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Title:Time-critical cooperative path-following control of multiple unmanned aerial vehicles
Author(s):Xargay Mata, Enric
Director of Research:Hovakimyan, Naira
Doctoral Committee Chair(s):Hovakimyan, Naira
Doctoral Committee Member(s):Basar, Tamer; Dullerud, Geir E.; Kaminer, Isaac; Voulgaris, Petros G.; Wise, Kevin A.
Department / Program:Aerospace Engineering
Discipline:Aerospace Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:Ph.D.
Genre:Dissertation
Subject(s):Cooperative path following
Coordination
Unmanned aerial vehicles
Time-critical missions
Communications limitations
Quantized consensus
Abstract:This thesis addresses the problem of steering a fleet of unmanned aerial vehicles (UAVs) along desired 3D spatial paths while meeting stringent relative temporal constraints. A representative example is the challenging mission scenario where the UAVs are tasked to cooperatively execute collision-free maneuvers and arrive at their final destinations at the same time, or at different times so as to meet a desired inter-vehicle schedule. In the proposed framework, the UAVs are assigned nominal spatial paths and speed profiles along those, and then the vehicles are requested to execute cooperative path following, rather than "open-loop" trajectory-tracking maneuvers. This strategy yields robust behavior against external disturbances by allowing the UAVs to negotiate their speeds along the paths in response to information exchanged over a supporting inter-vehicle communications network. The proposed approach addresses explicitly the situation where each vehicle transmits coordination-relevant information to only a subset of the other vehicles, as determined by the time-varying communications topology. Furthermore, the thesis considers the case where the graph that captures the underlying communications topology is disconnected during some interval of time or even fails to be connected at all times. Conditions are given under which the complete time-critical cooperative path-following closed-loop system is stable and yields convergence of a conveniently defined cooperation error to a neighborhood of the origin. The thesis also derives lower bounds on the convergence rate of the coordination dynamics as a function of the quality of service of the supporting network, and proposes a coordination algorithm to improve the rate of convergence of the coordination dynamics in low-connectivity scenarios. Moreover, motivated by the exchange of information over networks with finite-rate communication links, the effect of quantization on vehicle coordination is also analyzed. Simulation and flight-test results verify the theoretical findings and demonstrate the efficacy of the multi-vehicle cooperative control framework adopted in this thesis.
Issue Date:2013-08-22
URI:http://hdl.handle.net/2142/45339
Rights Information:Copyright 2013 Enric Xargay Mata
Date Available in IDEALS:2013-08-22
Date Deposited:2013-08


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