Minimizing Jitter in Ethernet Using a Linear Backoff for Real-Time Robot Control Communication and Its Implementation on FPGA

  • Mohamad Khairi Ishak
  • Guido Herrmann
  • Martin J. Pearson
Part of the Lecture Notes in Computer Science book series (LNCS, volume 7429)


Deterministic control communication is a backbone of many novel robotic complex systems, e.g HUBO uses CAN. The aim of this paper, in contrast, is to develop an approach for cheap and deterministic control communication using Ethernet real-time control communication. A half-duplex Ethernet network populated with a small/medium number of Media Access Controllers (MACs) is used for timed real-time communication. Matlab and Field-programmable gate array (FPGA) technology, i.e Xilinx XC3S500E from the Spartan-3E family, are used to simulate and implement the Ethernet communication strategy. The FPGA units are programmed in Verilog using Xilinx ISE 11.1 software tools. For communication, a time-triggered approach is used, i.e a synchronization signal triggers the sending of data from each Ethernet data transmitting unit. Moreover, data packages are sent at well defined times after each trigger instant to reduce collisions. Collisions mainly occur due to jitter of the transmitter system, so that arbitration (similar to CANopen) is necessary. A Linear Backoff scheme is used in comparison to the Binary Exponential backoff scheme. This paper analyzes and investigates how the backoff scheme affects the performance of the Carrier Sense Multiple Access protocol with Collision Detection (CSMA/CD) in a basic MAC, in terms of data arrival characteristics, i.e jitter and delay for deterministic control communication. We propose to assign different minimal back-off times for each of the CSMA/CD controller units and FPGA boards to minimize packet collisions.


FPGA Ethernet real-time Linear Backoff CSMA/CD 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. 1.
    Road vehicles – interchange of digital information controller area network (can) for high-speed communication. In: Vehicle Power and Propulsion Conference, VPPC 2008. IEEE ISO 11898:1993 (1993)Google Scholar
  2. 2.
    Hartwich, F., Muller, B., Fuhrer, T., Hugel, R.: Time triggered communication on can. In: Proceedings 7th International CAN Conference (2000)Google Scholar
  3. 3.
    Hartwich, F., Muller, B., Fuhrer, T., Hugel, R.: Timing in the ttcan network. In: Proceeding 8th International CAN Conference, Las Vegas (2002)Google Scholar
  4. 4.
    Hartwich, F., Muller, B., Fuhrer, T., Hugel, R.: Fault tolerant ttcan networks. In: Proceedings 8th International CAN Conference, Las Vegas (2002)Google Scholar
  5. 5.
    Oh, J.-H., Hanson, D., Kim, W.-S., Han, Y., Kim, J.-Y., Park, I.-W.: Design of android type humanoid robot albert hubo. In: 2006 IEEE/RSJ International Conference on Intelligent Robots and Systems, pp. 1428–1433 (October 2006)Google Scholar
  6. 6.
    Buschmann, T., Lohmeier, S., Ulbrich, H.: Humanoid robot lola: Design and walking control. Journal of Physiology 103(3-5), 141–148 (2009)Google Scholar
  7. 7.
    Leen, G., Heffernan, D.: Ttcan: a new time-triggered controller area network. Microprocessors and Microsystems 26(2), 77–94 (2002)CrossRefGoogle Scholar
  8. 8.
    O’Ryan, C., Kuhns, F., Schmidt, D.C., Othman, O., Parsons, J.: The Design and Performance of a Pluggable Protocols Framework for Real-Time Distributed Object Computing Middleware. In: Coulson, G., Sventek, J. (eds.) Middleware 2000. LNCS, vol. 1795, pp. 372–395. Springer, Heidelberg (2000)CrossRefGoogle Scholar
  9. 9.
    Wang, K., Zhang, C., Ding, X., Ji, S., Hu, T.: A new real-time ethernet for numeric control. In: 2010 8th World Congress on Intelligent Control and Automation (WCICA), pp. 4137–4141 (July 2010)Google Scholar
  10. 10.
    Talledo, J.: Design and implementation of an ethernet frame analyzer for high speed networks. In: Proceedings. 15th International Conference on Electronics, Communications and Computers, CONIELECOMP 2005, pp. 171–176 (February 2005)Google Scholar
  11. 11.
    Ke, C.-H., Wei, C.-C., Lin, K.W., Ding, J.-W.: A smart exponential-threshold-linear backoff mechanism for IEEE 802.11 wlans. Int. J. Commun. Syst. 24, 1033–1048 (2011)CrossRefGoogle Scholar
  12. 12.
    Chlamtac, I., Eisinger, M.: Voice/data integration on ethernet - backoff and priority considerations. Computer Communications 6(5), 236–244 (1983)CrossRefGoogle Scholar
  13. 13.
    Medepalli, K., Tobagi, F.: On optimization of csma/ca based wireless lans: Part i - impact of exponential backoff. In: IEEE International Conference on Communications, ICC 2006, vol. 5, pp. 2089–2094 (June 2006)Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • Mohamad Khairi Ishak
    • 1
  • Guido Herrmann
    • 1
  • Martin J. Pearson
    • 2
  1. 1.Queens School of EngineeringUniversity WalkBristolUnited Kingdom
  2. 2.Bristol Robotics LaboratoryBristolUnited Kingdom

Personalised recommendations