Aerial photography obtained by UAVs (Unmanned Aerial Vehicles) is an emerging market for civil applications. Small UAVs are believed to close gaps in niche markets, such as acquiring airborne image data for remote sensing purposes. Small UAVs will be able to fly at low altitudes, in dangerous environments and over long periods of time. However, the small lightweight constructions of these UAVs lead to new problems, such as higher agility leading to more susceptibility to turbulence and limitations in space and payload for sensor systems. This research investigates the use of low-cost fisheye lenses to overcome such problems which theoretically makes the airborne imaging less sensitive to turbulence. The fisheye lens has the benet of a large observation area (large field of view) and doesn't add additional weight to the aircraft, like traditional mechanical stabilizing systems. This research presents the implementation of a fisheye lens for aerial photography and mapping purposes, including theoretical background of fisheye lenses. Based on the unique feature of the distortion being a function of the viewing angle, methods used to derive the fisheye lens distortion are presented. The lens distortion is used to rectify the fisheye images before these images can be used in aerial photography. A detailed investigation into the inner orientation of the camera and inertial sensor is given, as well as the registration of airborne collected images. It was found that the attitude estimation is critical towards accurate mapping using low quality sensors. A loosely coupled EKF filter applied to the GPS and inertial sensor data estimated the attitude to an accuracy of 3-5° (1-sigma) using low-cost sensors typically found in small UAVs. However, the use of image stitching techniques may improve the outcome. On the other hand, lens distortion caused by the fisheye lens can be addressed by rectification techniques and removed to a sub-pixel level. Results of the process present image sequences gathered from a piloted aircraft demonstrating the achieved performance and potential applications towards UAVs. Further, an unforeseen issue with a vibrating part in the lens lead to the need for vibration compensation. The vibration could be estimated to ±1 pixel in 75% of the cases by applying an extended Hough transform to the fisheye images.

The details of an experimental investigation focusing on obtaining the static and vibration characteristics of a full-scale carbon composite wing and fuselage structural assemblies of an ultralight unmanned aerial vehicle (UAV) are presented. The UAV has a total empty weight of 155-lb and an overall length of approximately 20.6t. A three-tier whiffletree system and the tail fixture were designed and used to load the wing and the fuselage in a manner consistent with a high-g flight condition. A shaker-table approach was used for the wing vibration testing, whereas the modal characteristics of the fuselage structure were determined for a freeree configuration. The static responses of the both structures under simulated loading conditions as well as their dynamic properties such as the natural frequency, damping coefficient and associated mode shapes were obtained. The design and implementation of the static and vibration tests along with the experimental results are presented in this thesis.

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.

Η παρούσα διπλωματική έχει ως αντικείμενο την μελέτη των συστημάτων προώθησης και την εξέταση των δυνατοτήτων χρησιμοποίησης νέων μορφών προωθητηρίων. Συγκεκριμένα θεωρώντας ότι μέχρι σήμερα το κύριο σύστημα προώθησης UAV είναι οι DC κινητήρες σε συνδυασμό με έλικες μελετάται η δυνατότητα χρήσης Jet κινητήρων για την παραγωγή της απαιτούμενης ώσης που χρειάζεται ένα UAV κατά την αιώρηση. Οι στροβιλοκινητήρες έχουν την δυνατότητα παραγωγής σταθερής ώσης και χρησιμοποιούνται σχεδόν αποκλειστικά στα μεγάλης κλίμακας ιπτάμενα οχήματα. Υπάρχουν διάφοροι τύποι στροβιλοκινητήρων στην αγορά, οι οποίοι όμως βασίζονται στις ίδιες αρχές λειτουργίας. Κατά την εργασία μελετήθηκε ο μοντελιστικός Jet κινητήρας JetCat P20. Έγινε προσπάθεια μοντελοποίησης του εν λόγω κινητήρα λαμβάνοντας υπόψη όλα τα χαρακτηριστικά του. Το άγνωστο έως τώρα σύστημα μοντελοποιήθηκε και έγινε μελέτη της δυναμικής του. Οι Jet κινητήρες λόγω της φυσικών νόμων που τους διέπουν παρουσιάζουν σχετικά αργές αποκρίσεις. Οι σταθερές χρόνου αυτών των κινητήρων καθιστούν την δυνατότητα χρήσης τους σε UAV εφαρμογές αρκετά δύσκολη. Με την χρήση του JetCat P20 σε μια πραγματική εφαρμογή ελέγχου της γωνιάς ενός οδηγούμενου εκκρεμούς αναζητήθηκαν τα όρια και οι δυνατότητες ελέγχου αυτού του προωθητικού συστήματος. Οι Jet κινητήρες τελικά, όπως ο JetCat P20 έχουν αρκετά καλές δυνατότητες παραγωγής συγκεκριμένου επιπέδου ώσης, επομένως και ρύθμισης της γωνίας του εκκρεμούς, ωστόσο οι χρόνοι απόκρισής του είναι αρκετά μεγάλοι για τα δεδομένα UAV εφαρμογών, χωρίς να υπάρχουν πολλά περιθώρια βελτίωσης μέσω κλασσικού έλεγχου. / This thesis object is the study of propulsion systems and the examination of using new systems for propulsion. Especially, considering that until now the main propulsion system for UAV's are DC motors in combination with propellers we are examining the possibility of using Jet engine to generate the required thrust needed a UAV in hover. The turbines have the ability to produce constant thrust and are used almost exclusively in large-scale flight vehicles. There are different types of turbines on the market, but they are based on the same principles of operation. During this thesis, we are experimenting with the Jet engine JetCat P20. The Jet Engine system was modeled and we examined its dynamic.The Jet engines ,because of the physical laws governing them, have relatively slow time responses. The time constants of these motors makes it difficult to use in UAV applications. We have used the JetCat P20 in a real application ,where we tried to control the angle of a driven pendulum.The Jet engines finally, like JetCat P20 have pretty good production capabilities thrust level, and thus adjusting the angle of the pendulum, but their response time is large enough for the UAV applications, without much scope for improvement through classical control.

Unmanned aerial vehicles (UAVs) have been used increasingly over the past few years. Special Forces of various countries utilise these systems successfully in war zones such as Afghanistan. The biggest advantage is rapid information gathering without endangering human lives. The South African National Defence Force (SANDF) also identified the need for local short range aerial reconnaissance and information gathering. A detailed literature survey identified various international players involved in the development of small hand-launch UAV systems. Unfortunately, these overseas systems are too expensive for the SANDF. A new system had to be developed locally to comply with the unique requirements, and budget, of the SANDF. The survey of existing systems provided valuable input to the detailed user requirement statement (URS) for the new South African development. The next step was to build a prototype using off-the-shelf components. Although this aircraft flew and produced good video images, it turned out to be unreliable. The prototype UAV was then replaced with a standard type model aircraft, purchased from Micropilot. Some modifications were needed to ensure better compliance with the URS. Laboratory and field tests proved that the aircraft can be applied for aerial images, within range of 10 km from the ground control station (GCS). The major limitation is that it can only fly for 40 minutes. Furthermore, the airframe is not robust, needing repairs after only 15 flights. Although the system has shortcomings, it has already been used successfully. It is expected that improved battery technologies and sturdier light-weight materials will further help to improve the system beyond user specifications. / Thesis (MIng (Electrical Engineering))--North-West University, Potchefstroom Campus, 2010.

Unmanned aerial vehicles (UAVs) have been used increasingly over the past few years. Special Forces of various countries utilise these systems successfully in war zones such as Afghanistan. The biggest advantage is rapid information gathering without endangering human lives. The South African National Defence Force (SANDF) also identified the need for local short range aerial reconnaissance and information gathering. A detailed literature survey identified various international players involved in the development of small hand-launch UAV systems. Unfortunately, these overseas systems are too expensive for the SANDF. A new system had to be developed locally to comply with the unique requirements, and budget, of the SANDF. The survey of existing systems provided valuable input to the detailed user requirement statement (URS) for the new South African development. The next step was to build a prototype using off-the-shelf components. Although this aircraft flew and produced good video images, it turned out to be unreliable. The prototype UAV was then replaced with a standard type model aircraft, purchased from Micropilot. Some modifications were needed to ensure better compliance with the URS. Laboratory and field tests proved that the aircraft can be applied for aerial images, within range of 10 km from the ground control station (GCS). The major limitation is that it can only fly for 40 minutes. Furthermore, the airframe is not robust, needing repairs after only 15 flights. Although the system has shortcomings, it has already been used successfully. It is expected that improved battery technologies and sturdier light-weight materials will further help to improve the system beyond user specifications. / Thesis (MIng (Electrical Engineering))--North-West University, Potchefstroom Campus, 2010.

Thesis (MScEng)-- Stellenbosch University, 2012. / ENGLISH ABSTRACT: This thesis presents the analysis, design, simulation and practical implementation of a control system to achieve an accurate autonomous landing of a fixed-wing unmanned aerial vehicle in the presence of wind gust atmospheric disturbances. Controllers which incorporate the concept of direct-lift control were designed based on a study of the longitudinal dynamics of the UAV constructed as a testbed. Direct-lift control offers the prospect of an improvement in the precision with which aircraft height and vertical velocity can be controlled by utilising actuators which generate lift directly, instead of the conventional method whereby the moment produced by an actuator results in lift being indirectly generated. Two normal specific acceleration controllers were designed. The first being a conventional moment-based controller, and the second a direct-lift-augmented controller. The moment-based controller makes use of the aircraft’s elevator while the direct-lift augmented controller in addition makes use of the flaps of the aircraft which serve as the direct-lift actuator. Controllers were also designed to regulate the airspeed, altitude, climb rate, and roll angle of the aircraft as well as damp the Dutch roll mode. A guidance controller was implemented to allow for the following of waypoints. A landing procedure and methodology was developed which includes the circuit and landing approach paths and the concept of a glide path offset to calibrate the touchdown point of a landing. All controllers and the landing procedure were tested in a hardware-in-the-loop simulation environment as well as practically in a series of flight tests. Five fully autonomous landings were performed, three of these using the conventional NSA controller, and the final two the direct-lift-augmented NSA controller. The results obtained during the landing flight tests show that the project goal of a landing within five meters along the runway and three meters across the runway was achieved in both normal wind conditions as well as in conditions where wind gusts prevailed. The flight tests also showed that the direct-lift-augmented NSA controller appears to achieve a more accurate landing than the conventional NSA controller, especially in the presence of greater wind disturbances. The direct-lift augmented NSA controller also exhibited less pitch angle rotation during landing. / AFRIKAANSE OPSOMMING: Hierdie tesis verteenwoordig die analise, ontwerp, simulasie en praktiese implementering van ’n beheerstelsel wat ten doel het om ’n akkurate en outonome landing van ’n onbemande vastevlerk vliegtuig in rukwind atmosferiese toestande te bewerkstellig. Gegrond op ’n studie van die longitudinale dinamika van die vliegtuig wat as proeftuig gebruik is, is beheerders ontwerp wat die beginsel van direkte-lig insluit. Direkte-lig beheer hou die potensiaal in om die vliegtuig se hoogte en vertikale snelheid akkuraat te beheer deur gebruik te maak van aktueerders wat lig direk genereer in teenstelling met die konvensionele metode waar die moment van die aktueerder indirek lig genereer. Twee normaal-versnellings beheerders is ontwerp. Die eerste is ’n konvensionele moment-gebaseerde beheerder wat gebruik maak van die hys-aktueerder van die vliegtuig, en die tweede is ’n direkte-lig-bygestaande beheerder wat addisioneel gebruik maak van die flappe van die vliegtuig wat as die direkte-lig aktueerder dien. Vedere beheerders is ontwerp wat die lugspoed, hoogte, klimkoers, en rolhoek van die vliegtuig reguleer asook die “Dutch roll” gedrag afklam. ’n Leiding-beheerder wat die volg van vliegbakens hanteer, is ingestel. Die landingsprosedure en -metodologie is ontwikkel wat die landingspad sowel as die sweef-pad bepaal en wat terselfdertyd ’n metode daarstel om die posisie van die landingspunt te kalibreer. Die beheerders en landingsprosedure is in ’n hardeware-in-die-lus omgewing gesimuleer en deur middel van ’n reeks proefvlugte getoets. Vyf ten volle outonome landings is uitgevoer waarvan drie van die konvensionele normaal-versnellings beheerder gebruik gemaak het, en die laaste twee die direkte-lig-bygestaande normaal-versnellings beheerder. Die vlugtoetsuitslae bevestig dat die navorsingsdoel om ’n landing binne vyf meter in lyn met en drie meter dwarsoor die landingstrook te bewerkstellig, behaal is. Hierdie akkuraatheid is verkry in beide goeie atmosferiese toestande sowel as toestande met rukwinde. Volgens die vlugtoetse blyk dit dat die direkte-lig-bygestaande normaalversnellings beheerder ’n meer akkurate landing kan bewerkstellig as die konvensionele normaal-versnellings beheerder, veral dan in toestande met rukwinde. Die direkte-ligbygestaande normaal-versnellings beheerder het ook ’n laer hei-hoek rotasie tydens die landing vertoon.

Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In this thesis the strategy for performing System Identification on an aircraft is presented. The ultimate aim of this document is to outline the steps required for successful aircraft parameter estimation within a Fault Tolerant Control Framework. A brief derivation of the classical 6 degree-of-freedom aircraft model is firstly presented. The derivation gives insight into the aircraft dynamics that are to be used to estimate the aircraft parameters, and provides a basis for the methods provided in this thesis. Different techniques of System Identification were evaluated, resulting in the choice of the Regression method to be used. This method, based on the Least-Squares method, is chosen because of its simplicity of use and because it does not require as much computational time as the other methods presented. Regression methods, including a recursive algorithm, are then applied to aircraft parameter estimation and practical considerations such as Identifiability and corrupted measurements are highlighted. The determination of unknown measurements required for System Identification of aircraft parameters is then discussed. Methods for both estimating and measuring the Angle-of-Attack (AoA) and angular accelerations are presented. The design and calibration of an AoA probe for AoA measurements, as well as a novel method that uses distributed sensors to determine the angular accelerations is also presented. The techniques presented in this thesis are then tested on a non-linear aircraft model. Through simulation it was shown that for the given sensor setup, the methods do not provide sufficiently accurate parameter estimates. When using the Regression method, obtaining measurements of the angle-of-attack solely through estimation causes problems in the estimation of the aerodynamic lift coefficients. Flight tests were performed and the data was analyzed. Similar issues as experienced with estimation done on the non-linear aircraft simulation, was found. Recommendations with regards to how to conduct future flight tests for system identification is proposed and possible sources of errors are highlighted. / AFRIKAANSE OPSOMMING: In hierdie tesis word die strategie vir die uitvoering van Stelsel Identifikasie op 'n vliegtuig aangebied. Die uiteindelike doel van hierdie document is om die stappe wat nodig is vir 'n suksesvolle vliegtuig parameter beraming, binne 'n Fout Tolerante Beheer Raamwerk, uit eente sit. 'n Kort afleiding van die klassieke 6 graad-van-vryheid vliegtuig model word eerstens aangebied. Die afleiding gee insig in die vliegtuig dinamika wat gebruik moet word om die vliegtuig parameters te beraam, en bied 'n basis vir die metodes wat in hierdie tesis verskyn. Verskillende tegnieke van Stelsel Identifikasie is geëvalueer, wat lei tot gebruik van die regressie-metode. Hierdie metode is gekies as gevolg van sy eenvoudigheid en omdat dit nie soveel berekening tyd as die ander metodes vereis nie. Regressie metodes, insluitend 'n rekursiewe algoritme, word dan toegepas op vliegtuig parameter beraming en praktiese orwegings soos identifiseerbaarheid en korrupte metings word uitgelig. Die bepaling van onbekende afmetings wat benodig is, word vir Stelsel Identifisering van die vliegtuig parameters bespreek. Metodes om die invalshoek en hoekige versnellings te meet en beraam, word aangebied. Die ontwerp en kalibrasie van 'n invalshoek sensor vir invalshoek metings, sowel as 'n nuwe metode wat gebruik maak van verspreide sensore om die hoekversnellings te bepaal, word ook aangebied. Die tegnieke wat in hierdie tesis aangebied is, word dan op 'n nie-lineêre vliegtuig model getoets. Deur simulasie is dit getoon dat die metodes vir die gegewe sensor opstelling nie voldoende akkurate parameters beraam nie. Dit is ook bewys dat met die gebruik van die Regressie metode, die vekryging van metings van die invalshoek slegs deur skatting, probleme in die beraming van die aerodinamiese lug koëffisiente veroorsaak. Die tegnieke wat in hierdie tesis verskyn, word dan op werklike vlug data toegepas.Vlugtoetse is uitgevoer en die data is ontleed. Aanbeveling met betrekking tot hoe om toekomstige vlug toetse vir Stelsel Identifikasiete word voorgestel, en moontlike bronne van foute word uitgelig.

Due to the changing climate and inherent atypically occurring meteorological events in the Arctic regions, more accurate snow quality predictions are needed in order to support the Sámi reindeer herding communities in northern Sweden that struggle to adapt to the rapidly changing Arctic climate. Spatial snow depth distribution is a crucial parameter not only to assess snow quality but also for multiple environmental research and social land use purposes. This contrasts with the current availability of affordable and efficient snow monitoring methods to estimate such an extremely variable parameter in both space and time. In this thesis, a novel approach to determine spatial snow depth distribution in challenging alpine terrain is presented and tested during a field campaign performed in Tarfala, Sweden in April 2019. A multispectral camera capturing five spectral bands in wavelengths between 470 and 860 nanometers on board of a small Unmanned Aerial Vehicle is deployed to derive 3D snow surface models via photogrammetric image processing techniques. The main advantage over conventional photogrammetric surveys is the utilization of accurate RTK positioning technology that enables direct georeferencing of the images, and thus eliminates the need for ground control points and dangerous and time-consuming fieldwork. The continuous snow depth distribution is retrieved by differencing two digital surface models corresponding to the snow-free and snow-covered study areas. An extensive error assessment based on ground measurements is performed including an analysis of the impact of multispectral imagery. Uncertainties and non-transparencies due to a black-box environment in the photogrammetric processing are, however, present, but accounted for during the error source analysis. The results of this project demonstrate that the proposed methodology is capable of producing high-resolution 3D snow-covered surface models (< 7 cm/pixel) of alpine areas up to 8 hectares in a fast, reliable and cost-efficient way. The overall RMSE of the snow depth estimates is 7.5 cm for data acquired in ideal survey conditions. The proposed method furthermore assists in closing the scale gap between discrete point measurements and regional-scale remote sensing, and in complementing large-scale remote sensing data by providing an adequate validation source. As part of the Swedish cooperation project ’Snow4all’, the findings of this project are used to support and validate large-scale snow models for improved snow quality prediction in northern Sweden. / På grund av klimatförändringar och naturliga meteorologiska händelser i arktis behövs mer exakta snökvalitetsprognoser för att stödja samernas rensköttsamhällen i norra Sverige som har problem med att anpassa sig till det snabbt föränderliga arktiska klimatet. Rumslig snödjupsfördelning är en avgörande parameter för att inte bara bedöma snökvaliteten utan även för flera miljöforskning och sociala markanvändningsändamål. Detta står i motsats till den nuvarande tillgången till överkomliga och effektiva metoder för snöövervakning för att uppskatta sådan extremt varierande parameter i tid och rum. I detta arbete presenteras och testas en ny metod för att bestämma rumslig snödjupssdistribution i utmanande alpin terräng under en fältstudie som genomfördes i Tarfala i norra Sverige i april 2019. Via fotogrammetrisk bildbehandlingsteknik hämtades snöytemodeller i 3D med hjälp av en multispektral kamera monterad på en liten obemannad drönare. En viktig fördel, i jämförelse med konventionella fotogrammetriska undersökningar, är användningen av exakt RTK-positioneringsteknik som möjliggör direkt georeferencing och eliminerar behovet av markkontrollpunkter. Den kontinuerliga snödjupfördelningen hämtas genom att ytmodellerna delas upp i snöfria respektive snötäckta undersökningsområden. En omfattande felsökning som baseras på markmätningar utförs, inklusive en analys av effekten av multispektrala bilder. Resultaten från denna studie visar att den famtagna metoden kan producera högupplösta snötäckta höjdmodeller i 3D (< 7 cm/pixel) av alpina områden på upp till 8 hektar på ett snabbt, pålitligt och kostnadseffektivt sätt. Den övergripande RMSE för det beräknade snödjupet är 7,5 cm för data som förvärvats under idealiska undersökningsförhållanden. Som ett led i det svenska projektet “Snow4all” används resultaten från projektet för att förbättra och validera storskaliga snömodeller för att bättre förutse snökvaliteten i norra Sverige.

This study aimed to develop and evaluate a method to obtain a proportional-integral-derivative (PID) controller. The controller is for a control surface that controls pitch motion, by using data from flight tests with an unmanned aerial vehicle (UAV). Finding a suitable method to develop the controllers is essential to make the UAV autonomous, whilst being stable and controllable. Before developing the PID, data from test flights were used to model a transfer function for the control surface with MATLAB's toolbox for system identification. Thereafter, using the transfer function, the PID was developed by using MATLAB’s toolbox for control systems. The whole method was evaluated by studying the rise time, settling time, and overshoot for the PID, and studying how well the transfer function fits with the flight data. The method of modeling the pitch motion with system identification and finding the PID gains has good potential to simplify the process of finding a PID controller. However, to acquire an accurate model for the pitch motion, which in turn can give a well-performing PID, an improved data sampling was suggested. Additionally, flight tests conducted before and after PID tuning, and in different conditions are recommended to be done in future studies. The flight test would work as a validation for the model to acquire a robust PID that performs as expected. / Syftet med denna studie var att utveckla och utvärdera en metod för att hitta en proportionerlig integrerande deriverande (PID) regulator. Regulatorn är för en kontrollyta som kontrollerar tipprörelsen genom att använda data från flygtester med en drönare. Att hitta en lämplig metod för att utveckla regulatorer är nödvändigt för att göra drönaren autonom, samtidigt som den är stabil och kontrollerbar. Innan PID:n utvecklades användes data från flygtester för att modellera överföringsfunktionen för kontrollytan med MATLAB:s programvara för systemidentifiering. Därefter, genom att använda överföringsfunktionen, utvecklades PID:n med MATLAB:s programvara för reglersystem. Hela metoden utvärderades genom att studera stigtid, insvängningstid och översläng för PID regulatorn, samt studera hur väl överföringsfunktionen modellerar flygdata. Metoden för att modellera tipprörelsen och att hitta PID förstärkningarna har en god potential att förenkla processen av att hitta en PID regulator. Däremot för att få en precis modell för tipprörelsen, vilket i sin tur kan ge en välpresterande PID, föreslogs det att förbättra datainsamlingen. Dessutom rekommenderades det i framtida studier att flygtester genomförs i olika förhållande, både före och efter att PID regulatorn har hittats. Flygtesterna skulle fungera som en bekräftelse för modellen för att få en robust PID som presterar som väntat. / Kandidatexjobb i elektroteknik 2022, KTH, Stockholm