The last decade has seen significant advances in the development of Vertical takeoff and landing (VTOL) unmanned aerial vehicles (UAVs). The emergence of enabling technologies, in addition to the practical usefulness of such systems has driven their development to a point where numerous technology demonstrators and commercial products are now in existence. Of particular interest has been the development of small scale, VTOL UAVs commonly referred to as mini and micro-VTOL UAVs. The versatility and agility of such vehicles offers great potential for the use in clustered, urban environments. Despite recent advancements, the autonomous navigation of VTOL UAVs remains a very challenging research area. The dynamics of VTOL UAVs are heavily nonlinear, underactuated and non-minimum phase. This, coupled with the aggressive maneuvers that such vehicles are expected to execute provides a stimulating problem in dynamic control. This is particularly true in the case of micro-VTOL UAVs. The fast, nonlinear nature of these systems render classical, linear control approaches inadequate. The past twenty years has seen great interest in the development of nonlinear control strategies. This has led to the emergence of a number of standard design tools, most notably feedback linearisation and Lyapunov-based, backstepping approaches. Such design techniques offer a framework for the derivation of model based control laws capable of achieving global stabilisation and trajectory tracking control for heavily nonlinear systems. Recently, there has been significant interest in the application of such nonlinear control paradigms for the stabilisation and control of VTOL UAVs. The aim of this thesis is to further the application and analysis of nonlinear control design techniques for the control of VTOL UAVs. In particular, focus is placed on Lyapunov-based, backstepping-type control approaches. The first half of this thesis investigates Lyapunov-based control strategies that cast the closed-loop VTOL dynamics into a globally stable, cascade structure. This work was directly inspired by, and builds on, a variety of previously published works. Firstly, an alternative design approach to that previously published is presented, resulting in an improved closed-loop dynamic structure. Although inspired by the VTOL system, this idea may be generalised for the control of a broad class of systems, and is presented as such. A singularity issue arising in the cascade control of VTOL vehicles is then investigated, and a novel approach to overcome this issue is formulated. The second half of this thesis is dedicated to the trajectory tracking control of VTOL UAVs at velocities where the influence of aerodynamics is significant. In general, the aerodynamic models of VTOL UAVs are heavily nonlinear and poorly known. The use of such models in a backstepping framework that uses explicit differentiation of these models for dynamic inversion is questioned, due to the potential sensitivity of such nonlinear models. Consequently, an alternative approach utilising coupled filters to avoid such sensitivity issues is proposed. All control designs formulated in this thesis are accompanied by proofs guaranteeing their global stability, and numerical simulations demonstrating their time domain response characteristics. / http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1298413 / Thesis (Ph.D.) -- University of Adelaide, School of Mechanical Engineering, 2007

<p>The market for vertical takeoff and landing unmanned aerial vehicles, VTOL UAVs, is growing rapidly. To reciprocate the demand of VTOL UAVs in offshore applications, CybAero has developed a novel concept for landing on moving objects called MALLS, Mobile Automatic Launch and Landing Station. MALLS can tilt its helipad and is supposed to align to either the horizontal plane with an operator adjusted offset or to the helicopter skids. Doing so, eliminates the gyroscopic forces otherwise induced in the rotordisc as the helicopter is forced to change attitude when the skids align to the ground during landing or when standing on a jolting boat with the rotor spun up. This master’s thesis project is an attempt to get the concept of MALLS closer to a quarter scale implementation. The main focus lies on the development of the measurement methods for achieving the references needed by MALLS, the hori- zontal plane and the plane of the helicopter skids. The control of MALLS is also discussed. The measurement methods developed have been proved by tested implementations or simulations. The theories behind them contain among other things signal filtering, Kalman filtering, sensor fusion and search algorithms. The project have led to that the MALLS prototype can align its helipad to the horizontal plane and that a method for measuring the relative attitude between the helipad and the helicopter skids have been developed. Also suggestions for future improvements are presented.</p>

The market for vertical takeoff and landing unmanned aerial vehicles, VTOL UAVs, is growing rapidly. To reciprocate the demand of VTOL UAVs in offshore applications, CybAero has developed a novel concept for landing on moving objects called MALLS, Mobile Automatic Launch and Landing Station. MALLS can tilt its helipad and is supposed to align to either the horizontal plane with an operator adjusted offset or to the helicopter skids. Doing so, eliminates the gyroscopic forces otherwise induced in the rotordisc as the helicopter is forced to change attitude when the skids align to the ground during landing or when standing on a jolting boat with the rotor spun up. This master’s thesis project is an attempt to get the concept of MALLS closer to a quarter scale implementation. The main focus lies on the development of the measurement methods for achieving the references needed by MALLS, the hori- zontal plane and the plane of the helicopter skids. The control of MALLS is also discussed. The measurement methods developed have been proved by tested implementations or simulations. The theories behind them contain among other things signal filtering, Kalman filtering, sensor fusion and search algorithms. The project have led to that the MALLS prototype can align its helipad to the horizontal plane and that a method for measuring the relative attitude between the helipad and the helicopter skids have been developed. Also suggestions for future improvements are presented.

The Diploma thesis is concerned with aerodynamic designi of the ducted fan. The aim of this thesis is to compile the metod of the calculation for the effect of ducted fan. The thesis includes the statistical analysis of compare Rotorcraft, which is used to support the proposal of the basic design parameters. The next part of the thesis contains practical utilization, view of the possible pay load, view of the suitable engines and conrol units. The main part is concerned whit aerodynamic calculation of the stream and fan parameters. In the last part of the thesis, basic parameters of flight performances are calculated.

Esta dissertação apresenta o desenvolvimento da teoria de dinâmica de voo e o conceito de controle a ser aplicado na modelagem e simulação de voo de um VANT com decolagem e pouso vertical proposto. Um conceito de aeronave de asa semi-tandem é projetado e os coeficientes aerodinâmicos, propriedades inerciais e parâmetros de controle são estimados, o que permitiu a implementação da teoria proposta. O modelo fez uso das equações de movimento multi-corpos onde a aeronave é dividida em partes de forma que a asa, o estabilizador horizontal e os rotores sejam entidades independentes. Além disso, o sucesso da fase de transição de voo pairado para cruzeiro e de cruzeiro para voo pairado pode ser verificado se houver a possibilidade da aeronave trimar ao longo do regime de velocidades de voo, em outras palavras, se houver uma combinação de estados de movimento que mantenha a aeronave estável do voo pairado para a condição de cruzeiro. Assim, as curvas de trimagem que expressam os estados são calculadas usando a minimização de uma função de custo envolvendo a soma dos quadrados de alguns dos estados de movimento, definidos pelas equações de movimento mencionadas anteriormente. Tal minimização é realizada usando o algoritmo Simplex Sequencial. Além disso, é apresentada uma estratégia de controle que estabiliza a aeronave durante a transição de voo pairado para configuração de cruzeiro, que é testada em simulação computacional de um voo longitudinal acelerado e desacelerado, ou seja, de voo pairado para cruzeiro e de cruzeiro para voo pairado. Finalmente, um protótipo da aeronave estudada é apresentado. / This thesis presents the development of the flight dynamics theory and control concept to be applied in the modeling and flight simulation of a proposed VTOL UAV. A semi-tandem wing aircraft concept is designed and the aerodynamic coefficients, inertial properties and controls parameters are estimated, which allowed the implementation of the proposed theory. The model made use of the multi-body equations of motion where the aircraft is divided in parts so that the wing, horizontal stabilizer and rotors are independent entities. Additionally, the success of the transition phase from hovering to cruise and from cruise to hovering can be verified if there is the possibility of the aircraft to trim along the flight speed regime, in other words, if there is a combination of states of motion that keep the aircraft stable from hover to cruise condition. So, the trim curves expressing the states are computed using the minimization of a cost function involving the sum of the squares of some of the states of motion, defined through the equations of motion previously mentioned. Such minimization is performed using the Sequential Simplex algorithm. Moreover, a control strategy that stabilizes the aircraft while it transitions from hovering to cruise configuration is presented, which is tested in computer simulation of an accelerated and decelerated longitudinal flight, that is, from hovering to cruise condition, and from cruise to hovering condition. Finally, a prototype of the aircraft studied is presented.

Esta dissertação apresenta o desenvolvimento da teoria de dinâmica de voo e o conceito de controle a ser aplicado na modelagem e simulação de voo de um VANT com decolagem e pouso vertical proposto. Um conceito de aeronave de asa semi-tandem é projetado e os coeficientes aerodinâmicos, propriedades inerciais e parâmetros de controle são estimados, o que permitiu a implementação da teoria proposta. O modelo fez uso das equações de movimento multi-corpos onde a aeronave é dividida em partes de forma que a asa, o estabilizador horizontal e os rotores sejam entidades independentes. Além disso, o sucesso da fase de transição de voo pairado para cruzeiro e de cruzeiro para voo pairado pode ser verificado se houver a possibilidade da aeronave trimar ao longo do regime de velocidades de voo, em outras palavras, se houver uma combinação de estados de movimento que mantenha a aeronave estável do voo pairado para a condição de cruzeiro. Assim, as curvas de trimagem que expressam os estados são calculadas usando a minimização de uma função de custo envolvendo a soma dos quadrados de alguns dos estados de movimento, definidos pelas equações de movimento mencionadas anteriormente. Tal minimização é realizada usando o algoritmo Simplex Sequencial. Além disso, é apresentada uma estratégia de controle que estabiliza a aeronave durante a transição de voo pairado para configuração de cruzeiro, que é testada em simulação computacional de um voo longitudinal acelerado e desacelerado, ou seja, de voo pairado para cruzeiro e de cruzeiro para voo pairado. Finalmente, um protótipo da aeronave estudada é apresentado. / This thesis presents the development of the flight dynamics theory and control concept to be applied in the modeling and flight simulation of a proposed VTOL UAV. A semi-tandem wing aircraft concept is designed and the aerodynamic coefficients, inertial properties and controls parameters are estimated, which allowed the implementation of the proposed theory. The model made use of the multi-body equations of motion where the aircraft is divided in parts so that the wing, horizontal stabilizer and rotors are independent entities. Additionally, the success of the transition phase from hovering to cruise and from cruise to hovering can be verified if there is the possibility of the aircraft to trim along the flight speed regime, in other words, if there is a combination of states of motion that keep the aircraft stable from hover to cruise condition. So, the trim curves expressing the states are computed using the minimization of a cost function involving the sum of the squares of some of the states of motion, defined through the equations of motion previously mentioned. Such minimization is performed using the Sequential Simplex algorithm. Moreover, a control strategy that stabilizes the aircraft while it transitions from hovering to cruise configuration is presented, which is tested in computer simulation of an accelerated and decelerated longitudinal flight, that is, from hovering to cruise condition, and from cruise to hovering condition. Finally, a prototype of the aircraft studied is presented.