Control of Cooperative Unmanned Aerial Vehicles

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CONTROL OF COOPERATIVE UNMANNED AERIAL VEHICLES

A Thesis submitted for the degree of Doctor of Philosophy (Ph.D) by

Kostas ALEXIS
Dipl. ELECTRICAL & COMPUTER ENGINEERING

UNIVERSITY OF PATRAS DEPARTMENT OF ELECTRICAL & COMPUTER ENGINEERING THESIS NO: 277 JULY 2011

The following dissertation by Kostas Alexis, Dipl. Electrical & Computer Engineering, is approved: “Control of Cooperative Unmanned Aerial Vehicles” The dissertation was presented in public on July 6th . The seven member committee: 1. Anthony Tzes, Professor at Electrical & Computer Engineering Department, University of Patras, Member of the advisor committee 2. Konstantinos Eustathiou, Assistant Professor at Electrical & Computer Engineering Department, University of Patras, Member of the advisor committee 3. Kimon Valavanis, Professor at Electrical & Computer Engineering Department, University of Denver, Member of the advisor committee 4. Stamatios Manesis, Associate Professor at Electrical & Computer Engineering Department, University of Patras 5. Stauros Koubias, Professor at Electrical & Computer Engineering Department, University of Patras 6. Evangelos Dermatas, Assistant Professor at Electrical & Computer Engineering Department, University of Patras 7. Nikolaos Aspragathos, Professor at Mechanical Engineering & Aeronautics, University of Patras July 2011, Patras, Greece The Supervisor and Head of Electrical and Computer Engineering Department, University of Patras:

Anthony Tzes, Professor

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Abstract

This thesis addresses the problems of design and control of small cooperative unmanned autonomous quadrotor aerial vehicles. A new approach for the modeling of the system’s dynamics using linearized Piecewise Affine Models, is proposed. The Piecewise Affine dynamic–models cover a large part of the quadrotor’s flight envelope while also taking into account the additive effects of environmental disturbances. The effects of aerodynamic forces and moments were also examined. A small quadrotor is designed and developed that emphasizes in the areas of increased on–board computational capabilities, state estimation and modular connectivity. Based on the translational and rotational system’s dynamics: a) a switching model predictive controller, b) an explicitly solved constrained finite time optimal control strategy, and c) a cascade control scheme comprised of classical Proportional Integral Derivative control scheme augmented with angular acceleration feedback, were designed and experimentally tested in order to achieve trajectory tracking under the presence of wind–gusts. The efficiency of the proposed control methods was verified through extended experimental studies. The final quadrotor design utilizes a powerful control unit, a sensor system that provides state estimation based on inertial sensors, ultrasound sonars, GPS and vision chips, and an efficient actuating system. The research effort extended in the field of unmanned aerial vehicles cooperation. Cooperation strategies were proposed in order to address the problems of: a) Forest Fire Monitoring and b) Unknown Area Exploration and Target Acquisition. The Forest Fire Monitoring algorithm is formulated based on consensus systems theory formulated as a spatiotemporal rendezvous problem in between the quadrotors. The Area Exploration and Target Acquisition algorithm is formulated based on market–based approaches.

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This dissertation is dedicated to my family, my mother, father, and brother for their continuous love and support

Acknowledgements

During the last four years and during my research process, i was helped and encouraged from several people. First of all I would like to thank my advisor, Prof. A. Tzes for his help and scientific guidance. His support and his trust in my research all these years helped me accomplish my goals and complete this arduous task. Especially, I would also like to thank Prof. K. Valavanis for believing in my work, supporting me in order to gain a...
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