Mobile Robot Navigation in Dynamic Environments


Service robots which act in environments populated by humans have become very popular in the last few years. A variety of systems exists which act for example in hospitals, office buildings, department stores, and museums. Furthermore, several multi-robot systems have been developed for tasks which can be accomplished more efficiently by a whole team of robots than just by a single robot. These tasks include surface cleaning, deliveries, and the exploration of unknown terrain. Whenever teams of mobile robots are operating in the same environment their motions have to be coordinated in order to avoid congestions or collisions. At the same time the robots should perform their navigation tasks in a minimum amount of time. Thus, sophisticated path planning techniques are needed that fulfill these requirements. Since the joint configuration space of the robots is typically huge and grows exponentially with the number of robots, existing path planning methods for single robot systems cannot directly be transferred to multi-robot systems. Many existing path planning methods for multi-robot systems are decoupled, which means that they first plan paths for the individual robots independently. Af-terward, they check if the robots would get too close to each other if the paths were executed. In such a case the paths are recomputed to avoid these conflicts. Many decoupled methods assign priorities to the individual robots. These priorities define an order in which the paths of the robots have to be recomputed. By computing the path of a robot, the paths of the robots with higher priority are considered as fixed. This way, the size of the search space is extremely reduced. Most of the existing prioritized decoupled methods use a fixed priority scheme (order of the robots). However, the order in which the paths of the robots are recom-puted has a serious influence on whether a solution can be found at all and on how efficient the solution is for the overall multi-robot system. In the first part of this thesis we present an approach which searches in the space of all priority schemes to find an order of the robots for which a solution to the path planning problem can be computed. During the search, we utilize constraints between the priorities of the robots which are automatically derived from the task specification. After an appropriate priority scheme has been found, our technique tries to improve it by using a hill-climbing strategy. Our search …

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@inproceedings{Bennewitz2004MobileRN, title={Mobile Robot Navigation in Dynamic Environments}, author={Maren Bennewitz and Wolfram Burgard and Thomas Ottmann and Raja Chatila}, year={2004} }