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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.
11

Blända kommersiella UAV:er med laservapen

Nilsson, Patrik January 2017 (has links)
Försvarsmakten har idag problem under övningar med oidentifierade UAV:er som befinner sig över övningsområdet. UAV:er som har möjlighet till att spana på övningar och kartlägga infrastruktur och förmågor. Denna uppsats syftar till att undersöka vilka möjligheter en handhållen laserpekare skulle skapa för att motverka problemet med UAV:er som befinner sig över övningsområden alternativt intill skyddsobjekt. Tanken med att undersöka handhållna laserpekare är att handhållna laserpekare inte är stora, tunga eller energikrävande. Detta skulle möjliggöra att sprida dem inom Försvarsmakten till samtliga förband. Experiment med olika handhållna laserpekare genomförs för att kontrollera vilka effekter de ger på bestämda avstånd. Det genomförs även experiment för att kontrollera vilka avstånd en specifik UAV kan genomföra spaningsuppdrag på samt möjligheter att upptäcka en UAV på olika avstånd med och utan hjälpmedel. Experimenten visar att om observatören är medveten om i vilken riktning UAV befinner sig är det möjligt att upptäcka den på 600m avstånd. Detta skapar ett problem eftersom UAV kan genomföra spaning på längre avstånd. Experimenten visar även att laser ger en bländningseffekt på 75m vilket inte är i närheten av UAV:ers möjliga spaningsavstånd / The Swedish Armed Forces today have problems during exercises with unidentified UAVs located over the exercise area. UAVs which can observe exercises and map infrastructure and abilities. This paper aims to investigate what capabilities a handheld laser pointer would create to counteract the problem of UAVs that are located over training areas or adjacent to protected area. The thought of examining handheld laser pointers is that handheld laser pointers are not large, heavy or energy-intensive, which would enable them to spread within the Armed Forces to all services. Experiments with different handheld laser pointers are performed to investigate the effects they give at a certain distance. Experiments are also carried out to check at which distances a specific UAV can perform reconnaissance assignments, as well as the ability to detect a UAV at various distances with and without aids. The experiments showed that if the observer is aware of the direction of the UAV, it is possible to detect it at 600m distance with aids and at 500m without. The experiments also showed that laser gives a glare effect at 75m which is not close to a UAV's possible reconnaissance distances.
12

Damage detection methodology for composite UAV wings using modal analysis and probabilistic concepts

Prinsloo, Timothy January 2011 (has links)
Monitoring of structural integrity is critical in many fields today, and particularly so in the civil, mechanical and aerospace engineering industries. In the aerospace industry, appreciably sized and almost exclusively composite UAVs share the airspace with other aircraft. Such composite structures also pose numerous uncertainties to structural health monitoring and analysis techniques. This necessitates research into a methodology for practical and effective structural health monitoring techniques. This work presents a methodology for structural health monitoring and particularly delamination detection in composite wing structures. The approach uses experimental modal analysis with due consideration for the probabilistic effects of random variations in material and geometrical properties, for the purpose of a general and non wing-specific damage detection technique. A large number of composite material coupons were tested to determine statistical distributions of 2D orthotropic material properties, using an optical image correlation system to reduce the expense of testing. Uncertainties in the wing geometry arising from manufacturing variances were taken into consideration. The material properties of the foam spar and resin beadings were considered isotropic and deterministic. A finite element model of the wing was subsequently improved using a scanning laser vibrometer to conduct detailed experimental modal analyses of five wings, and a multi-model updating approach based on frequency and mode shape information was used to update selected sensitive material properties. Significant improvement was accomplished. Using the probabilistic material property database, a confidence region was established for wing mode shapes through a Monte Carlo procedure. It was shown that delamination effects are capable of perturbing the dynamic mode shapes beyond the confidence regions implied by the material uncertainties. This provides a basis for further development of a structural health monitoring methodology for composite structures, taking due account of the many uncertainties in the structure. / Dissertation (MEng)--University of Pretoria, 2011. / gm2013 / Mechanical and Aeronautical Engineering / unrestricted
13

Ota-quadrotor: An Object-tracking Autonomous Quadrotor for Real-time Detection and Recognition

Coelho, Gavin 05 1900 (has links)
The field of robotics and mechatronics is advancing at an ever-increasing rate and we are starting to see robots making the transition from the factories to the workplace and homes as cost is reduced and they become more useful. In recent years quadrotors have become a popular unmanned air vehicle (UAV) platform. These UAVs or micro air vehicles (MAV) are being used for many new and exciting applications such as aerial monitoring of wildlife, disaster sites, riots and protests. They are also being used in the film industry, as they are significantly cheaper means of getting aerial footage. While quadrotors are not extremely expensive a good system can cost in the range of $3000 - $8000 and thus too costly as a research platform for many. There are a number of cheaper open source platforms. The ArduCopter is under constant development, has the largest community and is inexpensive making it an ideal platform to work with. The goal of this thesis was to implement video processing on a ground control station allowing for the ArduCopter to track moving objects. This was achieved by using the OpenCV video-processing library to implement object tracking and the MAVLink communication protocol, available on the ArduCopter platform, for communication.
14

Stochastic Geometry-Based Analysis of Aerial-Aided Vehicular Communications

Abu Zaid, Abdullah 04 April 2022 (has links)
Vehicular ad hoc networks (VANETs) will require improved communications, especially for critical scenarios. The improvement of these communications will be more crucial in dense urban environments where urban air mobility (UAM) is expected to witness significant growth during the next decade. We propose the use of networked tethered flying platforms (NTFPs) to enhance VANET communications. NTFPs are unmanned aerial platforms that are secured to the ground via a tether that supplies the platform with continuous power and data. To improve the spectral efficiency of communications, we implement non-orthogonal multiple access (NOMA) scheme. Additionally, to increase the bandwidth and data rates of communications, we use millimeter-wave (mmWave) frequencies. In UAM, NTFPs will coexist with other flying platforms, such as unmanned aerial vehicles (UAVs) and electric vertical takeoff and landing (eVTOL) aircraft. Hence, we study the performance of vehicular communications in the presence of interfering UAVs/eVTOLs and other road vehicles, and we compare the use of NTFPs with traditional terrestrial roadside units (RSUs).
15

Couverture d'un chemin planifié composé de points de passage à optimiser avec des algorithmes évolutionnaires. / Coverage path planning based on waypoint optimization, with evolutionary algorithms.

Strubel, David 09 May 2019 (has links)
L'objectif de cette thèse est d'optimiser la couverture visuelle d'une zone vaste et complexe de façon à ce que ses images puissent composer une mosaïque à partir d'un drone.Pour trouver les meilleurs points de passage, deux méthodes ont été étudiées : l'optimisation par essaims particulaires (PSO) et les algorithmes génétiques (GA).Notre étude a prouvé que le GA est la méthode offrant de meilleures performances en raison de ses performances et de sa capacité d'adaptation.Après avoir réalisé des expériences pour comparer les algorithmes, une hybridation de GA et PSO a été réalisée et étudiée.La méthode proposée peut être appliquée sur de grandes surfaces de formes irrégulières, comme les terrains agricoles, et fournit un nombre réduit de points de passage qui doivent être survolés par un véhicule aérien de type drone (UAV).Des essais ont été réalisés pour simuler le vol d'un drone dans un environnement intérieur, les images générées pendant la simulation sont utilisées pour représenter une image de la totalité de l'environnement sous la forme d'une mosaïque.La méthode proposée est également appliquée dans de vastes zones extérieures. Des images satellitaires sont utilisées pour visualiser la couverture du trajet qui a été planifié.Les expériences valident l'efficacité de la méthode proposée pour trouver le nombre et la position des points de passage. / The goal of this paper is to optimize the coverage of a vast and complexarea such that its mosaic image can be created. To find the best waypoints, twomethods have been investigated: Particle Swarm Optimization (PSO) and GeneticAlgorithms (GA). Our investigation proved that GA is a better method due toits performance and adaptability. After having performed experiments to compare the algorithms, a hybridization of GA and PSO is investigated.The proposed method can be applied on large areas with irregular shapes, such as agricultural fields, and it provides a minimized number of waypoints that must be flown over by the Unmanned Aerial Vehicle (UAV). The experiments were made to simulate the flight of the UAV in an indoor environment, and the images generated during the simulated flight have been used to show the final mosaic. The proposed method is also applied in the vast outdoor area using satellite images to visualize the final result of the coverage path planning. The experiments validate the efficiency of the proposed method for finding the number and the poses of the waypoints. The solution proposed to approach the problem of coverage path planning is rather different than the stateof the art by dividing the Coverage Path Planning on independent sub-problems to optimize and then using GA and later on GAPSO.
16

Der Einsatz unbemannter Flugsysteme zur Charakterisierung von gesprengtem Haufwerk

Tscharf, Alexander, Mostegel, Christian, Gaich, Andreas, Mayer, Gerhard, Fraundorfer, Friedrich, Bischof, Horst 28 September 2017 (has links) (PDF)
Die erreichte Zerkleinerung und die Form des Haufwerks sind die beiden wichtigsten Ergebnisse einer Tagebausprengung. Schnelle Informationen über die Eigenschaften des gesprengten Haufwerks ermöglichen eine zielgerichtete und effiziente Produktionsplanung und Kenntnisse über die erreichte Zerkleinerung ermöglichen außerdem Anpassungen in der weiteren Zerkleinerungskette. Durch den Einsatz von UAVs (unmanned aerial vehicles) gemeinsam mit modernen Algorithmen aus dem Bereich Computer Vision und des maschinellen Lernens soll eine schnelle Erfassung und Interpretation der Daten bei gleichzeitiger Integration in die herkömmlichen betrieblichen Abläufe ermöglicht werden, und außerdem können Schwächen bodengebundener Systeme hinsichtlich Vollständigkeit und Repräsentativität umgangen werden. Im vorliegenden Beitrag wird einerseits auf den relevanten Stand des Wissens und der Technik eingegangen und andererseits wird die verfolgte Stoßrichtung bei der Systementwicklung dargelegt sowie erste Arbeiten präsentiert. / The fragmentation and the shape of the muck pile are the two major outcomes of open pit mine and quarry blasts. Fast information about the muck pile properties will help to improve the production scheduling and furthermore this information could be used to optimize the blasting patterns of future production blasts. The combined use of unmanned aerial vehicles (UAVs) and modern machine learning and computer vision systems offers a new way of acquiring spatial data to determine on-site fragment size distribution, while at the same time enabling integration into common work flows and mitigating the weaknesses of ground-based systems with special regard to completeness and representativeness. In the present paper, we will discuss the relevant related work, present the planned path for system development and give examples of first work.
17

Modelování a simulace příjímače komunikačního systému pro bezpilotní letadla / Modelling and simulation of communication system receiver for unmanned aircraft

Hoferek, Jakub January 2018 (has links)
This paper deals with the modeling of receiver properties for the transfer of command information for unmanned airplanes.
18

Lossless convexification of quadrotor motion planning with experiments

Pehlivantürk, Can 09 October 2014 (has links)
This thesis describes a motion planning method that is designed to guide an autonomous quadrotor. The proposed method is based on a novel lossless convexication, which was first introduced in (12), that allows convex representations of many non-convex control constraints, such as that of the quadrotors. The second contribution of this thesis is to include two separate methods to generate path constraints that capture non-convex position constraints. Using the convexied optimal trajectory generation problem with physical and path constraints, an algorithm is developed that generates fuel optimal trajectories given the initial state and desired final state. As a proof of concept, a quadrotor testbed is developed that utilize a state-of-the-art motion tracking system. The quadrotor is commanded via a ground station where the convexified optimal trajectory generation algorithm is successfully implemented together with a trajectory tracking feedback controller. / text
19

Development of a Multiple Vehicle Collaborative Unmanned Aerial System

Mize, Lloyd B., IV 28 July 2011 (has links)
The purpose of this research was to design a multiple UAV system with collaborative operation. This project is built on work that has been done in the field of Unmanned Systems at VCU and is aimed at providing a starting point for research into collaborative control of multiple UAVs. The current GCS software was extended to include multiple vehicles per single controller via a new communication protocol. Many changes were made to the user interface to facilitate controlling multiple vehicles with a single operator. A second processor, called an MCS, was added to each vehicle to allow for greater flexibility and processing power, while maintaining backwards-compatibility and limiting infringement on the real-time processing of the FCS itself. The system was fully simulated via both hardware and software simulators, and ultimately the system was field tested using multiple vehicles collaboratively searching a defined area.
20

Autonomous Vertical Recovery of Fixed Wing Unmanned Aerial Vehicles

Smouter, Trevor 17 April 2013 (has links)
As unmanned aerial vehicles (UAVs) prevail in commercial and first responder applications, the need for safer and more consistent recovery methods is growing. Standard aircraft landing manoeuvres are only possible with a suitable runway which is often unavailable outside of military applications. Alternative recovery approaches can be either contained within the aircraft, ie. parachute or be setup on the ground ie. net landing. By integrating the recovery system into the vehicle, the flight preparation can be streamlined due to the fact that setting up recovering devices is no longer required. The goal of this thesis is to investigate the application of an autonomous vertical landing capability for fixed wing UAVs using articulated motors to enter vertical flight. Using an experimental UAV design, the dynamics of the problem were investigated using recorded flight data. Implementing a decoupled control approach, the aircraft was stabilized to maintain a horizontal hover. Through the characterized plant model that defines the vertical descent behaviour, a control topology was developed and tested in simulation using an optimal control approach. The developed controller was tested on the experimental UAV to verify the vertical landing performance. It was determined that this approach was well suited to autonomous vertical recovery of a fixed wing UAV. In employing this approach to UAV recovery, operators can easily operate in theatres where space for conventional landing does not exist.

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