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Evolution-based Dynamic Path Planning for Autonomous Vehicles  143
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                                                          Time sample

                                 Fig. 25. Evolution of dynamic path planning with moving obstacles


                              We present an evolutionary algorithm suitable for dynamic path plan-
                           ning problems. The algorithm was developed as part of the Evolution-based
                           Cooperative Planning System for teams of autonomous vehicles. The algo-
                           rithm is used to find an optimal path that maximizes an objective function.
                           This function is formulated using the stochastic world model to capture the
                           dynamics and uncertainties in the system. The algorithm has been applied to
                           path planning for UAVs in real wind fields and predicted icing conditions [22].
                           Extensions to apply this algorithm to the coupled task of the path planning
                           problem for multiple cooperating vehicles are reported in [19].
                              Simulation results demonstrate that the path planning algorithm can
                           provide computationally feasible effective solutions to all of the path plan-
                           ning problems which include planning with timing constraints and dynamic
                           planning with moving targets and obstacles. Even though there are some
                           uncertainties in the knowledge of the environment, the algorithm can generate
                           feasible paths which are within the capabilities of the vehicle to complete all
                           tasks and to avoid collision with the obstacles. During the mission, the planner
                           is able to quickly adapt the path in response to changes in the environment.



                           8 Acknowledgments

                           The research presented in this paper is partially funded by the Washington
                           Technology Center. The simulation software is provided by the Boeing
                           Company. Professor Emeritus Juris Vagners at the University of Washington
                           provided direction and advice for this research.
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