Cooperative Localization and Multi-Robot Exploration

Abstract


This thesis has two main contributions. The first contribution is the employment of cooperative localization for the decoupling of the positional error of the moving robot from the environment. The second contribution is the development of efficient multi-robot exploration strategies of an unknown environment.

The proposed method is designed to be robust in the face of arbitrarily large odometry errors or objects with poor reflectance characteristics. Central to the exploration strategy is a sensor (robot tracker) mounted on a robot that could track a second mobile robot and report accurately its relative position. Our exploration strategies use the robot tracker sensor to sweep areas of free space between stationary and moving robots and to generate a graph-based description of the environment. This graph is used to guide the exploration process. Depending on the size of the environment relative to the range of the robot tracker, different spatial decompositions are used: a triangulation or a trapezoidal decomposition of the free space. Complete exploration without any overlaps is guaranteed as a result of the guidance provided by the dual graph of the spatial decomposition of the environment.

The uncertainty in absolute robot positions and the resulting uncertainty in the map is reduced through the use of a probabilistic framework based on particle filtering (a Monte Carlo simulation technique). Particle filtering is a probabilistic sampling technique used to efficiently model complex probability distributions that cannot be effectively described using classical methods (such as Kalman filters).

We present experimental results from two different implementations of the robot tracker sensor, in simulated and in real environments. The accuracy of the resulting map increases with the use of cooperative localization. Furthermore, the deterioration of the floor conditions did not affect the quality of the map verifying the decoupling of positioning error from the environment.

Video

Selected References

  1. abstract bibtex pdf postscript

    Cooperative Localization and Multi-Robot Exploration

    Ioannis M. Rekleitis
    Ph.D. thesis, School of Computer Science, McGill University, Montreal, Quebec, Canada, 2003.

  2. abstract bibtex pdf postscript

    Multi-Robot Collaboration for Robust Exploration

    Ioannis M. Rekleitis and Gregory Dudek and Evangelos Milios
    In Annals of Mathematics and Artificial Intelligence 2001

  3. abstract bibtex pdf mpg video

    Experiments in Free-Space Triangulation Using Cooperative Localization

    Ioannis M. Rekleitis and Gregory Dudek and Evangelos Milios
    IEEE/RSJ International Conference on Intelligent Robots and Systems, pages 1777-1782, Las Vegas, NV, Oct. 27-31, 2003

  4. abstract bibtex pdf postscript

    Probabilistic Cooperative Localization and Mapping in Practice

    Ioannis M. Rekleitis and Gregory Dudek and Evangelos Milios
    IEEE International Conference in Robotics and Automation, pages 1907-1912, Taipei Taiwan, Sept. 2003.

  5. abstract bibtex pdf postscript

    Graph-based exploration using multiple robots

    Ioannis M. Rekleitis, Gregory Dudek and Evangelos Milios
    5th International Symposium on Distributed Autonomous Robotic Systems (DARS), pages 241-250, Knoxville, Tennessee, USA, Oct. 4-6 2000. Springer. Appeared also as a chapter in ``Distributed Autonomous Robotic Systems 4''

  6. abstract bibtex pdf postscript

    Multi-robot collaboration for robust exploration

    Ioannis M. Rekleitis, Gregory Dudek and Evangelos Milios
    IEEE International Conference in Robotics and Automation, pages 3164-3169, San Francisco, USA, Apr. 2000

  7. abstract bibtex pdf

    Multi-robot exploration of an unknown environment, efficiently reducing the odometry error

    Ioannis M. Rekleitis, Gregory Dudek and Evangelos Milios
    Proc. of International Joint Conference on Artificial Intelligence (IJCAI), volume 2, pages 1340-1345, Nagoya, Japan, Aug. 1997, Morgan Kaufmann Publishers, Inc.

Complete List of Publications and bibtex entries.



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