Avaliação em Voo das Características de uma Asa de Envergadura Variável

O presente documento descreve o trabalho desenvolvido relativo à instrumentação e ensaios de voo de avaliação do desempenho aerodinâmico do veículo aéreo não tripulado (Unmanned Aerial Vehicle – UAV) desenvolvido no Departamento de Ciências Aeroespaciais (DCA) da Universidade da Beira Interior. Este UAV, denominado Olharapo, possui duas configurações diferentes: a primeira com uma asa convencional fixa instalada e outra com uma asa morphing de envergadura variável (VSW). Diversos sistemas de voo, tais como um sistema First Person View (FPV), um sistema de rádio controlo de longo alcance e um piloto automático, foram incorporados de forma a adquirir toda a informação essencial para a determinação da eficiência aerodinâmica de ambas as asas e para permitir o controlo e comunicações em tempo real. Para validar de forma segura a integração de todos estes sistemas, foi utilizado um aeromodelo denominado Skywalker. Após diversos testes de voo com este aeromodelo, verificou-se que todos os sistemas funcionaram da forma pretendida, permitindo assim a sua instalação no UAV Olharapo. Foram realizados diversos voos direcionados para a determinação do desempenho aerodinâmico, onde se obteve uma curva de eficiência aerodinâmica bem definida para o UAV com a asa convencional instalada. A razão de planeio máxima atingida com esta asa foi de 10 para uma velocidade correspondente de 15.4 m/s e coeficiente de sustentação (CL) de 0.71. Em relação à VSW, três configurações distintas de envergadura foram ensaiadas, sendo uma configuração de envergadura máxima de 2.5m, uma configuração intermédia de 2m e uma configuração de envergadura mínima de 1.5m. Apesar de não existir ainda informação suficiente que caracterize a curva de eficiência da VSW, duas principais zonas de pontos de eficiência foram observadas. Para a configuração de envergadura máxima, obteve-se uma razão de planeio de 8.5 a uma velocidade correspondente de 15 m/s e CL de 0.67. Em relação à configuração de envergadura intermédia, foi possível constatar que para baixos coeficientes de sustentação, a razão de planeio tendia para os mesmos valores obtidos para o UAV com a asa convencional instalada. Tal facto pode levar à conclusão que a determinado momento, a eficiência aerodinâmica da VSW possa ultrapassar a da asa convencional. De forma a caracterizar na sua plenitude a eficiência aerodinâmica do UAV com a VSW instalada, deverão ser realizados um maior número de ensaios de voo, particularmente com baixos coeficientes de sustentação.The present document describes the work developed regarding the instrumentation and flight testing, to evaluate the aerodynamic performance, of the Unmanned Aerial Vehicle (UAV) developed at the Department of Aerospace Sciences of University of Beira Interior. This UAV, called Olharapo, has two different configurations: one fitted with a conventional fixed wing and another with a variable span morphing wing (VSW). Several flight systems, such as a First Person View (FPV) system, a long range radio control system and an autopilot, were integrated and incorporated in order to acquire all the relevant data for aerodynamic efficiency determination of both wings and to allow real time control and communications. To safely validate the integration of all these systems, an off-the-shelf RC model called Skywalker was used. After several flight tests with this RC model, all the systems proved to work properly, allowing their installation on the Olharapo UAV. A series of flights aimed for aerodynamic performance determination were conducted where a curve of aerodynamic efficiency for the conventional fixed wing was obtained. For this wing, the maximum lift-to-drag ratio achieved was 10 for a corresponding airspeed of 15.4 m/s and lift coefficient (CL) of 0.71. Regarding the VSW, three different wingspan configurations were tested: a full wingspan configuration of 2.5m, an intermediate configuration of 2m, and a minimum wingspan configuration of 1.5m. Although there were not data that could completely characterize the efficiency curve for the VSW, two major clusters of efficiency points were observed. For the full wingspan configuration, a lift-to-drag ratio of 8.5 was obtained at a airspeed of 15.7 m/s and CL of 0.67. Concerning the intermediate wingspan configuration, it was possible to perceive that for low lift coefficients, the lift-to-drag ratio tends to the same values obtained for the UAV with the conventional wing. This may indicate that at a certain speed, the aerodynamic efficiency of the VSW can surpass that the conventional fixed wing. In order to fully characterize the UAV aerodynamic performance with the VSW, more flight tests should be conducted particularly at low lift coefficients

Aerial Forest Fire Detection and Monitoring Using a Small UAV

In recent years, large patches of forest have been destroyed by fires, bringing tragic consequences for the environment and small settlements established around these regions. In this context, it is essential that fire fighting teams possess an increased situational awareness about the fire propagation, in order to promptly act in the extinguishing process. Recent advances in UAV technology allied with remote sensing and computer vision techniques show very promising UAVs applicability in forest fires detection and monitoring. Besides presenting lower operational costs, these vehicles are able to reach regions that are inaccessible or considered too dangerous for fire fighting crews operations. This paper describes the application of a real-time forest fire detection algorithm using aerial images captured by a video camera onboard    an Unmanned Aerial Vehicle (UAV). The forest fire detection algorithm consists of a rule-based colour model that uses both RGB and YCbCr colour spaces to identify fire pixels. An intuitive targeting system was also developed, allowing the detection of multiple fires at the same time. Additionally, a fire geolocation algorithm was developed in order to estimate the fire location in terms of latitude (φ),  longitude     (λ) and altitude (h). The geolocation algorithm consists of applying two coordinates systems transformations between the body-fixed frame, North-East-Down frame (NED) and Earth-Centered, Earth Fixed (ECEF) frame. Flight tests were performed during  a controlled burn in order to assess the fire detection algorithm performance. The algorithm was able to detect the fire with few false positive detections. Keywords: Aerial fire detection algorithm, Aerial fire monitoring, Forest fire, UAV, Remote sensin