3,441 research outputs found

    Coordinated Sensor-Based Area Coverage and Cooperative Localization of a Heterogeneous Fleet of Autonomous Surface Vessels (ASVs)

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    Sensor coverage with fleets of robots is a complex task requiring solutions to localization, communication, navigation and basic sensor coverage. Sensor coverage of large areas is a problem that occurs in a variety of different environments from terrestrial to aerial to aquatic. In this thesis we consider the aquatic version of the problem. Given a known aquatic environment and collection of aquatic surface vehicles with known kinematic and dynamic constraints, how can a fleet of vehicles be deployed to provide sensor coverage of the surface of the body of water? Rather than considering this problem in general, in this work we consider the problem given a specific fleet consisting of one very well equipped robot aided by a number of smaller, less well equipped devices that must operate in close proximity to the main robot. A boustrophedon decomposition algorithm is developed that incorporates the motion, sensing and communication constraints imposed by the autonomous fleet. Solving the coverage problem leads to a localization/communication problem. A critical problem for a group of autonomous vehicles is ensuring that the collection operates within a common reference frame. Here we consider the problem of localizing a heterogenous collection of aquatic surface vessels within a global reference frame. We assume that one vessel -- the mother robot -- has access to global position data of high accuracy, while the other vessels -- the child robots -- utilize limited onboard sensors and sophisticated sensors on board the mother robot to localize themselves. This thesis provides details of the design of the elements of the heterogeneous fleet including the sensors and sensing algorithms along with the communication strategy used to localize all elements of the fleet within a global reference frame. Details of the robot platforms to be used in implementing a solution are also described. Simulation of the approach is used to demonstrate the effectiveness of the algorithm, and the algorithm and its components are evaluated using a fleet of ASVs

    Optical Speed Measurement and Applications

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    Path-Constrained Data Gathering Scheme

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    Several studies in recent years have considered the use of mobile elements for data gathering in wireless sensor networks so as to reduce the need for multi-hop forwarding among the sensor nodes and thereby prolong the network lifetime Since typically practical constraints preclude a mobile element from visiting all nodes in the sensor network the solution must involve a combination of a mobile element visiting a subset of the nodes cache points while other nodes communicate their data to the cache points wirelessly This leads to the optimization problem of minimizing the communication distance of the sensor nodes while keeping the tour length of the mobile element below a given constraint In this paper we investigate the problem of designing the mobile elements tours such that the length of each tour is below a per-determined length and the number of hops between the tours and the nodes not included in the tour is minimized To address this problem we present an algorithmic solution that consider the distribution of the nodes during the process of building the tours We compare the resulting performance of our algorithm with the best known comparable schemes in the literatur
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