Phasing of Periodic Tasks Distributed over Real-time Fieldbus

  • Sang-Hun Lee Hyundai Mobis 17-2, 240 Mabuk-ro, Giheung-gu, Yongin-si, Gyeounggi-do 16891, Korea
  • Hyun-Wook Jin
  • Kanghee Kim Department of Smart Systems Software Soongsil University 369 Sangdo-ro, Dongjak-gu, Seoul 06978, Korea
  • Sangil Lee Agency for Defense Development Songpa P.O.Box 132, Seoul 05661, Korea

Abstract

In designing a distributed hard real-time system, it is important to reduce the end-to-end delay of each real-time message in order to ensure quick responses to external inputs and a high degree of synchronization among cooperating actuators. In order to provide a real-time guarantee for each message, the related literature has focused on the analysis of end-to-end delays based on worst-case task phasing. However, such analyses are too pessimistic because they do not assume a global clock. With the assumption that task phases can be managed by using a global clock provided by emerging real-time fieldbuses, such as EtherCAT, we can try to calculate the optimal task phasing that yields the minimal worst-case end-to-end delay. In this study, we propose a heuristic to manage the phase offsets in the distributed tasks to reduce the theoretical end-to-end delay bound. The proposed heuristic reduces the search time for a solution by identifying time intervals where actual communication occurs among inter-dependent tasks. Furthermore, to analyze the distribution of endto- end delays in different phases, we implemented a simulation tool. The simulation results showed that the proposed heuristic can reduce worst-case end-to-end delay as well as jitter in end-to-end delays.

References

[1] Bril R.J., Steffens E.F.M., Verhaegh W.F.J. (2004); Best-case response times and jitter analysis of real-time tasks, Journal of Scheduling, 7(2), 133-147, 2004.
https://doi.org/10.1023/B:JOSH.0000014069.63823.e7

[2] Cena G., Bertolotti I.C., Scanzio S., Valenzano A., Zunino C. (2012); Evaluation of EtherCAT distributed clock performance, IEEE Trans. Industrial Informatics, 8(1), 20-29, 2012.
https://doi.org/10.1109/TII.2011.2172434

[3] Cena G., Bertolotti I.C., Scanzio S., Valenzano A., Zunino C. (2010); On the accuracy of the distributed clock mechanism in EtherCAT, In Proc. the 8th IEEE Int. Workshop on Factory Communication Systems, 43-52, 2010.

[4] Craciunas S.S., Oliver R.S., Ecker V. (2014); Optimal static scheduling of real-time tasks on distributed time-triggered networked systems, Proc. IEEE Int. Conf. on Emerging Technologies and Factory Automation, 1-8, 2014.

[5] Farsi M., Ratcliff K., Barbosa M. (1999); An introduction to CANopen, Computing & Control Engineering Journal, 10(4), 161-168, 1999.
https://doi.org/10.1049/cce:19990405

[6] Garner G.M., Gelter A., Teener M.J. (2009); New simulation and test results for IEEE 802.1 as timing performance, Int. Symp. on Precision Clock Synchronization for Measurement, Control and Communication, 1-7, 2009.

[7] Harbour M.G., Gutiérrez J.J., Drake J.M., Martínez P.L., Palencia J.C. (2013); Modeling distributed real-time systems with MAST2, Journal of Systems Architecture, 59(6), 331-340, 2013.
https://doi.org/10.1016/j.sysarc.2012.02.001

[8] Henia R., Racu R., Ernst R. (2007); Improved Output Jitter Calculation for Compositional Performance Analysis of Distributed Systems, Proc. IEEE Int. Parallel and Distributed Processing Symp., 1-8, 2007. doi: 10.1109/IPDPS.2007.370356
https://doi.org/10.1109/IPDPS.2007.370356

[9] International Electrotechnical Commission (2007); Industrial Communication Networks Fieldbus specifications - Part 3-12: Data-Link Layer Service Definition - Part 4-12: Data-link layer protocol specification-Type 12 elements, IEC, 61158-3/4-12 (Ed. 1.0), 2007.

[10] Kang H., Kim K., Jin H.-W. (2016); Real-Time Software Pipelining for Multidomain Motion Controllers, IEEE Trans. Industrial Informatics, 12(2), 705-715, 2016.
https://doi.org/10.1109/TII.2016.2528225

[11] Kim I.; Kim T. (2015); Guaranteeing isochronous control of networked motion control systems using phase offset adjustment, Sensors, 15(6), 13945-13965, 2015.
https://doi.org/10.3390/s150613945

[12] Kim K., Sung M., Jin H.-W. (2012); Design and implementation of a delay-guaranteed motor drive for precision motion control, IEEE Trans. Industrial Informatics, 8(2), 351-365, 2012.
https://doi.org/10.1109/TII.2011.2166774

[13] Liu C., Layland J. (1973); Scheduling Algorithms for Multiprogramming in a Hard-Real- Time Environment, Journal of the ACM, 20(1), 46-61, 1973.
https://doi.org/10.1145/321738.321743

[14] Potra S., Sebestyen G. (2006); EtherCAT protocol implementation issues on an embedded linux platform, Proc. IEEE Int. Conf. on Automation, Quality and Testing, Robotics, 420-425, 2006.

[15] Prytz G. (2008); A performance analysis of EtherCAT and PROFINET IRT, Proc. IEEE Int. Conf. on Emerging Technologies and Factory Automation, 408-415, 2008.
https://doi.org/10.1109/ETFA.2008.4638425

[16] Redell O., Sanfridson M. (2002); Exact Best-Case Response Time Analysis of Fixed Priority Scheduled Tasks, Proc. Euromicro Conf. on Real-Time Systems, 165-172, 2002.

[17] Steinbach T., Kenfack H.D., Korf F., Schmidt T.C. (2011); An extension of the OMNeT++ INET framework for simulating real-time Ethernet with high accuracy, Proc. the 4th Int. ICST Conf. on Simulation Tools and Techniques, 375-382, 2011.

[18] Sung M., Kim I., Kim T. (2013); Toward a Holistic Delay Analysis of EtherCAT Synchronized Control Processes, International Journal of Computers Communications & Control, 8(4), 608-621, 2013.
https://doi.org/10.15837/ijccc.2013.4.384

[19] Tindell K., Clark J. (1994); Holistic schedulability analysis for distributed hard real-time systems, Microprocessing and Microprogramming, 40(2), 117-134, 1994.

[20] Valls M.G., Alonso A., de la Puente J.A. (2012); A dual-band priority assignment algorithm for dynamic QoS resource management, Future Generation Computer Systems, 28(6), 902- 912, 2012.
https://doi.org/10.1016/j.future.2011.10.005

[21] Valls M.G., López I.R., Villar L.F. (2013); iLAND: An enhanced middleware for real-time reconfiguration of service oriented distributed real-time systems, IEEE Trans. Industrial Informatics, 9(1), 228-236, 2013.
https://doi.org/10.1109/TII.2012.2198662

[22] Zeng H., Di Natale M., Giusto P., Sangiovanni-Vincentelli A. (2009); Stochastic analysis of CAN-based real-time automotive systems, IEEE Trans. Industrial Informatics, 5(4), 388-401, 2009.
https://doi.org/10.1109/TII.2009.2032067
Published
2017-09-10
How to Cite
LEE, Sang-Hun et al. Phasing of Periodic Tasks Distributed over Real-time Fieldbus. INTERNATIONAL JOURNAL OF COMPUTERS COMMUNICATIONS & CONTROL, [S.l.], v. 12, n. 5, p. 645-660, sep. 2017. ISSN 1841-9844. Available at: <http://univagora.ro/jour/index.php/ijccc/article/view/2894>. Date accessed: 23 nov. 2020. doi: https://doi.org/10.15837/ijccc.2017.5.2894.

Keywords

task phasing, end-to-end delay, real-time, fieldbus, EtherCAT