Continuum Deformation of a Multiple Quadcopter Payload Delivery Team without Inter-Agent Communication

This paper proposes continuum deformation as a strategy for controlling the collective motion of a multiple quadcopter system (MQS) carrying a common payload. Continuum deformation allows expansion and contraction of inter-agent distances in a 2D motion plane to follow desired motions of three team leaders. The remaining quadcopter followers establish the desired continuum deformation only by knowing leaders positions at desired sample time waypoints without the need for inter-agent communication over the intermediate intervals. Each quadcopter applies a linear-quadratic-Gaussian (LQG) controller to track the desired trajectory given by the continuum deformation in the presence of disturbance and measurement noise. Results of simulated cooperative aerial payload transport in the presence of uncertainty illustrate the application of continuum deformation for coordinated transport through a narrow channel

Automatisierte Unkrauterkennung auf dem Acker – Möglichkeiten und Grenzen

Unbemannte Fluggeräte, unmanned aerial vehicles (UAV), sind inzwischen allgegenwärtig genutzte Werkzeuge, um hochauflösende räumliche Informationen landwirtschaftlicher Kulturflächen zu generieren. Ihr Einsatz zur Vegetations-Naherkundung eröffnet dabei eine Reihe an Möglichkeiten, die im Bereich des teilflächenspezifischen Pflanzenschutzes künftig eine wesentliche Rolle spielen werden. In einer zunehmend präzisierten Landwirtschaft steigt zudem das Interesse an innovativen Technologien und es ist erkennbar, dass sich der Fokus von der landwirtschaftlichen Forschung allmählich in die praktische Anwendung verschiebt. Dies erfordert eine rasche und intensive Beurteilung von Möglichkeiten und Grenzen von UAV-gestützten Verfahren.Während spektral auflösende Sensoren an UAV zur Kartierung des Nährstoff- oder Wasserbedarfs einer Kultur pro Flächeneinheit bereits eingesetzt werden, ist die bildgebende Erkennung von Unkräutern aus der Luft ungleich komplexer und daher bisher nicht praxisrelevant. Zum einen sind die spektralen Unterschiede zwischen Unkräutern und Kulturpflanzen zu gering für eine sichere Unterscheidung und objektbasierte Ansätze separieren Pflanzen bisher weder artspezifisch noch sind sie ausreichend an morphologische Veränderungen innerhalb der Entwicklungsstadien angepasst. Zum anderen fehlen verlässliche Lösungen für eine stabile Kleinraumnavigation, wie sie für eine optisch hinreichende Abbildungsleistung in konstanter niedriger Flughöhe bei unterschiedlichen Geländeprofilen erforderlich ist.Zur Abschätzung der Möglichkeiten und Grenzen einer automatisierten Unkrauterkennung, hinsichtlich der notwendigen Abbildungsleistung als Voraussetzung für eine automatisierte Unkrauterkennung, erfolgten Messflüge mit einem Hexakopter in 5 m Flughöhe über unterschiedlich verunkrauteten Ackerflächen. Die Flughöhe wurde mittels GPS-gesteuerten Autopiloten gehalten. Luftbildaufnahmen erfolgten über georeferenzierten Punkten an denen zeitgleich manuell bonitiert wurde. Die erforderliche optische Auflösung am Boden (mm/Pixel) wurde durch manuelle Auszählung der Unkräuter am PC und Vergleich mit den Boniturdaten abgeschätzt. Automated weed detection in the field - possibilities and limitsUnmanned Aerial Vehicles (UAV) have become omnipresent and adequate tools to generate high-resolution spatial data of agricultural cropland. Their implementation into remote sensing approaches of weeds provides suitable applications for a site-specific herbicide management. In general, an increasingly use of innovative technologies gradually leads from agricultural research into the practical application. This requires an evaluation of possibilities and limits of UAV-based remote sensing procedures.While spectrals from UAVs are being used already for mapping needs of nutrient or water, the image supported weed detection is much more complex and at the moment not relevant in practice.In this regard, there is a lack of weed and crop differentiation through spectral analyses and object-based approaches separate different plants not species-specific or are not adapted to morphologic changes of the growth. Moreover, there is a need for alternative positioning techniques without GPS, as it is required for a precise optical imaging analysis at low altitudes.To evaluate the possibilities and limitations of automated weed identification regarding the optical and sampling requirements, flights were carried out with a hexacopter at an altitude of 5 m over agricultural crop land with variable weed patches. The altitude was controlled by the GPS-autopilot. Images were captured at geo-referenced points and the number of different weed species was simultaneously determined by manually counting. The required optical resolution on the ground was estimated by comparing the number of weeds between image analysis on the PC and with the field rating data

Multidisciplinary design and flight testing of a remote gas/particle airborne sensor system

The main objective of this paper is to describe the development of a remote sensing airborne air sampling system for Unmanned Aerial Systems (UAS) and provide the capability for the detection of particle and gas concentrations in real time over remote locations. The design of the air sampling methodology started by defining system architecture, and then by selecting and integrating each subsystem. A multifunctional air sampling instrument, with capability for simultaneous measurement of particle and gas concentrations was modified and integrated with ARCAA’s Flamingo UAS platform and communications protocols. As result of the integration process, a system capable of both real time geo-location monitoring and indexed-link sampling was obtained. Wind tunnel tests were conducted in order to evaluate the performance of the air sampling instrument in controlled nonstationary conditions at the typical operational velocities of the UAS platform. Once the remote fully operative air sampling system was obtained, the problem of mission design was analyzed through the simulation of different scenarios. Furthermore, flight tests of the complete air sampling system were then conducted to check the dynamic characteristics of the UAS with the air sampling system and to prove its capability to perform an air sampling mission following a specific flight path

IPM2.0: PRECISION AGRICULTURE FOR SMALL-SCALE CROP PRODUCTION

In order to manage pests impacting New England crop production integrated pest management (IPM) practices should be reevaluated or updated regularly to ensure that effective control of crop pests is being achieved. Three fungal taxa, Colletotrichum gloeosporioides, C. acutatum, and Glomerella cingulata, are currently associated with bitter-rot of apple (Malus domestica), with C. acutatum typically being the dominant species found in the northeastern United States. However, a recent phylogenetic study demonstrated that both C. gloeosporioides and C. acutatum are species complexes with over 10 distinct species being recovered from apple between the two studies. Based on this recent information, the objectives of this study were 1) to complete a phylogenetic analysis to determine species diversity and distribution of Colletotrichum isolates associated with bitter-rot and Glomerella leaf spot in the northeastern United States and 2) to evaluate the sensitivity of these isolates to several commercially used fungicides. A multi-gene phylogenetic analysis was completed using ITS, GADPH and BT gene sequences in order to determine which species and how many species of Colletotrichum were infecting apples in the northeastern U.S. The results of this study demonstrated that C. fioriniae is the primary pathogen causing both bitter rot and Glomerella leaf spot in the northeastern U.S. A second experiment was conducted in order to update management practices for apple scab, caused by the ascomycete Venturia inaequalis. The objective of this project was to evaluate the ability of RIMpro, an apple scab warning system, to control apple scab in New England apple orchards in addition to evaluating the performance of potassium bicarbonate + sulfur as a low-cost alternative spray material for the control of apple scab suitable for organic apple production. Use of RIMpro allowed for the reduction in the total number of spray applications made during the primary scab season by two sprays in 2013 and one spray in 2014 (28% and 25% reductions, respectively). Also, the potassium bicarbonate + sulfur treatment was shown to provide the same level of control as Captan. Finally, disease outbreaks, insect infestation, nutrient deficiencies, and weather variation constantly threaten to diminish annual yields and profits in orchard crop production systems. Automated crop inspection with an unmanned aerial vehicle (UAV) can allow growers to regularly survey crops and detect areas affected by disease or stress and lead to more efficient targeted applications of pesticides, water and fertilizer. The overall goal of this project was to develop a low cost aerial imaging platform coupling imaging sensors with UAVs to be used for monitoring crop health. Following completion of this research, we have identified a useful tool for agricultural and ecological applications

Development and Characterization of a Filter-Based Bioaerosol Sampler Capable of Integration into Small Unmanned Aerial Systems

In developing functional SUAS, performance characteristics that indicate system capability should be developed prior to initiating initial system design. Key performance parameters should be developed involving all system elements (including vehicle body, operator, ground station, sensor, and algorithm or processing module). A bioaerosol sampler designed specifically for the use in SUAS was characterized based on designated performance measures to determine overall effectiveness compared to traditional bioaerosol samplers. For a system with a goal of accurately identifying and quantifying areas of airborne biological contamination or surveying background levels for longitudinal studies, performance parameters such as weight of the vehicle with payload and sampler specific parameters will be quantitatively evaluated. These sampler-specific parameters include operational noise levels, power demand compared to performance, and sampling fraction. These were evaluated in a series of lab-based tests to determine if the developed model of bioaerosol sampler could be deployed for use in military environments. Overall, it was found that the developed EOS inlet oversampled for the background concentrations compared to the modeled performance for the inlet, and oversampled compared to the closed face cassette filter. This may be due to ground effects acting on the system—as the bottom placement for the sampler performed worse than expected based on previous research in comparison to the sampler closer to the rotors

Sensors and biosensors for pathogen and pest detection in agricultural systems : recent trends and oportunities

Pathogen and pest-linked diseases across agriculture and ecosystems are a major issue towards enhancing current thresholds in terms of farming yields and food security. Recent developments in nanotechnology allowed the designing of new generation sensors and biosensors in order to detect and mitigate these biological hazards. However, there are still important challenges concerning its respective applications in agricultural systems, typically related to point-of-care testing, cost reduction and real-time analysis. Thus, an important question arises: what are the current state-of-the-art trends and relationships among sensors and biosensors for pathogen and pest detection in agricultural systems? Targeted to meet this gap, a comparative study is performed by a literature review of the past decade and further data mining analysis. With the majority of the results coming from recent studies, leading trends towards new technologies were reviewed and identified, along with its respective agricultural application and target pathogens, such as bacteria, viruses, fungi, as well as pests like insects and parasites. Results have indicated lateral flow assay, lab-on-a-chip technologies and infrared thermography (both fixed and aerial) as the most promising categories related to sensors and biosensors driven to the detection of several different pathogenic varieties. The main existing interrelations between the results are especially associated to cereals, fruits and nuts, meat and dairy along with vegetables and legumes, mostly caused by bacterial and fungal infections. Additional results also presented and discussed, providing a fertile groundwork for decision-making and further developments in modern smart farming and IoT-based agriculture

Spatio-temporal analysis of vegetation dynamics of selected successional stages of dry acidic grasslands : experimental studies and model simulations

Austenfeld M. Spatio-temporal analysis of vegetation dynamics of selected successional stages of dry acidic grasslands : experimental studies and model simulations. Bielefeld (Germany): Bielefeld University; 2009.Eine allgemeine Entwicklungsumgebung wurde für die Analyse und Simulation von räumlich-zeitlichen Phänomenen in ökologischen Systemen entwickelt. Die gesamte Plattform basiert auf einer "Rich-Client-Platform" (RCP), die neue Konzepte der Modularisierung und allgemeinen Programmarchitektur mitbringt. Damit bietet sie die Grundlage für eine nachhaltige Weiterentwicklung und ist somit eine solide Basis für eine integrierte Entwicklungsumgebung für ökologische Modelle. Die Integration verschiedener statistischer Werkzeuge, Methoden der Bildverarbeitung und spezielle Visualisierungen qualifizieren diese Umgebung besonders für die Analyse der oben genannten räumlich-zeitlichen Prozesse. Aufgrund ihrer vergleichsweise geringen Komplexität wurden Sandlebensräume wiederholt für Studien von Vegetationsmustern und ihrer zugrunde liegenden biotischen Interaktionen genutzt. Für einen integrativen Überblick und weitere integrative Ansätze mit Hilfe von Simulationsmodellen wurde die oben genannte Plattform genutzt, um eine individuenbasierte Modellstruktur für die Analyse von Langzeiteffekten aufgrund von Umweltveränderungen auf die Stabilität von Sandlebensräumen zu entwickeln, die typischerweise von zwei Pionierarten, Corynephorus canescens und Polytrichum piliferum, dominiert werden. Das Modell wurde mit experimentellen Daten verifiziert, und die vom Modell erzeugten räumlich-zeitlichen Muster zeigten eine hohe Übereinstimmung mit natürlich gemessenen Mustern. Das Modell wurde dann genutzt, um Langzeiteffekte von Veränderungen der Temperatur, Nährstoffversorgung und Störungsraten in diesem System zu untersuchen. Die Ergebnisse zeigten eine generell hohe Stabilität des Systems unter veränderten Temperatur- und Nährstoffbedingungen, wobei temporal wiederkehrende, kleinräumige Störungen als Grundlage notwendig waren. Schließlich wurde noch eine Untersuchung über die Auswirkungen von Herbivorie und Konkurrenz auf Corynephorus canescens durchgeführt. In einem kontrollierten Freilandexperiment wurden die Auswirkungen von entfernter Biomasse von Blättern sowie die An- oder Abwesenheit eines intraspezifischen und interspezifischen Konkurrenten (Hieracium pilosella) auf die überirdische und unterirdische Allokation von Biomasse in der folgenden Regenerationsphase analysiert. Die Ergebnisse zeigten, dass Corynephorus canescens die Fähigkeit besitzt, leichte bis mittlere Blattverluste (die typische natürliche Herbivorie von Kaninchen und Paarhufern simulieren sollten) zu kompensieren, ohne dabei an Konkurrenzstärke zu verlieren. Unterirdisch konnten keine Auswirkungen der simulierten Herbivorie bzw. Konkurrenz festgestellt werden. Aufgrund dieser zu vernachlässigenden Effekte wurde Herbivorie nicht in dem Modell berücksichtigt.A generic modeling environment for the analysis and simulation of spatio-temporal phenomena in ecosystems was developed. This framework was built upon a Rich Client Platform (RCP) which uses new concepts of extensibility and software architecture for sustainable development and provides a solid basis for an Integrated Development Environment (IDE) for ecological models. The integration of various statistical tools, imaging routines and several specialized drawing panels makes this environment particularly suitable for the analysis of the above mentioned spatio-temporal ecological processes. Because of their comparatively low complexity, dry acidic grassland ecosystems have been repeatedly used for studying vegetation pattern formation and the underlying biotic interactions. In order to obtain an integrative view of the existing knowledge as well as to provide a possibility for further integrative analysis with the help of model simulations, the above described platform was used to develop an individual based Model structure for the investigation of long term effects of environmental changes on the stability of early successional stages of such dry acidic grasslands which are typically dominated by the two pioneer species Corynephorus canescens and Polytrichum piliferum. The model was validated with experimental data and the spatio-temporal patterns created by the model were in good accordance with the measured natural patterns. The model was then used to analyze the effect of changes in temperature, nutrient supply and disturbance rate on the long term behavior of this ecosystem. The results showed an overall high stability of this system under different temperature and nutrient scenarios as long as an intermediate disturbance frequency is assured. Finally, an experimental study on the effect of herbivory and competition on the Corynephorus canescens was conducted. In a controlled field experiment, the effects of the removal of various amounts of aboveground biomass on the above and belowground biomass allocation during the following regeneration phase was analyzed in the presence or absence of an intraspecific and interspecific competitor (Hieracium pilosella). The results show a rather high ability of C. canescens to compensate low to medium amounts of foliage loss (reflecting the typical natural herbivory induced by grasshoppers and rabbits) without significant changes in its competitive ability. Belowground, no biomass effects of foliage removal and/or competition could be detected. Because of these negligible effects, herbivory was not implemented in the above described model