IEEE Industrial Electronics Society
IEEE Industrial Electronics Society
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Introducing Associate Editor Adriano Valenzano
Page(s): 1
Guest Editorial: Special Section on Communication in Automation – Part I
Gianluca Cena and Francisco Vasques
Page(s): 2
1. Fine-Tuning MAC-Level Protocols for Optimized Real-Time QoS
Navet, Nicolas; Grenier, Mathieu
Page(s): 6
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 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 on-line scheduling policies targeted at scheduling frames at the MAC level, and provides a schedulability analysis that is valid for all policies within the considered class. As it will be shown, these algorithms are easily 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.
2. A Distributed Instrument for Performance Analysis of Real-Time Ethernet networks
Ferrari, Paolo; Flammini, Alessandra; Marioli, Daniele; Taroni, Andrea
Page(s): 16
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 µs and cycle jitter less than 1 µs, making network testing and debugging very critical. Existing Network & 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 work 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.
3. On the Analysis of CSMA-Based Control Nets with Priorities and Multicast
Buchholz, Peter; Panchenko, Andriy
Page(s): 26
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 those 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 analyse 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 analysed analytically before. Furthermore, the integration of timeouts and multicast communication into the analysis approach is outlined.
4. Automatically Configuring Time-Triggered Schedulers for Use with Resource-Constrained, Single-Processor Embedded Systems
Gendy, Ayman K. and Pont, Michael J.
Page(s): 37
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: (i) all task constraints are met; (ii) CPU power consumption is "as low as possible"; (iii) a fully co-operative scheduler architecture is employed whenever possible. Our search process is not exhaustive, and 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.
5. Damping of Torsional Vibrations in Two-Mass System using Adaptive Sliding Neuro-Fuzzy Approach
Orlowska-Kowalska, Teresa and Szabat, Krzysztof
Page(s): 47
Abstract: –In the 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.
6. A MCDM Knowledge Based Scheme for Real Time Power Voltage Control
Man, Kim; Ma, Haomin
Page(s): 58
Abstract: A new real time power voltage control strategy is proposed in the paper. This scheme utilizes a novel off-line evolutionary multiobjective optimization algorithm called jumping genes for generating the wide spread control solutions and be readily stored into a knowledge data base. A separate on-line multiple criteria decision making scheme is established for selecting the appropriate control solution. This concept of power voltage control has been demonstrated by a representative 6-buses nonlinear power system model. The system output performance was speedy and accurate.
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