Master of Engineering (Research) / This thesis, by developing a Miniature Aerial Vehicle (MAV) hovering platform, presents a practical solution to allow researchers and students to implement their theoretical methods for guidance and navigation in the real world. The thesis is not concerned with the development of guidance and navigation algorithms, nor is it concerned with the development of external sensors. There have been some recent advances in guidance and navigation towards developing algorithms and simple sensors for MAVs. The task of developing a platform to test such advancements is the subject of this thesis. It is considered a difficult and time consuming process due to the complexities of autonomous flight control and the strict size, weight and computational requirements of this type of system. It would be highly beneficial to be able to buy a platform specifically designed for this task that already possesses autonomous hovering capability and the expansion connectivity for interfacing your own custom developed sensors and algorithms. Many biological and computer scientists would jump at the opportunity to maximize their research by real world implementation. The development of such a system is not a trivial task. It requires a great deal of understanding in a broad range of fields including; Aeronautical, Microelectronic, Mechanical, Computer and Embedded Software Engineering in order to create a successful prototype. The challenge of this thesis was to design a research platform to enable easy implementation of external sensors and guidance algorithms, in a real world environment for research and education. The system is designed so it could be used for a broad range of testing experiments. After extensive research in current MAV and avionics design it became obvious in several areas the best available products were not sufficient to meet the needs of the proposed platform. Therefore it was necessary to custom design and build; sensors, a data acquisition system and a servo controller. The latter two products are available for sale by Jimonics (www.jimonics.com). It was then necessary to develop a complete flight control system with integrated sensors, processor and wireless communications network which is called ‘The MicroBrain’. ‘The MicroBrain’ board measures only 45mm x 35mm x 11mm and weighs ~11 grams. The coaxial contra-rotating MAV platform design provides a high level of mechanical stability to help minimise the control system complexity. The platform was highly modified from a commercially available remotely controlled helicopter. The system incorporates a novel collision protection system that was designed to also double as a mounting place for external sensors around its perimeter. The platform equipped with ‘The MicroBrain’ is capable of fully autonomous hover. This provides a great base for testing guidance and navigational sensors and algorithms by decoupling the difficult task of platform design and low-level stability control. By developing a platform with these capabilities the researcher can now focus on the guidance and navigation task, as the difficulties in developing a custom platform have been taken care of. This therefore promotes a faster evolution of guidance and navigational control algorithms for MAVs.

Master of Engineering (Research) / This thesis, by developing a Miniature Aerial Vehicle (MAV) hovering platform, presents a practical solution to allow researchers and students to implement their theoretical methods for guidance and navigation in the real world. The thesis is not concerned with the development of guidance and navigation algorithms, nor is it concerned with the development of external sensors. There have been some recent advances in guidance and navigation towards developing algorithms and simple sensors for MAVs. The task of developing a platform to test such advancements is the subject of this thesis. It is considered a difficult and time consuming process due to the complexities of autonomous flight control and the strict size, weight and computational requirements of this type of system. It would be highly beneficial to be able to buy a platform specifically designed for this task that already possesses autonomous hovering capability and the expansion connectivity for interfacing your own custom developed sensors and algorithms. Many biological and computer scientists would jump at the opportunity to maximize their research by real world implementation. The development of such a system is not a trivial task. It requires a great deal of understanding in a broad range of fields including; Aeronautical, Microelectronic, Mechanical, Computer and Embedded Software Engineering in order to create a successful prototype. The challenge of this thesis was to design a research platform to enable easy implementation of external sensors and guidance algorithms, in a real world environment for research and education. The system is designed so it could be used for a broad range of testing experiments. After extensive research in current MAV and avionics design it became obvious in several areas the best available products were not sufficient to meet the needs of the proposed platform. Therefore it was necessary to custom design and build; sensors, a data acquisition system and a servo controller. The latter two products are available for sale by Jimonics (www.jimonics.com). It was then necessary to develop a complete flight control system with integrated sensors, processor and wireless communications network which is called ‘The MicroBrain’. ‘The MicroBrain’ board measures only 45mm x 35mm x 11mm and weighs ~11 grams. The coaxial contra-rotating MAV platform design provides a high level of mechanical stability to help minimise the control system complexity. The platform was highly modified from a commercially available remotely controlled helicopter. The system incorporates a novel collision protection system that was designed to also double as a mounting place for external sensors around its perimeter. The platform equipped with ‘The MicroBrain’ is capable of fully autonomous hover. This provides a great base for testing guidance and navigational sensors and algorithms by decoupling the difficult task of platform design and low-level stability control. By developing a platform with these capabilities the researcher can now focus on the guidance and navigation task, as the difficulties in developing a custom platform have been taken care of. This therefore promotes a faster evolution of guidance and navigational control algorithms for MAVs.

<p>Flapping flight is one of the most widespread mean of transportation. It is a complex unsteady aerodynamic problem that has been studied extensively in the past century. Nevertheless, by its complex nature, flapping flight remains a challenging subject. With the development of micro air vehicles, researchers need new computational methods to design these aircrafts efficiently. </p><p>In this dissertation, I will present three different methods of optimization for flapping flight with an emphasis on hovering with each their advantages and drawbacks. The first method was developed by Hall et al. It is an extremely fast and powerful three-dimensional approach. However, the assumptions made to develop this theory limit its use to lightly loaded wings. In addition, it only models the motion of the trailing edge and not the actual motion of the wing. </p><p>In a second part, I will present a two-dimensional unsteady potential method. It uses a freely convected wake which removes the lightly loaded restriction. This method shows the existence of an optimal combination of plunging and pitching motion. The motion is optimal in the sense that for a required force vector, the aerodynamic power is minimal.</p><p>The last method incorporates the three-dimensional effects. These effects are especially important for low aspect ratio wings. Thus, a three-dimensional unsteady potential vortex method was developed. This method also exhibits the presence of an optimal flapping/pitching motion. In addition, it agrees really well with the two previous methods and with the actual kinematics of birds during hovering flapping flight.</p><p>To conclude, some preliminary design tools for flapping wings in forward and hovering flight are presented in this thesis.</p> / Dissertation

Being able to fly has always been one of humanities greatest dreams, and today anyone can purchase a Radio-Controlled (RC) airplane or helicopter and learn how to fly. Experienced RC pilots perform stunts such as “prop hanging”. This is when an airplane flies vertically while maintaining its position with the propeller being the only motive force. In this thesis, the first steps towards converting a manually controlled hovering airplane to an autonomous one are taken by using one single accelerometer to measure differences in acceleration as input data for a height regulator. A built prototype with the height regulator implemented is tested in a test rig. The finished regulator is able to adjust and keep the airplane stable when exposed to small to medium disturbances. The regulator’s biggest weakness is the lack of input data regarding the velocity. Big disturbances result in a constant velocity, which gives zero acceleration input data, and an airplane flying away from its equilibrium position. / Att kunna flyga har alltid varit en av mänsklighetens största drömmar och idag kan vem som helst köpa ett radiostyrt flygplan eller helikopter och lära sig att flyga. Erfarna piloter som flyger radiostyrda flygplan utför konster som att ”hänga i propellern”, vilket innebär att flygplanet flyger vertikalt samtidigt som den behåller sin position där propellern är den enda drivkraften. I den här avhandlingen tas det första steget att konvertera ett manuellt styrt hovrande flygplan till ett autonomt genom att använda en enda accelerometer för att mäta skillnaden i acceleration som indata för en höjdregulator. Ett byggt prototypflygplan med höjdregulatorn implementerad testas i en testställning. Den färdiga regulatorn fungerar och kan justera och hålla flygplanet stabilt när den utsätts för små till medelmåttiga störningar. Regulatorns största svaghet är bristen på indata av hastigheten. Stora störningar resulterar i konstant hastighet, vilket ger noll acceleration som indata och ett flygplan som flyger ifrån sitt jämviktsläge.

Being able to fly has always been one of humanities greatestdreams, and today anyone can purchase a Radio-Controlled(RC) airplane or helicopter and learn how to fly. ExperiencedRC pilots perform stunts such as “prop hanging”.This is when an airplane flies vertically while maintainingits position with the propeller being the only motive force.In this thesis, the first steps towards converting a manuallycontrolled hovering airplane to an autonomous one aretaken by using one single accelerometer to measure differencesin acceleration as input data for a height regulator.A built prototype with the height regulator implementedis tested in a test rig. The finished regulator is able toadjust and keep the airplane stable when exposed to smallto medium disturbances. The regulator’s biggest weaknessis the lack of input data regarding the velocity. Big disturbancesresult in a constant velocity, which gives zeroacceleration input data, and an airplane flying away fromits equilibrium position. / Att kunna flyga har alltid varit en av mänsklighetens störstadrömmar och idag kan vem som helst köpa ett radiostyrtflygplan eller helikopter och lära sig att flyga. Erfarna pilotersom flyger radiostyrda flygplan utför konster som att”hänga i propellern”, vilket innebär att flygplanet flygervertikalt samtidigt som den behåller sin position där propellernär den enda drivkraften. I den här avhandlingen tasdet första steget att konvertera ett manuellt styrt hovrandeflygplan till ett autonomt genom att använda en endaaccelerometer för att mäta skillnaden i acceleration som indataför en höjdregulator. Ett byggt prototypflygplan medhöjdregulatorn implementerad testas i en testställning. Denfärdiga regulatorn fungerar och kan justera och hålla flygplanetstabilt när den utsätts för små till medelmåttigastörningar. Regulatorns största svaghet är bristen på indataav hastigheten. Stora störningar resulterar i konstanthastighet, vilket ger noll acceleration som indata och ettflygplan som flyger ifrån sitt jämviktsläge.

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Fall-related injuries are common problems in elderly care in particular. These can cause brain damage and hip fractures, which in many cases can be serious. To reduce or mitigate the damage, various safety measures have been developed. One of them concerns a change in the surroundings, more specifically, the floor. At KTH within the Division of Neuronic Engineering, research has been done on how the impact of the case can be minimized and a shock absorbing floor (SAF) was developed. Diving problems with this type of flooring are that heavy medical beds sink into the floor, which means increased rolling resistance and thus long-term damage to both the floor and the medical staff. The aim of this thesis was to investigate how much rolling resistance can be minimized by building a downscaled hovering device based on hovercraft technology. The purpose was to enable the device to possibly be mounted under hospital beds and create a lifting force. To evaluate the performance, force measurements were performed on KTH SAF with different weights and with the use of a dynamometer. The results showed that the device reduced rolling resistance by up to 57.4% with additional weight. Four axial fans were used together with manual control of the speed of each fan. The selected components were made taking into account, in particular, cost, weight and dimensions and can thus also be limiting factors for this thesis. For future work, effective soundproofing is needed for this solution to be possible to be implemented in a hospital environment. Furthermore, studies needs to be carried out for a full-scale prototype to confirm that an equally large reduction in rolling resistance can be achieved.

Fixed-wing unmanned aerial vehicles (UAVs) with the ability to hover combine the speed and endurance of traditional fixed-wing fight with the stable hovering and vertical takeoff and landing (VTOL) capabilities of helicopters and quadrotors. This combination of abilities can provide strategic advantages for UAV operators, especially when operating in urban environments where the airspace may be crowded with obstacles. Traditionally, fixed-wing UAVs with hovering capabilities had to be custom designed for specific payloads and missions, often requiring custom autopilots and unconventional airframe configurations. With recent government spending cuts, UAV operators like the military and law enforcement agencies have been urging UAV developers to make their aircraft cheaper, more versatile, and easier to repair. This thesis discusses the use of the commercially available ArduPilot open source autopilot, to autonomously transition a fixed-wing UAV to and from hover flight. Software modifications were made to the ArduPilot firmware to add hover flight modes using both Proportional, Integral, Derivative (PID) Control and Model Reference Adaptive Control (MRAC) with the goal of making the controllers robust enough so that anyone in the ArduPilot community could use their own ArduPilot board and their own fixed-wing airframe (as long as it has enough power to maintain stable hover) to achieve autonomous hover after some simple gain tuning. Three new hover flight modes were developed and tested first in simulation and then in flight using an E-Flight Carbon Z Yak 54 RC aircraft model, which was equipped with an ArduPilot 2.5 autopilot board. Results from both the simulations and flight test experiments where the airplane transitions both to and from autonomous hover flight are presented.

Nectarivorous hummingbirds subsist almost exclusively on a mixture of sucrose, glucose and fructose found in floral nectar. Previous studies have shown that hummingbirds can fuel hovering flight almost exclusively using recently ingested sucrose. However, the relative capacities for the direct utilization of glucose and fructose by hovering hummingbirds remain unknown. 13C-enriched solutions of glucose and fructose were administered separately. Exhaled breath samples were collected using feeder-mask respirometry and sent for subsequent mass spectrometric analysis. I found hovering hummingbirds transition from exclusively oxidizing endogenous fatty acids when fasted, to oxidizing newly ingested carbohydrates when given access to either glucose or fructose solutions. Interestingly, the amount ingested, fractional turnover of stable carbon isotope signatures, amount oxidized, energy expended and proportion of hovering metabolism supported by each hexose, were each similar between glucose and fructose. These results demonstrate hovering hummingbirds’ ability to utilize fructose and glucose equally.

Nectarivorous hummingbirds subsist almost exclusively on a mixture of sucrose, glucose and fructose found in floral nectar. Previous studies have shown that hummingbirds can fuel hovering flight almost exclusively using recently ingested sucrose. However, the relative capacities for the direct utilization of glucose and fructose by hovering hummingbirds remain unknown. 13C-enriched solutions of glucose and fructose were administered separately. Exhaled breath samples were collected using feeder-mask respirometry and sent for subsequent mass spectrometric analysis. I found hovering hummingbirds transition from exclusively oxidizing endogenous fatty acids when fasted, to oxidizing newly ingested carbohydrates when given access to either glucose or fructose solutions. Interestingly, the amount ingested, fractional turnover of stable carbon isotope signatures, amount oxidized, energy expended and proportion of hovering metabolism supported by each hexose, were each similar between glucose and fructose. These results demonstrate hovering hummingbirds’ ability to utilize fructose and glucose equally.