Mapping boulders in rivers is commonly done manually with direct measurements, marking the location and size of each boulder in the field. This method is precise but time consuming and in study areas that are inaccessible by foot or has to turbulent water the danger or expense can prohibit measurements. Using Uncrewed Aerial vehicles (UAV) could prove an effective alternative method, however how accurate UAVs are for mapping boulders in rivers is yet to be determined since the ability to map submerged boulders is limited. The aim of this study is to compare boulder data derived from UAV orthophotos to in-situ field data. Additionally, I investigate if the error between the two methods is controlled by catchment- and reach- scale characteristics. Instream boulders were manually digitized from UAV orthophotos of 8 river reaches in Northern Sweden. Fewer boulders with smaller area were found for UAV, and the error between the two methods correlated with bankfull depth, water level and sediment size distribution. This highlights the importance of water level during UAV flights, since higher water levels resulted in more boulders partially or fully submerged below the water surface decreasing the amount and area of boulders found. Similar correlations between reach-scale channel characteristics were for the UAV data as for the field data showing that data derived from UAV images can be used to better understand boulder- bed rivers. Through mapping and understanding boulder distribution in pre-disturbance reference sites, UAVs can help guide river restoration in a safe, cost and time efficient way.

The main objective of this thesis is to propose a localization method for a UAV using various computer vision and machine learning techniques. It plays a major role in planning the strategy for the flight, and acts as a navigational contingency method, in event of a GPS failure. The implementation of the algorithms employs high processing capabilities of the graphics processing unit, making it more efficient. The method involves the working of various neural networks, working in synergy to perform the localization. This thesis is a part of a collaborative project between The University of North Texas, Denton, USA, and the University of Windsor, Ontario, Canada. The localization has been divided into three phases namely object detection, recognition, and location estimation. Object detection and position estimation were discussed in this thesis while giving a brief understanding of the recognition. Further, future strategies to aid the UAV to complete the mission, in case of an eventuality, like the introduction of an EDGE server and wireless charging methods, was also given a brief introduction.

No description available.

International Telemetering Conference Proceedings / October 18-21, 2004 / Town & Country Resort, San Diego, California / This paper describes a system of Total Border Surveillance, which is cost effective, closes existing gaps and is less manpower intensive than the current techniques. The system utilizes a fleet of commercially available aircraft converted to unmanned capability, existing GPS and surveillance systems and autonomous ground stations to provide the desired coverage.

Thesis (PhD (Electrical and Electronic Engioneering))--Stellenbosch University, 2008. / Unmanned Aerial Vehicle (UAV) technology is classified as being disruptive since it has the potential to radically change the utilization of airspace. Most unmanned vehicles are aimed at military applications, yet civilian applications of unmanned aerial vehicle technology could benefit South Africa considerably. At present, the lack of UAV regulations and standards precludes UAVs from being certified to operate on a file and fly basis in un-segregated civilian airspace. The inability for UAVs to be certified because of a lack of standards creates a “chicken and egg” – “stale mate” situation. If principles such as “equivalence”, initially proposed by Eurocontrol are adopted in South Africa, it then follows that equivalent standards used by manned aircraft could be used by UAVs. UAVs must therefore be tested and evaluated in order to prove compliance with equivalent existing manned aircraft regulations in the foreseeable future until UAV regulations and standards become available. It has been suggested that specific UAV missions such as maritime patrol, border control, search & rescue, and cargo transport could fulfil current requirements. Design considerations and possible concepts of UAV operations, maintenance and training that will enable UAVs to satisfy the immediate South African strategic requirements whilst complying with existing airspace and airworthiness regulations have been proposed in this document while further UAV specific standards and regulations are being developed. UAV testing is an essential part of proving the enabling technology, and part of the process of gaining acceptance into wider airspace. Fortunately, flight test methods and procedures applicable to manned aircraft are directly applicable to UAVs, while systems unique to UAVs can be adapted from existing procedures applied to missiles and military UAVs. Once UAVs are developed and tested, it will be necessary to start full scale operations. Some considerations will be necessary during mission planning. Air traffic management regulations however will prohibit some UAVs from operating in all airspace until enabling technology is developed and tested, while some existing UAVs will never be permitted to “file and fly”. This study also analyses existing airspace and UAV platforms in order to identify the airspace and platforms that will have the most chance of being successfully permitted to “file and fly” in civil airspace. For South Africa to advance as a UAV operating and manufacturing nation, it is therefore essential to compile a roadmap that will guide the process of developing, certifying and operating UAVs. The roadmap must include an interim process, as well as stating the end objective, which is “file and fly”. This South African UAV Roadmap proposal is based on international research that uses documentation and lessons learned from elsewhere to guide the process for creating UAV regulations and standards, while allowing existing UAV operations to expand into the existing airspace in order for further UAV research to take place. This roadmap proposal is the conclusion of a 3 year study, and references to the applicable literature are made throughout the document.

Thesis (MScEng)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: This thesis presents the development of an adaptive longitudinal control system for an unmanned aerial vehicle (UAV). The project forms part of a research effort at Stellenbosch University into different fault-tolerant control techniques for UAVs. In order to demonstrate the usefulness of fault-tolerant adaptive control, the control system was designed to handle damage-induced longitudinal shifts in the centre of gravity (CG) of the aircraft, which are known to have a dramatic effect on the stability of a fixed-wing aircraft. Using a simplified force and moment model, equations were derived which model the effect of longitudinal CG shifts on the behaviour of the aircraft. A linear analysis of the longitudinal dynamics using these equations showed that the short period mode can become unstable for backward CG shifts. An adaptive pitch rate controller with the model reference adaptive control structure was designed to re-stabilise the short period mode when the CG shifts backwards. The adaptive law was designed using Lyapunov stability theory. Airspeed, climb rate and altitude controllers were designed around the pitch rate controller to allow full autonomous control of the longitudinal dynamics of the UAV. These outer loops were designed with constant parameters, since they would be unaffected by CG shifts if the adaptive pitch rate controller performed as desired. Pure software simulations as well as hardware-in-the-loop simulations showed that the adaptive control system is able to handle instantaneous shifts in the centre of gravity which would destabilise a fixed-gain control system. These simulation results were validated in flight tests, where the aircraft was destabilised using positive feedback and re-stabilised by the adaptive control system. Thus the simulation and flight test results showed that an adaptive control can re-stabilise an unstable aircraft without explicit knowledge of the change in the aircraft dynamics, and therefore could be effective as part of an integrated fault-tolerant control system. / AFRIKAANSE OPSOMMING: Hierdie tesis bied die ontwikkeling aan van ’n aanpassende longitudinale beheerstelsel vir ’n onbemande vliegtuig. Die projek is deel van navorsing by die Universiteit van Stellenbosch oor verskillende fout-tolerante beheertegnieke vir onbemande vliegtuie. Om die doeltreffendheid van aanpassende beheer te demonstreer, is die beheerstelsel ontwerp om situasies te kan hanteer waar die vliegtuig só beskadig word dat sy massamiddelpunt agtertoe skuif, wat ’n groot invloed op die stabiliteit van ’n vastevlerk-vliegtuig kan hê. ’n Vereenvoudigde model van die kragte en momente wat op die vliegtuig inwerk is gebruik om vergelykings af te lei wat beskryf hoe die gedrag van die vliegtuig verander as die massamiddelpunt agtertoe verskuif. Hierdie vergelykings is gebruik in ’n lineêre analise van die longitudinale dinamika van die vliegtuig, wat getoon het dat die kortperiode-modus onstabiel kan raak as die massamiddelpunt agtertoe verskuif. ’n Aanpassende heitempobeheerder met die modelverwysings-aanpassende beheerstruktuur is ontwerp om die kortperiode-modus weer te stabiliseer wanneer die massamiddelpunt agtertoe verskuif. Die aanpassingswet is ontwerp deur die gebruik van Lyapunov se stabiliteitsteorie. Lugspoed-, klimtempo- en hoogtebeheerders is rondom die aanpassende heitempobeheerder ontwerp sodat die longitudinale dinamika van die vliegtuig heeltemal outonoom beheer kan word. Hierdie buitelusse is ontwerp met vaste parameters, aangesien hulle nie geraak sal word deur verskuiwings in die massamiddelpunt as die aanpassende heitempobeheerder na wense werk nie. Suiwer sagteware-simulasies, sowel as hardeware-in-die-lus-simulasies, het getoon dat die aanpassende beheerstelsel oombliklike verskuiwings in die massamiddelpunt goed kan hanteer, waar sulke verskuiwings ’n beheerstelsel met vaste parameters onstabiel sou maak. Hierdie simulasie-resultate is bevestig deur vlugtoetse te doen, waar die vliegtuig onstabiel gemaak is deur positiewe terugvoer, en weer deur die aanpassende beheerstelsel stabiel gemaak is. Die simulasie- en vlugtoetsresultate wys dus dat aanpassende beheer ’n onstabiele vliegtuig weer kan stabiliseer sonder eksplisiete kennis van die veranderinge in die dinamika van die vliegtuig. Aanpassende beheer kan dus doeltreffend wees as deel van ’n geïntegreerde fout-tolerante beheerstelsel.

Veículos Aéreos não Tripulados (VANTs) são aeronaves que voam sem tripulação e são capazes de realizar diversos tipos de missões, como vigilância, coleta de dados topográficos e monitoramento ambiental. Este é um domínio que tem muito a ganhar com a aplicação da abordagem de Linha de Produtos de Software (LPS), uma vez que é rico em variabilidades e cada modelo de VANT tem também muitas partes comuns. Neste trabalho é apresentada uma infraestrutura tecnológica e de configuração de ativos em Simulink, gerenciados pelas ferramentas Pure::variant e Hephaestos para uma LPS de VANTs. Um conjunto de padrões para especificação de variabilidades em Simulink é proposto, bem como uma extensão para a ferramenta Hephaestus. Uma comparação entre as ferramentas Pure::variants e Hephaestus é apresentada / Unmanned Aerial Vehicles (UAVs) are aircrafts that can fly without any crew and are capable to realize several types of missions such as surveillance, topographic data collection and environmental monitoring. This is a domain which can benefit very much with the adoption of the Software Product Lines (SPL) approach, as each UAV model is rich in variabilities and has many common parts. In this work it is presented a software asset configuration infrastructure for the Simulink environment, managed by the tools Pure::variants and Hephaestus for a UAV SPL. A set of patterns of variability specification in Simulink is proposed as well as an extension to Hephaestus to support a SPL product engineering for Simulink. A comparison between Pure::variants and Hephaestus is also presented

Este trabalho dedica-se ao projeto e desenvolvimento de um veículo aéreo não tripulado. Tais veículos podem ser utilizados em diversas aplicações como monitoramento, vigilância, transporte, resgate, entre outros. Dentre os diversos tipos de veículos aéreos, este trabalho irá focar no modelo do quadrirotor, composto por quatro hélices contra-rotoras que estabilizam e movimentam o veículo. Para alcançar o objetivo de controlar este tipo de veículo, várias propostas e metodologias podem ser aplicadas, todas buscando contemplar o controle de todas ou parte das variáveis de estado presentes nesta planta. Neste texto serão descritas: as equações cinemáticas e dinâmicas que regem este sistema; o projeto e composição mecânica da aeronave; definição de sensores e atuadores juntamente com seus métodos de utilização; implementação de controlador linear por alocação direta de polos e Regulador Linear Quadrático juntamente com observador de estados de ordem plena e filtro de Kalman, para recuperação de estados não mensurados e filtragem de ruídos. Serão apresentados resultados em simulações para cada método de controle selecionado visando optar pelo melhor controlador para a aplicação da aeronave. O método selecionado será implementado para controlar a aeronave com os sensores e atuadores selecionados. Esta implementação será realizada a partir da técnica HIL Hardware in The Loop juntamente com o software MATLAB/Simulink visando validar o controlador em conjunto com a planta real, bem como o modelo dinâmico construído. / This work is dedicated to the project and development of an unmanned aerial vehicle. Such vehicles can be employed in various applications such as monitoring, surveillance, transportation, rescue and others. Among the types of aerial vehicles, this work is focused on the quadrotor, composed by four counter-rotating propellers which stabilize and displace the vehicle. In order to fulfill the objective of controlling this vehicle, many methodologies and propositions can be applied, seeking the control of all or a snippet of the state variables present in the system. There will be described in this work: the cinematic and dynamic equations that govern this system; the mechanical project and construction of the aircraft; sensors and actuators definition, along with its usage methods; linear control implementation of the pole placement and Linear Quadratic Regulator techniques along full order state observer and Kalman filtering in order to recover and filter non-measured states. Performance results in simulations will be presented on each control implementation to validate the best controller for the application and this implementation will be applied on the projected aircraft using the sensors and actuators selected. This implementation will be given through the HIL - Hardware in the Loop method using MATLAB/Simulink software to validate the control technique applied and the constructed dynamic model.

Sistemas de Transportes Inteligentes (STIs) englobam um conjuntos de tecnologias (Sensoriamento Remoto, Tecnologia da Informação, Eletrônica, Sistemas de Comunicação de Dados entre outros) que visam oferecer serviços e gerenciamento de tráfego avançado para meios de transporte rodoviário, aéreo e outros. A obtenção de informações a respeito das características e das condições do pavimento das estradas constitui uma parte importante dentro do sensoriamento nesses STIs. Investigar novas técnicas, metodologias e meios de automatizar a obtenção dessas informações é parte deste trabalho. Uma vez que existem diferentes tipos de defeitos em vias pavimentadas, esta tese apresenta a proposta de uma metodologia que permite a obtenção, de forma automática, das condições dos pavimentos asfálticos. A obtenção dos dados foi realizada por meio do Sensoriamento Remoto com uso de Veículos Aéreos Não Tripulados. A utilização de técnicas de Aprendizado de Máquina na detecção automática possibilitou alcançar uma acurácia de 99% na detecção de pavimentos asfálticos flexíveis e 92% na identificação de defeitos em alguns experimentos. Como resultado obteve-se o diagnóstico automático, não só das condições da via, mas de diferentes tipos de defeitos presentes em pavimentos. / Intelligent Transport Systems (ITS) is a set of integrated technologies (Remote Sensing, Information Technology, Electronics, Data Communication Systems among others) that aims to provide services and advanced traffic management for road, air, rail and others transportation systems. Obtaining information about characteristics and road pavement conditions is an important part within the sensing these ITS. Investigating new techniques, methods and means to optimize and automate obtaining these information are part of this work, since there are different types of defects on paved roads. Thus, this thesis proposes a methodology that allows automatically obtain information about the condition of the pavement. Data collection was performed with remote sensing technology using Unmanned Aerial Vehicles. Automatic detection was possible through the use of Machine Learning techniques with 99% of accuracy in pavements and 92% in distress identification. As a result we obtained the self-diagnosis, not just the pavement, but different types of distress present in the pavement.

A aplicação de defensivos químicos em áreas agrícolas é de primordial importância para o rendimento de lavouras. O uso de aeronaves é cada vez mais comum em tal tarefa, principalmente pelo fato de aumentar a agilidade na operação. Entretanto, características climáticas, como intensidade e orientação do vento, podem causar prejuízo aos produtores (e.g. aplicação sobreposta dos defensivos e multas por aplicação de defensivos na borda exterior da lavoura). Essa lacuna motivou este trabalho de mestrado, que tem por objetivo avaliar um sistema integrado de veículos aéreos não tripulados (VANTs) e redes de sensores sem fio (RSSFs) para aumentar a eficiência da aplicação de defensivos químicos em campos agrícolas. Um VANT é utilizado para percorrer o campo enquanto aplica defensivos químicos. Uma RSSF com nós capazes de sensoriar a concentração de defensivos químicos é instalada no solo do campo. Os nós da RSSF e o VANT são equipados com módulos de rádio, possibilitando a troca de informação entre eles. Desse modo, o VANT consegue obter a distribuição de defensivos químicos aplicados no campo, podendo então tomar decisões para aumentar a eficiência da aplicação. Para análise desse sistema, dois experimentos foram realizados utilizando o simulador OMNeT++ e o framework MiXiM. Em um primeiro experimento é comparada a eficiência do sistema proposto com o sistema tradicional de pulverização agrícola, mostrando que é possível aumentar, em média, 16% a quantidade de defensivos químicos aplicados dentro do campo agrícola. E, em alguns casos, é possível obter um aumento de até 118,25%. No segundo experimento são analisados cinco diferentes protocolos de comunicação, mostrando que é possível otimizar o uso da bateria nos nós sensores sem fio em até 10 vezes, sem diminuir a eficiência do sistema / The use of chemical defensives in crop fields is important for the agricultural production. Often airplanes are used for spraying these products, because it adds agility in such task. But climatic characteristics, such as wind speed, may cause loss to farmers (e.g. superimposed application and fines for environment contamination). This text details an integrated system of unmanned aerial vehicle (UAV) and wireless sensor network (WSN) with the purpose of letting the aerial spraying process more precise. An UAV is used to spray chemicals in the crop field. A WSN composed of sensor nodes capable of sensoring quantities of chemical defensives is installed in the crop. Both UAV and sensor nodes are equipped with radio modules, this way they can communicate each other. Thus, the UAV may obtain the information of where the chemicals are being applied, then the UAV may take some action to performs a better spraying. This system were developed in the simulator OMNET++ using the framework MiXiM and two experiments were executed. In the first experiment the objective is to compare the efficiency of this system with the tradicional system, without the WSN. Results shown that the proposed system can improve the spraying process in 16% on average, and 118.25% on some cases. In the second experiment, five different WSN protocols were evaluated in means of battery usage of the sensor nodes. Results shown that its possible to reduce the battery usage in 10 times without intervene in the system efficiency