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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Modeling, Stability Analysis And Control System Design Of A Small-sized Tiltrotor Uav

Cakici, Ferit 01 March 2009 (has links) (PDF)
Unmanned Aerial Vehicles (UAVs) are remotely piloted or self-piloted aircrafts that can carry cameras, sensors, communications equipment or other payloads. Tiltrotor UAVs provide a unique platform that fulfills the needs for ever-changing mission requirements by combining the desired features / hovering like a helicopter and reaching high forward speeds like an airplane. In this work, the conceptual design and aerodynamical model of a realizable small-sized Tiltrotor UAV is constructed, the linearized state-space models are obtained around the trim points for airplane, helicopter and conversion modes, controllers are designed using Linear Quadratic Regulator (LQR) methods and gain-scheduling is employed to obtain a simulation for the whole flight envelope. The ideas for making a real flying model are established according to simulation results.
152

Modellering av ett bränslesystem i Modelica : tillämpat på ett obemannat flygplan

Larsson, Emil January 2007 (has links)
<p>Mathematical models possible to simulate are of great importance in order to make successful projects in the aircraft manufacturing industry. An aircraft fuel system is very complex, containing pipes, tanks, orifices, valves and pumps. The principal of this thesis is using the tool Easy5, which no longer is considered reliable enough in terms of development and support. This thesis tries to evaluate the Modelica language as a possible alternative to Easy5. To make this evaluation, the components concerned in the fuel library in Easy5 are implemented to the Modelica language. Small hydraulic systems are built up in Dymola, and verified against Easy5 through simulation with high accuracy.</p><p>A model of the fuel system of an unmanned aerial vehicle (UAV) is built from the implemented Modelica components to examine how Dymola manage a large model. The simulation made in Dymola was considerably more time efficient than the one made in Easy5, in the range of minutes instead of hours. Thus, much time can be saved if Dymola is used instead of Easy5.</p><p>Finally, the components in the fuel library handle a two phase flow of fuel and air. Modeling a two phase flow is not trivial and discontinuous mass flow and pressure values are also implemented and discussed.</p> / <p>För att driva framgångsrika projekt inom flygindustrin är det av stor vikt att ha matematiska modeller som kan simuleras. Ett bränslesystem till ett flygplan kan ses som ett komplext system bestående av bl.a. rör, tankar, ventiler och pumpar. För närvarande använder uppdragsgivaren till detta examensarbete modeller till dessa komponenter i verktyget Easy5, vars framtid anses osäker med avseende på nyutveckling och support. Syftet med detta examensarbete är därför att utvärdera modelleringsspråket Modelica som möjligt alternativ till Easy5. För att kunna göra en utvärdering implementeras berörda komponenter i Modelica med utgångspunkt från Easy5s bränslebibliotek. Mindre hydrauliska system skapas i verktyget Dymola, och dessa verifieras mot Easy5 genom simuleringar. Simuleringsresultaten visar på hög överensstämmelse mellan de båda verktygen.</p><p>För att undersöka hur verktyget Dymola hanterar en stor modell skapas bränslesystemet till ett obemannat flygplan (UAV) utifrån de implementerade Modelicakomponenterna. Resultat tyder på att simuleringstiden kan kortas betydligt om Dymola används gentemot Easy5; storleksordningen minuter istället för timmar.</p><p>Avslutningsvis hanterar komponenterna i bränslebiblioteket ett massflöde av både bränsle och luft. Att modellera ett 2-fasflöde stöter på vissa simuleringstekniska komplikationer i form av diskontinuerliga massflöden och tryck, vilket visas och diskuteras.</p>
153

Design of a Semi-Autonomous Quadrotor Aircraft

Hickle, Mark, Wilson, Alexander, Kientzy, Joshua, Myers, Matthew 10 1900 (has links)
ITC/USA 2012 Conference Proceedings / The Forty-Eighth Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2012 / Town and Country Resort & Convention Center, San Diego, California / This paper describes the design and construction of a semi-autonomous quadrotor aircraft approximately 1 meter in diameter. Because of the mechanical simplicity of the aircraft, the design challenges primarily centered on the electrical and computer engineering (ECE) tasks, and was used as a capstone design experience in an undergraduate ECE program. An onboard microcontroller based system uses a network of digital sensors and differential thrust for autonomous attitude control. A wireless telemetry and command link allows a user to monitor the vehicle, control its direction of flight, and for flight safety control.
154

Tailorable Remote Unmanned Combat Craft

Jacobi, Loren, Campbell, Rick, Chau, Chee Nam, Ong, Chin Chuan, Tan, Szu Hau, Cher, Hock Hin, Alexander, Cory, Edwards, Christien, Diukman, Anner, Ding, Sze Yi, Hagstette, Matthew, Kwek, Howe Leng, Bush, Adam, Meeks, Matt, Tham, Kine Yin, Ng, Mei Ling, Yeo, Ing Kang, Loke, Yew Kok 06 1900 (has links)
Approved for public release; distribution is unlimited. / U.S. military and civilian vessels are critically vulnerable to asymmetric threats in littoral environments. Common asymmetric weapons such as Anti-Ship Cruise Missiles (ASCM), Low Slow Flying (LSF) aircraft and Fast Attack Craft (FAC) / Fast Inshore Attack Craft (FIAC) threaten U.S. strategic goals and can produce unacceptable losses of men and material. The SEA-18B team presents an operational concept for a family of Unmanned Surface Vessels USV) capable of defending ships from asymmetric swarm attacks. This USV, the Tailorable Remote Unmanned Combat Craft (TRUCC), can operate in concert with the next generation of capital surface vessels to combat this critical threat with maximum efficiency. Critical performance criteria of the TRUCC family were determined through agent-based simulation of a Straits of Hormuz Design Reference Mission. Additional models addressed ship synthesis and operational availability. A Technology and Capability Roadmap outlines areas of interest for investment and development of the next-generation USV. Interim technology and capability milestones in the Roadmap facilitate incremental USV operational capabilities for missions such as logistics, decoy operations and Mine Warfare. The TRUCC operational concept fills a critical vulnerability gap. Its employment will reduce combat risk to our most valuable maritime assets: our ships and our Sailors.
155

Modellering av ett bränslesystem i Modelica : tillämpat på ett obemannat flygplan

Larsson, Emil January 2007 (has links)
Mathematical models possible to simulate are of great importance in order to make successful projects in the aircraft manufacturing industry. An aircraft fuel system is very complex, containing pipes, tanks, orifices, valves and pumps. The principal of this thesis is using the tool Easy5, which no longer is considered reliable enough in terms of development and support. This thesis tries to evaluate the Modelica language as a possible alternative to Easy5. To make this evaluation, the components concerned in the fuel library in Easy5 are implemented to the Modelica language. Small hydraulic systems are built up in Dymola, and verified against Easy5 through simulation with high accuracy. A model of the fuel system of an unmanned aerial vehicle (UAV) is built from the implemented Modelica components to examine how Dymola manage a large model. The simulation made in Dymola was considerably more time efficient than the one made in Easy5, in the range of minutes instead of hours. Thus, much time can be saved if Dymola is used instead of Easy5. Finally, the components in the fuel library handle a two phase flow of fuel and air. Modeling a two phase flow is not trivial and discontinuous mass flow and pressure values are also implemented and discussed. / För att driva framgångsrika projekt inom flygindustrin är det av stor vikt att ha matematiska modeller som kan simuleras. Ett bränslesystem till ett flygplan kan ses som ett komplext system bestående av bl.a. rör, tankar, ventiler och pumpar. För närvarande använder uppdragsgivaren till detta examensarbete modeller till dessa komponenter i verktyget Easy5, vars framtid anses osäker med avseende på nyutveckling och support. Syftet med detta examensarbete är därför att utvärdera modelleringsspråket Modelica som möjligt alternativ till Easy5. För att kunna göra en utvärdering implementeras berörda komponenter i Modelica med utgångspunkt från Easy5s bränslebibliotek. Mindre hydrauliska system skapas i verktyget Dymola, och dessa verifieras mot Easy5 genom simuleringar. Simuleringsresultaten visar på hög överensstämmelse mellan de båda verktygen. För att undersöka hur verktyget Dymola hanterar en stor modell skapas bränslesystemet till ett obemannat flygplan (UAV) utifrån de implementerade Modelicakomponenterna. Resultat tyder på att simuleringstiden kan kortas betydligt om Dymola används gentemot Easy5; storleksordningen minuter istället för timmar. Avslutningsvis hanterar komponenterna i bränslebiblioteket ett massflöde av både bränsle och luft. Att modellera ett 2-fasflöde stöter på vissa simuleringstekniska komplikationer i form av diskontinuerliga massflöden och tryck, vilket visas och diskuteras.
156

Navigation of Unmanned Aerial Vehicles Using Image Processing

Hasnain, Syed Saad January 2008 (has links)
The purpose of this thesis is to investigate the possibility of using aerial or satellite images or eventually digital elevation models in order to localize the UAV helicopter in the environment. Matching techniques are investigated in order to match the available on-board image of the area with the live images acquired by the on-board video camera. The problem is interesting because it can provide a redundancy for the UAV navigation system which is based only on GPS. The thesis is in the context of the development of an integrated system for navigation using image sequences from an aircraft. The system is composed of relative position estimation, which computes the current position of the helicopter by accumulating relative displacement extracted from successive aerial images. These successive aerial images are then matched using certain image matching techniques.
157

A COMMUNICATION LINK RELIABILITY STUDY FOR SMALL UNMANNED AERIAL VEHICLES

Mylin, Alicia K. 01 January 2007 (has links)
Dependable communication links for unmanned aerial vehicles (UAV) are crucial to operational reliability and mission success. This study is focused on evaluating the probability of successful communication links for small UAVs. A program based on the Friis Transmission Equation was developed to calculate the power received in a line-of-sight communication link. The program was used to evaluate the probability of success for a variety of flight pa
158

En jämförelse mellan TLS och UAV-fotogrammetri : Inmätning av hårdgjorda ytor

Cedergren, Lucas, Paakkonen, Richard January 2015 (has links)
At present day there are several different methods for measuring of paved surfaces. The most common methods today are measuring with a total station, the Global Navigation Satellite System (GNSS) and terrestrial laser scanning (TLS). Recently the development of unmanned aerial vehicles, known as drones, has increased exponentially and today there are several ways of using drones for measuring surfaces by photographing and laser scanning. This thesis contains a comparison between the methods terrestrial laser scanning (TLS), and unmanned aerial vehicle photogrammetry (UAV). The measurements have been applied on two different test surfaces, one of asphalt and one of gravel. The purpose of the comparison is to investigate whether the airborne photogrammetry is equivalent accurate in its height levels as the terrestrial laser scanning. For the comparison to be more extensive, these two methods have not only been compared in precision but also in the areas of ease of use and economy. The precision was analyzed by comparing the height levels in randomly placed control points on the test surfaces. This has been made possible by the creation of terrain models of test surfaces in the software Geo where a surface scan of the models have been implemented. With the help of surface control the height deviations in the control points have been calculated and from these deviations the precision of the airborne photogrammetry has been evaluated. The ease of use has been analyzed based on observations made and information gathered from experienced consultants for each technology. For the economic aspect the costs for each measurement method has been presented to get an overall picture of each measurement method costs. The work has been carried out on behalf of the consulting firm Bjerking AB. The goal is to be able to provide Bjerking with a recommendation for which technology is best suited for measuring of paved surfaces. The results of the survey show that the UAV varies by a mean of 11 mm on the surface of gravel and 2 mm on the surface of the asphalt. The final recommendation given is that the UAV is preferred for measurement of asphalt roads, because since the precision is equivalent to TLS, the method is safe
159

Critical comparison of control techniques for a flight dynamics controller / Gustav Otto

Otto, Gustav January 2011 (has links)
This dissertation covers the process of modelling and subsequently developing a flight dynamics controller for a quad–rotor unmanned aerial vehicle. It is a theoretical study that focusses on the selection of a controller type by first analysing the problem on a system level and then on a technical level. The craft is modelled using the Newton– Euler model, accounting for multiple reference frames to account for the interpretation of orientation as seen by on–board sensors. The quad–rotor model and selected controllers are characterized and compared. The model is verified through simulation by comparison to a validated model. A series of generic control loops are derived and used as reference for the implementation of the controllers. A Simulator is developed and used to do a comparative study of the various controller types and the control approach. Finally a full simulation is done to demonstrate the interaction between the controllers. / Thesis (MIng (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2012.
160

Long-range Communication Framework for Autonomous UAVs

Elchin, Mammadov 10 July 2013 (has links)
The communication range between a civilian Unmanned Aerial Vehicle (UAV) and a Ground Control Station (GCS) is affected by the government regulations that determine the use of frequency bands and constrain the amount of power in those frequencies. The application of multiple UAVs in search and rescue operations for example demands a reliable, long-range inter-UAV communication. The inter-UAV communication is the ability of UAVs to exchange data among themselves, thus forming a network in the air. This ability could be used to extend the range of communication by using a decentralized routing technique in the network. To provide this ability to a fleet of autonomous dirigible UAVs being developed at the University of Ottawa, a new communication framework was introduced and implemented. Providing a true mesh networking based on a novel routing protocol, the framework combines long-range radios at 900 MHz Industrial, Scientific and Medical (ISM) band with the software integrated into the electronics platform of each dirigible. With one radio module per dirigible the implemented software provides core functionalities to each UAV, such as exchanging flight control commands, telemetry data, and photos with any other UAV in a decentralized network or with the GCS. We made use of the advanced networking tools of the radio modules to build capabilities into the software for route tracing, traffic prioritization, and minimizing self-interference. Initial test results showed that without acknowledgements, packets can be received in the wrong order and cause errors in the transmission of photos. In addition, a transmission in a presence of a third broadcasting node slows down by 4-6 times. Based on these results our software was improved to control to flow of transmit data making the fragmentation, packetization, and reassembly of photos more reliable. Currently, using radios with half-wavelength dipole antennas we can achieve a one-hop communication range of up to 5 km with the radio frequency line-of-sight (RF LOS). This can be extended further by adding as many radio nodes as needed to act as intermediate hops.

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