This thesis is a study of modelling and control of a multirotor unmanned aerial vehicle(UAV). On behalf of Intuitive Aerial, a model of their hexarotor aircraft has been developedas a tool in further development and testing of their product. The potential of using ModelPredictive Control (MPC) as control method for multirotor UAV:s has also been evaluated.The model was successfully implemented in MATLAB/Simulink, as was the Model Predic-tive Controller. Quaternion angle representation has been used to avoid singularities in themodel and non-linear dynamics have been included in the simulation model. Unknownmodel parameters have been estimated with data acquired from testing. Model validity hasalso been evaluated with flight data gathered from flights using a test vehicle. A basic MPCformulation has been expanded to include reference tracking, integral action and to ensurestability.Assessment proved the model to be feasible but in need of more rigorous evaluation to guar-antee good performance. The MPC controller showed promising performance compared toa linear feedback controller.

This master's thesis has been on modeling, identification and control of a hexarotor system. It has been carried out on behalf of UAS Europe in Link\"{o}ping. A set of non-linear dynamic equations describing the motion of the hexarotor were derived. These equations were then implemented in Matlab/Simulink, which became a good simulation environment for further studies. A decentralized control system using P-PD controllers was successfully implemented in both simulation and on a hexarotor platform. The non-linear simulation model and the hexarotor platform were then identified using black box identification between virtual controls and angular rates. The result from identification of the hexarotor platform was not bad at all, but left some room for improvements. These linear models ware then used to tune the parameters of the inner PD controllers using a method called placement of dominant poles. This method worked well in simulation environment but unfortunately not as well on the real platform.

Made available in DSpace on 2014-12-17T14:55:11Z (GMT). No. of bitstreams: 1 ArmandoSS_TESE.pdf: 2110397 bytes, checksum: c6ade2a7219938325c34c1856e93d29f (MD5) Previous issue date: 2013-02-01 / In this Thesis, the development of the dynamic model of multirotor unmanned aerial vehicle with vertical takeoff and landing characteristics, considering input nonlinearities and a full state robust backstepping controller are presented. The dynamic model is expressed using the Newton-Euler laws, aiming to obtain a better mathematical representation of the mechanical system for system analysis and control design, not only when it is hovering, but also when it is taking-off, or landing, or flying to perform a task. The input nonlinearities are the deadzone and saturation, where the gravitational effect and the inherent physical constrains of the rotors are related and addressed. The experimental multirotor aerial vehicle is equipped with an inertial measurement unit and a sonar sensor, which appropriately provides measurements of attitude and altitude. A real-time attitude estimation scheme based on the extended Kalman filter using quaternions was developed. Then, for robustness analysis, sensors were modeled as the ideal value with addition of an unknown bias and unknown white noise. The bounded robust attitude/altitude controller were derived based on globally uniformly practically asymptotically stable for real systems, that remains globally uniformly asymptotically stable if and only if their solutions are globally uniformly bounded, dealing with convergence and stability into a ball of the state space with non-null radius, under some assumptions. The Lyapunov analysis technique was used to prove the stability of the closed-loop system, compute bounds on control gains and guaranteeing desired bounds on attitude dynamics tracking errors in the presence of measurement disturbances. The controller laws were tested in numerical simulations and in an experimental hexarotor, developed at the UFRN Robotics Laboratory / Nesta Tese, s?o apresentados os desenvolvimentos da modelagem din?mica de um ve?culo a?reo n?o tripulado multirrotor com capacidade de decolagem e pouso vertical, considerando as n?o linearidades de entrada e o desenvolvimento de um controlador robusto por backstepping. A formula??o do modelo din?mico ? expressa usando-se as leis de Newton-Euler, visando ? obten??o de uma melhor representa??o matem?tica do sistema mec?nico para a an?lise e projeto das leis de controle, n?o apenas quando est? pairando, como tamb?m de decolagem, de pouso, ou de voo executando uma tarefa. As n?o linearidades de entrada s?o a zona morta e a satura??o, onde o efeito gravitacional e as inerentes restri??es f?sicas dos rotores s?o relacionadas e abordadas. O microve?culo experimental est? equipado com uma unidade de medida inercial e um sonar, que devidamente instrumentada fornece as medidas da atitude e altitude. Foi desenvolvido um estimador em tempo real para atitude usando quat?rnios e baseado em filtro de Kalman estendido. Para a formula??o robusta do controlador, os sensores foram modelados como o valor real, que ? o valor ideal com a adi??o de um vi?s e mais um ru?do branco desconhecidos e limitados. Os controladores de atitude e altitude foram derivados usando-se o crit?rio globalmente uniformemente praticamente assintoticamente est?vel para sistemas reais, que permanece globalmente uniformemente assintoticamente est?vel se e somente se suas solu??es s?o globalmente uniformemente limitadas, lidando com a converg?ncia e estabilidade dentro de uma regi?o com raio n?o nula, levando em considera??o algumas suposi??es como as incertezas nas medi??es. A t?cnica de an?lise de Lyapunov foi usada para: provar a estabilidade do sistema em malha fechada; calcular os limites dos ganhos de controle, e, obter a garantia limitada pretendida sobre o erro de rastreamento da din?mica de atitude na presen?a de dist?rbios nas medi??oes. As leis de controle foram testadas em simula??es num?ricas e em um hexarrotor experimental, desenvolvido no Laborat?rio de Rob?tica da Universidade Federal do Rio Grande do Norte