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Proceedings Sixth Euromicro Workshop on Real-Time Systems

15-17 June 1994

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  • Proceedings Sixth Euromicro Workshop on Real-Time Systems

    Publication Year: 1994
    Request permission for commercial reuse | PDF file iconPDF (16 KB)
    Freely Available from IEEE
  • Determining the worst-case blocking sequences for distributed real-time programs

    Publication Year: 1994, Page(s):4 - 9
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (340 KB)

    For detecting timing errors in a distributed real-time program (distributed real-time debugging) it is essential to know all combinations of execution paths where a given path experiences a worst-case blocking time through communication (server calls) among the subprograms. In this paper we deal with the subproblem of blocking sequences of server call pairs between 2 paths. For determining their w... View full abstract»

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  • Application objects and modularity in real time graphical modelling

    Publication Year: 1994, Page(s):10 - 15
    Cited by:  Papers (2)  |  Patents (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (348 KB)

    LACATRE is a graphical language intended to help in the design of applications requiring the use of multitasking real time executives. Within the software life cycle, LACATRE covers both preliminary and detailed design. After a brief description of the LACATRE basic objects, this paper presents the use of the application objects (or high level objects) such as agency and process, associated to the... View full abstract»

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  • Modular specification of real-time systems

    Publication Year: 1994, Page(s):16 - 21
    Cited by:  Papers (1)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (348 KB)

    Duration Calculus, a real-time interval logic, has been embedded in the Z specification language to provide a notation for real-time systems that combines the modularisation and abstraction facilities of Z with a logic suitable for reasoning about real-time properties. In this article the notation is presented through a top-level specification of requirements for a simple air traffic monitoring sy... View full abstract»

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  • Integration of RTL and precedence graphs with a static scheduler as verifier

    Publication Year: 1994, Page(s):22 - 25
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (300 KB)

    We present an approach to specification and verification of distributed hard real-time systems. By integrating RTL and precedence constraints, we combine the comprehensiveness of precedence graphs with the expressive power and proofability of RTL. Thus, our approach allows easy comprehension by the human designer and formal correctness. We propose to use a static scheduling algorithm based on heur... View full abstract»

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  • A dynamic scheduling algorithm for semi-hard real-time environments

    Publication Year: 1994, Page(s):130 - 137
    Cited by:  Papers (2)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (620 KB)

    In many real-time systems, it is crucial for the application tasks to meet their specified deadlines, otherwise the tasks cause catastrophic results. Every task is generally periodic, and the value of its period depends on the dynamics of the process it controls. In addition, some additional time-critical tasks said to be sporadic can occur and require to be processed at unpredictable times. The p... View full abstract»

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  • Animation in CONRAD: informal analysis of timing properties

    Publication Year: 1994, Page(s):220 - 225
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (404 KB)

    It is suggested that timing restrictions are the fundamental part of the specification of a time-critical system (limiting the possible design solution space), because most of the timing restrictions have been objectively determined by the object to be controlled and thus cannot be changed arbitrarily. Timing correctness in real-time systems means that process activations, data production and cons... View full abstract»

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  • Dynamic scheduling for mobile robots

    Publication Year: 1994, Page(s):28 - 33
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (388 KB)

    This research concerns efficient multiprocessor threads-based implementation of reactive navigation for mobile robots. We present two important results: 1) Performance is improved significantly when CPU time allocated to individual navigational threads is adjusted dynamically according to a heuristic measure of their importance. 2) To implement this strategy, we present a multiprocessor scheduler ... View full abstract»

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  • Fixed priority scheduling with deadlines prior to completion

    Publication Year: 1994, Page(s):138 - 142
    Cited by:  Papers (9)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (288 KB)

    Standard analysis for fixed priority scheduling assumes that all the computations for each task must be completed by the task's deadline. In practice this is rarely the case. The deadline is more correctly associated with the last observable event of the task, interval events and kernel overheads (such as the context switch away from the task) can occur after the deadline. New analysis is presente... View full abstract»

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  • On-line sporadic task scheduling in hard real-time systems

    Publication Year: 1994, Page(s):186 - 191
    Cited by:  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (460 KB)

    We propose a set of scheduling procedures for dealing with the sporadic task scheduling in a dynamic periodic system. For this we mean a system in which periodic tasks change their parameters dynamically (at run-time), in an unpredictable way. So, the off-line periodic task set will be different from the current periodic task set. It means that the task schedulability tests in such systems have to... View full abstract»

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  • Relating specified time tolerances to implementation performances

    Publication Year: 1994, Page(s):226 - 233
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (688 KB)

    Real-time systems require that the high-level control constructs used by the designer have a rigorously defined semantics specifying their actual temporal behavior, which unfortunately depends on implementation details that the high-level view tends to hide from the user. Moreover the real implementations only approximate the typical ideal properties; in some systems these approximations cannot be... View full abstract»

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  • Supporting real-time update of an environment representation for autonomous mobile robots

    Publication Year: 1994, Page(s):34 - 39
    Cited by:  Papers (1)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (440 KB)

    A model of the environment is a mandatory requirement for the autonomy of a mobile robot. As the environment may change over time, methods are necessary to update the model information, keeping pace with the sensor frame rate. Our approach to cope with this real time problem is to predict virtual sensor images, which are then compared against the real perceptions. Two alternative methods are detai... View full abstract»

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  • Algorithms for scheduling computations with secondary deadlines to minimize penalty

    Publication Year: 1994, Page(s):143 - 148
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (464 KB)

    In many real-time applications, some job allows part of its computation to be executed after its primary deadline but before an extended, or secondary deadline. We study the scheduling issues for real-time computations with secondary deadlines. We call the part of a computation which must be completed before the primary deadline its hard part, and the rest its soft part. The soft part of a computa... View full abstract»

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  • Object-based design of embedded software using real-time operating systems

    Publication Year: 1994, Page(s):194 - 198
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (320 KB)

    Embedded systems are used in everyday electronic consumer products and industrial equipment, e.g. television sets, radios, cars, and mobile phones. Rapid developments which have taken place in computer hardware and software technologies have led to the increased complexity of embedded systems. Promising results have been achieved in the development of complex information processing systems using o... View full abstract»

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  • UltraSMART: a scalable multiprocessor architecture for real time

    Publication Year: 1994, Page(s):118 - 123
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (532 KB)

    Concurrent Computer Corporation's UltraSMART (scalable multiprocessor architecture for real time) architecture is a busless distributed shared memory multiprocessor architecture that enables higher levels of performance and better real-time behavior than can be obtained with bus-based global shared memory multiprocessors. The paper describes UltraSMART, the UltraSMART-based MAXION multiprocessor s... View full abstract»

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  • Scheduling in a hard real-time system with shared resources

    Publication Year: 1994, Page(s):234 - 239
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (500 KB)

    Hard real-time systems are those systems in which correctness depends on logical results of the computations as well as the times at which these results are produced. In a real-time context, concurrency control protocols for shared resources (as databases) must not only maintain the consistency constraints but also satisfy timing requirements of transactions. So, several protocols have been propos... View full abstract»

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  • Realtime-learning on an autonomous mobile robot with neural networks

    Publication Year: 1994, Page(s):40 - 44
    Cited by:  Papers (2)  |  Patents (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (360 KB)

    We discuss the usage of neural network clustering techniques on a mobile robot, in order to build qualitative topologic environment maps. This has to be done in realtime, i.e. the internal world-model has to be adapted by the flow of sensor-samples without the possibility to stop this data flow. Our experiments are done in a simulation environment as well as on a robot, called ALICE View full abstract»

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  • A software architecture for telerobotics

    Publication Year: 1994, Page(s):86 - 90
    Cited by:  Papers (3)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (280 KB)

    Describes a currently developed software architecture for telerobotics, based on a high-level and interpreted language, PILOT (Programming and Interpreted Language Of actions for Telerobotics), allowing one to plan the actions of a robot. Such a language allows the operator to modify a mission during its execution. A software architecture is developed for this language, and is composed of four mod... View full abstract»

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  • Interprocessor-blocking independent static task allocation for shared-bus real-time multiprocessors

    Publication Year: 1994, Page(s):53 - 58
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (392 KB)

    In real-time systems, guaranteeing the schedulability of high priority tasks is more important than being able to schedule more tasks under resource constraints. The system bus in bus-based multiprocessors is a shared resource that is usually arbitrated by priority and fairness. This paper presents a new static task allocation strategy that takes into consideration the impact of bus arbitration po... View full abstract»

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  • On using epsilon serializable locking protocol for concurrency control in real-time databases

    Publication Year: 1994, Page(s):150 - 155
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (388 KB)

    New non-serializable protocols based on incorporating epsilon serializability (ESR) into the real-time concurrency control protocol, Hybrid Two Phase Locking (Hb2PL) are proposed. The protocols try to maximize the values of the transactions by making a compromise between meeting transaction deadlines and maintaining consistent transaction view. Two different ways of incorporating ESR into Hb2PL ar... View full abstract»

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  • Guaranteed deadlines with dynamic recovery blocks in distributed systems

    Publication Year: 1994, Page(s):199 - 204
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (468 KB)

    In a hard real-time system, a timing fault is said to occur when a real time task delivers its results too late. An deadline mechanism has been proposed to avoid timing faults in uniprocessor machines. Under this approach, every task is implemented with two algorithms: on one hand, a primary program produces a good quality service but in an unknown and possibly infinite length of time due to softw... View full abstract»

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  • Object-oriented enhancement of real-time software using a heterogeneous re-engineering approach

    Publication Year: 1994, Page(s):98 - 103
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (460 KB)

    A technique for incremental modernisation and enhancement of an existing procedural real-time software to an object-oriented one is presented. The incremental enhancement enables the real-time system designer to make use of the advantages of object-oriented paradigm: the resulting re-engineered software is more maintainable, reusable and configurable. In this approach, the object structure and add... View full abstract»

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  • A resynchronization method for real-time supervision

    Publication Year: 1994, Page(s):66 - 71
    Cited by:  Papers (1)
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (536 KB)

    Real-time supervision is one technique used to improve the perceived reliability of software systems. A real-time supervisor observes the inputs and outputs of the system and reports failures that occur. The approach presented in this paper uses the specification of external behavior of the system to detect failures. Failures are reported in real-time. In addition, the approach permits the assessm... View full abstract»

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  • IRTC: integration of knowledge engineering with real-time control

    Publication Year: 1994, Page(s):162 - 166
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (308 KB)

    Integration of knowledge engineering into a control system introduces problems. These are caused by the fact that timing information for a knowledge engineering task is usually not well known. The indeterminate timing causes problems for real-time scheduling. A new approach is presented to solve this problem. The approach includes, among other things, usage of multiple versions for tasks, selectio... View full abstract»

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  • The modular multimicroprocessor system architecture for the power turbine control

    Publication Year: 1994, Page(s):124 - 127
    Request permission for commercial reuse | Click to expandAbstract | PDF file iconPDF (288 KB)

    The modular multimicroprocessor control system (MMCS) architecture for turbine control is presented. The turbine features which are produced by “Metalicheskiy Zavod” plc (St.-Petersburg) are considered. The multilayered MMCS system organization for these turbines is described. The architecture of distributed modular multimicroprocessor control system (MMCS) for turbo-unit technological... View full abstract»

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