A dual-axis fluidic thrust vectoring (FTV) system is proposed where the supersonic propulsive jet of an aircraft is exhausted over a scarfed (swept), curved surface to produce flight control moments in both the pitch and yaw axes. This work contributes towards practical dual-axis FTV through expansion of fundamental curved-wall jet (CWJ) understanding, development of the novel Superimposed Characteristics technique for supersonic nozzle design, and performance evaluation of an experimental scarfed curved wall FTV configuration. Previous work has suggested that the use of a sheared exhaust velocity profile improves the attachment of supersonic jets to curved surfaces; however, evidence to support this is limited. To address this, an inviscid numerical CWJ model was developed using the two-dimensional method of characteristics. A major outcome is improved understanding of the effect of exhaust velocity profile on CWJ wave structure and subsequent jet attachment. A sheared velocity exhaust is shown to generate a wave structure that diminishes adverse streamwise pressure gradients within a supersonic curved-wall jet. This reduces the likelihood of boundary layer separation and as a result, a sheared exhaust velocity CWJ is expected to be less readily separated compared to other exhaust velocity profiles. A novel method termed Superimposed Characteristics was developed for the low-order design of supersonic nozzles with rectangular exits. The technique is capable of generating 3D nozzle geometries based on independent exit plane orientation and exhaust velocity distribution requirements. The Superimposed Characteristics method was used to design scarfed rectangular exit nozzles with sheared velocity exhaust profiles. These nozzles were then evaluated using finite volume computational methods and experimental methods. From the analysis, the Superimposed Characteristics method is shown to be valid for preliminary nozzle design. Experimental methods were used to study the on- and off-design attachment qualities of uniform and sheared velocity exhaust jets for a FTV configuration with an external curved wall termination angle of 90 degrees and scarf angle of 30 degrees. Experiments at the on-design nozzle pressure ratio (NPR) of 3.3 demonstrated pitch and yaw jet deflection angles of 78 degrees and 23 degrees respectively for the uniform exhaust velocity CWJ. The sheared exhaust velocity CWJ achieved lower pitch and yaw deflection angles of 34 degrees and 14 degrees respectively at the same on-design NPR. The lower jet deflection angles observed for sheared exhaust velocity jets is inconsistent with the CWJ model prediction of reduced adverse streamwise pressure gradients; however, there was insufficient experimental instrumentation to identify the cause. In the off-design experiments, the uniform exhaust velocity CWJ was observed to detach at an NPR of 3.6, whilst the sheared exhaust velocity CWJ remained attached at NPRs in excess of 4. The capability of sheared exhaust velocity CWJs to remain attached at higher NPRs is consistent with the analytical theory and the CWJ model predictions. An actuation study was carried out to achieve controlled jet detachment using secondary blowing injected normal to the curved wall. Full separation of the wall jets was achieved downstream of the injection point. This provided vectoring angles of more than 20 degrees in pitch and 10 degrees in yaw, exceeding expected vectoring requirements for practical aircraft control. At the on-design NPR, the uniform and sheared exhaust velocity jets required secondary blowing mass flow rates of 2.1% and 3.8% of the primary mass flow respectively to achieve full separation.

This work deals with the assessment of the yaw moment control via active differential effects to the heavy commercial vehicle dynamics. Summarized are the findings about design of active differential, control algorithms and theoretical assumptions about overall effects to the vehicle dynamics. According to the described theory the own concept of the active differential for experimental heavy commercial vehicle is proposed. The main part of the work is focused on the effects of the active differential on vehicle manoeuvrability, controllability, stability and limits analysis. For this purpose, multibody dynamic model of the complete vehicle with standard open differential is assembled and results of the selected manoeuvre simulations validated by measurements of the real vehicle characteristics. The validated vehicle model is then extended by the model of the active differential with control algorithm. According to the simulations results the theoretical presumptions are confirmed and the effects of the active differential on vehicle dynamics in steady and transition states are evaluated. Based on the described findings the overall improvement of the vehicle dynamics by this technology, feasibility of the proposed concept and main advantages and disadvantages are evaluated.

This diploma thesis deals with a stability and manoeuvrability of experimental aircraft VUT 001 MARABU. It contains calculation of aerodynamic stability derivations and other data necessary for evaluation of static and dynamic stability. Assessment of convenient autopilot.

This thesis aims to analyze how different temperature deviations affect the components of wind turbines. A study of the temperatures in several different components was carried out to get a clearer picture of how these affects operational reliability. By trying to link, for example, extreme values of temperatures to possible alarms and downtime in the wind power plants, the hope is that this study will be able to contribute to safer and more maintenance-free wind turbines in the future. The 12 wind turbines that have been evaluated in this study are localized in southern Sweden. The time period for the collected data extends over 6 years. In the thesis, an analysis has been carried out with the help of the computer program Matlab to examine different types of data collected from the components in the wind turbines. The data was plotted with the help of various functions in Matlab and with the help of mathematical equations. The data was then observed ocularly by the authors, which led to the discovery of different connections between temperature variations in the components and different error codes. The generator bearing was the component that was found to have the highest correlation between temperature deviations and specific error codes related to various yaw-errors, which can be explained as error codes that occur when the wind turbine fails to adjust itself to the wind. An analysis has also been made to determine whether there was a temperature-related upward trend in any of the components in the wind turbines. This was carried out with the help of various standard deviation calculations and calculation of the mean temperature value of different components. The standard deviation in this case describes how much the temperature of each component varies from the mean value. It turned out that there was such an upward trend for the Generator Bearing and Generator Phase 3 components. Some turbines also turned out to have a more distinct upward trend than others

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For over a decade, Brigham Young University's Microwave Earth Remote Sensing (MERS) team has been developing SAR systems and SAR processing algorithms. In order to create the most accurate image reconstruction algorithms, detailed aircraft motion data is essential. In 2008, the MERS team purchased a costly inertial measurement unit (IMU) coupled with a high precision global positioning system (GPS) from NovAtel, Inc. In order to lower the cost of obtaining detailed motion measurements, the MERS group decided to build a system that mimics the capability the NovAtel system as closely as possible for a much lower cost. As a first step, the same sensors and a simplified set of flight dynamics are used. This thesis presents a standalone motion sensor recording system (MOTRON), and outlines a method of utilizing the square-root Unscented Kalman filter (SR-UKF) to estimate aircraft flight dynamics, based on recorded flight data, as an alternative to the extended Kalman filter. While the results of the SR-UKF are not as precise as the NovAtel results, they approach the accuracy of the NovAtel system despite the simplified dynamics model.

Active anti-roll bars have recently found greater acceptance among premium car manufacturers and optimal application of this technology has emerged as an important field of research. This thesis investigates the potential of implementing active anti-roll bars in a passenger vehicle with the purpose of increasing customer value. For active anti-roll bars, customer value is defined in terms of vehicle’s ride comfort and handling performance. The objective with this thesis is to demonstrate this value through development of a control algorithm that can reflect the potential improvement in ride comfort and handling. A vehicle with passive anti-roll bars is simulated for different manoeuvres to identify the potential and establish a reference for the development of a control algorithm and for the performance of active anti-roll bars. While ride is evaluated using single-sided cosine wave and single-sided ramps, handling is evaluated using standardized constant radius, frequency response and sine with dwell manoeuvres.The control strategy developed implements a combination of sliding mode control, feed forward and PI-controllers. Simulations with active anti-roll bars showed significant improvement in ride and handling performance in comparison to passive anti-roll bars. In ride comfort, the biggest benefit was seen in the ability to increase roll damping and isolating low frequency road excitations. For handling, most significant benefits are through the system’s ability of changing the understeer behaviour of the vehicle and improving the handling stability in transient manoeuvres. Improvement in the roll reduction capability during steady state cornering is also substantial. In conclusion, active anti-roll bars are undoubtedly capable of improving both ride comfort and handling performance of a vehicle. Although the trade-off between ride and handling performance is significantly less, balance in requirements is critical to utilise the full potential of active anti-roll bars. With a more comprehensive control strategy, they also enable the vehicle to exhibit different driving characteristics without the need for changing any additional hardware.

This dissertation addresses attitude control and inertial navigation of autonomous underwater vehicles (AUVs). We present theoretical justification for using simplified models, derive system identification algorithms, and verify our results through extensive field trials. Although this research focuses on small AUVs with limited instrumentation, the results are useful for underwater vehicles of any size. For attitude control of aircraft systems, second-order equivalent pitch-axis models are common and extensively studied. However, similar analysis has not been performed for the pitch-axis motion of underwater vehicles. In this dissertation, we study the utility and the limitations of second-order approximate models for AUVs. We seek to improve the flight performance and shorten the time required to re-design a control algorithm when the shape, mass-distribution, and/or net buoyancy of an AUV/payload configuration changes. In comparison to commonly implemented AUV attitude controllers, which neglect roll motion and address pitch and yaw dynamics separately, we derive a novel linear time-varying model that explicitly displays the coupling between pitch and yaw motion due to nonzero roll angle and/or roll rate. The model facilitates an Hâ control design approach that explicitly addresses robustness against those coupling terms and significantly reduces the effect of pitch and yaw coupling. To improve AUV navigation, we investigate algorithms for calibrating a triaxial gyroscope using angular orientation measurements and formally define AUV trajectories that are persistently exciting and for which the calibration coefficients are uniformly observable. To improve AUV guidance, we propose a near real-time ocean current identification method that estimates a non-uniform flow-field using only sparse flow measurements. / Ph. D.

One method to increase efficiency, robustness and accuracy of automatic control, is to introduce mathematical models of the system in question to increase performance. With these models, it is possible to predict the behavior of the system, which enables control according to the predictions. The problem here is that if these models do not describe the dynamics of the system well enough, this method could fail to increase performance. To address this problem, one idea is to estimate the dynamics of the system during operation, using methods for system identification, signal processing and sensor fusion. In this thesis, the possibilities of estimating a ship's dynamics during operation have been investigated. The mathematical model describing the dynamics of the ship is a graybox model, which is based on the physical and mechanical relations. This model's properties are therefore described by physical quantities such as mass and moment of inertia, all of which are unknown. This means that, when estimating the model, these physical properties will be estimated. For a systematic approach, first a simulation environment with a 4-degrees-of-freedom ship model has been developed. This environment has been used for validation of system identification methods. A model of a podded propulsion system has also been derived and validated. The methods for estimating the properties of the ship have been analyzed using the data collected from the simulations. For system identification and estimation of ship properties, the influence of measurement noise and potential of detecting a change in dynamics has been analyzed. This has been done through Monte Carlo simulations of the estimation method with different noise realizations in the simulations, to analyze how the measurement noise affects the variance and bias for the estimates. The results show that variance and bias vary a lot between the parameters and that even a small change in dynamics is visible in some parameter estimates when only ten minutes of data have been used. A method based on cumulative summation (CUSUM) has been proposed and validated to analyze if such a method could yield fast and effective detection of system deviations. The results show that the method is rather effective a with robust detection of changes in the dynamics after about four minutes of data collection. Finally, the methods have been validated on data collected on a real ship to analyze the potential of the methods under actual circumstances. The results show that the particular data is not appropriate for this kind of application along with some additional problems that can yield impaired results. / Genom att inkludera matematiska modeller som beskriver ett systems dynamik i styrningsalgoritmer, kan man åstadkomma en automatisk styrning med förbättrad effektivitet, robusthet och noggrannhet. Med dessa modeller går det att förutsäga beteendet hos systemet och därmed öppnas också möjligheten att använda sig av detta i styrningen. Problemet är att om dessa modeller inte beskriver systemets dynamik tillräckligt bra kan prestandan istället sänkas genom dessa metoder. Den här sortens problem kan man lösa genom att aktivt skatta systemets dynamik under körning, med hjälp av metoder för systemidentifiering, signalbehandling och sensorfusion. I denna exjobbsrapport har möjligheterna att skatta ett skepps girdynamik undersökts. Den matematiska modell som beskriver skeppets dynamik är en grålådemodell som baserar sig på fysikaliska och mekaniska samband. Denna modells egenskaper beskrivs därför av fysikaliska storheter så som massa, tröghetsmoment och tyngdpunkt, vilka alla är okända. Detta innebär att vid modellskattning skattas dessa fysikaliska storheter, vilka kan vara av stort intresse. En simuleringsmiljö med en skeppsmodell med fyra frihetsgrader har skapats och använts för att validera metoder för systemidentifiering. En modell av ett roterbart framdrivningssystem har också härletts och inkluderats i simuleringsmodellen. Vid systemidentifiering och skattning av skeppets egenskaper har dels inverkan av mätbrus analyserats samt även möjligheter till att detektera skillnader i dynamik. Detta har gjorts med Monte Carlo-simuleringar av skattningsmetoden med olika brusrealiseringar för att analysera hur mätbrus påverkar variansen och metodfelet hos skattningarna. Resultaten visar att vissa parametrar skattas med större noggrannhet och hos dessa kan därmed en förändring i dynamik identifieras när endast tio minuter av data har använts. En metod baserad på kumulativ summering av residualer har formulerats och validerats, detta för att undersöka om en sådan metod kan ge snabb och effektiv detektion av systemförändringar. Resultat visar på robusthet i att detektera skillnader i dynamik efter ungefär fyra minuter av datainsamling. Slutligen har metoderna validerats på data insamlad på ett riktigt skepp för att undersöka potentialen under verkliga omständigheter. Resultaten visar att just denna data inte är lämplig för denna applikation samt några problem som kan leda till försämrade resultat.