<p>The ducted fan UAV is an unmanned aerial vehicle consisting mainly of a propeller enclosed in a open ended tube. The UAV has the same basic functions as an ordinary helicopter UAV but has several advantages to the same.</p><p>This thesis aims to estimate the performance of the concept of the ducted fan UAV. The company where this thesis has been written, DST Control AB, is currently investigating the economical possibilities to continue the development of this kind of UAV. This thesis shall provide DST Control AB with a theoretical as well as experimental ground for the investigation by estimation the lift capacity, position accuracy and wind tolerance.</p><p>A ducted fan UAV prototype and a mathematical model for that UAV have been developed by DST Control AB and a student project at Linköping University. The model is constructed through pure physical modeling. Several noise sources have been added to better fit the reality. Several experiments have been conducted to validate the model with satisfying results. Experiments to determine the lift capacity of the craft have also been conducted. These experiments showed a slightly smaller lift capacity than the theoretically calculated lift capacity. The wind tolerance has not been tested in experiments because of the lack of available wind tunnels but simulations have given an estimation of this tolerance.</p><p>To estimate the position accuracy, two different control systems have been implemented. The simplest control system is a system consisting of several PID controllers. The system is divided into two separate subsystems connected in cascade. The inner subsystem takes the pitch, roll and yaw angle as inputs and gives the rudder angles as outputs. The outer subsystem takes the inertial position as input and gives roll, pitch and yaw as outputs. Together, the two subsystems can be used to control the entire craft. The inner subsystem has also been replaced with a small LQ Compensator. An LQ Compensator for the entire system is also implemented giving about as good performance as the PID controller and better performance than the PID/LQ combination.</p>

<p><em>This bachelor thesis is dedicated to assemble the hardware system of a UAV (Unmanned Aerial Vehicle) in order to prepare the platform for an autonomous flight in the air for a given path through the pre-programmed check points. A UAV is an aircraft that contains sensors, GPS, radio system, servomechanisms and computers, which provide the capability of an autonomous flight without a human pilot in the cockpit. A stable flight requires sensing the roll, pitch, and yaw angles of aircraft. Roll and pitch angles were ensured by a sensor system of FMA Direct Company called co-pilot flight stabilization system (CPD4), which allows controlling ailerons and elevator manually.</em></p><p><em>An autopilot is required for steering the aircraft autonomously according the GPS data and the establish waypoints that the airplane have to pass by. The GPS gives heading information to the autopilot, and this uses the information of the next waypoint to decide which direction to go. Hereby an autonomous flight is provided. In this project a lego mindstorm NXT was used as an autopilot that is product of LEGO Company [1]. The output of the autopilot is used to control the airplane servos to fly in the desired direction. A software and hardware interface was designed to allow the autopilot to receive the data from the co-pilot sensor and to transmit data to the co-pilot processor, which will finally steer the actuator servos. Experiments were performed with different parts of the system and the results reported.</em></p>

In unmanned aerial systems an autopilot controls the vehicle without human interference. Modern autopilots use an inertial navigation system, GPS, magnetometers and barometers to estimate the orientation, position, and velocity of the aircraft. In order to make correct decisions the autopilot must rely on correct information from the sensors. Fault diagnosis can be used to detect possible faults in the technical system when they occur. One way to perform fault diagnosis is model based diagnosis, where observations of the system are compared with a mathematical model of the system. Model based diagnosis is a common technique in many technical applications since it does not require any additional hardware. Another way to perform fault diagnosis is hardware diagnosis, which can be performed if there exists hardware redundancy, i.e. a set of identical sensors measuring the same quantity in the system. The main contribution of this master thesis is a model based diagnosis system for a fixed wing UAV autopilot. The diagnosis system can detect faults in all sensors on the autopilot and isolate faults in vital sensors as the GPS, magnetometer, and barometers. This thesis also provides a hardware diagnosis system based on the redundancy obtained with three autopilots on a single airframe. The use of several autopilots introduces hardware redundancy in the system, since every autopilot has its own set of sensors. The hardware diagnosis system handles faults in the sensors and actuators on the autopilots with full isolability, but demands additional hardware in the UAV.

There are a number of ongoing projects developing autonomous vehicles, both helicopters and airplanes. The purpose of this thesis is to study a concept for calculating the height and attitude of a helicopter. The system will be active during landing. This thesis includes building an experimental setup and to develop algorithms and software. The basic idea is to illuminate the ground with a certain pattern and in our case we used laser pointers to create this pattern. The ground is then filmed and the images are processed to extract the pattern. This provides us with information about the height and attitude of the helicopter. Furthermore, the concept implies that no equipment on the ground is needed. With further development the sensor should be able to calculate the movement of the underlying surface relative to the helicopter. This is very important when landing on a moving surface, e.g. a ship at sea. To study the concept empirically an experimental setup was constructed. The setup provides us with the necessary information to evaluate how well the system could perform in reality. The setup is built with simple and cheap materials. In the setup an ordinary web camera and laser pointers that are avaliable for everyone have been used. / Det finns flera pågående projekt inom autonomflygande farkoster, både för helikoptrar och flygplan. Syftet med vårt examensarbetet är att undersöka ett koncept för en landningssensor för autonom landning med helikopter. Examensarbetet innebär att bygga en fysisk modell för test av konceptet samt att utveckla mjukvara. Konceptet för sensorn består av att belysa marken med ett speciellt mönster, i vårt fall skapas mönstret av laserpekare, som därefter fotograferas och bildbehandlas. Detta mönster ger sedan information om helikopterns höjd och attityd i luften. Vidare innebär konceptet också att ingen markutrustning krävs för att sensorn ska fungera. I förlängningen ska man med detta koncept kunna beräkna hur underlaget rör sig relativt helikoptern, vilket är väldigt viktigt vid landning på objekt som rör sig, till exempel ett fartyg. För att undersöka hur bra sensorn presterar i verkligheten så har en rigg byggts. Riggen är byggd med enkla och billiga material. I det här fallet används en webbkamera och laserpekare som går att köpa i vanliga elektronikaffärer.

This bachelor thesis is dedicated to assemble the hardware system of a UAV (Unmanned Aerial Vehicle) in order to prepare the platform for an autonomous flight in the air for a given path through the pre-programmed check points. A UAV is an aircraft that contains sensors, GPS, radio system, servomechanisms and computers, which provide the capability of an autonomous flight without a human pilot in the cockpit. A stable flight requires sensing the roll, pitch, and yaw angles of aircraft. Roll and pitch angles were ensured by a sensor system of FMA Direct Company called co-pilot flight stabilization system (CPD4), which allows controlling ailerons and elevator manually. An autopilot is required for steering the aircraft autonomously according the GPS data and the establish waypoints that the airplane have to pass by. The GPS gives heading information to the autopilot, and this uses the information of the next waypoint to decide which direction to go. Hereby an autonomous flight is provided. In this project a lego mindstorm NXT was used as an autopilot that is product of LEGO Company [1]. The output of the autopilot is used to control the airplane servos to fly in the desired direction. A software and hardware interface was designed to allow the autopilot to receive the data from the co-pilot sensor and to transmit data to the co-pilot processor, which will finally steer the actuator servos. Experiments were performed with different parts of the system and the results reported.

Uppgiften har inneburit att utreda och redovisa några av de möjliga sensoralternativ som med ett 10-årigt perspektiv är möjliga att implementera i en svensk UAV motsvarande det svenska UAV - systemet ”Ugglan”. Fokus avseende uppgifter för UAV – systemet har legat på taktisk nivå med inriktning mot spaning och ledning av indirekt eld. Slutligen har uppgiften varit att värdera de olika sensoralternativen och förorda vilken eller vilka sensorer i kombination som ger bäst effekt sett till tänkt användningsområde för UAV´n. Den metod som använts är inledningsvis deskriptiv och därefter komparativ. Ett antal utvalda sensorer har beskrivits avseende egenskaper, fördelar och nackdelar. Vidare har det framtida stridsfältets karaktär beskrivits. Därefter har en jämförelse skett mellan de valda sensorerna i syfte att finna den mest optimala lösningen som svarar mot ställda krav. Den sensorlösning som författaren skulle önskat rekommendera för en framtida svensk taktisk UAV visade sig vara omöjlig att implementera främst pga. en alltför hög vikt samt i viss mån volym. Den valda lösningen har kommit att bli en multisensorlösning bestående av en kamera för navigation, en lågljustv (LLTV) för spaning samt en SAR – radar och en LADAR (laserradar) som huvudsensorer för spaning samt positionsbestämning. Fördelarna med den sensorlösning som föreslagits är bla. goda möjligheter att spana oberoende av yttre atmosfärförhållanden (väder), en mycket god förmåga att upplösa och därmed detektera mål samt en mycket god förmåga att mäta in ett måls position. Främsta nackdelen är att systemets spaningsvinkel blir begränsad. / The purpose of this paper has been to investigate and present some possible sensor alternatives, which in a future perspective of 10 years, will be possible to implement in a Swedish UAV such as the Swedish UAV  system “Ugglan”. A focus on the tasks for the UAV system has been at the tactical level with  an emphasis  on intelligence and directing fire from artillery. Finally, the purpose has been to make an assessment and to propose what sensor alternative or alternatives in combination (multi-sensor solution) will be the most optimum solution for the tactical UAV. The method which has been used in the paper is initially in the form of a description and subsequently in a comparative form. Some possible sensor alternatives have been chosen and described with regard to qualities, both from positive and negative aspects. Furthermore, the future battlefield has been described. After this, a  comparison has been made between the chosen sensor systems in order to find the most optimum sensor solution which can fulfil the demands. The sensor solution which the author would have wished to recommend for a future Swedish tactical UAV has proved to be impossible to implement because it is too heavy and has too great a volume. The chosen sensor solution is a multi-sensor solution consisting of a camera for navigation, a LLTV (Low – Light TV) for recce and finally a SAR – radar (Synthetic Aperture Radar) and a LADAR (laser radar), which are the main sensors for reconnaissance and positioning of targets. The advantages with this sensor solution are the possibilities to carry our surveillance independently of weather conditions, a very good possibility of separating and therefore detecting targets and also a very good possibility of positioning targets. The greatest disadvantage is the system’s low field of view. / Avdelning: ALB - Slutet Mag 3 C-upps.Hylla: Upps. ChP 99-01

This thesis has been written at Linköping University for the company Instrument Control Sweden AB (ICS). ICS is a small company located in Linköping that develops software and hardware for Unmanned Aerial Vehicles, UAV. At present, ICS has a fully functional autopilot called EasyPilot but they want to reduce the autopilot’s size to make it more attractive. The purpose of this thesis was to investigate if it was possible to reduce the size of the autopilot and how, in that case, it would be done. It was also necessary to examine whether the old processors should be replaced by new ones and how hard it would be to convert the old software to these new processors. To succeed with the goals many of the old components had to be changed for new, smaller ones. Some less necessary parts were also completely removed. The results showed that the size could be reduced quite a bit, exactly how much is hard to say since no PCB-layout were done. By doing some programming tests on the new components it could be shown that some parts of the old code could be reused on the new design. It was mainly algorithms and other calculations. However, a lot of new code still had to be written in order to successfully convert the old software to the new hardware.

Denna uppsats avser lämna ett bidrag till ökad spårbarhet mellan den svenska UAV-utvecklingen och Försvarsmaktsidé 2020. Detta görs genom att undersöka vilka uppgifter UAV:er kan komma att lösa vid ett väpnat angrepp på Sverige. / The Swedish development of Unmanned Air Vehicles (UAV) is not entirely in accordance with the Swedish Armed Forces’ intention for the future battlefield in Defence Idea 2020 (FMI 2020). This essay aims at increasing the accordance between Defence Idea 2020 and the development of UAVs by examining tasks for UAVs in one out of three strategic situations in Defence Idea 2020. The chosen strategic situation 1 (STS 1) deals with an armed attack on Sweden. Furthermore an attempt will be made to decide if there are any tasks given to UAVs in STS 1 that are unsuitable for its development as well as if there are any tasks that could be given priority. The essay gives proposals on a definition of UAVs, a classification of them and describes the experiences of the global UAV-development. These experiences are analysed and compared with the Swedish intention for the future battlefield represented by the nature of the future battle, Revolution in Military Affairs and STS 1. The analysis will result in an example of what tasks UAVs can fulfil in STS 1. / Avdelning: ALB - Slutet Mag 3 C-upps.Hylla: Upps. ChP 99-01

The ducted fan UAV is an unmanned aerial vehicle consisting mainly of a propeller enclosed in a open ended tube. The UAV has the same basic functions as an ordinary helicopter UAV but has several advantages to the same. This thesis aims to estimate the performance of the concept of the ducted fan UAV. The company where this thesis has been written, DST Control AB, is currently investigating the economical possibilities to continue the development of this kind of UAV. This thesis shall provide DST Control AB with a theoretical as well as experimental ground for the investigation by estimation the lift capacity, position accuracy and wind tolerance. A ducted fan UAV prototype and a mathematical model for that UAV have been developed by DST Control AB and a student project at Linköping University. The model is constructed through pure physical modeling. Several noise sources have been added to better fit the reality. Several experiments have been conducted to validate the model with satisfying results. Experiments to determine the lift capacity of the craft have also been conducted. These experiments showed a slightly smaller lift capacity than the theoretically calculated lift capacity. The wind tolerance has not been tested in experiments because of the lack of available wind tunnels but simulations have given an estimation of this tolerance. To estimate the position accuracy, two different control systems have been implemented. The simplest control system is a system consisting of several PID controllers. The system is divided into two separate subsystems connected in cascade. The inner subsystem takes the pitch, roll and yaw angle as inputs and gives the rudder angles as outputs. The outer subsystem takes the inertial position as input and gives roll, pitch and yaw as outputs. Together, the two subsystems can be used to control the entire craft. The inner subsystem has also been replaced with a small LQ Compensator. An LQ Compensator for the entire system is also implemented giving about as good performance as the PID controller and better performance than the PID/LQ combination.

The use of unmanned systems is becoming widespread in commercial and military sectors. The ability of these systems to take on dull, dirty, and dangerous tasks which were formerly done by humans is encouraging their rapid adoption. In particular, a subset of these undesirable tasks are uniquely suited for small unmanned aerial vehicles such as quadrotor helicopters. Examples of such tasks include surveillance, mapping, and search and rescue. Many of these potential tasks require quadrotors to be deployed in environments where a degree of position estimation is required and traditional GPS-based positioning technologies are not applicable. Likewise, since unmanned systems in these environments are often intended to serve the purpose of scouts or first--responders, no maps or reference beacons will be available. Additionally, there is no guarantee of clear features within the environment which an onboard sensor suite (typically made up of a monocular camera and inertial sensors) will be able to track to maintain an estimate of vehicle position. Up to 90% of the features detected in the environment may produce motion estimates which are inconsistent with the true vehicle motion. Thus, new methods are needed to compensate for these environmental deficiencies and measurement inconsistencies. In this work, a RANSAC-based outlier rejection technique is combined with an Extended Kalman Filter (EKF) to generate estimates of vehicle position in a 2--D plane. A low complexity feature selection technique is used in place of more modern techniques in order to further reduce processor load. The overall algorithm was faster than the traditional approach by a factor of 4. Outlier rejection allows the abundance of low quality, poorly tracked image features to be filtered appropriately, while the EKF allows a motion model of the quadrotor to be incorporated into the position estimate. The algorithm is tested in real-time on a quadrotor vehicle in an indoor environment with no clear features and found to be able to successfully estimate position of the vehicle to within 40 cm, superior to those produced when no outlier rejection technique was used. It is also found that the choice of simple feature selection approaches is valid, as complex feature selection approaches which may take over 10 times as long to run still result in outliers being present. When the algorithm is used for vehicle control, periodic synchronization to ground truth data was required due to nearly 1 second of latency present in the closed--loop system. However, the system as a whole is a valid proof of concept for the use of low quality images for quadrotor position control. The overall results from the work suggest that it is possible for unmanned systems to use visual data to estimate state even in operational environments which are poorly suited for visual estimation techniques. The filter algorithm described in this work can be seen as a useful tool for expanding the operational capabilities of small aerial vehicles.