Fault-Tolerant Flocking in a k-Bounded Asynchronous System

  • Samia Souissi
  • Yan Yang
  • Xavier Défago
Part of the Lecture Notes in Computer Science book series (LNCS, volume 5401)


This paper studies the flocking problem, where mobile robots group to form a desired pattern and move together while maintaining that formation. Unlike previous studies of the problem, we consider a system of mobile robots in which a number of them may possibly fail by crashing. Our algorithm ensures that the crash of faulty robots does not bring the formation to a permanent stop, and that the correct robots are thus eventually allowed to reorganize and continue moving together. Furthermore, the algorithm makes no assumption on the relative speeds at which the robots can move.

The algorithm relies on the assumption that robots’ activations follow a k-bounded asynchronous scheduler, in the sense that the beginning and end of activations are not synchronized across robots (asynchronous), and that while the slowest robot is activated once, the fastest robot is activated at most k times (k-bounded).

The proposed algorithm is made of three parts. First, appropriate restrictions on the movements of the robots make it possible to agree on a common ranking of the robots. Second, based on the ranking and the k-bounded scheduler, robots can eventually detect any robot that has crashed, and thus trigger a reorganization of the robots. Finally, the third part of the algorithm ensures that the robots move together while keeping an approximation of a regular polygon, while also ensuring the necessary restrictions on their movement.


Mobile Robot Failure Detection Regular Polygon Autonomous Mobile Robot Half Circle 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. 1.
    Daigle, M.J., Koutsoukos, X.D., Biswas, G.: Distributed diagnosis in formations of mobile robots. IEEE Transactions on Robotics 23(2), 353–369 (2007)CrossRefGoogle Scholar
  2. 2.
    Coble, J., Cook, D.: Fault tolerant coordination of robot teams,
  3. 3.
    Gervasi, V., Prencipe, G.: Coordination without communication: the Case of the Flocking Problem. Discrete Applied Mathematics 143(1-3), 203–223 (2004)MathSciNetzbMATHGoogle Scholar
  4. 4.
    Hayes, A.T., Dormiani-Tabatabaei, P.: Self-organized flocking with agent failure: Off-line optimization and demonstration with real robots. In: Proc. IEEE Intl. Conference on Robotics and Automation, vol. 4, pp. 3900–3905 (2002)Google Scholar
  5. 5.
    Saber, R.O., Murray, R.M.: Flocking with Obstacle Avoidance: Cooperation with Limited Communication in Mobile Networks. In: Proc. 42nd IEEE Conference on Decision and Control, pp. 2022–2028 (2003)Google Scholar
  6. 6.
    Canepa, D., Potop-Butucaru, M.G.: Stabilizing flocking via leader election in robot networks. In: Masuzawa, T., Tixeuil, S. (eds.) SSS 2007. LNCS, vol. 4838, pp. 52–66. Springer, Heidelberg (2007)CrossRefGoogle Scholar
  7. 7.
    Défago, X., Gradinariu, M., Messika, S., Raipin-Parvédy, P.: Fault-tolerant and self-stabilizing mobile robots gathering. In: Dolev, S. (ed.) DISC 2006. LNCS, vol. 4167, pp. 46–60. Springer, Heidelberg (2006)CrossRefGoogle Scholar
  8. 8.
    Prencipe, G.: CORDA: Distributed Coordination of a Set of Autonomous Mobile Robots. In: Proc. European Research Seminar on Advances in Distributed Systems, pp. 185–190 (2001)Google Scholar
  9. 9.
    Flocchini, P., Prencipe, G., Santoro, N., Widmayer, P.: Pattern Formation by Autonomous Robots Without Chirality. In: Proc. 8th Intl. Colloquium on Structural Information and Communication Complexity (SIROCCO 2001), pp. 147–162 (2001)Google Scholar
  10. 10.
    Gervasi, V., Prencipe, G.: Flocking by A Set of Autonomous Mobile Robots. Technical Report, Dipartimento di Informatica, Università di Pisa, Italy, TR-01-24 (2001)Google Scholar
  11. 11.
    Reynolds, C.W.: Flocks, Herds, and Schools: A Distributed Behavioral Model. Journal of Computer Graphics 21(1), 79–98 (1987)Google Scholar
  12. 12.
    Brogan, D.C., Hodgins, J.K.: Group Behaviors for Systems with Significant Dynamics. Autonomous Robots Journal 4, 137–153 (1997)CrossRefGoogle Scholar
  13. 13.
    John, T., Yuhai, T.: Flocks, Herds, and Schools: A Quantitative Theory of Flocking. Physical Review Journal 58(4), 4828–4858 (1998)MathSciNetGoogle Scholar
  14. 14.
    Yamaguchi, H., Beni, G.: Distributed Autonomous Formation Control of Mobile Robot Groups by Swarm-based Pattern Generation. In: Proc. 2nd Int. Symp. on Distributed Autonomous Robotic Systems (DARS 1996), pp. 141–155 (1996)Google Scholar
  15. 15.
    Dieudonné, Y., Petit, F.: A Scatter of Weak Robots. Technical Report, LARIA, CNRS, France, RR07-10 (2007)Google Scholar
  16. 16.
    Chandra, T.D., Toueg, S.: Unreliable Failure Detectors for Reliable Distributed Systems. Journal of the ACM 43(2), 225–267 (1996)MathSciNetCrossRefzbMATHGoogle Scholar
  17. 17.
    Schreiner, K.: NASA’s JPL Nanorover Outposts Project Develops Colony of Solar-powered Nanorovers. IEEE DS Online 3(2) (2001)Google Scholar
  18. 18.
    Souissi, S., Yang, Y., Défago, X.: Fault-tolerant Flocking in a k-bounded Asynchronous System. Technical Report, JAIST, Japan, IS-RR-2008-004 (2008)Google Scholar
  19. 19.
    Konolige, K., Ortiz, C., Vincent, R., Agno, A., Eriksen, M., Limketkai, B., Lewis, M., Briesemeister, L., Ruspini, E., Fox, O., Stewart, J., Ko, B., Guibas, L.: CENTIBOTS: Large-Scale Robot Teams. Journal of Multi-Robot Systems: From Swarms to Intelligent Autonoma (2003)Google Scholar
  20. 20.
    Bellur, B.R., Lewis, M.G., Templin, F.L.: An Ad-hoc Network for Teams of Autonomous Vehicles. In: Proc. 1st IEEE Symp. on Autonomous Intelligent Networks and Systems (2002)Google Scholar
  21. 21.
    Jennings, J.S., Whelan, G., Evans, W.F.: Cooperative Search and Rescue with a Team of Mobile Robots. In: Proc. 8th Intl. Conference on Advanced Robotics, pp. 193–200 (1997)Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2008

Authors and Affiliations

  • Samia Souissi
    • 1
    • 2
  • Yan Yang
    • 1
  • Xavier Défago
    • 1
  1. 1.School of Information ScienceJapan Advanced Institute of Science and Technology (JAIST)IshikawaJapan
  2. 2.Now at Nagoya Institute of Technology, Department of Computer Science and EngineeringJapan

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