time-stamping procedure. Moreover, the assumption of a connection oriented transmission channel is taken...
Many applications such as distributed measurements or real-time networks benefit from a common notion of time. Protocols providing high precision and simple clock synchronization are necessary to achieve such a common time base. However, most of the available protocols are lacking with regard to fault tolerance and performance in case of a fault. The project IMAGINE (Introduction of Master Group Based...
Within this paper the design and the implementation of a component based framework for distributed control applications based on Java will be presented. It has been developed over the course of the JAKOBI project. This project targets the applicability of Java in control applications using extensions such as the RTSJ specification. It introduces concepts similar to IEC 61499 allowing the execution...
Consider a network where all nodes share a single broadcast domain such as a wired broadcast network. Nodes take sensor readings but individual sensor readings are not the most important pieces of data in the system. Instead, we are interested in aggregated quantities of the sensor readings such as minimum and maximum values, the number of nodes and the median among a set of sensor readings on different...
The article deals with a design of application for scheduling and process behavior monitoring in operating systems Linux and RTLinux. Described application gathers data by remote machines (targets) with ethernet connection possibility and shows processes and scheduler activities. The monitoring application stores data in database and allows diagrammatizing target system behavior for online or offline...
The successful use of IEC 61499 in the industry requires software development processes that utilize the standard's support for best practices of software engineering, such as CORFU. The adoption of such a process would involve upgrading existing practices, tacit knowledge and legacy software, which constitute much of the core competence and essential assets of a company. This paper reports on a two...
This paper discusses the use of distributed instruments for performance evaluation of Real-Time Ethernet (RTE) networks. A new instrument, composed of several logging probes connected in different points of a RTE target network, is characterized and compared with commercially available test equipments. The most important problem in performance evaluation is the timestamp assignment to network events;...
The distributed control applications of today are usually assumed to be run on a hardware consisting of heterogeneous processing elements. A standard like IEC 61499 attempts to provide an unanimous software infrastructure for these applications. An important research interest thereof is to find possible deployment of the components of the distributed application on these heterogeneous nodes. Since...
Professionals' assessments on the usefulness of IEC 61499 depend on several factors that are outside of the scope of the standard. Automation design in the industry is largely routine work that is based on copying and modifying existing domain-specific solutions, so the lack of legacy software exacerbates learning difficulties. Other factors such as team organization and the development environment...
This paper presents a low cost, flexible and customizable delay measurement system developed to assess the performance of the VTPE-hBEB protocol. The proposed system can be used to evaluate other communication protocols as well as to measure the delay between two repetitive events.
Control systems for industrial processes are more and more using PC-based platforms instead of dedicated devices such as controllers or PLCs. Software packages allow running a ??soft PLC?? on a normal PC with a general purpose operating system. These solutions present several advantages in terms of flexibility, communications, multi-vendor interfacing, and costs. On the other hand the use of multi-tasking...
Many distributed real-time embedded systems often perform critical functions, which implicitly require high reliability. Consequently, the application designer for a distributed real-time embedded system is confronted with a challenge of deriving a reliable schedule for a real-time application in the presence of individual com- ponent and common cause failures of the system. This paper proposes a...
To conserve space and power, and to incorporate dynamic adaptability in embedded systems, it is important to utilize hardware components as best as possible. The hardware customization of application kernels reduces the execution time and possibly the power consumption. Reconfiguring the same hardware to facilitate various customized kernels as execution proceeds greatly reduces the space requirements...
Existing embedded software development methodologies can hardly cope with platform changes such as CPU upgrades, different RTOS or distributed systems. The Timing Definition Language (TDL) enables the development of deterministic real-time components regardless of the deployment platform. The proposed virtual execution environment enables parallel execution and deterministic run-time composition of...
The problem of controlling the lateral position of tractor - trailer vehicle is studied. A robust asymptotic tracking and disturbance attenuation controller is proposed. The goal of the controller is to keep the vehicle centered to a desired lane despite physical uncertainties and velocity variations. The robust controller parameters are computed using an analytic algorithm. The effectiveness of the...
The main purpose of this study is to investigate how to provide authentication in wireless sensor networks and how it can be done in an energy efficient way. Other goals are to give an introduction to general security in wireless sensor networks and to see how the addition of message authentication codes (MAC) of various lengths affects the lifetime of a sensor node. To do this, a study of security...
Consider the problem of deciding whether a set of n sporadic message streams meet deadlines on a Controller Area Network (CAN) bus for a specified priority assignment. It is assumed that message streams have implicit deadlines and no release jitter. An algorithm to solve this problem is well known but unfortunately it time complexity is non-polynomial. We present an algorithm with polynomial timecomplexity...
The paper deals with the problem of modeling and implementation of distributed automation systems for manufacturing applications. In particular, a novel approach has been conceived. A suitable meta-model of the production system has been derived, compliant with the state-of-the-art industrial standards. After the compilation and validation stages, an ontology is derived containing all the necessary...
The problem of controlling the suspension deflection of a quarter-car active suspension system using a robust tracking controller is proposed. The proposed robust asymptotic tracking and disturbance attenuation controller aims to keep the suspension deflection asymptotically to zero despite road disturbances and physical system uncertainties. The robust controller design technique is based on the...
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