Optimal Search For Moving Targets

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ISBN 13 :
Total Pages : 277 pages
Book Rating : 4.:/5 (914 download)

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Download or read book Minimum Time Search of Moving Targets in Uncertain Environments written by and published by . This book was released on 2013 with total page 277 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis is concerned with the development of an autonomous system to search a dynamic target in the minimum possible time in uncertain environments, that is, to solve the minimum time search problem, which is presented as an especial problem within the optimal search theory. This work proposes a Bayesian approach to nd the target using several moving agents with constrained dynamics and equipped with sensors that provide information about the environment. The minimum time search involves two process: the target location estimation using the information collected by the agents, and the planning of the searching routes that the agents must follow to nd the target. The target location estimation is tackled using Bayesian techniques, more precisely, the recursive Bayesian lter. Moreover, an improved information lter, based on the extended Kalman lter, that deals with the team communication delays (i.e. out of sequence problem) is presented. The agents trajectory planning is faced as a sequential decision making problem where, given the a priori target location estimation, the best actions that the agents have to perform are computed. For that purpose, three Bayesian strategies are proposed: minimizing the local expected time of detection, maximizing the discounted time probability of detection, and optimizing a probabilistic function that integrates an heuristic that approximates the expected observation. To implement the strategies, three solutions are proposed. The rst one, based on constraint programming, provides exact solutions in the discrete case when the target is static and the number of decision variables is small. The second one is an approximated algorithm stood on the cross entropy optimization method that tackles the discrete case for dynamic targets. The third solution is a gradient-based decentralized algorithm that achieves non-myopic solutions for the continuous case. The minimum time search problems are found inside the core of many real applications, such as search and rescue emergency operations (e.g. shipwreck accidents) or pollution substances di usion control (e.g. oil spill monitoring). This thesis reveals how to reduce the searching time of a moving target e ciently, determining which searching strategies take into account the time and under which conditions are valid, and providing approximated polynomial algorithms to compute the actions that the agents must perform to find the target.