Showing papers in "IEEE Transactions on Industrial Informatics in 2008"
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TL;DR: This paper discusses a selection of promising and interesting research areas in the design of protocols and systems for wireless industrial communications that have either emerged as hot topics in the industrial communications community in the last few years, or which could be worthwhile research Topics in the next few years.
Abstract: In this paper we discuss a selection of promising and interesting research areas in the design of protocols and systems for wireless industrial communications. We have selected topics that have either emerged as hot topics in the industrial communications community in the last few years (like wireless sensor networks), or which could be worthwhile research topics in the next few years (for example cooperative diversity techniques for error control, cognitive radio/opportunistic spectrum access for mitigation of external interferences).
696 citations
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TL;DR: A new MGrid resource service composition and optimal-selection method, based on the principles of particle swarm optimization (PSO), is proposed, which follows a collaborative population-based search, which modelsbased on the social behavior of bird flocking and fish schooling.
Abstract: In distributed manufacturing systems, especially in a manufacturing grid (MGrid) system, there are primarily two kinds of manufacturing tasks (or resource service requests): (1) single resource service request task (SRSRTask), which can be completed by invoking only one resource service, and (2) multi-resource service request task (MRSRTask), which is completed by invoking several resource services in a certain sequence. For an SRSRTask, the system searches the resource services that are qualified for its function requirements and chooses the optimal one to execute it. For an MRSRTask, in addition to the search for all qualified resource services according to each subtask, the system selects one candidate resource service for each subtask. Then the system generates a new composite resource service (CRS) and selects the optimal resource service composite path from all possible paths to execute the task with the given multi-objective (e.g., time minimization, cost minimization, and reliability maximization) and constraints. The above problem is defined as multi-objective MGrid resource service composition and optimal-selection (MO-MRSCOS) problem in this paper. The formulation is presented for an MO-MRSCOS problem to minimize execution time and cost, and maximize the reliability. The basic resource service composite modes (RSCM) for CRS are described, and the principles for translating a complicated RSCM into a simple sequence RSCM are presented for simplifying the resolving process and complexity of MO-MRSCOS. A new MGrid resource service composition and optimal-selection method, based on the principles of particle swarm optimization (PSO), is then proposed. The PSO follows a collaborative population-based search, which models based on the social behavior of bird flocking and fish schooling. The case study demonstrates that the proposed method is useful in solving MO-MRSCOS problems. The experimental results and performance comparison show that the proposed method is both effective and efficient.
261 citations
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TL;DR: Stability analysis is presented and a practical design procedure of the time delayed control systems with CDOB is studied and comparative study of the method to the Smith predictor is presented.
Abstract: In a research field of network-based control systems (NBCSs), the time delay problem is one of the most significant issues. Efficient stabilization methods of time delayed control systems enable NBCSs to be flexibly applied to many kinds of situations. A novel time delay compensation method based on the concept of network disturbance (ND) and communication disturbance observer (CDOB) has been proposed. The compensation method has the same effectiveness as that of the Smith predictor. In addition, since the method is simple and does not need time delay model or time delay measurement, it can be easily implemented to various applications. However, the design method has not been concerned so far. This paper therefore presents stability analysis and studies a practical design procedure of the time delayed control systems with CDOB. At first, the concept of ND is introduced and the validity of the time delay compensation method is described. Then an analysis about the effects of parameters in control systems on stability is conducted. Characteristics of the effects of parameters on stability come out. Then we study a practical design procedure of the time delayed control systems. The validity of the design procedure is validated by experimental results. In the experiment, we also verify the performance of the system in the case of time-varying delay. Finally, comparative study of the method to the Smith predictor is presented.
129 citations
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TL;DR: The damping ability of the proposed system has been confirmed for a wide range of the system parameters and compared with the other control concepts, like the adaptive Pi-type neuro-fuzzy controller and the classical cascade PI structure.
Abstract: In this paper, a new robust control system with the adaptive sliding neuro-fuzzy speed controller for the drive system with the flexible joint is proposed. A model reference adaptive control structure (MRAC) is used in this drive system. The torsional vibrations are successfully suppressed in the control structure with only one basic feedback from the motor speed. The damping ability of the proposed system has been confirmed for a wide range of the system parameters and compared with the other control concepts, like the adaptive Pi-type neuro-fuzzy controller and the classical cascade PI structure.
81 citations
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TL;DR: A new low-cost distributed measurement instrument to measure timing characteristics of RTE nodes (end-to-end delays, synchronization, etc.) that has multiple FPGA-based probes that allow for simultaneous/synchronized logging on different place of the target RTE network.
Abstract: Ethernet technology is widely used in real-time industrial automation. Thanks to real-time Ethernet (RTE) protocols, defined in IEC61784-2 standard, new top-performance automation solutions can be created. Such systems may have communication cycle time down to tens of mus and cycle jitter less than 1 mus, making network testing and debugging very critical. Existing network and protocol analyzers can perform detailed local analysis, but characterization of high-performance RTE systems requires measurement of transmission delays and these instruments cannot be adequately synchronized among them to realize a distributed measurement network. This paper introduces a new low-cost distributed measurement instrument to measure timing characteristics of RTE nodes (end-to-end delays, synchronization, etc.). The proposed instrument has multiple FPGA-based probes that allow for simultaneous/synchronized logging on different place of the target RTE network. A PC-based "monitor station" stores all the data, ready for further elaboration. Architecture details are discussed, a prototype has been realized, and some experimental results are presented. For instance, synchronization accuracy between probes is below 100 ns.
65 citations
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TL;DR: A novel identification technique, that is high-gain observer-based identification approach, is proposed for systems with bounded process and measurement noises and an adaptive change detection and parameter identification algorithm is presented.
Abstract: In this study, a novel identification technique, that is high-gain observer-based identification approach, is proposed for systems with bounded process and measurement noises. For system parameters with abnormal changes, an adaptive change detection and parameter identification algorithm is next presented. The presented technique and algorithm are finally applied to the parameter identification of the gas turbine engine by using the recorded input data from the engine test-bed. The identified parameters and the response curves are desirable. The simulations have proved the effectiveness of the proposed procedure compared with the previous identification approach.
51 citations
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TL;DR: The novel control task model is built upon control theoretical results that indicate that standard control laws can be implemented considering only periodic actuation and can minimize the harmful effects that long I/O latencies have on control performance.
Abstract: Embedded control systems are often implemented in small microprocessors enabled with real-time technology. In this context, control laws are often designed according to discrete-time control systems theory and implemented as hard real-time periodic tasks. Standard discrete-time control theory mandates to periodically sample (input) and actuate (output). Depending on how input/output (I/O) operations are performed within the hard real-time periodic task, different control task models can be distinguished. However, existing task models present important drawbacks. They generate task executions prone to violate the periodic control demands, a problem known as sampling and latency jitter, or they impose synchronized I/O operations at each task job execution that produce a constant but artificially long I/O latency. In this paper, the one-shot task model for implementing control systems in embedded multitasking hard real-time platforms is presented. The novel control task model is built upon control theoretical results that indicate that standard control laws can be implemented considering only periodic actuation. Taking advantage of this property, the one-shot task model is shown to remove endemic problems for real-time control systems such as sampling and latency jitters. In addition, it can minimize the harmful effects that long I/O latencies have on control performance. Extensive simulations and real experiments show the feasibility and effectiveness of the novel task model, compared to previous real-time and/or control-based solutions.
48 citations
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TL;DR: This paper focuses on the test of distributed systems based on FlexRay, the protocol that is envisioned as the communication backbone for future automotive systems, and presents a decomposition of the system into layers and mechanisms, and a versatile strategy for monitoring and stimulation under various conditions.
Abstract: The introduction of computer-controlled intelligent safety and comfort features has turned cars into complex distributed computing systems. In such a system the proper operation of the communication backbone as well as the proper interaction of components from different vendors must be ensured for all configurations and operating conditions. This system-level test goes far beyond the (isolated) test of single components and represents a substantial problem, that seems to be still largely unsolved, although its solution is crucial for maintaining the consumers' trust in modern automotive electronics. In this paper we concentrate on the test of distributed systems based on FlexRay, the protocol that is envisioned as the communication backbone for future automotive systems. The cornerstones of our approach are a decomposition of the system into layers and mechanisms, and a versatile strategy for monitoring and stimulation under various conditions. Our concept can be adapted to diverse needs ranging from an early debugging with full access to the system, over non-intrusive online testing during interoperability tests, to maintenance testing that is restricted to a remote access only. We give detailed discussions of the requirements and present our solutions for the various issues involved. Selected use cases demonstrate the usefulness of the taken approach.
46 citations
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TL;DR: A service-oriented architectural framework for human task execution is proposed, which improves their execution by automating and semi-automating decision making based on ontologies and agent technology.
Abstract: Due to increasingly demanding requirements for business flexibility and agility, automation of end-to-end industrial processes has become an important topic. Business process execution needs to support automated tasks execution as well as human tasks. In this paper we show that for certain types of human tasks it is relevant to consider their further automation. We propose a service-oriented architectural framework for human task execution, which improves their execution by automating and semi-automating decision making based on ontologies and agent technology. The approach is generic and can be used for any type of industrial or industrial support business process. As a proof-of-concept we have developed a system providing the above-described support for human task intensive business processes in an electric power transmission company, which has shown considerable improvements in the efficiency of human tasks.
44 citations
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TL;DR: This paper presents a solution to this problem by representing sensor measurements with an approximate representation-an interpolation of sensor measurements as a function of space coordinates, which greatly reduces the time for obtaining a snapshot of the environment state and therefore supports the real-time requirements of feedback control loops.
Abstract: The availability of small inexpensive sensor elements enables the employment of large wired or wireless sensor networks for feeding control systems. Unfortunately, the need to transmit a large number of sensor measurements over a network negatively affects the timing parameters of the control loop. This paper presents a solution to this problem by representing sensor measurements with an approximate representation-an interpolation of sensor measurements as a function of space coordinates. A priority-based medium access control (MAC) protocol is used to select the sensor messages with high information content. Thus, the information from a large number of sensor measurements is conveyed within a few messages. This approach greatly reduces the time for obtaining a snapshot of the environment state and therefore supports the real-time requirements of feedback control loops.
43 citations
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TL;DR: A control strategy of a proportional-integral-derivative (PID) controller based on stability analysis considering passivity in null space motion of redundant manipulator is described, which makes it possible to realize stable and dexterousnull space motion effectively.
Abstract: This paper describes a control strategy of a proportional-integral-derivative (PID) controller based on stability analysis considering passivity in null space motion of redundant manipulator. Control spaces of redundant manipulator are divided into work space and null space. In the proposed approach, a disturbance observer is employed in work space, which is called work space observer. On the other hand, null space uses PID controller which is passive controller. Using gamma-dissipative property, the PID controller can compensate null space without deteriorating the motion stability. This means that the proposed approach makes it possible to realize stable and dexterous null space motion effectively. The validity of the proposed approach is verified by simulations and experiments of 4-link redundant manipulator.
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TL;DR: This paper highlights a class of online scheduling policies targeted at scheduling frames at the MAC level that are implementable on COTS components and offer good trade-offs between feasibility and the satisfaction of other application-dependent criteria such as the response time jitter.
Abstract: In distributed real-time systems, meeting the real-time constraints is mandatory, but the satisfaction of other application-dependent criteria is most generally required as well. In particular, networked control systems (NCS) are known to be sensitive to communication delays such as frame response time jitters. Well-known medium access control (MAC) algorithms such as non-preemptive deadline monotonic (NP-DM) or non-preemptive earliest deadline first (NP-EDF) are efficient in terms of bandwidth usage, but they may perform poorly regarding other application-dependent performance criteria. This paper highlights a class of online scheduling policies targeted at scheduling frames at the MAC level, and it provides a schedulability analysis that is valid for all policies within the considered class. As it will be shown, these algorithms are implementable on COTS components (e.g., Controller Area Network controllers) and offer good trade-offs between feasibility and the satisfaction of other application-dependent criteria such as the response time jitter.
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TL;DR: This paper discusses the relevance of clock synchronization in the future of CAN systems and describes a novel solution to supply this service, which provides very high precision, causes very low communication and computation overhead, and includes mechanisms to provide fault tolerance.
Abstract: The controller area network (CAN) is facing a great opportunity. The maturity of this technology makes many researchers believe that CAN may be adopted in more critical systems. However, the suitability of CAN for these challenging applications strongly depends on our capacity to integrate all the solutions already available into a single, comprehensive architecture. We claim that clock synchronization plays a fundamental role in such architecture. Therefore, the means to achieve a solution fulfilling the expected requirements on reliability, cost, and precision must be deeply investigated. This paper discusses the relevance of clock synchronization in the future of CAN systems and describes a novel solution to supply this service. This solution exhibits several advantages: it provides very high precision, causes very low communication and computation overhead, and includes mechanisms to provide fault tolerance. Moreover, and in contrast to previous proposals, it is designed to be orthogonal to the rest of the system. Thus, it can be directly incorporated to any CAN system, without having to replace any of the components, which reduces the cost increment caused by the new service.
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TL;DR: A comparison of microcontrollers and FPGAs with respect to safety and reliability properties is presented, and own empirical evaluations in the area of software fault handling identified advantages of FPG as a platform for encapsulation of real-time functions.
Abstract: An increasing number of safety-critical functions is taken over by embedded systems in today's automobiles. While standard microcontrollers are the dominant hardware platform in these systems, the decreasing costs of new devices as field programmable gate arrays (FPGAs) make it interesting to consider them for automotive applications. In this paper, a comparison of microcontrollers and FPGAs with respect to safety and reliability properties is presented. For this comparison, hardware fault handling was considered as well as software fault handling. Own empirical evaluations in the area of software fault handling identified advantages of FPGAs with respect to the encapsulation of real-time functions. On the other hand, several dependent failures were detected in versions developed independently on microcontrollers and FPGAs.
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TL;DR: A robust and efficient method to discover knowledge for classification problems through data summarization that discretizes continuous features and then summarizes the data using a contingency table, which is capable of handling missing values when used for prediction.
Abstract: This paper presents a robust and efficient method to discover knowledge for classification problems through data summarization. It discretizes continuous features and then summarizes the data using a contingency table. Inconsistency rate for different subsets of features can then be easily calculated from the contingency table. Sequential search is then used to find the best feature subset. After the number of features is reduced to a certain extent, easy-to-understand knowledge can be intuitively derived from data summary. Another desirable feature of the proposed method is its capability to learn incrementally; namely, knowledge can be updated quickly whenever new data are obtained. Moreover, the proposed method is capable of handling missing values when used for prediction. The method is applied on two benchmark data sets showing its effectiveness on selecting discriminative features. The practical usefulness of this method in manufacturing is demonstrated through an application on welding fault diagnosis.
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TL;DR: This paper describes a novel two-stage search technique which is intended to support the configuration of time-triggered schedulers for use with resource-constrained embedded systems which employ a single processor.
Abstract: This paper describes a novel two-stage search technique which is intended to support the configuration of time-triggered schedulers for use with resource-constrained embedded systems which employ a single processor. Our overall goal is to identify a scheduler implementation which will ensure that: 1) all task constraints are met; 2) CPU power consumption is "as low as possible"; and 3) a fully cooperative scheduler architecture is employed whenever possible. Our search process is not exhaustive, and it might be described as "best characteristics first" approach. We proceed iteratively, stopping the search when we have identified the first workable solution. We assume that - because we have begun the search with "best characteristics" - any schedule identified will represent a good (but not necessarily completely optimal) solution. We show that the proposed configuration algorithm is highly effective. We also demonstrate that the algorithm has much lower complexity than alternative "branch and bound" search schemes. We conclude by making some suggestions for future work in this area.
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TL;DR: It is shown that these conflicting demands can be softened and that a compromise solution can be reached and significant control performance improvement can be achieved without increasing hardware costs.
Abstract: In recent years, approaches to control performance and resource optimization for embedded control systems have been receiving increased attention. Most of them focus on theory, whereas practical aspects are omitted. Theoretical advances demand flexible real-time kernel support for multitasking and preemption, thus requiring more sophisticated and expensive software/hardware solutions. On the other hand, embedded control systems often have cost constraints related with mass production and strong industrial competition, thus demanding low-cost solutions. In this paper, it is shown that these conflicting demands can be softened and that a compromise solution can be reached. We advocate that recent research results on optimal resource management for control tasks can be implemented on simple multitasking preemptive real-time kernels targeting low-cost microprocessors, which can be easily built in-house and tailored to actual application needs. The experimental evaluation shows that significant control performance improvement can be achieved without increasing hardware costs.
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TL;DR: Considering the widely-used model of enhanced function flow block diagrams (EFFBDs), it is proposed a structural translation of EFFBDs to transition time Petri nets ( TPNs) and this translation is proved to preserve the behavioral semantics, leading to a formal verification tool within a development platform for system design for defense applications.
Abstract: Safety analysis in systems engineering (SE) processes, as usually implemented, rarely relies on formal methods such as model checking since such techniques, however powerful and mature, are deemed too complex for efficient use. This paper thus aims at improving the verification practice in SE design: considering the widely-used model of enhanced function flow block diagrams (EFFBDs), it formally establishes its syntax and behavioral semantics. It also proposes a structural translation of EFFBDs to transition time Petri nets ( TPNs); this translation is then proved to preserve the behavioral semantics (i.e., timed bisimilarity). After proving results on the boundedness of the resulting TPNs, it was possible to extend a number of fundamental properties (such as the decidability of liveness, state-access, etc.) from bounded TPNs to so-called bounded EFFBDs. Finally, these results led to both implementing and integrating a formal verification tool within a development platform for system design for defense applications and in which the underlying complexity is totally concealed from the end-user.
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TL;DR: The security requirements resulting from the usage of a single tag for multiple companies are analyzed and a novel system architecture and accompanying cryptographic protocols that address the security objectives entity authentication, controlled access, data confidentiality and integrity, as well as untraceability of RFID tags are proposed.
Abstract: Current systems for automatic identification of goods presume a single administrative domain. However, in supply chain management systems temporary cooperations of multiple companies exist, and the usage of one identification device, such as a radio-frequency identification (RFID) tag, per company is infeasible for reasons of costs, space requirements, traceability, and higher collision rate. This paper analyzes the security requirements resulting from the usage of a single tag for multiple companies and proposes a novel system architecture and accompanying cryptographic protocols that address the security objectives entity authentication, controlled access, data confidentiality and integrity, as well as untraceability of RFID tags. The architecture is designed to provide high availability and graceful degradation in case of compromise of system parts. The results of an implementation and simulation study give insights on appropriate data structures for realizing key functionality, and demonstrate the feasibility with off-the-shelf hardware.
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TL;DR: A novel method is introduced which is intended to assist in the design and implementation of optimal H-infinity (H infin) algorithms in low-cost mechatronic applications and shows marginal stability when the low-resolution sensor is employed.
Abstract: This paper introduces a novel method which is intended to assist in the design and implementation of optimal H-infinity (H infin) algorithms in low-cost mechatronic applications. The particular problem considered is position control in a situation where there are both sensor-related uncertainties (caused by low-resolution sensors) and limited computational resources. The first part of the method presented in this paper describes how to design the H infin algorithm based on dynamic features of the sensor. The second part of the method involves finding a suitable numerical controller representation in order to reduce memory and CPU load. Evaluation of the method is based on empirical studies using three industrial sensors employed in a sub-acted robot. Results for a classic proportional integral derivative (PID) controller are included, in order to provide comparisons with the H infin approach. In the empirical evaluation, the PID implementation shows marginal stability when the low-resolution sensor is employed; by contrast, the H infin implementation is found to remain stable in the same circumstances.
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TL;DR: A new real-time power voltage control strategy is proposed in this paper that utilizes a novel offline evolutionary multiobjective optimization algorithm called jumping genes for generating the widespread control solutions and be readily stored into a knowledge data base.
Abstract: A new real-time power voltage control strategy is proposed in this paper. This scheme utilizes a novel offline evolutionary multiobjective optimization algorithm called jumping genes for generating the widespread control solutions and be readily stored into a knowledge data base. A separate online multiple criteria decision-making scheme is established for selecting the appropriate control solution. This concept of power voltage control has been demonstrated by the New England 39-bus power system. The system output performance was speedy and accurate.
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TL;DR: A novel modeling analysis of jitter as applicable to testing of serial data channels is presented and a good agreement between theory and simulation is verified; these results allow test engineers to have an insight into the interactions among jitter components inserial data channels.
Abstract: This paper presents a novel modeling analysis of jitter as applicable to testing of serial data channels. Jitter is analyzed by considering separate and combined components. The primary goal is the generation of a signal containing a known amount of each jitter component. This signal can then be used for testing high speed serial data channels. Initially, jitter components are analyzed and modeled individually. Next, sequences for combining them are modeled, simulated and evaluated. Model simulation using Matlab is utilized to show the unique features of the components when they are combined into different injection sequences for producing the total jitter. Sequence dependency is investigated in depth and the validity of superposition of jitter components for typical values is confirmed. A good agreement between theory and simulation is verified; these results allow test engineers to have an insight into the interactions among jitter components in serial data channels.
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TL;DR: This paper presents an efficient two-level hierarchical DSE framework for TTP-based distributed embedded systems, with the objective of minimizing the total bus utilization while meeting an end-to-end deadline constraint.
Abstract: Time-triggered protocol (TTP) is a time-division multiple access (TDMA)-based bus protocol designed for use in safety-critical avionics and automotive distributed embedded systems. Design space exploration (DSE) for TTP-based distributed embedded system involves searching through a vast design space of possible task-to-CPU mappings, task/message schedules and bus access configurations to achieve certain design objectives. In this paper, we present an efficient two-level hierarchical DSE framework for TTP-based distributed embedded systems, with the objective of minimizing the total bus utilization while meeting an end-to-end deadline constraint. Logic-based Benders decomposition (LBBD) is used to divide the problem into a master problem of mapping tasks to CPU nodes to minimize the total bus utilization, solved with a satisfiability modulo theories (SMT) solver, and a subproblem of finding a feasible solution of bus access configuration and task/message schedule under an end-to-end deadline constraint for a given task-to-CPU mapping, solved with a constraint programming (CP) solver. Performance evaluation results show that our approach is scalable to problems with realistic size.
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TL;DR: An adaptive multilevel code update protocol (AMCUP) for real-time sensor operating systems that adaptively selects a protocol which meets deadline of applications and consumes less energy based on a cost analysis of several protocols.
Abstract: In wireless sensor networks each sensor node has very limited resources, and it is very difficult to find and collect them. For this reason, updating or adding programs in sensor nodes must be performed via a communication channel at run-time. Many code update protocols have been developed for sensor networks, ranging from function-level update to full-image replacement. However, they provide only a fixed level of code update protocols. These protocols require manual selection of an appropriate protocol because they do not consider a cost analysis of the update protocols. In addition, they do not consider real-time response while updating codes. In this paper, we present an adaptive multilevel code update protocol (AMCUP) for real-time sensor operating systems. AMCUP enables energy-efficient code update via support for multilevel protocols (i.e., full-image, module-level, function-level, and instruction-level). It adaptively selects a protocol which meets deadline of applications and consumes less energy based on a cost analysis of several protocols. Our simulation and experimental results show that AMCUP can reduce energy consumption and execution time compared with existing single-level code update protocols while meeting deadline of the running applications.
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TL;DR: A schedulability analysis for TDMA/SS is proposed, assuming knowledge of all message streams in the system, and that each node schedules messages in its output queue according to deadline monotonic, and also presents an algorithm that computes exact queuing times.
Abstract: Distributed real-time systems, such as factory automation systems, require that computer nodes communicate with a known and low bound on the communication delay. This can be achieved with traditional time division multiple access (TDMA). But improved flexibility and simpler upgrades are possible through the use of TDMA with slot-skipping (TDMA/SS), meaning that a slot is skipped whenever it is not used and consequently the slot after the skipped slot starts earlier. We propose a schedulability analysis for TDMA/SS. We assume knowledge of all message streams in the system, and that each node schedules messages in its output queue according to deadline monotonic. Firstly, we present a non-exact (but fast) analysis and then, at the cost of computation time, we also present an algorithm that computes exact queuing times.
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TL;DR: This paper will develop a diagnosis model based on fault trees that is able to use the huge amount of performance analysis results to identify design errors and analyze their coherences.
Abstract: Network performance engineering can verify the design and dimensioning of large-scale control networks like CSMA-based building automation networks. It combines performance analysis with diagnosis methods to evaluate the network utilization and to detect design errors before installation and can therewith save the expenses of overdimensioning and redesign. This paper will develop a diagnosis model based on fault trees that is able to use the huge amount of performance analysis results to identify design errors and analyze their coherences. This enables not only a fast tracing back of fault causes and the derivation of solutions; it can also visualize the fault coherence to the user and help him to understand his design. Additional consulting tools implement best practice strategies, to support the user in parameterization.
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TL;DR: This paper presents an approach to analyze the quality of service of CSMA-based control nets using a variant of the CSMA access scheme which has not been analyzed analytically before and the integration of timeouts and multicast communication into the analysis approach is outlined.
Abstract: In contemporary control nets, random access schemes like CSMA are commonly used and are often enhanced by fixed priorities for some message types to guarantee an upper bound for the transmission time of high-priority messages. The introduction of priorities has a significant impact on the overall quality of service, which means that messages with a low priority may have long transmission times or high loss rates if the whole network is not adequately dimensioned. Thus, capacity planning includes as one of the first steps a model-based analysis of the network. This paper presents an approach to analyze the quality of service of CSMA-based control nets. Based on open queueing networks, analytical formulas are derived that allow one to compute performance measures like mean throughputs, loss rates, and response times in an extremely efficient way and with limited information about the system load. Particular emphasis is spent on the analysis of priorities in networks using a variant of the CSMA access scheme which has not been analyzed analytically before. Furthermore, the integration of timeouts and multicast communication into the analysis approach is outlined.
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TL;DR: The three papers in part 1 of this special section focus on communication in automation, and the papers are summarized here.
Abstract: The three papers in part 1 of this special section focus on communication in automation. The papers are summarized here.