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The wind field has a great influence on the control stability of Tilt-rotor unmanned aerial vehicle (UAV), especially during the take-off and landing phase. The airspeed of UAV is so small during these phases that it cannot generate stable aerodynamic forces, which will significantly reduce the wind robustness of Tilt-rotor UAV. In this article, the disturbance of wind field is analyzed from two perspectives: the wind field acting on the UAV fuselage, which is regarded as external interference, and the wind acting on the propeller, which is considered as modeling error. After analyzing the interference mechanism of wind field, a generalized extended state observer (GESO) and a $H\infty $ robust control method with mixed sensitivity are proposed, which could empower the Tilt-rotor UAV with good interference suppression ability as well as better performance tracking ability. Finally, the laboratory simulation and flight experiment are studied. The results validate the theory and prove that the proposed method could resist the interference of wind field and shows excellent control effect.

Na última década, com o desenvolvimento contínuo de Drones ou Veículos Aéreos Não Tripulados (VANTs), uma grande variedade de modelos foi testada e criada, destacando dois tipos de Drones: multicópteros e asas fixas. Contudo, recentemente, tem havido uma demanda crescente por explorar a combinação entre esses dois tipos de veículos, levando aos modelos de decolagem e pouso vertical (Vertical Take Off and Landing - VTOL), que buscam produzir uma aeronave capaz de ter as características de estabilidade de um multicóptero no modo de voo pairado no ar (hover) e a velocidade e autonomia de voo elevada que uma asa fixa geralmente fornece no modo de voo cruzeiro (voo reto nivelado). Em contrapartida às vantagens do VTOL, o desafio com esta classe de aeronaves é que estas estão sujeitas a um alto grau de não-linearidade, próprio da mistura entre duas arquiteturas de aeronave diferentes. Adicionalmente, como todo veículo aéreo, devem ser capazes de lidar com perturbações atmosféricas no ar. O objetivo principal deste trabalho é o de propor uma nova arquitetura de VANT VTOL com topologia tricóptero. Esta aeronave conta com inclinação independente de rotores em conjunto com asas, vetorizando forças de propulsão e forças aerodinâmicas, com o objetivo de auxiliar no controle da aeronave, diminuir o impacto de downwash e aproveitar uma mesma estrutura de rotores para exercer movimento do veículo em várias direções. O veículo usa rotores-coaxiais para balancear o torque induzido entre os rotores para todo ângulo de inclinação dos mesmos e, adicionalmente, aumentar a força de tração. A modelagem dinâmica foi desenvolvida tomando como base as leis físicas que regem sobre os princípios propulsivos, aerodinâmicos e inerciais. Destacando especialmente o centro de gravidade (CG) móvel devido ao veículo se caracterizar por ser um sistema multi corpo, com capacidade de assumir uma morfologia não simétrica. O design da aeronave foi feito através do software de desenho 3D SolidWorks®, considerando componentes elétricos e mecânicos reais de forma a obter um modelo teórico da aeronave o mais próximo da realidade. O tensor de inércia do veículo foi validado através da comparação do tensor de inércia gerado pelo modelo matemático e o tensor de inércia gerado pelo SolidWorks®. Para a simulação, o modelo da aeronave foi linearizado nas condições de voo hover e cruzeiro e o controle da aeronave foi implementado através de uma estratégia de controle em cascata. Um controlador regulador linear quadrático com integração de estados (LQRI) foi utilizado para controlar as velocidades lineares e angulares da aeronave, enquanto que um controlador proporcional integral derivativo (PID) foi usado para controlar a posição e atitude da aeronave no espaço. A estratégia de controle adotada permitiu realizar o seguimento de trajetórias de forma satisfatória, mesmo na presença de perturbações atmosféricas. In the last decade, with the continuous development of Drones or Unmanned Aerial Vehicles (UAVs), a wide variety of models were tested and created, highlighting two types of Drones: multicopters and fixed wings. However, recently, there has been a growing demand to explore the “mixture” between these two types of vehicles. Leading to Vertical Take Off and Landing (VTOL) models, which seek to produce an aircraft capable of having the stability characteristics of a multicopter in hover flight mode, and the speed and high flight time that a fixed wing typically provides in cruise mode (straight level flight). In contrast to the advantages of VTOLs, the challenge with this class of aircraft is that they are subject to a high degree of non-linearity, typical of the mixture between two different aircraft architectures. Additionally, like all air vehicles, they must be able to deal with aerodynamic disturbances in the air. The main objective of this work is to propose a new UAV VTOL architecture with tricopter topology. This aircraft has independent rotor inclination together with wings, vectoring propulsion forces and aerodynamic forces, in order to help control the aircraft, reduce the downwash impact and take advantage of the same rotor structure to exert vehicle movement in several directions. The vehicle uses coaxial-rotors to balance the induced torque between the rotors for every tilting angle and, additionally, to increase the thrust force. The dynamic modeling was developed based on the physical laws that govern the propulsive, aerodynamic and inertial principles. Especially highlighting the mobile center of gravity (CG) due to the fact that the vehicle is characterized as a multi-body system, capable of assuming a non-symmetrical morphology. The aircraft design was made using SolidWorks® 3D design software, considering real electrical and mechanical components in order to obtain a theoretical model of the aircraft as close to reality. The vehicle's inertia tensor was validated by comparing the inertia tensor generated by the mathematical model and the inertia tensor generated by SolidWorks®. For the simulation, the aircraft model was linearized under the hover and cruise flight conditions and the aircraft control was implemented through a cascade control strategy. A state-integrated linear quadratic regulator controller (LQRI) was used to control the linear and angular velocities of the aircraft, while a proportional derivative integral controller (PID) was used to control the aircraft's position and attitude in space. The control strategy adopted allowed for the tracking of trajectories in a satisfactory manner, even in the presence of aerodynamic disturbances. Dissertação (Mestrado)

The design of efficient, environmentally friendly and quiet powerplant for rotorcraft architectures constitutes a key enabler for Urban Air Mobility application. This work focuses on the development and application of a generic methodology for the design, performance and environmental impact assessment of a parallel hybrid-electric propulsion system, utilizing simple and advanced recuperated engine cycles. A simulation framework for rotorcraft analysis comprising models for rotor aerodynamics, flight dynamics and hybrid-electric powerplant performance is deployed for the design exploration and optimization of a hybrid-electric rotorcraft, modelled after the NASA XV-15, adapted for civil applications. Optimally designed powerplants for payload-range capacity, energy efficiency and environmental impact have been obtained. A comparative evaluation has been performed for the optimum designs. The respective trade-offs between engine, heat exchanger weight, thermal efficiency, as well as mission fuel burn and environmental impact have been quantified. It has been demonstrated that a recuperated gas turbine based hybrid-electric architecture may provide improvements of up to 6% in mission range capability without sacrificing useful load. At the same time, analyses performed for a representative 100 km mission suggest reductions in fuel burn and NOX emissions of up to 12.9% and 5.2% respectively. Analyses are carried at aircraft and mission level using realistic UAM mission scenarios.

The increasing demands for air-taxi operations together with the ambitious targets for reduced environmental impact have driven significant interest in alternative rotorcraft architectures and propulsion systems. The design of hybrid-electric propulsion systems (HEPSs) for rotorcraft is seen as being able to contribute to those goals. This work aims to conduct a comprehensive design and tradeoff analysis of hybrid powerplants for rotorcraft, targeting enhanced payload-range capability and fuel economy. An integrated methodology for the design, performance assessment, and optimal implementation of HEPSs for conceptual rotorcraft has been developed. A multidisciplinary approach is devised comprising models for rotor aerodynamics, flight dynamics, HEPS performance, and weight estimation. All models are validated using experimental or flight test data. The methodology is deployed for the assessment of a hybrid-electric tilt-rotor, modeled after the NASA XV-15. This work targets to provide new insight into the preliminary design and sizing of optimally designed HEPSs for novel tilt-rotor aircraft. The paper demonstrates that at present, current battery energy densities (250 Wh/kg) severely limit the degree of hybridization if a fixed useful payload and range are to be achieved. However, it is also shown that if advancements in battery energy density to 500 Wh/kg are realized, a significant increase in the level of hybridization and hence reduction of fuel burned and carbon output relative to the conventional configuration can be attained. The methodology presented is flexible enough to be applied to alternative rotorcraft configurations and propulsion systems.

This paper presents the dynamic modelling and control technique for a tilt-rotor aerial vehicle operating in bi-rotor mode. This kind of aircraft combines two flight envelopes, making it ideal for scenarios that require hovering, vertical take-off/landing and fixed-wing capabilities. In this work, a detailed mathematical model is derived using Newton–Euler formalism. Based on the obtained model, a new control scheme that incorporates six Proportional-Derivative (PD) controllers is proposed for the attitudes (roll (φ), pitch (θ), yaw (ψ)) and the positions (x, y, z) of the aircraft. Then, intelligent Particle Swarm Optimization (PSO) and conventional Reference Model (RM) techniques are applied for optimal tuning of the controllers' parameters. The stability analysis is developed using the Lyapunov approach and its application to the tilt-rotor system in the case of intelligent and conventional PD controllers. Numerical results of two scenarios prove the efficiency of the controllers tuned using the PSO method. Indeed, its ability to track the desired trajectories is demonstrated through 3D path tracking simulations, even in the presence of wind disturbances. Finally, experimental tests of stabilization and trajectory tracking are carried out on our prototype. These testing showed that our tilt-rotor was stable and suitably follows the imposed trajectories.

[ES] El presente trabajo desarrolla mediante la herramienta UAV Toolbox de Mathworks, un entorno virtual completo que permite la simulación del comportamiento dinámico de una aeronave con propulsores eléctricos tilt-rotor. Este sistema de simulación permite realizar misiones autónomas, excluyendo las fases de descenso y aterrizaje, en una aeronave con una envolvente de vuelo dual que permite sacar provecho de las ventajas características de un multirrotor en despegue y de un aeroplano en vuelo horizontal. Para ello, la descripción de la dinámica no convencional de este tipo de aeronaves se lleva a cabo mediante el conjunto de ecuaciones diferenciales no lineales descritas en formato Simulink, realizando la hibridación de los dos modelos, el de despegue vertical y el de vuelo horizontal. Además, la definición de la misión se realiza a través de una estación de control terrestre que se comunica con Simulink. Todo esto, junto con la visualización de la aeronave mediante el simulador de vuelo Flight Gear, posibilita una simulación muy realista del comportamiento de la aeronave en entornos reales, [EN] This work develops, using the Mathworks UAV Toolbox, a complete virtual environment that allows the simulation of the dynamic behaviour of an aircraft with electric tilt-rotor propellers. This simulation system allows to perform autonomous missions, excluding the descent and landing phases, in an aircraft with a dual flight envelope that allows to take advantage of the characteristic advantages of a multi-rotor at takeoff and of an aeroplane in horizontal flight. For this purpose, the description of the non-conventional dynamics of this type of aircraft is carried out by means of a set of non-linear differential equations described in Simulink format, hybridising the two models, the vertical take-off and the horizontal flight model. In addition, the definition of the mission is carried out through a ground control station that communicates with Simulink. All this, together with the visualisation of the aircraft by means of the flight simulator Flight Gear, makes possible a very realistic simulation of the aircraft’s behaviour in real environments, [CA] Aquest treball desenvolupa mitjançant l’eina UAV Toolbox de Mathworks, un entorn virtual complet que permet la simulació del comportament dinàmic d’una aeronau amb propulsors elèctrics tilt-rotor. Aquest sistema de simulació permet realitzar missions autònomes, excloent-ne les fases de descens i aterratge, en una aeronau amb una envolupant de vol dual que permet treure profit dels avantatges característiques d’un multirrotor en enlairament i d’un aeroplà en vol horitzontal. Per fer-ho, la descripció de la dinàmica no convencional d’aquest tipus d’aeronaus es duu a terme mitjançant el conjunt d’equacions diferencials no lineals descrites en format Simulink, realitzant la hibridació dels dos models, el d’enlairament vertical i el de vol horitzontal. A més, la definició de la missió es fa a través d’una estació de control terrestre que es comunica amb Simulink. Tot això, juntament amb la visualització de l’aeronau mitjançant el simulador de vol Flight Gear, possibilita una simulació molt realista del comportament de l’aeronau en entorns reals

This paper introduces a novel gimballed rotor mathematical model for real-time flight simulation of tilt-rotor aircraft and other vertical take-off and landing (VTOL) concepts, which improves the previous version of a multi-purpose rotor mathematical model developed by ZHAW and Politecnico di Torino as part of a comprehensive flight simulation model of a tilt-rotor aircraft currently implemented in the Research and Didactics Simulator of ZHAW and used for research activities such as handling qualities studies and flight control systems development. In the novel model, a new formulation of the flapping dynamics is indroduced to account for the gimballed rotor and better suit current tilt-rotor designs (XV-15, V-22, AW-609). This paper describes the mathematical model and provides a generic formulation as well as a specific one for 3-blades proprotors. The method expresses the gimbal attitude but also considers the variation of each blade&rsquo, s flapping due to the elasticity of the blades, so that the rotor coning angle can be represented. A validation of the mathematical model is performed against the available literature on the XV-15 Tilt-rotor aircraft and a comparison between the previous model is provided to show the improvements achieved. The results show a good correlation between the model and the reference data and the registered performance allow real-time flight simulation with pilot and hardware in the loop.

A nonlinear unsteady aerodynamics model is coupled with a three degree of freedom quadplane to control the forward and backward transition between hover and steady level flight. The unsteady lift and drag forces are modeled using a lumped vortex model for flat plates. Two variants for the quadplane are considered: (i) a pusher and (ii) a tilt-rotor configuration in the absence of control surfaces to assess the controllability for altitude, attitude and forward speed. Conventional PID control is applied to generate the control inputs. The simulation results conclude that the pusher quadplane configuration is effortless to control as all the selected states are controllable, whereas for the tilt-rotor configuration, even though the vehicle is stable, altitude control is significantly more challenging due to one less control input when compared to the pusher configuration.

This paper presents a novel transition flight mathematical model of tilt-rotor unmanned aerial vehicles and demonstrates an application of a novel learning controller on the developed model. Instead of conventional steady aerodynamic models, an unsteady aerodynamic model capable of representing rapid changes in the air flow is developed for the tilt-rotor transition flight. The vehicle is controlled by a neuro-fuzzy learning controller, consisting of a type-2 fuzzy neural network and a proportional-derivative controller. Its results are compared with the results of proportional-integral-derivative controllers. It is evident from the results that the learning controller is capable of capturing the rapid changes in the aerodynamics and outperforms its nonlearning counterpart under perturbed conditions.

A mature Special Operations Forces (SOF) capability requires dedicated airpower, yet the Royal Canadian Air Force (RCAF) has not responded to the deepening relevance of Canadian Special Operations Forces Command (CANSOFCOM). This study qualitatively analyzes eight trends that Canada should address to optimize SOF airpower. The trends are: remote piloting; artificial intelligence and machine autonomy; processing, exploitation, and dissemination (PED); Intelligence, Surveillance, and Reconnaissance (ISR); SOF mobility; precision strike; Alternative Service Delivery; and fuel sources. From these trends, this study finds ten implications for Canada and like-minded nations: the enduring need for human involvement as only human influence achieves long-term success; human-machine teaming that fuses human discernment and machine learning; the concept of joint by design; the idea of modular by design; Alternative Service Delivery and roll-on/roll-off platforms; alternative fuel futures like high-altitude pseudo-satellites and the Airfield Surface Assessment and Reconnaissance capability; big data PED, including smart sensors and novel analytics; employment considerations for Manned ISR assets; tilt-rotor and the future of vertical lift; and the trade-offs between fifth-generation stealth fighters like the F-35 and the down-teched OA-X observation-attack aircraft. This study ultimately advocates for greater interoperability between CANSOFCOM and the RCAF. Both are stronger together. http://archive.org/details/lunionfaitlaforc1094559692 Outstanding Thesis Major, Canada Army Approved for public release; distribution is unlimited.

In order to calculate the unsteady aerodynamic characteristics of a tilt-rotor in a conversion mode, a virtual blade model (VBM) and an real blade model (RBM) are established respectively. A new multi-layer moving-embedded grid technique is proposed to reduce the numerical dissipation of the tilt-rotor wake in a conversion mode. In this method, a grid system generated abound the rotor accounts for rigid blade motions, and a new searching scheme named adaptive inverse map (AIM) is established to search corresponding donor elements in the present moving-embedded grid system to translate information among the different computational zones. A dual-time method is employed to fulfill unsteady calculations on the flowfield of the tilt-rotor, and a second-order centered difference scheme considering artificial viscosity is used to calculate the flux. In order to improve the computing efficiency, the single program multiple data (SPMD) model parallel acceleration technology is adopted, according to the characteristic of the current grid system. The lift and drag coefficients of an NACA0012 airfoil, the dynamic pressure distributions below a typical rotor plane, and the sectional pressure distributions on a three-bladed Branum–Tung tilt-rotor in hover flight are calculated respectively, and the present VBM and RBM are validated by comparing the calculated results with available experimental data. Then, unsteady aerodynamic forces and flowfields of an XV-15 tilt-rotor in different modes, such as a fixed conversion mode at different tilt angles (15°, 30°, 60°) and a whole conversion mode which converses from 0° to 90°, are numerically simulated by the VBM and RBM respectively. By analyses and comparisons on the simulated results of unsteady aerodynamic forces of the tilt-rotor in different modes, some meaningful conclusions about distorted blade-tip vortex distribution and unsteady aerodynamic force variation in a conversion mode are obtained, and these investigation results could provide a good foundation for tilt-rotor aircraft design in the future.

El presente trabajo pretende realizar el diseño teórico y la simulación numérica del sistema de potencia de una aeronave. Los datos de partida del sistema vienen limitados por su pertenencia a un proyecto de diseño global de una aeronave tilt-rotor llevada a cabo por un grupo de distintos departamentos de la Escuela Técnica Superior de Ingeniería de la Universidad de Sevilla. El procedimiento seguido para la realización de las diversas partes del trabajo sigue un orden lógico, primero se realizan cálculos teóricos básicos y los desarrollos necesarios para obtener los datos de partida que se introducen en la simulación numérica. Esta simulación numérica exige el modelado del sistema de potencia mediante el software Simulink®, parte del entorno de programación MatLab®. Obtenido el modelo, se pretende diseñar el control interno del sistema para hacer frente a las exigencias marcadas por las especificaciones que se espera que cumpla la aeronave. El conjunto del modelo permite realizar cambios en su configuración y poder seguir un proceso de optimización, mediante diversas pruebas y simulaciones, que permiten un ajuste de los distintos bloques del modelo. Es necesario destacar que estos bloques modelan subsistemas disponibles en el mercado mediante el uso de las especificaciones de producto que distintas empresas ofertan en sus catálogos actualmente. Se intenta no perder de vista el objetivo final del trabajo, servir como apoyo a una implementación real del sistema de producción de potencia de forma estable para una aeronave, lo que sirve para tomar diversas elecciones durante el estudio. In this project it is designed and numerically simulated the power train system of an aerial vehicle. It is part of a bigger project that is being developed by the Escuela Técnica Superior de Ingeniería, Universidad de Sevilla. This major project is about the construction of a tilt-rotor autonomous airplane. At first, it is calculated the basic theoretical data that are necessary for the numerical simulation. The data are added to a model software which shapes the power train system performance. This software is programmed with Simulink®, that is a part of Matlab® software package. It is designed the internal control of the power train system to make the airplane execute all performance specifications, using the theoretical initial data and the software model. The model is changed during the development of the project to optimize and set the parameters of the different Simulink blocks. It is necessary to emphasize that the blocks represent real subsystems on sale and the parameters are extracted from different companies data sheets. This project has to prove the viability of the real implementation of the power train system on the tilt-rotor airplane. This target is important to be remember on choice situations during the project. Universidad de Sevilla. Grado en Ingeniería Aeroespacial

This thesis studies some of the most relevant problems in the sense of guidance,navigation and control presented in a particular class of mini aerial vehicles (MAV) : the convertible MAV with fixed wings and tilting rotors. This aircraft is able to change its flight configuration from hover to level flight and vice-versaby means of a transition maneuver. Motivated by civilian applications, we theoretically and experimentally study Lyapunov-based control laws for dynamics presented in the convertible MAV. Results of asymptotic convergence are obtained over the complete flight envelope of the vehicle : from low-speed vertical flight through high-speed forward flight. We have divided this thesis in four main parts : the study of 1) the fixed-wingaircraft; 2) the quadrotor; 3) the convertible aircraft and 4) vision applications by using the convertible aircraft. In a first part, a Lyapunov-based controllaw is developed to steer a fixed wing mini aerial vehicle along a desired path. Furthermore a path generator is proposed. The resulting control strategy yields global convergence of the current path of the MAV to the desired path. In a second part, a Lyapunov-based control using singular perturbation theory is proposed and applied on dynamics of the MAV. Furthermore, in this part we address the problem of fault detection and diagnosis (FDD) for a quad-rotor. In the third part a new control strategy for the transition between airplane and helicopter mode, and vice versa, in convertible planes is presented. The analysis is carried out for the longitudinal model of the PVHAT (Planar VerticalHelicopter-Airplane Transition) aircraft, which is an airplane having tilting rotors in order to achieve the transition maneuver. The resulting closed loop control algorithm is proved to be globally asymptotically stable. Finally in thefourth part of this thesis the problem of estimation and tracking of a road using avision embedded system in the PVHAT aircraft is solved. The global exponential stability of the position subsystem together with the switching controller is demonstrated. Illustrative simulations and experimental results obtained on several experimental platforms developed in this thesis, assess the implementability of the proposed control laws and highlight the merits of the approach., Cette thèse étudie certains problèmes plus importants dans le sens de guidage, navigation et contrôle présentés dans une catégorie particulière de mini véhicules aériens (MVA) : le MVA convertible avec des ailes fixes et disques pendulaires. Cet aéronef est capable de changer sa configuration de vol, du vol stationnaire au vol palier et vice versa, au moyen d’une manœuvre de transition. Motivé par des applications civiles, on étudie théoriquement et expérimentalement les principes de contrôle en fonction de Lyapunov pour les dynamiques présentées dans le MVA convertible. Des résultats de convergence asymptotique sont obtenus sur l’enveloppe de vol complet du véhicule : d’un vol vertical à basse vitesse à un vol vers l’avant à grande vitesse. Cette thèse est divisée en quatre parties principales : l’étude de 1) les aéronefs à voilure fixe ; 2) le quadrirotor (avion équipe de quatre moteurs) ; 3) l’aéronef convertible ; 4) les applications de vision en utilisant l’aéronef convertible. Dans la première partie, un principe de contrôle en fonction de Lyapunov est développé pour diriger un mini véhicule aérien à voilure fixe tout au long d’un chemin d’accès souhaité. En outre, un générateur de chemin d’accès est proposé. Le résultant de la stratégie du contrôle donne une convergence globale du chemin actuel du MVA au chemin d’accès souhaité. Dans la deuxième partie, un contrôle en fonction de Lyapunov à l’aide de la théorie de la perturbation du singulier est proposé et appliqué sur la dynamique du MVA. En effet, dans cette partie on a abordé le problème diagnostic et la détection de pannes fault detection and diagnosis (FDD) pour un quadrirotor. Dans la troisième partie une nouvelle stratégie de contrôle pour effectuer la transition d’un avion convertible entre le mode avion et le mode hélicoptère, et vice versa, est présenté. L’analyse est effectuée pour le modèle longitudinal du PVHAT (Planar Vertical Helicopter-Airplane Transition) aéronef, lequel est un avion ayant disques pendulaires afin de réaliser la manœuvre de transition. L’algorithme de contrôle de boucle fermée qui en résulte, est prouvé être globalement asymptotiquement stable. Finalement, dans la quatrième partie de cette thèse, le problème de l’estimation et suivi d’un chemin à l’aide de vision système embarqué dans l’avion PVHAT est résolu. La stabilité globale exponentielle de la position sous-système ainsi que le contrôleur de commutation est démontrée. Des simulations illustratives et résultats expérimentaux sont obtenus sur plusieurs plateformes expérimentales développées dans cette thèse, pour évaluer l’applicabilité des principes contrôle proposés et mettre en valeur les mérites de l’approche.

International audience; A comparison of experimental data with several numerical predictions of the aerodynamic loads on the ERICA model is presented. The calculations are carried out by several Partners of the NICETRIP consortium, with different codes, turbulence models and grids, with the objective of validating the predictive capability of the CFD tools. Concerning the highly loaded minimum speed aircraft mode AC1, a large separation on the wings has been shown, both by experimental measurements and CFD simulations. Despite this large separation, a good agreement has been obtained between CFD simulations and wind tunnel measurements. Strong aerodynamic interactions between the 4/rev. blades passage and the tiltable wing, the nacelle and the fixed wing loads have been confirmed. Finally, we recommend increasing the aircraft speed flight and reducing the angle of attack for this configuration in order to avoid flow separation and reduce aircraft vibrations. In the highly loaded conversion mode CC4, a good agreement between CFD and experimental results has also been shown, in addition to 4/rev. loads fluctuations leading to aircraft vibrations.

Nessa dissertação são apresentadas estratégias de controle para solucionar o problema de transporte de carga suspensa ao longo de uma trajetória desejada por um Veículo Aéreo Não Tripulado (VANT) na configuração Tilt-rotor. Para o presente estudo, é importante que a aeronave seja capaz de manter tanto a si mesma quanto a carga transportada estável mesmo na presença de perturbações externas, incertezas paramétricas e erros de medição. Em geral, é importante que se tenha um modelo dinâmico preciso do sistema para que se possa projetar estratégias de controle avançadas para o mesmo. Dessa forma, um modelo dinâmico para o VANT Tilt-rotor com carga suspensa é rigorosamente derivado usando a formulação de Euler-Lagrange. Com o modelo obtido, é possível então projetar leis de controle que satisfaçam as especificações desejadas. Para tanto, leis de controle lineares e não lineares são projetadas. Para projetar leis de controle lineares, lineariza-se o sistema em torno do seu ponto de operação. Com o sistema linearizado, duas leis de controle são projetadas: uma por D-estabilidade e outra que leva em consideração D-estabilidade e a norma H simultaneamente. Já para o projeto do sistema de controle não linear, uma estratégia em cascata é proposta. Cada nível do sistema em cascata executa uma lei de controle através do método de linearização por realimentação de saída, sendo considerados três níveis. Cada um desses níveis controla um grupo diferente de variáveis do sistema até que a aeronave esteja estável por completo. Para essa estratégia, dois controladores para seguimento de trajetória são especificados. O primeiro controlador considera a carga apenas como uma perturbação e não atua para impedi-la de balançar, preocupando-se apenas com o seguimento de trajetória. O segundo controlador, por sua vez, busca encontrar um compromisso entre seguir a trajetória e reduzir o balanço da carga. Por fim, como prova de conceito, a estratégia não linear é modificada de forma a fazer com que a aeronave estabilize um pêndulo invertido. Para os projetos de controle descritos, considera-se que todas as medições físicas da aeronave são precisamente conhecidas em todos instantes de tempo. Entretanto, ´r sabido que toda medição física é sujeita a erros e imprecisões e nem sempre é possível obter alta frequência de amostragem ao medir alguma variável de processo. Portanto, parte desse trabalho é destinada ao estudo de incertezas em medições de posição da aeronave em uma situação na qual o controlador possua frequência de amostragem superior à frequência de amostragem do GPS. Diante desse problema, deve-se estimar a posição da aeronave enquanto não se tem novas medições levando em consideração que existem entradas de perturbação no sistema. Esse problema é solucionado usando o Filtro de Kalman com Entradas Desconhecidas. This dissertation presents control strategies to solve the problem of suspended load transportation by a Tilt-rotor Unmanned Air Vehicle (UAV) passing through a desired trajectory. For the present study, it is important for the aircraft to maintain itself and the load stable even in the presence of external disturbances, parametric uncertainties and measurement errors. In general, a precise dynamic model of a system is needed in order to design advanced control strategies to it. Therefore, a rigorous dynamic model is derived for the Tilt-rotor UAV with suspended load using Euler-Lagrange formulation. After obtaining the model, it is then possible to design control laws that satisfy the desired specifications. Consequently, linear and nonlinear control laws are designed. In order to design linear control laws, the system is linearized around its operation point. Two linear control laws are designed: one using D-stability control design and the second using simultaneous D-stability and minimization of the H1 norm. As for the nonlinear control design, a three-level cascade strategy is proposed. Each level of the cascade system executes a control law through the method of input-output feedback linearization. Each one of these levels controls a different group of the system's state variables until the aircraft becomes fully stable. Two path tracking controllers are specified for this strategy. The first considers the load only as a disturbance and does not actuate to avoid its swinging. The second controller, on the other hand, seeks to find a compromise between path tracking and reducing the load's swing. At last, as proof of concept, the nonlinear strategy is modified so that the aircraft is able to stabilize an inverted pendulum. For all the described control laws, it is considered that the physical measurements of the aircraft are precisely known in all time instants. However, every physical measure is subject to errors and uncertainties and one cannot always obtain a high sampling frequency when measuring process variables. Therefore, part of this work is dedicated to the study of uncertainties when measuring the position of the aircraft in a situation where the controller has a higher sampling frequency than the GPS. In face of this problem, the aircraft's position must be estimated while no new measurements are available taking also into the consideration the existence of disturbance inputs on the system. This whole problem is solved by using the Kalman Filter with Unknown Inputs.

Multi-rotor autonomous aerial vehicles have been proposed for several missions where the capability of controlled flight in small areas is required. Unfortunately, small-size electrically powered rotary wings UAVs have usually very short endurance, because of inherent limitation in battery energy density and constraints on maximum weight of the battery pack. At the same time, maneuverability can be improved by a variation of rotor thrust orientation. This paper presents a novel quad—rotor configuration where the use of a combustion engine and variable pitch propeller will allow for increasing endurance performance, whereas tilting of rotor disks improves maneuverability. A preliminary design of simple control laws is also discussed for this particular configuration, tested on a few basic maneuvers.

An inverse simulation algorithm is applied to the determination of the control laws for tracking desired maneuvers by means of an unconventional quad-rotor configuration. This novel configuration features four rotors that are allowed to tilt around the axis of the support, thus changing the thrust vector direction in order to achieve unprecedented maneuvering capabilities. The novel configuration is compared with a conventional quad-rotor, where control moments are generated by variations of rotor rotation rates. A 90 deg roll maneuver in forward flight is also presented, to highlight the increased maneuvering capabilities of the new configuration.

This paper presents the development and implementation of a single tilting rotor multirotor helicopter. A single tilting rotor multirotor helicopter is proposed that allows for decoupled lateral acceleration and attitude states. A dynamics model of the proposed multirotor helicopter is established to enable control system development. A control system architecture and daisy chaining-based control allocation scheme is developed and implemented. The control architecture facilitates the control of decoupled lateral accelerations and attitudes. Further, a computational and experimental analysis is undertaken and offers evidence that the proposed multirotor helicopter and control system architecture enables the multirotor helicopter to achieve lateral accelerations without requiring attitude actuation.

Pri stalnom povećanju male avijacije vrlo važnu ulogu odigrali su projekti razvoja. Oni su osigurali dodatna sredstva i poticaje koji su doveli do povećanja ovog segmenta zračnog prometa. Također, ti projekti su doveli do revolucionarnih otkrića u pogledu smanjenja buke, potrošnje goriva, emisije štetnih plinova te povećane sigurnosti, udobnosti te dostupnosti i mobilnosti. Mala avijacija će ispuniti praznine koje nastaju između redovnih letova tako da će omogućiti putovanje na zahtjev od točke do točke bez operativnih i geografskih ograničenja sa kojima se susreću veliki zrakoplovi. Zatim, omogućiti će bolju povezanost za zračnim lukama na koje zrakoplovne kompanije ne lete radi ekonomskih i operativnih ograničenja. Za razliku od Sjedinjenih država Europa nema jedinstven zračni prostor u kojem se odvija zrakoplovna navigacija na Europskoj razini. Europski zračni prostor je među prometnijima u svijetu i svakim danom će biti sve zagušeniji prometom, a prognoze sugeriraju udvostručenje prometa kroz slijedećih 15 godina. Većina sustava za zrakoplovnu navigaciju već sada radi s punim kapacitetom tako da su potrebna dodatna istraživanja i inovativne tehnologije koje će moći pratiti taj rast. U Europi ima oko 50.000 zrakoplova generalne i poslovne avijacije, uključujući i 2.800 turbinski pogonjenih. U usporedbi sa oko 5.000 koliko ih je u europskim komercijalnim flotama. Tome još treba dodati i 180-200 tisuća mikrolakih zrakoplova te letjelica bez pogona koje se koriste u sportske i rekreativne svrhe. Cilj diplomskog rada je istraživanje razvoja male avijacije odnosno generalne i poslovne avijacije kao segmenta zračnog prometa sa najbržim porastom te pratećih programa i projekata koji imaju za cilj vraćanje male avijacije na zavidnu poziciju koju je imala krajem 70-ih godina. Svrha ovoga istraživanja je usmjerena na stručne i znanstvene analize trenutnog stanja ovog segmenta zračnog prometa u Sjedinjenim državama i Europi te projekciju mogućnosti primjene u Republici Hrvatskoj. Tilt-rotori i microjetovi pojavili su se kao revolucionarno otkriće prijevoza budućnosti i već sada pišu novu povijest male avijacije.

U radu je opisana konceptualna konstrukcija i primjena zrakoplova koji imaju mogućnosti okomitog polijetanja i slijetanja. Izvršena je klasifikacija i kvalifikacija nakonvencionalnih zrakoplova.

There is currently little data available for trend analysis of tile-rotor performance. This study analyzed the sensitivity of predicted tile-rotor performance to variations in six design parameters: disk loading, tip speed, solidity, download, wing loading, and wing thickness ratio. Two mission profiles were analyzed: a combat search-and-rescue (CSAR) mission and an antisubmarine warfare (ASW) mission. A tilt-rotor preliminary design code (TR-87) was used to perform computer simulations; and data available from independent tests completed by NASA and the military were encoded in the input data disks. Results were presented as graphs of performance aspects plotted against the parameters varied. Because the study was a trend analysis, no specific conclusions were drawn; but a summary was made of the more significant results. It is hope that the results of this project can serve as a guide to preliminary selection of design parameters for tile-rotor configurations that would be suitable for a broad range of military and civil applications. http://archive.org/details/astudyofeffectof1094523413 Lieutenant, United States Navy Approved for public release; distribution is unlimited.

The advent of tilt rotor technology asks for rotors that have different twist and RPM requirements in hover and in forward flight to optimize for operational conditions. In order to get an assessment of the capabilities to fulfill these requirements this report presents a mapping of twist angle variation as a function of RPM and laminate orientation. The basic laminate for the six models as well the D-shape spar that represents the structurally active part of the blade is assumed to be constant (0°/90°/0°/90°/90°/0°) . This six layer cross ply laminate is chosen as it provides the necessary extension-twist coupling without a hygrothermally induced twist that is highly undesirable. The couplings and trends in the models are visualized in carpet plots, one for each model, in an attempt to establish a method to answer the basic question of the magnitude of twist angle available due to a particular geometry, material and load system. http://archive.org/details/anpproachfordesi1094525698 Major Aviador, Forca Aérea Brasileira Approved for public release; distribution is unlimited.

This paper introduces a tilt-rotor flight simulation platform for research and teaching purposes implementing a real-time simulation of the Bell XV-15 aircraft. The mathematical model of the XV-15 aircraft has been implemented including simplified models for the aerodynamics of the whole aircraft, rotors, and engine dynamics. Hence, the simulation is performed in a graphic environment to reproduce the simulated flight and to interact with it using commands given by the pilot. The simulation platform is implemented using MATLAB/Simulink®, while the input commands are set using USB peripherals, i.e., a flight stick and a pedal board. Instead, the visualization environment is performed using FlightGear, an open-source and cross-platform software that is widely used in research. The result is a portable tilt-rotor simulator to be executed on a commercial pc, while ensuring real-time performance. The tilt-rotor flight simulator is also validated by a licensed helicopter pilot returning positive feedback regarding the flight experience.

This paper aims at describing the effort performed by the joint research group of Politecnico di Torino and ZHAW (Zurich University of Applied Sciences) in achieving a novel implementation of a mathematical model for real-time flight simulation of tilt-rotors and tilt-wings aircraft. The focus is on the description of the current stage of the project, the achievements of the first version of the model, on-going improvements and future developments. The first part of the work describes the initial development of the overall simulation model: relying on several NASA reports on the Generic Tilt Rotor Simulator (GTRS), the mathematical model is revised and the rotor dynamic model is improved in order to enhance computational performance. In particular, the model uses the conventional mathematical formulation for non-dynamic inflow modelling based on Blade Element Momentum Theory. A novel but simple numerical method is used to ensure the convergence of the non-linear equation in every tested condition. The resulting simulation model and its development and implementation in the MATLAB/Simulink® environment is described. The second part of the work deals with the integration of the model in the ZHAW Research and Didactics Simulator (ReDSim), the replacement of the pilot controls by the introduction of a center stick and the corresponding adjustment of the force-feel system to suitable values for the tilt-rotor model. Subsequently, several pilot tests are carried out and preliminary feedbacks about the overall behaviour of the system are collected. Limits and weaknesses of the first release of the model are investigated and future necessary improvements are assessed, such as the development of a novel generic prop-rotor mathematical model. The third part introduces the novel multi-purpose rotor mathematical model which was developed to improve the overall tilt-rotor simulation model. The multi-purpose rotor model implements non-approximated flapping dynamics and inflow dynamic based on Pitt-Peters formulation. The validation of the nover rotor model is carried out with available data of both the XV-15 Research Aircraft and the UH-60 Helicopter.