Lake Imaging and Monitoring Aerial Drone

We describe the development of a BVLOS (Beyond Visual Line-Of-Sight) model aircraft (UAV). The broad design requirements included (i) fuselage capable of accommodating an imaging package or other instrumentation, (ii) suitability for over-lake BVLOS authorization in Switzerland, (iii) capability of land or water take-offs/landing, (iv) at least 90-min flight autonomy, (v) modularity of the imaging package and (vi) real-time IR/RGB imagery. Requirement (i) was to ensure an aircraft amenable to future developments. Requirements (ii)-(iv) were driven by the goal of improving estimates of lake surface energy fluxes, since such fluxes have a major impact on long-term lake temperatures and hence ecological status. Requirement (v), in conjunction with (i), allows the UAV to be adapted to other imaging applications. The real-time imagery requirement (vi) permits modifications of on-going missions to map areas of specific interest as they are detected. The prototype UAV produced to satisfy these characteristics was built on the twin-motor My Twin Dream (MTD) aircraft, which has a 1.8-m wing span airframe and a spacious fuselage. The legal authorization necessitated, where feasible, hardware redundancy as well as installation of a parachute system. Continuous communication between the ground station and UAV is provided by the LTE cellular telephone network. The UAV communication is handled by an on-board Linux computer, which is also responsible for control of the imagery package. The avionics involved modifications of the open-source APM autopilot software and the associated ground control station. A key modification was to support a custom-built emergency recovery system, which is triggered by loss of a heartbeat signal from the autopilot. The MTD airframe was modified to accommodate the system electronics and imaging hardware. Results from test flights over Lake Geneva demonstrate the ability of the aircraft to produce imagery data

Investigation and modeling of direct toppling using a three-dimensional distinct element approach with incorporation of point cloud geometry

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordBlock toppling instability can be a common problem in natural rock masses, especially in mining environments where excavation activity may trigger discontinuity-controlled instability by modifying the natural slope geometry. Traditional investigations of block toppling failure consider classic kinematic analyses and simplified two-dimensional limit equilibrium methods. This approach is still the most commonly adopted, but the simple two-dimensional conceptual model may often oversimplify the instability mechanisms, ignoring potential critical factors specifically related to the three-dimensional geometry. This paper uses a three-dimensional distinct element method approach applied to an example case study, identifying the critical parameters that influence direct toppling instability in an open pit environment. Terrestrial laser scanning was used to obtain detailed three-dimensional geometrical information of the slope face geometry for subsequent stability analyses. A series of sensitivity analyses on critical parameters such as friction angle, discontinuity shear and normal stiffness, discontinuity spacing, and orientation was performed, using simple conceptual three-dimensional numerical modeling. Results of the analyses revealed the importance of undertaking three-dimensional analyses for direct toppling investigations that allow identification of critical parameters. A three-dimensional distinct element analysis was then performed using a more realistic complex volumetric mesh model of the case study slope which confirmed the previous modeling results but also identified unstable blocks in high slope angle areas, providing useful information for life of mine design. The paper highlights the importance of slope geometry and fracture network orientation on potential slope instability mechanisms.European CommissionEuropean Commissio

Brief communication: Remotely piloted aircraft systems for rapid emergency response: road exposure to rockfall in Villanova di Accumoli (central Italy)

The use of remotely piloted aircraft systems (RPASs) in geosciences is often aimed at the acquisition of an image sequence to produce digital models and orthophotographs of the topographic surface. The technology can be applied for rockfall hazard and risk assessment. To study rockfalls, an approach consists in the application of numerical models for the computation of rockfall trajectories. Data required for such simulations include digital terrain models, location of the instability source areas, and the mechanical properties of the terrain. In this article, we present an analysis of the earthquake-triggered rockfall that occurred along the SP18 in Villanova di Accumoli (Lazio, central Italy) during the seismic sequence that started on 24 August 2016. A survey with a multicopter was carried out to obtain a surface model of the terrain and identify and characterize the source areas and other instable blocks in areas not accessible in the field. The investigated area extends for 6500&thinsp;m2 and was covered by 161 photographs that were used to obtain an orthophoto with a ground resolution of 2.5&thinsp;cm and a digital surface model with a ground resolution of 20&thinsp;cm&thinsp;×&thinsp;20&thinsp;cm, which was processed and fused with GNSS real-time kinematic data. To obtain a map of potential rockfall trajectories, we run the numerical model STONE, using as origin of the boulders both source areas mapped in the field and pixels with a slope angle above a selected threshold. Results showed that only the part of the road SP18 already affected by the rockfall was exposed to further rockfall impacts. In particular, it was observed that 29.2&thinsp;% (i.e. 12&thinsp;123) of the 41&thinsp;500 simulated trajectories may potentially reach or cross this tract of the road. Based on these data, limited protection measures were suggested. The combined use of RPAS data, fused with ground GPS points, an accurate geomorphological survey, and terrain static and dynamic parameters from the literature allows fast, low-cost, and replicable rockfall numerical modelling useful for emergency response and adoption of proper protection measures.</p

NOVI PRISTUP PRAĆENJA POMAKA KLIZIŠTA POMOĆU BESPILOTNIH FOTOGRAMETRIJSKIH SUSTAVA

Landslides represent great dangers that can cause fatalities and huge property damage. To prevent or reduce all possible consequences that landslides cause, it is necessary to know the kinematics of the surface and undersurface sliding masses. Geodetic surveying techniques can be used for landslide monitoring and creating a kinematic model of the landslide. One of the most used surveying techniques for landslide monitoring is the photogrammetric survey by Unmanned Aerial System. The results of the photogrammetric survey are dense point clouds, digital terrain models, and digital orthomosaic maps, where landslide displacements can be determined by comparing these results in two measurement epochs. This paper presents a new data processing method with a novel approach for calculating landslide displacements based on Unmanned Aerial System photogrammetric survey data. The main advantage of the new method is that it does not require the production of dense point clouds, digital terrain models, or digital orthomosaic maps to determine displacements. The applicability and accuracy of the new method were tested in a test field with simulated displacements of known values within the range of 20-40 cm in various directions. The new method successfully determined these displacements with a 3D accuracy of ±1.3 cm.Klizišta predstavljaju velike opasnosti koje mogu uzrokovati katastrofalne ljudske žrtve te nanijeti veliku materijalnu štetu. Da bi se spriječile ili umanjile sve moguće posljedice koje klizišta prouzročuju, važno je poznavati kinematiku kretanja površinskih i podzemnih kliznih masa klizišta. Geodetske tehnike izmjere mogu se koristiti za potrebe praćenja te za izradu kinematičkoga modela klizišta. U današnje vrijeme jedna od najčešće korištenih geodetskih tehnika za potrebe praćenja klizišta jest fotogrametrijsko snimanje pomoću bespilotnih zrakoplovnih sustava. Rezultati su takvih snimanja gusti oblaci točaka, digitalni modeli terena te digitalne ortomozaik karte, a na temelju usporedbe tih rezultata u dvjema mjernim epohama mogu se odrediti pomaci klizišta. Ovaj rad predstavlja novu metodu obrade podataka s novim pristupom za određivanje pomaka klizišta na temelju podataka fotogrametrijskoga snimanja bespilotnim zrakoplovnim sustavima. Glavna je prednost nove metode u tome što ne zahtijeva izradu gustih oblaka točaka, digitalnih modela terena ili digitalnih ortomozaik karata za određivanje pomaka. Primjenjivost i točnost nove metode ispitane su na testnome polju sa simuliranim pomacima poznatih vrijednosti čiji su se iznosi kretali u rasponu od 20 do 40 cm u različitim smjerovima. Nova metoda uspješno je odredila te pomake s 3D točnošću od ±1,3 cm

Potencial de uso de drones em inspeções de barragens : estudo de caso da Barragem dos Rios Vacacaí e Vacacaí-Mirim e Barragem Rodolfo da Costa e Silva

As barragens são construções que desafiam a natureza, devido ao fato de armazenarem fluidos. Sendo assim, é inerente que uma barragem apresente riscos associados para a sociedade, bens materiais e infraestrutura, economia e meioambiente. Mediante a adoção de programas de segurança de barragens que incluam inspeções periódicas, é possível mitigar riscos e garantir boas condições de operação. As inspeções visuais são atividades exaustivas e barragens possuem estruturas de difícil acesso, além de que, na grande maioria do tempo estão vertendo. Assim, é necessário que os inspetores utilizem equipamentos especializados de acesso que ofereçam condições de segurança. Nesse contexto, a utilização de drones, tem o potencial de oferecer vantagens significativas na coleta de dados, representando alternativas de baixo custo para aquisição de imagens de forma completa ou complementar às inspeções tradicionais. O objetivo geral do trabalho é avaliar como o uso de drones pode auxiliar na gestão da segurança de barragens, notadamente na execução de inspeções de segurança de barragens para acumulação de água. O objeto do estudo trata-se de duas barragens, uma de aterro e uma de concreto, nas quais realizou-se estudo de caso. Além de análise documental e geração de modelos 3D das mesmas, as imagens obtidas com drone foram disponibilizadas a um grupo de engenheiros especialistas, que realizaram inspeção virtual das barragens, sem que os mesmos estivessem presetes nas barragens previamente. Os questionários de inspeção preenchidos pelos especialistas foram confrontados com os resultados das inspeções in loco realizadas. Como resultados da pesquisa, verifica-se que a barragem de aterro apresentou um percentual de 81 % de respostas condizentes com as inspeções in loco e; a barragem de concreto, apresentou 65 %. O trabalho conclui que a adoção de drones para as inspeções de barragens traz inúmeras vantagens e possibilidades. Esse estudo permitiu a identificação de alguns fatores limitantes, que devem ser planejados, para que resultem em imagens de qualidade, facilitando e complementando as atividades de inspeção.Dams are constructions that defy nature, due to the fact that they store fluids. Therefore, it is inherent that a dam presents associated risks for the society, material assets, infrastructure, economy and environment. By adopting dams safety programs including periodic inspections, it is possible to minimize risks and ensure good and safety operating conditions. Visual inspections are exhausting activities and dams have structures with poor accessibility, and most of the time they are leaking. Thus, it is necessary for inspectors to use specialized access equipment that provides security conditions. In this context, the use of drones has the potential to offer significant advantages in data collection, resulting low-cost alternatives for image acquisition in a complete way or complementary to traditional inspections. The general goal of this work is to evaluate how the use of drones can help in the management of dam safety, notably in the performance of dam safety inspections for water reservation. The object of the study is two dams, one of embankment and one of concrete, which a case study was performed. In addition to document analysis and generation of 3D models of the dams, the images obtained with drones were provided to a group of specialist engineers, who carried out virtual inspection of the dams, instead of them being in the dams previously. The inspection questionnaires filled by the specialists were compared with the results of the in-site inspections carried out. As a result of the research, it leads to the conclusion that the earthfill dam revealed 81% of responses consistents according the in-site inspections and; the concrete dam, presented 65%. Therefore the work concludes that the adoption of drones for dam inspections brings numerous advantages and possibilities. This study allowed the identification of some limiting factors, which must be planned, resulting in better precision images, facilitating and complementing inspection activities