Flygfotografering med Unmanned Aircraft System (UAS) är i jämförelse med traditionell fotogrammetri effektivare, billigare och säkrare vilket har medfört att denna teknik föredras av många aktörer. Ett tidskrävande arbete som varit svårt att kringgå är att etablera flygsignaler på marken som används för att georeferera och kontrollera flygbilderna med. Under 2018 presenterade UAS-tillverkaren DJI sin nya quadcopter med integrerad Real-Time Kinematic (RTK)-modul. I samband med detta kan kontinuerliga och noggranna positioner levereras via Nätverks-RTK (NRTK) och behovet av markstödpunkter reduceras. I denna studie undersöktes lägesosäkerheterna i plan för ortofoton som framställdes med hjälp av en DJI Phantom 4 RTK där flygbilderna georefererades med begränsat antal eller utan markstödpunkter. Lägesosäkerheterna beräknades och kontrollerades enligt Handbok i mät- och kartfrågor (HMK) – Ortofoto, vilket är ett stöddokument inom ämnet. Vid framställning av ett ortofoto krävs även en digital terrängmodell (DTM) eller en digital ytmodell (Digital Surface Model, DSM) och kvaliteten av denna har stor inverkan på ortofotots kvalitet. I denna studie kontrollerades och utvärderades därför en del av den DSM som användes vid ortofotoframställning för respektive uppsättning enligt den tekniska specifikationen SIS-TS 21144:2016. Resultatet från studien visar att ett ortofoto går att framställas utan markstödpunkter och samtidigt klara kraven på specificerad lägesosäkerhet enligt HMK-standardnivå 3. Den sammanlagda lägesosäkerheten beräknades till 0,029 m vilket är 5 mm högre i jämförelse med ett ortofoto som baserats på traditionell georefereringsmetod, dvs. med markstödpunkter. Kravet på kvalitet i höjddata uppfylldes också för ortofotoframställning trots att en systematisk effekt i höjd uppkom. Denna effekt påverkade inte ortofotots koordinater i plan då standardosäkerheterna i höjd var låga. Resultatet visade att om två markstödpunkter adderades i vardera änden av området, kunde de systematiska effekterna i höjd minimeras och det var då möjligt att skapa en DSM som uppfyller kraven för detaljprojektering (noggrannhetsklass 1–3) enligt SIS-TS 21144:2016. / Aerial photography with UAS is in comparison with traditional photogrammetry more efficient, cheaper and safer which has led to this technology being preferred by many performers. A time-consuming job that has been difficult to avoid is to establish signals at the ground that are used for georeferencing and evaluate the results. In 2018, the UAS manufacturer DJI presented its new quadcopter with integrated Real-Time Kinematic (RTK) module. This allows continuous and accurate positions delivered via Network RTK (NRTK) and the need of ground control points can be reduced. In this study, investigations of the position uncertainties in orthophotos produced using a DJI Phantom 4 RTK carried out where the aerial images were georeferenced with limited numbers or without ground control points. The position uncertainties were calculated and controlled according to the Swedish HMK – Ortofoto (Orthophoto) which is a document within the subject. When producing an orthophoto, a digital terrain model (DTM) or a digital surface model (DSM) is also required and the quality of this has a great impact on the result. Therefore, a part of the DSM used for orthophoto production for each set was checked and evaluated according to the Swedish technical specification, SIS-TS 21144:2016. The result of the study shows that an orthophoto can be produced without ground control points and at the same time meet the requirements for specified position uncertainty according to HMK standard level 3. The total position uncertainty was calculated to be 0,029 m, which is 5 mm higher compared to the orthophoto based on the traditional georeferencing method, i.e. with ground control points. The requirement for quality in height data was also met for orthophoto production even though a systematic effect in height occurred. This effect did not affect the plane coordinates in the orthophoto because of the low standard uncertainties in height. The result showed that if two ground control points were added at each end of the area, the systematic effects were minimized, and it was possible to produce a DSM that fulfils the requirements for accuracy class 1-3 according to SIS-TS 21144:2016.

Intelligence, surveillance, and reconnaissance unmanned aircraft systems (UAS) are the most common variety of UAS in use today and provide invaluable capabilities to both the military and civil services. Keeping the sensors centered on a point of interest for an extended period of time is a demanding task requiring the full attention and cooperation of the UAS pilot and sensor operator. There is great interest in developing technologies which allow an operator to designate a target and allow the aircraft to automatically maneuver and track the designated target without operator intervention. Presently, the barriers to entry for developing these technologies are high: expertise in aircraft dynamics and control as well as in real- time motion video analysis is required and the cost of the systems required to flight test these technologies is prohibitive. However, if the research intent is purely to develop a vehicle maneuvering controller then it is possible to obviate the video analysis problem entirely. This research presents a solution to the target tracking problem which reliably provides automatic target detection and tracking with low expense and computational overhead by making use of the infrared sensor from a Nintendo Wii Remote Controller.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Search and Rescue is an essential service provided by States and Militaries to search for, locate and rescue survivors of accidents and incidents. Civil Search and Rescue utilizes a system of well-trained professionals or volunteers, an effective Search and Rescue organization, supported by industry and other providers of infrastructure and assets. The service is rendered to save the lives of civilian individuals in imminent danger of losing their lives. Military (Combat) Search and Rescue is provided by militaries to save the lives of military practitioners in a similar predicament. In addition, Search and Rescue is performed over land and over the sea. All forms of Search and Rescue rely on capable, specialized assets for efficiency en affectivity. Assets are specified and chosen on the grounds of various factors, amongst others operating environment, operational profile, performance and special abilities. This thesis has determined the need for a Search and Rescue asset, capable of performing effective and efficient Search and Rescue over the entire national maritime Search and Rescue Region, up to the Region extremities. An analysis was performed to prove this deficit, and quantify the key performance and special equipment requirements for such an asset. An analysis was also performed which proves that an Unmanned Aircraft System should be an ideal choice to meet this need. Finally, an Unmanned Aircraft System concept was specified that could potentially meet this need. / AFRIKAANSE OPSOMMING: Soek en Redding is ‘n essentiële diens wat deur State en militêre organisasies gebied word om oorlewendes van ongelukke en insidente te soek, op te spoor en na veiligheid te bring. Siviele Soek en Redding maak gebruik van ‘n stelsel van goedopgeleide professionele persone, sowel as vrywilligers, asook ‘n effektiewe Soek en Reddingsorganisasie, ondersteun deur die industrie en ander voorsieners van infrastruktuur en toerusting. Derglike dienste word daargestel om die lewens van siviele persone, wie se lewens in gevaar is, te red. Militêre Soek en Redding word deur militêre organisasies daargetel om die lewens van militêre persone, wie in gevaar is, te red. Soek en Redding word oor land sowel as oor die see uitgevoer. Alle vorms van Soek en Redding maak staat op die beskikbaarheid van gespesialiseerde toerusting met gespesialiseerde gebruiksaanwending, vir maksimale effektiwiteit en doeltreffendheid. Toerusting word gekies op grond van verskeie faktore, onder meer die gebruiksomgewing, operasionele profiele, verlangde prestasie en spesiale vermoëns. Hierdie tesis het die behoefte aan ‘n gespesialiseerde Soek en Redding platform, wat die vermoë het om effektiewe en doeltreffende Soek en Redding uit te voer oor die hele nationale Soek en Redding Gebied, tot en met die ekstreme daarvan, vasgestel. ‘n Analise is uitgevoer om hierdie tekortkoming uit te wys, asook om die sleutel prestasie- en gespesialiseerde toerustingbehoeftes vir so ‘n platform te kwantifiseer. ‘n Verdere analise is uitgevoer om te bewys dat ‘n Onbemande Vliegtuig die beste opsie sou wees vir ‘n platform om aan hierdie behoeftes te voldoen. Ten slotte is ‘n konsep vir ‘n Onbemande Vliegtuig Stelsel voorgetsel wat potensieël hierdie behoefte sou kon vervul.

As Unmanned Aerial Vehicles (UAVs) are getting more popular and their area of use is expanding rapidly, the security aspect becomes important to investigate. This thesis is a systematic literature review that examines which type of cyber attacks are most common among attacks directed at civilian use UAVs and what consequences they bring. All cyber attacks presented in the report are categorized using the STRIDE threat model, which risk they pose and what equipment is required for the adversary to follow through with the attack. The findings are that Spoofing and Denial of Service attacks are the most common cyber attack types against UAVs and that hijacking and crashing are the most common results of the attacks. No equipment that is difficult to access is required for either of the attack types in most cases, making the result an indicator that the security state for civilian use UAVs today needs improving. / Obemannade luftburna farkoster (OLF) blir mer vanliga allteftersom deras användningsområde utökas, vilket innebär att cybersäkerhetsaspekten behöver studeras. Detta arbete är en systematisk litteraturstudie som undersöker vilka typer av cyberattacker riktade mot drönare som är vanligast och vilka risker de medför. Attackerna i rapporten är kategoriserade med hjälp av metoden STRIDE samt efter vilka mål attackerna haft och vilken utrustning som krävs. Resultatet är att Spoofing och Denial of Service-attacker är vanligast och att de medför att attackeraren kan kapa eller krascha drönaren. Ingen svåråtkomlig utrustning krävs för någon av dessa attacktyper vilket indikerar att säkerhetsläget för civila drönare behöver förbättras.

With the popularity of unmanned aircraft systems (UAS), there is a growing need to assess airworthiness for safe operations in shared airspace. In the context of this thesis, shared airspace implies the introduction of UAS into airspace designated for manned aircraft. Airworthiness guidelines are generally statements that state safety requirements to prevent unwanted consequences, such as aircraft accidents. Many governmental agencies such as the U.S. Federal Aviation Administration (FAA) analyzed the risks of UAS to third-parties, all personnel and properties exterior to the aircraft. This thesis concerns the adaptation of existing airworthiness documents written for manned aircraft to UAS. The proposed method has three stages that are applied in sequence to identify relevant and irrelevant airworthiness statements, the building blocks of an airworthiness document, with regard to UAS. This method is applied to MIL-HDBK-516C, used as a case study; however, the proposed methodology can be applied to any airworthiness document developed for manned aircraft. This thesis presents a list of all MIL-HDBK-516C airworthiness statements that are directly relevant, indirectly relevant, and irrelevant to UAS; additionally, the indirectly relevant airworthiness statements to UAS are provided along with suggested modification. / M.S. / With the popularity of unmanned aircraft systems (UAS), there is a growing need to assess airworthiness for safe operations in shared airspace. Airspace is the available air for aircraft to fly in; most airspaces are regulated and are subject to the jurisdiction of a particular country. In the context of this thesis, shared airspace implies the introduction of UAS into airspace designated for manned aircraft. Airworthiness guidelines are generally statements that state safety requirements to prevent unwanted consequences, such as aircraft accidents. Many governmental agencies such as the U.S. Federal Aviation Administration (FAA) analyzed the risks of UAS to third-parties, all personnel and properties exterior to the aircraft. This thesis concerns the adaptation of existing airworthiness documents written for manned aircraft to UAS. The proposed method has three stages that are applied in sequence to identify relevant and irrelevant airworthiness statements, the building blocks of an airworthiness document, with regard to UAS. This method is applied to MIL-HDBK-516C, Department of Defense Handbook: Airworthiness Certification Criteria, used as a case study. MIL-HDBK-516C is a military handbook used for airworthiness guidance. However, the proposed methodology can be applied to any airworthiness document developed for manned aircraft. This thesis presents a list of all MIL-HDBK-516C airworthiness statements that are directly relevant, indirectly relevant, and irrelevant to UAS; additionally, the indirectly relevant airworthiness statements to UAS are provided along with suggested modification.

<p>A dual core Atmel DIOPSIS 940 chip consists of a DSP and an ARM9 functional units in a single silicon die. This thesis presents the process of integration and assessment of using this processor in a flight control system. A complete design of the system is provided including a description of the DIOPSIS 940 from the perspective of requirements of the application. The integration of the processor with a typical set of components of a flight control system is provided. Additionally, a suite of programs required for developing software for the system is included. Capabilities of both cores of the processor are analysed in a series of experiments. Computational performance in typical tasks of a flight control system is analyzed and compared. The application of attitude stabilization for a micro-scale UAS is described.</p>

For unmanned aircraft systems to gain full access to the National Airspace System (NAS), they must have the capability to detect and avoid other aircraft. This research focuses on the development of a detect-and-avoid (DAA) system for small unmanned aircraft systems. To safely avoid another aircraft, an unmanned aircraft must detect the intruder aircraft with ample time and distance. Two analytical methods for finding the minimum detection range needed are described. The first method, time-based geometric velocity vectors (TGVV), includes the bank-angle dynamics of the ownship while the second, geometric velocity vectors (GVV), assumes an instantaneous bank-angle maneuver. The solution using the first method must be found numerically, while the second has a closed-form analytical solution. These methods are compared to two existing methods. Results show the time-based geometric velocity vectors approach is precise, and the geometric velocity vectors approach is a good approximation under many conditions. The DAA problem requires the use of a robust target detection and tracking algorithm for tracking multiple maneuvering aircraft in the presence of noisy, cluttered, and missed measurements. Additionally these algorithms needs to be able to detect overtaking intruders, which has been resolved by using multiple radar sensors around the aircraft. To achieve these goals the formulation of a nonlinear extension to R-RANSAC has been performed, known as extended recursive-RANSAC (ER-RANSAC). The primary modifications needed for this ER-RANSAC implementation include the use of an EKF, nonlinear inlier functions, and the Gauss-Newton method for model hypothesis and generation. A fully functional DAA system includes target detection and tracking, collision detection, and collision avoidance. In this research we demonstrate the integration of each of the DAA-system subcomponents into fully functional simulation and hardware implementations using a ground-based radar setup. This integration resulted in various modifications of the radar DSP, collision detection, and collision avoidance algorithms, to improve the performance of the fully integrated DAA system. Using these subcomponents we present flight results of a complete ground-based radar DAA system, using actual radar hardware.

The increasing demand to integrate unmanned aircraft systems (UAS) into the national airspace is motivated by the rapid growth of the UAS industry, especially small UAS weighing less than 55 pounds. Their use however has been limited by the Federal Aviation Administration regulations due to collision risk they pose, safety and regulatory concerns. Therefore, before civil aviation authorities can approve routine UAS flight operations, UAS must be equipped with sense-and-avoid technology comparable to the see-and-avoid requirements for manned aircraft. The sense-and-avoid problem includes several important aspects including regulatory and system-level requirements, design specifications and performance standards, intruder detecting and tracking, collision risk assessment, and finally path planning and collision avoidance. In this dissertation, our primary focus is on developing an collision detection, risk assessment and avoidance framework that is computationally affordable and suitable to run on-board small UAS. To begin with, we address the minimum sensing range for the sense-and-avoid (SAA) system. We present an approximate close form analytical solution to compute the minimum sensing range to safely avoid an imminent collision. The approach is then demonstrated using a radar sensor prototype that achieves the required minimum sensing range. In the area of collision risk assessment and collision prediction, we present two approaches to estimate the collision risk of an encounter scenario. The first is a deterministic approach similar to those been developed for Traffic Alert and Collision Avoidance (TCAS) in manned aviation. We extend the approach to account for uncertainties of state estimates by deriving an analytic expression to propagate the error variance using Taylor series approximation. To address unanticipated intruders maneuvers, we propose an innovative probabilistic approach to quantify likely intruder trajectories and estimate the probability of collision risk using the uncorrelated encounter model (UEM) developed by MIT Lincoln Laboratory. We evaluate the proposed approach using Monte Carlo simulations and compare the performance with linearly extrapolated collision detection logic. For the path planning and collision avoidance part, we present multiple reactive path planning algorithms. We first propose a collision avoidance algorithm based on a simulated chain that responds to a virtual force field produced by encountering intruders. The key feature of the proposed approach is to model the future motion of both the intruder and the ownship using a chain of waypoints that are equally spaced in time. This timing information is used to continuously re-plan paths that minimize the probability of collision. Second, we present an innovative collision avoidance logic using an ownship centered coordinate system. The technique builds a graph in the local-level frame and uses the Dijkstra's algorithm to find the least cost path. An advantage of this approach is that collision avoidance is inherently a local phenomenon and can be more naturally represented in the local coordinates than the global coordinates. Finally, we propose a two step path planner for ground-based SAA systems. In the first step, an initial suboptimal path is generated using A* search. In the second step, using the A* solution as an initial condition, a chain of unit masses connected by springs and dampers evolves in a simulated force field. The chain is described by a set of ordinary differential equations that is driven by virtual forces to find the steady-state equilibrium. The simulation results show that the proposed approach produces collision-free plans while minimizing the path length. To move towards a deployable system, we apply collision detection and avoidance techniques to a variety of simulation and sensor modalities including camera, radar and ADS-B along with suitable tracking schemes.

The use of magnetometers combined with unmanned aerial vehicles (UAVs) is an emerging market for commercial and military applications. This study presents the methodology used to magnetically characterize a novel fixed-wing vertical take-off and landing (VTOL) UAV. The most challenging aspect of integrating magnetometers on manned or unmanned aircraft is minimizing the amount of magnetic noise generated by the aircraft’s onboard components. As magnetometer technology has improved in recent years magnetometer payloads have decreased in size. As a result, there has been an increase in opportunities to employ small to medium UAV with magnetometer applications. However, in comparison to manned aviation, small UAVs have smaller distance scales between sources of interference and sensors. Therefore, more robust magnetic characterization techniques are required specifically for UAVs. This characterization determined the most suitable position for the magnetometer payload by evaluating the aircraft’s static-field magnetic signature. For each aircraft component, the permanent and induced magnetic dipole moment characteristics were determined experimentally. These dipole characteristics were used to build three dimensional magnetic models of the aircraft. By assembling the dipoles in 3D space, analytical and numerical static-field solutions were obtained using MATLAB computational and COMSOL finite element analysis frameworks. Finally, Tolles and Lawson aeromagnetic compensation coefficients were computed and compared to evaluate the maneuver noise for various payload locations. The magnetic models were used to study the sensitivity of the aircraft configuration and to simultaneously predict the effects at potential sensor locations. The study concluded by predicting that a wingtip location was the area of lowest magnetic interference. / Graduate

A dual core Atmel DIOPSIS 940 chip consists of a DSP and an ARM9 functional units in a single silicon die. This thesis presents the process of integration and assessment of using this processor in a flight control system. A complete design of the system is provided including a description of the DIOPSIS 940 from the perspective of requirements of the application. The integration of the processor with a typical set of components of a flight control system is provided. Additionally, a suite of programs required for developing software for the system is included. Capabilities of both cores of the processor are analysed in a series of experiments. Computational performance in typical tasks of a flight control system is analyzed and compared. The application of attitude stabilization for a micro-scale UAS is described.