Aircraft control mechanisms, such as those that operate the flaps, ailerons, rudders, etc., are almost exclusively driven by hydraulic-based systems. Their popularity in flight control systems is not unfounded; hydraulic actuators are quite torque-dense and benefit from decades of development bringing operating performance to a high level. On the other hand the infrastructure to support this system increases weight, adds system development complexity, and reduces aircraft maintainability [Jensen et al, 2000]. Based on recent Electro-Mechanical Actuator (EMA) development and design efforts at the Robotics Research Group (RRG), a new opportunity exists to replace current hydraulic flight control systems with those powered by electricity through a national program [Tesar, 2005]. A literature review of the topic found a 30 year old effort by AiResearch to develop a similarly powered hingeline actuator with given traditional performance goals (torque capacity, redundancy, output speed, reliability). In this report,a thorough analysis is performed on each major component group to quantitatively evaluate this baseline device. Using component technologies developed at RRG, this report proposes a dual torque-summing electromechanical actuator, each with a star compound / hypocyclic combined gear train, designed to exceed the performance of the original (1976) AiResearch project. This preliminary design exercise includes a layout of the entire actuator along with an appropriate analysis of major components including bearings, gear train, motor, housing, and release mechanism. The performance of this gear train is critical to overall actuator success and fundamental analytics have already been developed in this area [Park and Tesar, 2005]. Finite Element Analysis on the gear train and housing provide early design feedback and verification of actuator performance characteristics. In particular, simulation results show the gear stiffness, load sharing, and torque capacities exceed analytical estimates. Finally, four different comparisons are presented that evaluate configuration variations of the two designs based on applicable performance criteria. Results show the RRG fault-tolerant actuator has a marked improvement over the baseline in average stiffness (14.2x), reflected inertia (3.2x) and nominal torque density (3.4x). The chapter next lists actuator test methods and aircraft qualification standards. Finally, a summary of future work is detailed in a ten step outline to bring this EMA technology to a level of early deployment in a large range of aircraft systems.

Abstrakt: This report examines different control design methods, linear as well as nonlinear, for a suborbital reusable launch vehicle. An investigation of the natural vehicle behavior is made, after which a baseline linear controller is constructed to fulfill certain handling quality criteria. Thereafter the nonlinear cascade control methods block backstepping and nonlinear dynamic inversion via time scale separation are examined and used to construct two nonlinear controllers for the vehicle. Optimal controllers, in terms of three different criteria, are found using the genetic optimization algorithm differential evolution. The optimal controllers are compared, and it is found that nonlinear dynamic inversion via time scale separation performs better than block backstepping with respect to the cases investigated. The results suggest control design by global optimization is a viable and promising complement to classical methods.

<p>Solar-powered Unmanned Aerial Vehicles (UAVs) solve the problem of loiter time as aircrafts can fly as long as sufficient illumination and reserve battery power is available. However, Solar-powered UAVs still face the problem of excessive wingspan to increase solar capture area, which detracts from maneuverability and portability. As a result, a feature of merit for solar UAVs has emerged that strives to reduce the wingspan of such UAVs. The purpose of this project is to improve energy use efficiency by applying a distributed propulsion system to reduce the wingspan of solar-powered UAVs and increase payload. The research focuses on optimizing a new design analysis method applied to the distributed propulsion system and further employs the novel application of solar arrays on both top and bottom of the wings. The design methodology will result in a 2.1-meter wingspan, which is the shortest at 2020, for a 24-hour duration solar-powered UAV.</p><br>

Účelem této práce je navrhnout zjednodušené modely klasického a fuzzy regulátoru pro automatické udržení výšky letu a porovnat jejich vlastnosti. Cílem je vyšetřit, zda fuzzy regulátor neprojeví lepší chování než klasický. Prostředkem pro návrh a srovnání vlastností obou regulátorů je posouzení odezev modelu systému letadlo-regulátor na požadavek změny výšky a modelu turbulence. Simulace jsou realizovány s pomocí prostředí MATLAB SIMULINK.

<p>The dissertation research was conducted to examine articles, research, and studies that have been collected in recent years to understand energy management for general aviation airplane pilots. The experiment was broken down into four phases with control and treatment groups which have evaluated the real-world problem of energy management in aviation. The four phases were to fly a flight profile, evaluate the energy state of the airplane within the flight by video, fly the same flight profile again, and a post-flight interview with the pilots. The idea of this experiment was to recognize the lack of understanding in energy management in pilots, build a conceptual model, and lastly verify and validate Phase II of the model by utilizing previous studies and research. Additionally, the three main goals were to assess the ability to interpret energy management, assess the ability to control the aircraft, and lastly, to interview for perception of energy management. The data was collected on the flight training device’s G1000, and the researcher analyzed the data using R, Minitab, Excel, and NVivo. The research provided ideas for creating a future model to evaluate energy management, validated by testing Phase II of the model to understand assessing energy management in real time, and interviewed pilots on their experiences with energy management, identified gaps in general aviation research, and suggested methods of how to facilitate understanding of energy management.</p>

<p>Current indirect optimal control problem (IOCP) solvers, like beluga or PINs, use symbolic math to derive the necessary conditions to solve the IOCP. This limits the capability of IOCP solvers by only admitting symbolically representable functions. The purpose of this thesis is to present a framework that extends those solvers to derive the necessary conditions of an IOCP with fully numeric methods. With fully numeric methods, additional types of functions, including conditional logic functions and look-up tables can now be easily used in the IOCP solver.</p> <p><br></p> <p>This aim was achieved by implementing algorithmic differentiation (AD) as a method to derive the IOCP necessary conditions into a new solver called Giuseppe. The Brachistochrone problem was derived analytically and compared Giuseppe to validate the automatic derivation of necessary conditions. Two additional problems are compared and extended using this new solver. The first problem, the maximum cross-range problem, demonstrates a trajectory can be optimized indirectly while utilizing a conditional density function that switches as a function of height according to the 1976 U.S. atmosphere model. The second problem, the minimum time to climb problem, demonstrates a trajectory can be optimized indirectly while utilizing 6 interpolated look up tables for lift, drag, thrust, and atmospheric conditions. The AD method yields the exact same precision as the symbolic methods, rather than introducing numeric error as finite difference derivatives would with the benefit of admitting conditional switching functions and look-up tables. </p>

<p dir="ltr">The electrification of pneumatic or hydraulic system on aircraft has been shown effective in reducing the fuel burn. Recently, electrifying propulsive loads has attracted a lot of atten- tion to further improve fuel economy. This work focuses on tools to facilitate more electric aircraft at conceptual design stage, particularly assuming a turbo-generator architecture. Specifically, we develop a simulation tool, mimicking SUAVE [1], which allows mission and fuel burn analysis. Major differences from SUAVE include more detailed models of compo- nents in the electric propulsive branch and degrees of freedom to adjust the velocity profile along the entire mission. Based on the simulator, this work further proposes to leverage a gradient-free optimization technique, which optimizes the optimal velocity profile along the entire mission to minimize fuel burn. Simulation results on two aircraft designs, a con- ventional Boeing 737-800 and NASA-STARC-ABL, verify the effectiveness of the proposed tools.</p>

Thesis (MScEng)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The air-to-air refuelling of large aircraft presents challenges such as a long fuel transfer time, slow aircraft responses and a large distance between the aircraft CG and the receptacle position. This project addresses some of these issues by adding a control system to keep the receiver aircraft in the correct position relative to the tanker to enable fuel transfer. This project investigates different control strategies which are designed to control the A330-300 during refuelling at one trim condition. The controllers are based on a mathematical aircraft model which was derived from a simulation model received from Airbus. The first set of controllers uses the aircraft actuators directly. Controllers that are based on the CG dynamics and the receptacle dynamics are compared. Due to the large distance between the CG and the receptacle it was found to be essential to control the receptacle position, and not only the CG position. Also, a controller that is based on a model of the receptacle dynamics performs better. The second set of controllers uses the aircraft manual control laws as an inner loop controller. This set of controllers and the last direct actuator controller use the same axial controller that uses the engine thrust to control axial position. It was found that both the direct actuator controller and the manual control laws controller are able to keep the receptacle within the disconnect envelope in moderate turbulence. In both sets of controllers the axial controller fails to keep the receptacle reliably within the disconnect envelope in light turbulence. From the results it is concluded that both the direct actuator control and manual control laws can be used to successfully control the receptacle position in the normal and lateral positions as long as the receptacle kinematics are included in the control design. Using only the engine thrust for axial control is insufficient. Several recommendations are made to improve the axial control and also how these results can be used in future work. / AFRIKAANSE OPSOMMING: Die lug-tot-lug brandstof hervulling van groot vliegtuie het uitdagings soos ’n lang hervullingstyd, stadige vliegtuig dinamika en ’n groot afstand tussen die hervullingspoort en die vliegtuig massamiddelpunt. Hierdie projek spreek sommige van hierdie uitdagings aan deur ’n beheerstelsel by te voeg wat die vliegtuig in die korrekte posisie relatief tot die tenker hou vir brandstofoordrag om plaas te vind. Hierdie projek ondersoek verskillende beheerstrategieë wat ontwerp is om die A330- 300 te beheer by ’n enkele gestadigde toestand. Die beheerders is gebaseer op ’n wiskundige vliegtuigmodel wat vanaf ’n simulasiemodel afgelei is. Die simulasiemodel is vanaf Airbus verkry. Die eerste stel beheerders beheer direk die vliegtuig se beheeroppervlakke. Beheerders wat onderskeidelik die massamiddelpunt en die hervullingspoort beheer word vergelyk. Daar is gevind dat dit essensieel is om die hervullingspoort te beheer en nie slegs die massamiddelpunt nie, as gevolg van die groot afstand tussen hierdie twee punte. Die tweede stel beheerders gebruik die vliegtuig se eie beheerwette as ’n binnelusbeheerder en vorm self die buitelus. Albei stelle beheerders gebruik dieselfde aksiale beheerder wat enjin stukrag gebruik om die aksiale posisie te beheer. Daar is gevind dat beide stelle beheerders die hervullingspoort binne die ontkoppelingsbestek kan hou in die normale en laterale rigtings tydens matige turbulensie. In beide stelle beheerders is dit die aksiale beheerder wat faal om die hervullingspoort betroubaar in posisie te hou, selfs in ligte turbulensie. Vanaf die resultate word afgelei dat beide die direkte beheerder en die buitelusbeheerder gepas is om die laterale en normale posisiebeheer toe te pas mits die dinamika van die hervullingspoort in ag geneem word. Om slegs stukrag te gebruik vir aksiale beheer is nie voldoende nie, en verskeie voorstelle word gemaak om die aksiale beheer te verbeter in toekomstige navorsing.

O presente trabalho descreve a aplicação de um método de ajuste de modelo, com base em resultados experimentais obtidos em túnel de vento, a uma aeronave com sistema de aumento de estabilidade longitudinal (LSAS). O estudo inclui uma revisão de métodos para ajuste de modelos, o desenvolvimento do modelo matemático da aeronave e uma descrição dos ensaios em túnel de vento da aeronave com o LSAS. O sistema automático de controle é composto de (1) um sistema de aquisição de dados, que processa o sinal do sensor e envia um sinal de comando para o atuador; (2) um potenciômetro, usado como sensor de ângulo de arfagem; e (3) um servo motor, usado como atuador do canard. O modelo de aeronave é baseado no Grumman X-29, que tem asa de enflechamento negativo e canard. Sua margem de estabilidade estática pode ser ajustada mudando a posição do centro de rotação que, por sua vez, coincide com a posição do centro de gravidade da aeronave através de balanceamento do peso. O ajuste do modelo matemático do avião é conduzido, no ambiente Matlab/Simulink, com a modificação dos parâmetros das derivadas de estabilidade da aeronave, do filtro digital e da dinâmica do sensor e do atuador. O objetivo é obter uma correlação ótima entre resultados teóricos e experimentais. O método da análise da sensibilidade paramétrica é escolhido para o ajuste do modelo. Numa primeira fase do estudo, a comparação entre resultados experimentais e numéricos é feita com base nas freqüências e razões de amortecimento da variação do ângulo de arfagem em resposta a uma entrada do tipo impulso de deflexão do canard. Numa segunda fase a comparação é baseada diretamente na resposta no tempo do ângulo de arfagem numérico e experimental para a mesma entrada impulso do canard. Três posições do centro de gravidade são analisadas, uma em que a aeronave é estaticamente estável e duas em que ela é instável. Os resultados mostram grande variação dos parâmetros ajustados indicando a necessidade de aperfeiçoamento na implementação da metodologia utilizada. / The present work describes the application of a model updating method, based on experimental wind tunnel data to an aircraft longitudinal stability augmentation system (LSAS). The study includes a revision of model updating methods, the development of the aircraft mathematical model and the description of a previously conducted, aircraft LSAS wind tunnel testing. The LSAS is comprised by (1) a data acquisition system, which processes the sensor signal and sends the control command to the actuator; (2) a potentiometer, used as a pitch angle sensor; and (3) a servo motor, used to actuate canard deflection. The aircraft model is based on the Grumman X-29, which has canard and forward swept wing. Its static stability margin can be adjusted by changing the center of rotation position which, in turn, coincides with the aircraft center of gravity position through weight balance. The airplane mathematical model updating is carried out, in the Matlab/Simulink environment, by adjusting model parameters for aircraft stability derivatives, digital filter, sensor and servo dynamics. The objective is to obtain an optimal correlation between numerical and experimental results. The parametric sensitivity analysis method is chosen for model updating. In a first phase of the study the comparison between theoretical and experimental results is based on frequencies and damping ratios for aircraft pitch angle response to an impulse canard deflection input. In a second phase the comparison is based directly on experimental and numerical pitch angle time response to the same impulse canard deflection input. Three center of gravity positions are analyzed, one for which the aircraft is statically stable and two for which it is unstable. Results show large variations among adjusted parameters indicating the need for improvements in the implementation of the adopted methodology.

O presente trabalho descreve a aplicação de um método de ajuste de modelo, com base em resultados experimentais obtidos em túnel de vento, a uma aeronave com sistema de aumento de estabilidade longitudinal (LSAS). O estudo inclui uma revisão de métodos para ajuste de modelos, o desenvolvimento do modelo matemático da aeronave e uma descrição dos ensaios em túnel de vento da aeronave com o LSAS. O sistema automático de controle é composto de (1) um sistema de aquisição de dados, que processa o sinal do sensor e envia um sinal de comando para o atuador; (2) um potenciômetro, usado como sensor de ângulo de arfagem; e (3) um servo motor, usado como atuador do canard. O modelo de aeronave é baseado no Grumman X-29, que tem asa de enflechamento negativo e canard. Sua margem de estabilidade estática pode ser ajustada mudando a posição do centro de rotação que, por sua vez, coincide com a posição do centro de gravidade da aeronave através de balanceamento do peso. O ajuste do modelo matemático do avião é conduzido, no ambiente Matlab/Simulink, com a modificação dos parâmetros das derivadas de estabilidade da aeronave, do filtro digital e da dinâmica do sensor e do atuador. O objetivo é obter uma correlação ótima entre resultados teóricos e experimentais. O método da análise da sensibilidade paramétrica é escolhido para o ajuste do modelo. Numa primeira fase do estudo, a comparação entre resultados experimentais e numéricos é feita com base nas freqüências e razões de amortecimento da variação do ângulo de arfagem em resposta a uma entrada do tipo impulso de deflexão do canard. Numa segunda fase a comparação é baseada diretamente na resposta no tempo do ângulo de arfagem numérico e experimental para a mesma entrada impulso do canard. Três posições do centro de gravidade são analisadas, uma em que a aeronave é estaticamente estável e duas em que ela é instável. Os resultados mostram grande variação dos parâmetros ajustados indicando a necessidade de aperfeiçoamento na implementação da metodologia utilizada. / The present work describes the application of a model updating method, based on experimental wind tunnel data to an aircraft longitudinal stability augmentation system (LSAS). The study includes a revision of model updating methods, the development of the aircraft mathematical model and the description of a previously conducted, aircraft LSAS wind tunnel testing. The LSAS is comprised by (1) a data acquisition system, which processes the sensor signal and sends the control command to the actuator; (2) a potentiometer, used as a pitch angle sensor; and (3) a servo motor, used to actuate canard deflection. The aircraft model is based on the Grumman X-29, which has canard and forward swept wing. Its static stability margin can be adjusted by changing the center of rotation position which, in turn, coincides with the aircraft center of gravity position through weight balance. The airplane mathematical model updating is carried out, in the Matlab/Simulink environment, by adjusting model parameters for aircraft stability derivatives, digital filter, sensor and servo dynamics. The objective is to obtain an optimal correlation between numerical and experimental results. The parametric sensitivity analysis method is chosen for model updating. In a first phase of the study the comparison between theoretical and experimental results is based on frequencies and damping ratios for aircraft pitch angle response to an impulse canard deflection input. In a second phase the comparison is based directly on experimental and numerical pitch angle time response to the same impulse canard deflection input. Three center of gravity positions are analyzed, one for which the aircraft is statically stable and two for which it is unstable. Results show large variations among adjusted parameters indicating the need for improvements in the implementation of the adopted methodology.