COCAP : a carbon dioxide analyser for small unmanned aircraft systems

Unmanned aircraft systems (UASs) could provide a cost-effective way to close gaps in the observation of the carbon cycle, provided that small yet accurate analysers are available. We have developed a COmpact Carbon dioxide analyser for Airborne Platforms (COCAP). The accuracy of COCAP's carbon dioxide (CO2) measurements is ensured by calibration in an environmental chamber, regular calibration in the field and by chemical drying of sampled air. In addition, the package contains a lightweight thermal stabilisation system that reduces the influence of ambient temperature changes on the CO2 sensor by 2 orders of magnitude. During validation of COCAP's CO2 measurements in simulated and real flights we found a measurement error of 1.2 mu mol mol(-1) or better with no indication of bias. COCAP is a self-contained package that has proven well suited for the operation on board small UASs. Besides carbon dioxide dry air mole fraction it also measures air temperature, humidity and pressure. We describe the measurement system and our calibration strategy in detail to support others in tapping the potential of UASs for atmospheric trace gas measurements.Peer reviewe

A case for a battery-aware model of drone energy consumption

The market of small drones has been recently increasing due to their use in many fields of application. The most popular drones are multirotors, in particular quadcopters. They are usually supplied with batteries of limited capacity, and for this reason their total flight time is also limited.As a consequence of the non linear characteristics of batteries, estimation of the real flight time may become an issue, since most battery models do not include all the non idealities. Consequently, applications such as delivery service, search and rescue, surveillance might not be accomplished correctly because of inaccurate energy estimations.This paper describes a battery-aware model for an accurate analysis of the drone energy consumption; this model is then applied to a scenario of drone delivery. Results show an accuracy greater of about 16% with respect to the traditional estimation model

Wetland Monitoring Using Unmanned Aerial Vehicles with Electrical Distributed Propulsion Systems

The inspection of wetlands in the Ecuadorian highlands has gained importance due to the environmental issues linked to the growth of human activities and the expansion of the agricultural and livestock frontiers. In this sense, unmanned aerial vehicles (UAVs) have been amply used in monitoring activities such as the supervision of threatened ecosystems, where cyclic measurements and high-resolution imagery are needed. However, the harsh operating conditions in the Andean highlands and sensitive ecosystem restrictions demand efficient propulsion configurations with low environmental impact. Electrical distributed propulsion (EDP) systems have surged as a forefront alternative since they offer benefits in both the propulsive and aerodynamic performance of fixed-wing UAVs. In this chapter, an EDP system is sized for a design point at the Andean operating conditions. Thereafter, two propulsion configurations were established based on off-the-shelf components, and their performance was characterized through analytical approaches. These results highlight the trends in power consumption and performance when the number of propulsors is increased. A significant contribution of this work is to exhibit important patterns in the performance of electric propulsion by using commercial components, and to set the operating limitations that can be further explored for analogous configurations in larger UAVs

Energy-efficient resource management for continuous scenario fulfillment by UAV fleets

Unbemannte Luftfahrzeuge (unmanned aerial vehicles, UAV) sind autonom fliegende und flexibel einsetzbare mobile Roboter, welche durch ihre große Flexibilität und Erweiterbarkeit viele Möglichkeiten bieten. Insbesondere im Bereich der Katastrophenbewältigung erlangen sie immer stärkere Bedeutung, da die Aufgaben zur Aufklärung im Gebiet und zur Erschaffung einer Kommunikationsinfrastruktur ungebunden und schnell durch sie bewältigt werden können. Der Forschungsschwerpunkt dieser Arbeit liegt in der Herausforderung der Ressourcenverwaltung in einem solchen Szenario. Während die Priorität des UAV Einsatzes klar darin besteht die Katastrophenbekämpfung unterbrechungsfrei zu unterstützten, muss ebenso auf die Verwaltung limitierter Ressourcen, wie elektrischer Energie, eingegangen werden. Wir präsentieren ein entsprechendes Systemdesign einer Ressourcenverwaltung und Strategien zur Verbesserung der Leistung und damit zur Erhöhung der Energieeffizienz des Gesamtsystems. Die Implementierung und gründliche Untersuchung eines solchen komplexen Systems von Teilsystemen ist verbunden mit hohen finanziellen Kosten, großem Test-Risiko und einer langen Entwicklungsdauer. Aus diesem Grund setzt diese Arbeit auf abstrakte ausführbare Modelle der Umgebung, des Verwaltungssystems und der UAVs. Die Verwendung dieser Modelle in einer Massensimulation mit beliebiger Komplexität und Konfiguration ermöglicht die schnelle und kostengünstige Verifikation der Funktionstüchtigkeit und die Bewertung verschiedener Verwaltungsstrategien. Im Vergleich zu der präsentierten trivialen Lösung ist die entwickelte verbesserte Lösung in der Lage den zeitlichen Anteil einzelner UAVs im Missionseinsatz zu erhöhen und die insgesamt nötige Menge an UAVs für die dauerhafte Abdeckung aller Aufgaben zu reduzieren. Die Schritte zur Optimierung reduzierten im analysierten Beispiel den Gesamtenergiebedarf aller UAVs um nahezu 20 Prozent.Unmanned aerial vehicles (UAV) are autonomous and flexible robotic systems with a remarkable degree of freedom and extendibility. They are especially valuable in the context of disaster scenarios, where arising use cases for reconnaissance and mobile communication infrastructure creation have to be addressed rapidly and unbound from restrictions in the operation field. The research focus of this thesis lies in the challenge of resource management during such an application. While the priority of the UAV utilization lies on uninterrupted task execution, concern for limited resources, like electrical energy, and resultant maintenance processes has to be dealt with on a lower management layer. We present a resource management system design and multiple competing strategies to improve its performance and overall energy efficiency. The implementation and thorough evaluation of such a complex system of systems is linked to high costs, great operational risks, and a long development time. For that reason, we developed executable models representing the environment, the resource management system, and the UAV. Through mass simulation of these models in various scenario constellations and configurations, we are able to verify the applicability of our proposed resource management system and to evaluate and optimize various aspects of its processes. In comparison to a presented trivial solution, we are able to increase the UAV flight utilization efficiency and decrease the needed amount of provided UAVs in the scenario. Our optimization efforts reduce the overall energy demand of UAVs in the analyzed example scenario by almost 20 percent

3D Active Metric-Semantic SLAM

In this letter, we address the problem of exploration and metric-semantic mapping of multi-floor GPS-denied indoor environments using Size Weight and Power (SWaP) constrained aerial robots. Most previous work in exploration assumes that robot localization is solved. However, neglecting the state uncertainty of the agent can ultimately lead to cascading errors both in the resulting map and in the state of the agent itself. Furthermore, actions that reduce localization errors may be at direct odds with the exploration task. We propose a framework that balances the efficiency of exploration with actions that reduce the state uncertainty of the agent. In particular, our algorithmic approach for active metric-semantic SLAM is built upon sparse information abstracted from raw problem data, to make it suitable for SWaP-constrained robots. Furthermore, we integrate this framework within a fully autonomous aerial robotic system that achieves autonomous exploration in cluttered, 3D environments. From extensive real-world experiments, we showed that by including Semantic Loop Closure (SLC), we can reduce the robot pose estimation errors by over 90% in translation and approximately 75% in yaw, and the uncertainties in pose estimates and semantic maps by over 70% and 65%, respectively. Although discussed in the context of indoor multi-floor exploration, our system can be used for various other applications, such as infrastructure inspection and precision agriculture where reliable GPS data may not be available.Comment: Submitted to RA-L for revie

Generalized software application for operation of a 3D vehicle in air, water and land

The unmanned vehicles (UV) and its applications are growing exponentially. Using the radio control is the most common way to control these types of vehicles for being a simple and cheap method to control an UV. However, it doesn’t have a visual interface that allows the user to see the vehicle’s information such as battery status, speed, distance, geolocation, etc. To deal with this problem, some mobile and desktop applications have been developed. To communicate between the control device and the vehicle, dongles are commonly used to establish the connection using radio, Bluetooth or Wi-Fi. In most cases, these technologies don’t allow the user to control at long distances, Beyond Line Of-Sight (BLOS), and these applications are focused to use mostly on multi-copters, and most of the times, they only allow to connect a vehicle at a time. The purpose of this dissertation is to study the reliability of an application able to control multiple types of vehicles, such as aerial, land and water vehicles. This application allows the user to connect multiple vehicles at the same time using a single device, easily change the vehicle assigned to control, by using mobile networks to perform the communication between the developed application and the vehicle. In this way, it will be possible to connect a 3D – hybrid vehicle, which is a vehicle capable of moving in water, land and air environments, allowing the user to control the vehicle at long distances with video feedback. To achieve the purpose of this dissertation, it was developed an Android application to allow controlling the vehicle by using mobile networks to communicate. In the vehicle, besides the common electronics used in an unmanned vehicle (ESC’s, motors, batteries, controller board, etc.), it will be used a Raspberry Pi 2 model B with a 3rd Generation (3G) and 4th Generation (4G) dongle that will connect the vehicle to the internet, routing the messages coming from the controller board placed in the vehicle to the mobile application. It was also developed a server application to do the user management and exchange the messages coming from both platforms: vehicle and application.Os veículos não tripulados e as suas aplicações estão em forte crescimento. O uso de rádio controlo é a maneira mais comum de controlar estes tipos de veículos, sendo o método mais barato e simples de controlar um veículo não tripulado. Contudo, não têm uma interface visual que permita ao utilizador ver as informações do veículo, tais como o nível da bateria, a velocidade, distância, geolocalização, entre outros. Para ajudar com este problema, têm sido desenvolvidas algumas aplicações para dispositivos móveis e computadores, que permitem controlar e monitorizar este tipo de veículos. Para estabelecer a comunicação entre o dispositivo de controlo e o veículo, são frequentemente usados dongles para comunicar por rádio, Bluetooth ou Wi-Fi. Na maioria dos casos, estas tecnologias não possibilitam ao utilizador o controlo a longas distâncias, para além da linha de vista, e costumam ser focadas para o uso em multicopteros, possibilitando, na maioria dos casos, a ligação de um único veículo. O âmbito desta dissertação pretende estudar e desenvolver uma aplicação com elevada fiabilidade, capaz de controlar vários tipos de veículos, nomeadamente, veículos aéreos, terrestres e aquáticos. Esta aplicação irá permitir a ligação a vários veículos ao mesmo tempo, trocar facilmente o veiculo a controlar, recorrendo aos sistemas de comunicação móveis celulares, 3ª geração (3G ) e 4ª geração (4G) para garantir a comunicação entre a aplicação desenvolvida e o veículo não tripulado. Seguindo estes princípios, é possível controlar um veículo 3D hibrido (em modo de ar, terra e mar). Esta permite ao utilizador controlar o veículo a longas distâncias com o uso de uma transmissão de vídeo. Para alcançar o objetivo desta dissertação foi desenvolvida uma aplicação Android para possibilitar o controlo recorrendo às redes móveis celulares. No veículo, além da eletrónica habitual, para um veículo não tripulado (motores, ESC’s, baterias, etc.), será também utilizado um Raspberry Pi 2 modelo B com um dongle 3G/4G que liga o veículo, redirecionando as mensagens vindas da placa de controlo para a aplicação móvel. Para a comunicação entre a aplicação e o veículo foi também desenvolvida uma aplicação instalada no servidor que é responsável pela gestão de utilizadores e pela troca de mensagens vindas de ambas as plataformas: veículo e aplicação

Measurement of atmospheric carbon dioxide abundance on board unmanned aircraft challenges and applications

In this dissertation the COmpact Carbon dioxide analyser for Airborne Platforms (COCAP) is presented. COCAP measures the abundance of carbon dioxide (CO2) in ambient air as well as air temperature, humidity and pressure, and is specifically designed for the use on board small unmanned aircraft systems (UASs). Accurate CO2 measurements are ensured by extensive calibration in an environmental chamber, by regular calibration in the field and by chemical drying of sampled air. In addition, the analyser is equipped with a custom-built, lightweight thermal stabilisation system that reduces the influence of ambient temperature changes on the CO2 sensor by two orders of magnitude. The robustness of COCAP under varying environmental conditions has been verified through a series of tests both in the lab and in the field. As a first application of the newly developed instrument, COCAP was used to constrain the nocturnal carbon dioxide emission of an ecosystem based on the nocturnal boundary layer (NBL) budget method. The NBL budgets were calculated from a series of CO2 profiles measured by COCAP on board a UAS during the course of two nights. The fluxes obtained in the pilot study are plausible and insensitive to experimental uncertainties. Given the versatility and moderate cost of UASs and their minimal infrastructure requirements, this innovative sampling technique makes the NBL budget method for the quantification of surface fluxes more accessible and cost-effective. This work demonstrates how the potential of UASs for measuring trace gases in theatmosphere can be exploited, thus opening up new possibilities for atmospheric research.In dieser Dissertation wird ein kompakter Kohlendioxidanalysator für Flugsysteme (COmpact Carbon dioxide analyser for Airborne Platforms, COCAP) vorgestellt. COCAP misst den Gehalt an Kohlendioxid (CO2), die Temperatur, die Feuchte und den Druck der Umgebungsluft und ist speziell für den Einsatz auf kleinen unbemannten Luftfahrtsystemen ausgelegt. Genaue Kohlendioxidmessungen werden durch umfangreiche Kalibrierungen in einer Klimakammer, regelmäßige Kalibrierungen während des Feldeinsatzes und durch chemische Trocknung der Probenluft sichergestellt. Darüber hinaus enthält das Messsystem einen speziell entwickelten Temperaturregler mit geringer Masse, der den störenden Einfluss äußerer Temperaturänderungen auf den CO2-Sensor um zwei Größenordnungen verringert. COCAPs Robustheit gegenüber wechselnden Umgebungsbedingungen wurde in einer Reihe von Tests im Labor und im Feld nachgewiesen. COCAPs erster wissenschaftliche Einsatz diente der Abschätzung nächtlicher Kohlendioxidflüsse mithilfe von Budgets der nächtlichen Grenzschicht (nocturnal boundary layer, NBL). Diese NBL-Budgets wurden aus CO2-Profilen errechnet, welche COCAP während einer Reihe von Flügen mit einem unbemannten Luftfahrtsystem im Verlauf zweier Nächte aufzeichnete. Die in dieser Pilotstudie ermittelten Flüsse sind plausibel und robust gegenüber experimentellen Unsicherheiten. Angesichts der Vielseitigkeit und der moderaten Kosten unbemannter Luftfahrtsysteme sowie ihrer minimalen Ansprüche an die Infrastruktur im Feld eröffnet diese innovative Messstrategie eine vergleichsweise einfache und günstige Möglichkeit, Flüsse durch NBL-Budgets zu bestimmen. Diese Arbeit zeigt auf, wie das Potenzial unbemannter Luftfahrtsysteme für Spurengasmessungen genutzt werden kann, wodurch sich neue Perspektiven für die Atmosphärenforschung ergeben