Upcoming Workshops

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Handover Control for Human-Robot and Robot-Robot Collaboration

Modern scenarios in robotics involve human-robot collaboration or robot-robot cooperation in unstructured environments. In human-robot collaboration, the objective is to relieve humans from repetitive and wearing tasks. This is the case of a retail store, where the robot could help a clerk to refill a shelf or an elderly customer to pick an item from an uncomfortable location. In robot-robot cooperation, automated logistics scenarios, such as warehouses, distribution centers and supermarkets, often require repetitive and sequential pick and place tasks that can be executed more efficiently by exchanging objects between robots, provided that they are endowed with object handover ability. Use of a robot for passing objects is justified only if the handover operation is sufficiently intuitive for the involved humans, fluid and natural, with a speed comparable to that typical of a human-human object exchange. The approach proposed in this paper strongly relies on visual and haptic perception combined with suitable algorithms for controlling both robot motion, to allow the robot to adapt to human behavior, and grip force, to ensure a safe handover. The control strategy combines model-based reactive control methods with an event-driven state machine encoding a human-inspired behavior during a handover task, which involves both linear and torsional loads, without requiring explicit learning from human demonstration. Experiments in a supermarket-like environment with humans and robots communicating only through haptic cues demonstrate the relevance of force/tactile feedback in accomplishing handover operations in a collaborative task

Control of sliding velocity in robotic object pivoting based on tactile sensing

Control of robots manipulating objects using only the sense of touch is a challenge. In-hand motion of the manipulated object highly depends on the friction forces acting at the contact surfaces. Soft contacts allow torsional frictions as well as friction forces, therefore robots can perform more complex manipulation abilities, like object pivoting. Control of the pivoting sliding motion is very difficult especially without any visual feedback. The paper proposes a novel method to control the sliding velocity of the object by using a simple parallel gripper endowed with force/tactile sensors only. The strategy is based on a nonlinear observer that estimates the sliding velocity from force/torque measurements and a model of the sliding dynamics

Caldera unrest driven by CO2-induced drying of the deep hydrothermal system

Interpreting volcanic unrest is a highly challenging and non-unique problem at calderas, since large hydrothermal systems may either hide or amplify the dynamics of buried magma(s). Here we use the exceptional ground displacement and geochemical datasets from the actively degassing Campi Flegrei caldera (Southern Italy) to show that ambiguities disappear when the thermal evolution of the deep hydrothermal system is accurately tracked. By using temperatures from the CO2-CH4 exchange of 13C and thermodynamic analysis of gas ascending in the crust, we demonstrate that after the last 1982-84 crisis the deep hydrothermal system evolved through supercritical conditions under the continuous isenthalpic inflow of hot CO2-rich gases released from the deep (~8 km) magma reservoir of regional size. This resulted in the drying of the base of the hot hydrothermal system, no more buffered along the liquid-vapour equilibrium, and excludes any shallow arrival of new magma, whose abundant steam degassing due to decompression would have restored liquid-vapour equilibrium. The consequent CO2-infiltration and progressive heating of the surrounding deforming rock volume cause the build-up of pore pressure in aquifers, and generate the striking temporal symmetry that characterizes the ongoing uplift and the post-1984 subsidence, both originated by the same but reversed deformation mechanism

The geothermal potential of Campanian volcanoes: evaluation and opportunities.

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On the Long Range Clustering of Global Seismicity and its Correlation With Solar Activity: A New Perspective for Earthquake Forecasting

Large earthquakes occurring worldwide have long been recognized to be non Poisson distributed, so involving some large scale correlation mechanism, which could be internal or external to the Earth. We have recently demonstrated this observation can be explained by the correlation of global seismicity with solar activity. We inferred such a clear correlation, highly statistically significant, analyzing the ISI-GEM catalog 1996–2016, as compared to the Solar and Heliospheric Observatory satellite data, reporting proton density and proton velocity in the same period. However, some questions could arise that the internal correlation of global seismicity could be mainly due to local earthquake clustering, which is a well-recognized process depending on physical mechanisms of local stress transfer. We then apply, to the ISI-GEM catalog, a simple and appropriate de-clustering procedure, meant to recognize and eliminate local clustering. As a result, we again obtain a non poissonian, internally correlated catalog, which shows the same, high level correlation with the proton density linked to solar activity. We can hence confirm that global seismicity contains a long-range correlation, not linked to local clustering processes, which is clearly linked to solar activity. Once we explain in some details the proposed mechanism for such correlation, we also give insight on how such mechanism could be used, in a near future, to help in earthquake forecasting

Tamanho da amostra foliar para avaliação do estado nutricional e índice SPAD de capim-elefante irrigado para corte.

Resumo: compor a amostra promoverá a otimização da mão de obra, além de diminuir erros inerentes à recomendação e avaliação do estado nutricional. A coleta de folhas de forrageiras para a diagnose do estado nutricional é uma etapa importante para subsidiar a adubação, sendo o tamanho da amostra imprescindível para representar adequadamente a população de plantas a ser manejada. Assim, objetivou-se dimensionar o número de amostras de folhas para a diagnose do estado nutricional de capim-elefante irrigado para corte, bem como o índice de clorofila SPAD (Soil Plant Analysis Development). A avaliação foi realizada em capineira de capim-elefante, var. Cameroon, com irrigação fixa de baixa aspersão, em área localizada em Sobral-CE, em solo Neossolo fluvico. Coletaram-se 40 amostras simples, em zigue-zague, de maneira aleatória, escolhendo-se folhas recém-expandidas. As variáveis mensuradas foram os teores foliares de macro (N, P, K, Ca, Mg e S) e micronutrientes (B, Cu, Fe, Mn e Zn) e o índice indireto de clorofila, com auxílio de um clorofilômetro. Considerando aceitável um erro amostral de 10%, a coleta de amostras simples de 16 e 80 plantas, respectivamente, para macro e micronutrientes em capim-elefante seria adequada. Para a medida indireta da clorofila, 8 amostras são necessárias para obter um erro de 10%. [Leaf size sample to nutritional state and SPAD index evaluation in elephant grass irrigated under cuts management]. Abstract: The determination of the amount of sample units that will compose the sample express the optimization of the workforce, and reduce errors inherent in the report of recommendation and evaluation of nutritional status. The leaf collection for diagnosis of nutritional status is an important step, and the sample size necessary to adequately represent the population to be assessed. Thus, the objective was evaluation to the number simple design of leaf samples for the diagnosis of nutritional status of elephant grass irrigated for cutting and SPAD (Soil Plant Analysis Development) index. The study was conducted in elephant grass, with a low fixed sprinkler irrigation, in an area located in Sobral-CE in alluvial soil. It was collected 40 samples simple, randomly, choosing newly expanded leaves. The variables measured were foliar concentrations of macro (N, P, K, Ca, Mg and S) and micronutrients (B, Cu, Fe, Mn and Zn) and the indirect index of chlorophyll, using a chlorophyll meter. Considering an acceptable error of 10%, the collection of single samples of 16 and 80 plants, respectively, for macronutrients and micronutrients in elephant grass would be appropriate. For the indirect measurement of chlorophyll (SPAD index) 8 plants would be required to obtain a 10% error

Relações biométricas e índice SPAD do milho submetido a fontes e doses de nitrogênio na regiao Semiárida do Brasil.

Resumo: O correto manejo da adubação nitrogenada e o emprego de tecnologias agregadas visam o melhor aproveitamento do N pelas culturas, em especial a cultura do milho. Objetivou-se avaliar as variáveis biométricas e os teores de clorofila, através de medidas indiretas em folhas de milho, em função da aplicação de fertilizantes nitrogenados em diferentes doses. O estudo foi conduzido no campo experimental da Empresa Brasileira de Pesquisa Agropecuária (Embrapa/CNPC) em Sobral-CE. Os tratamentos consistiram de cinco fontes de nitrogênio: uréia; uréia + NBPT; uréia + polímero; uréia + inibidor enzimático; e uréia + capeamento com enxofre elementar, em três níveis de adubação nitrogenada em cobertura: 100%, 75% e 50% da dose recomendada para a cultura, aplicados em cobertura 30 dias após o plantio. Quando as plantas apresentavam-se 50% pendoadas, foram avaliadas quanto às características biométricas (altura; diâmetro do caule; número de folhas) e medidas indiretas de clorofila com o auxílio de um medidor portátil. A variedade estudada foi o milho Catingueiro, adaptado às condições Semiáridas. Pode-se constatar que as plantas apresentaram diferentes comportamentos para o índice SPAD, em função das doses e dos adubos utilizados. Houve diferença significativa para número de folhas, quando comparadas fontes e doses de adubos, em relação à testemunha sem adubação, evidenciando a importância da adubação nitrogenada para a cultura do milho

Tectonic stress and renewed uplift at Campi Flegrei caldera, southern Italy: New insights from caldera drilling

Deep drilling is a key tool for the investigation of active volcanoes in the modern Earth Sciences, as this provides the only means to obtain direct information on processes that occur at depth. Data acquired from drilling projects are fundamental to our understanding of volcano dynamics, and for mitigation of the hazards they pose for millions of people who live close to active volcanoes. We present here the first borehole measurement of the stress field in the crust of Campi Flegrei (southern Italy), a large active caldera, and one of the highest risk volcanoes worldwide. Measurements were performed to depths of ∼500 m during a pilot study for the Campi Flegrei Deep Drilling Project. These data indicate an extensional stress field, with a minimum horizontal stress of ca. 75% to 80% of the maximum horizontal stress, which is approximately equal to the vertical stress. The deviation from lithostatic conditions is consistent with a progressive increase in applied horizontal stress during episodes of unrest, since at least 1969. As the stress field is evolving with time, the outcome of renewed unrest cannot be assessed by analogy with previous episodes. Interpretations of future unrest must therefore accommodate the possibility that Campi Flegrei is approaching conditions that are more favourable to a volcanic eruption than has previously been the case. Such long-term accumulation of stress is not expected to be unique to Campi Flegrei, and so might provide a basis for improved forecasts of eruptions at large calderas elsewhere

Medida indireta da clorofila, estado nutricional em N e produção de frutos de goiabeiras adubadas com subproduto da indústria processadora de goiabas.

RESUMO ? O reaproveitamento de subprodutos é uma alternativa interessante para a reciclagem de nutrientes e melhoria do estado nutricional das plantas. A utilização de ferramentas que auxiliem na diagnose foliar pode contribuir para a tomada de decisão sobre a adubação. Assim, objetivaram-se avaliar o teor foliar de N, a medida indireta da clorofila, a produção de frutos e suas correlações, em um pomar de goiabeiras adultas cv. Paluma, por três safras consecutivas. Foram aplicadas as seguintes doses do subproduto da indústria processadora de goiabas: zero; 9; 18; 27; 36 t ha-1. O material foi aplicado superficialmente no pomar, sem incorporação uma vez por ano, entre 2006 e 2009, sendo avaliados em três safras consecutivas o teor de N, o índice SPAD, a produção de frutos, realizando-se a correlação entre as variáveis. A medida indireta da clorofila, o teor foliar de N e a produção de frutos apresentaram alta relação com as doses de subproduto da indústria processadora de goiabas. A leitura SPAD apresenta correlação linear e positiva com o teor foliar de nitrogênio, bem como com a produção de frutos de goiabeiras adultas