Unmanned Aerial Systems for Wildland and Forest Fires

Wildfires represent an important natural risk causing economic losses, human death and important environmental damage. In recent years, we witness an increase in fire intensity and frequency. Research has been conducted towards the development of dedicated solutions for wildland and forest fire assistance and fighting. Systems were proposed for the remote detection and tracking of fires. These systems have shown improvements in the area of efficient data collection and fire characterization within small scale environments. However, wildfires cover large areas making some of the proposed ground-based systems unsuitable for optimal coverage. To tackle this limitation, Unmanned Aerial Systems (UAS) were proposed. UAS have proven to be useful due to their maneuverability, allowing for the implementation of remote sensing, allocation strategies and task planning. They can provide a low-cost alternative for the prevention, detection and real-time support of firefighting. In this paper we review previous work related to the use of UAS in wildfires. Onboard sensor instruments, fire perception algorithms and coordination strategies are considered. In addition, we present some of the recent frameworks proposing the use of both aerial vehicles and Unmanned Ground Vehicles (UV) for a more efficient wildland firefighting strategy at a larger scale.Comment: A recent published version of this paper is available at: https://doi.org/10.3390/drones501001

Smokey comes of age: unmanned aerial systems for fire management

During the past century, fire management has focused on techniques both to protect human communities from catastrophic wildfire and to maintain fire-dependent ecological systems. However, despite a large and increasing allocation of resources and personnel to achieve these goals, fire management objectives at regional to global scales are not being met. Current fire management techniques are clearly inadequate for the challenges faced by fire managers, and technological innovations are needed. Advances in unmanned aerial systems (UAS) technology provide opportunities for innovation in fire management and science. In many countries, fire management organizations are beginning to explore the potential of UAS for monitoring fires. We have taken the next step and developed a prototype that can precisely ignite fires as part of wildfire suppression tactics or prescribed fires (fire intentionally ignited within predetermined conditions to reduce hazardous fuels, improve habitat, or mitigate for large wildfires). We discuss the potential for these technologies to benefit fire management activities, while acknowledging the sizeable sociopolitical barriers that prevent their immediate broad application

Coordinated Control of UAVs for Human-Centered Active Sensing of Wildfires

Fighting wildfires is a precarious task, imperiling the lives of engaging firefighters and those who reside in the fire's path. Firefighters need online and dynamic observation of the firefront to anticipate a wildfire's unknown characteristics, such as size, scale, and propagation velocity, and to plan accordingly. In this paper, we propose a distributed control framework to coordinate a team of unmanned aerial vehicles (UAVs) for a human-centered active sensing of wildfires. We develop a dual-criterion objective function based on Kalman uncertainty residual propagation and weighted multi-agent consensus protocol, which enables the UAVs to actively infer the wildfire dynamics and parameters, track and monitor the fire transition, and safely manage human firefighters on the ground using acquired information. We evaluate our approach relative to prior work, showing significant improvements by reducing the environment's cumulative uncertainty residual by more than $10^2$ and $10^5$ times in firefront coverage performance to support human-robot teaming for firefighting. We also demonstrate our method on physical robots in a mock firefighting exercise

Aerial Drone-based System for Wildfire Monitoring and Suppression

Wildfire, also known as forest fire or bushfire, being an uncontrolled fire crossing an area of combustible vegetation, has become an inherent natural feature of the landscape in many regions of the world. From local to global scales, wildfire has caused substantial social, economic and environmental consequences. Given the hazardous nature of wildfire, developing automated and safe means to monitor and fight the wildfire is of special interest. Unmanned aerial vehicles (UAVs), equipped with appropriate sensors and fire retardants, are available to remotely monitor and fight the area undergoing wildfires, thus helping fire brigades in mitigating the influence of wildfires. This thesis is dedicated to utilizing UAVs to provide automated surveillance, tracking and fire suppression services on an active wildfire event. Considering the requirement of collecting the latest information of a region prone to wildfires, we presented a strategy to deploy the estimated minimum number of UAVs over the target space with nonuniform importance, such that they can persistently monitor the target space to provide a complete area coverage whilst keeping a desired frequency of visits to areas of interest within a predefined time period. Considering the existence of occlusions on partial segments of the sensed wildfire boundary, we processed both contour and flame surface features of wildfires with a proposed numerical algorithm to quickly estimate the occluded wildfire boundary. To provide real-time situational awareness of the propagated wildfire boundary, according to the prior knowledge of the whole wildfire boundary is available or not, we used the principle of vector field to design a model-based guidance law and a model-free guidance law. The former is derived from the radial basis function approximated wildfire boundary while the later is based on the distance between the UAV and the sensed wildfire boundary. Both vector field based guidance laws can drive the UAV to converge to and patrol along the dynamic wildfire boundary. To effectively mitigate the impacts of wildfires, we analyzed the advancement based activeness of the wildfire boundary with a signal prominence based algorithm, and designed a preferential firefighting strategy to guide the UAV to suppress fires along the highly active segments of the wildfire boundary

Trajectory and aerodynamic analyses of air launched fire-extinguishing projectiles

Wildfires are a devastating source of human and environmental loss, and the available means to combat them in their early stages can be improved. With the aid of Unmanned Aerial Systems and FEB (Fire-extinguishing balls), wildfires’ early stages might be suppressed while keeping human lives safe and firefighters risk-free. Considering the use of a fixed wing Unmanned Aircraft Vehicle to launch the fire-extinguishing projectile, launching the FEB as it is, without any modification, does not seem to be the best available option, with problems ranging from difficulty in predicting its trajectory to the possible bad impact performance, with the possibility of the FEB rolling away from the target as it lands. Therefore, three other configurations for the projectile with FEB as its basis were studied, all of them utilizing fins for the means of stability. These configurations differed in terms of tail design attached to the FEB: one is a tube, the other a tangential cone, and the other a symmetrical NACA airfoil revolved around its axis. Their aerodynamic static coefficients were obtained through CFD (computational fluid dynamics), while the dynamic ones were obtained through analytical expressions. Using an implemented 6-DOF (degrees of freedom) model, 17 trajectories were studied for each of these configurations. Other analyses were carried out, as the consideration of the influence of wind turbulence, consideration of a fourth configuration with double the area of the fins, and asserting the importance of the consideration of the dynamic coefficients while testing different values for some of these coefficients. Regarding the FEB-projectile configurations, CFD results suggest that the tube configuration has a transient behavior in the tested speeds, and that the tangential cone is a very suitable way of streamlining the FEB in these range of speeds, with no considerable difference to the NACA tail configuration. Trajectory results highlight the importance of considering the mean wind speed and direction, the importance of obtaining an appropriate estimate of the wind turbulence, and the importance of the dynamic coefficients for the full aerodynamic characterization of the projectile, concretely for its stability and attitude results. Ultimately, between the tested configurations, the best candidate is the cone tail configuration, for its simplicity in construction and performance in the trajectories.Os incêndios florestais são uma fonte devastadora de custos humanos e ambientais, e os meios disponíveis para combater as suas fases iniciais poderão ser melhoradas. Com o auxílio de sistemas de aeronaves não-tripuladas e de FEB (bolas extintoras), os incêndios florestais poderão ser extintos nas suas fases iniciais, mantendo vidas humanas livres de risco. Considerando o uso de uma aeronave não tripulada de asa fixa para lançar o projétilextintor, lançar a bola extintora tal como é não aparenta ser a melhor opção, sendo alguns dos problemas relacionados com o seu lançamento a dificuldade em prever a sua trajetória e um possível mau desempenho no impacto, com a possibilidade da bola rolar para longe do seu alvo. Assim, três configurações para o projétil extintor que tem a FEB como base foram estudados, todos eles utilizando empenagens como forma de estabilização. As configurações diferem em termos da cauda acoplada à FEB: uma delas é um tubo, outra um cone tangencial, e outra um perfil NACA simétrico girado em torno do seu eixo. Os coeficientes aerodinâmicos estáticos foram obtidos através de CFD (dinâmica de fluidos computacional), enquanto que os dinâmicos foram obtidos por expressões analíticas. Implementando um modelo de trajetória 6-DOF (6 graus de liberdade) 17 trajetórias foram estudadas para cada uma das configurações. Outras análises foram realizadas, como a relevância na trajetória da turbulência do vento, a consideração de uma quarta configuração com o dobro da área das empenagens, e a determinação da importância dos coeficientes dinâmicos, testando vários valores para alguns dos coeficientes. Em relação às configurações do projétil testadas, os resultados CFD sugerem que a configuração com o tubo possui um comportamento transiente nas velocidades testadas, e que o cone tangencial é uma forma bastante eficaz de tornar a esfera mais aerodinâmica, nesta gama de velocidades não havendo uma diferença considerável entre esta configuração e a configuração com a cauda NACA. Os resultados das trajetórias destacam a importância da consideração da velocidade e orientação do vento médio, a importância de obter uma estimativa apropriada para a turbulência do vento, e a relevância dos coeficientes dinâmicos para a caracterização aerodinâmica completa do projétil, concretamente em relação à estabilização e atitude. Entre as configurações testadas, o melhor candidato é a configuração com cauda em cone, pela sua simplicidade de construção e desempenho nas trajetórias