Enhanced teleoperation interfaces for multi-second latency conditions: System design and evaluation

Adding human cognitive skills to planetary exploration through remote teleoperation can lead to more effective and valuable scientific data acquisition. Still, even small amounts of latency can significantly affect real-time operations, often leading to compromised robot safety, goal overshoot, and high levels of human mental fatigue and cognitive workload. Thus, novel operational strategies are necessary to cope with these effects. This paper proposes three augmented teleoperation interfaces that allow the user to operate a robot subject to 3 seconds of latency: (1) Avatar-Aided Interface (AAI), a semi-autonomous approach based on a virtual element; (2) Predictive Interface (PI), an approach with direct control and predictive elements; and (3) Hybrid Interface (HI), where the operator can easily switch between PI and AAI. We conducted a systematic within-subject experiment to evaluate the proposed interfaces in a realistic virtual environment with frequent traction losses. The user study compared AAI and PI to a Control Interface (CI), which did not display any augmented elements. The main results of this comparison showed that: (1) AAI led to a significant reduction in workload and a significant increase in usability and robot safety; (2) the use of the PI caused a significant increase in path length, indicating that operators overshoot their goals more often with this approach; (3) PI and AAI had lower reported effort; and (4) AAI is more flexible and effortless than PI and CI. Finally, the presented results show the need to consider uncertainty (e.g., traction loss) in future interface design.info:eu-repo/semantics/publishedVersio

Traction awareness through haptic feedback for the teleoperation of UGVs*

Teleoperation of Unmanned Ground Vehicles (UGVs) is dependent on several factors as the human operator is physically detached from the UGV. This paper focuses on situations where a UGV designed for search and rescue loses traction, thus becoming unable to comply with the operator's commands. In such situations, the lack of Situation Awareness (SA) may lead to an incorrect and inefficient response to the current UGV state usually confusing and frustrating the human operator. The exclusive use of visual information to simultaneously perform the main task (e.g. search and rescue) and to be aware of possible impediments to UGV operation, such as loss of traction, becomes a very challenging task for a single human operator. We address the challenge of unburdening the visual channel by using other human senses to provide multimodal feedback in UGV teleoperation. To achieve this goal we present a teleoperation architecture comprising (1) a laser-based traction detector module, to discriminate between traction losses (stuck and sliding) and (2) a haptic interface to convey the detected traction state to the human operator through different types of tactile stimuli provided by three haptic devices (E-Vita, Traction Cylinder and Vibrotactile Glove). We also report the experimental results of a user study to evaluate to what extent this new feedback modality improves the user SA regarding the UGV traction state. Statistically significant results were found supporting the hypothesis that two of the haptic devices improved the comprehension of the traction state of the UGV when comparing to exclusively visual modality.info:eu-repo/semantics/acceptedVersio

Aplicação fracionada de nitrogênio no algodoeiro irrigado.

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On the use of haptic tablets for UGV teleoperation in unstructured environments: system design and evaluation

Teleoperation of Unmanned Ground Vehicles (UGVs), particularly for inspection of unstructured and unfamiliar environments still raises important challenges from the point of view of the operator interface. One of these challenges is caused by the fact that all information available to the operator is presented to the operator through a computer interface, providing only a partial view of the robot situation. The majority of existing interfaces provide information using visual, and, less frequently, sound channels. The lack of Situation Awareness (SA), caused by this partial view, may lead to an incorrect and inefficient response to the current UGV state, usually confusing and frustrating the human operator. For instance, the UGV may become stuck in debris while the operator struggles to move the robot, not understanding the cause of the UGV lack of motion. We address this problem by studying the use of haptic feedback to improve operator SA. More precisely, improving SA with respect to the traction state of the UGV, using a haptic tablet for both commanding the robot and conveying traction state to the user by haptic feedback. We report (1) a teleoperating interface, integrating a haptic tablet with an existing UGV teleoperation interface, and (2) the experimental results of a user study designed to evaluate the advantage of this interface in the teleoperation of a UGV, in a search and rescue scenario. Statistically significant results were found supporting the hypothesis that using the haptic tablet elicits a reduction in the time that the UGV spends in states without traction.info:eu-repo/semantics/publishedVersio

General approach for studying first-order phase transitions at low temperatures

By combining different ideas, a general and efficient protocol to deal with discontinuous phase transitions at low temperatures is proposed. For small $T$'s, it is possible to derive a generic analytic expression for appropriate order parameters, whose coefficients are obtained from simple simulations. Once in such regimes simulations by standard algorithms are not reliable, an enhanced tempering method, the parallel tempering -- accurate for small and intermediate system sizes with rather low computational cost -- is used. Finally, from finite size analysis, one can obtain the thermodynamic limit. The procedure is illustrated for four distinct models, demonstrating its power, e.g., to locate coexistence lines and the phases density at the coexistence.Comment: 5 page

Controle da podridão cinzenta da maçã por produtos naturais biologicamente ativos

Indexación: Web of Science; ScieloBiorend SC (chitosan), BC-1000 EC (grapefruit extract plus bioflavonoids) and ECO-100 SC (bioflavonoids plus organic acids, citric phytoalexins, fatty acids, glycerides and sugars), respectively, suppressed grey rot of apple caused by B. cinerea by 80.1%, 79.0% and 76.5% when used as post-harvest treatments under controlled conditions. When applied as combined pre- and post-harvest treatments Biorend SC inhibited fruit rot by 49.9 %, while BC-1000 EC and ECO-100 SC were ineffective. None of the products inhibited fruit rot when applied as pre-harvest treatments under controlled conditions or as post-harvest treatments under commercial conditions. The algal polysaccharide ulvan used in post-harvest treatments suppressed grey rot by 56.0% under controlled conditions, but had no inhibitory effect on combined pre- and post-harvest treatments. The inability of products to activate defense mechanisms (chitinase and peroxidase) of fruits was consistent with the unsuccessful control of rot by pre-harvest treatment. The results suggest that the natural products used have potential for use in integrated management of Botrytis rot when applied after harvest.Biorend SC (quitosana), BC-1000 EC (extrato de toranja mais flavonóides), e ECO-100 SC (bioflavonóides mais ácidos orgânicos, fitoalexinas cítricas, ácidos graxos glicerídeos e açúcares) inibiram em 80,1%, 79,0% e 76,5%, respectivamente, a podridão causada por Botrytis cinerea quando utilizados no tratamento pós-colheita de frutos de maçã sob condições controladas.Tratamento combinado de Biorend SC, com aplicação tanto em pré como no pós-colheita, proporcionou 49,9% de inibição da podridão, enquanto BC-1000 e ECO-100 EC não foram efetivos. Nenhum desses produtos inibiu a podridão cinzenta, quando utilizados em tratamento de pré-colheita em condições controladas ou em tratamento de pós-colheita em condições comerciais. O polissacarídeo algal ulvana, utilizado nos tratamentos de pós-colheita, reduziu em 56% a podridão cinzenta das maçãs em condições controladas, mas não teve efeito inibitório nos tratamentos combinados de pré e pós-colheita. A incapacidade dos produtos em ativar mecanismos de defesa (quitinases e peroxidases) nos frutos, após o tratamento em pré-colheita, foi consistente com a falta de controle da podridão nesse tipo de ensaio. Pelos resultados, sugere-se que os produtos naturais utilizados apresentam potencial para a utilização no manejo integrado da podridão de Botrytis quando aplicados em pós-colheita.http://ref.scielo.org/kcxb9

Critical fluctuations and random-anisotropy glass transition in nematic elastomers

We carry out a detailed deuterium NMR study of local nematic ordering in polydomain nematic elastomers. This system has a close analogy to the random-anisotropy spin glass. We find that, in spite of the quadrupolar nematic symmetry in 3-dimensions requiring a first-order transition, the order parameter in the quenched ``nematic glass'' emerges via a continuous phase transition. In addition, by a careful analysis of the NMR line shape, we deduce that the local director fluctuations grow in a critical manner around the transition point. This could be the experimental evidence for the Aizenman-Wehr theorem about the quenched impurities changing the order of discontinuous transition

Fertilização nitrogenada do algodoeiro herbáceo irrigado. 1. Qualidade da fibra.

Com o objetivo de avaliar a qualidade da fibra do algodoeiro, cv. BRS 201, fertilizado com diferentes doses de uréia, um experimento de campo foi conduzido no município de Barbalha, CE, no ano de 2005. Utilizou-se o delineamento experimental em blocos ao acaso com quatro repetições e seis tratamentos, constituídos por seis doses de uréia (0, 60, 120, 180, 240, -1 300 kg.ha ), aplicadas em datas previamente estabelecidas, via água de irrigação. Utilizou-se para a aplicação da quantidade de água em cada evento de irrigação um sistema de aspersão em linha. Pela análise dos resultados, não se detectou diferença significativa entre as doses de uréia, sobre a qualidade da fibra, a qual atende ás exigências da indústria têxtil nacional para fibra média (30/32 mm) ou longa (32/34 mm), exceto com relação á finura, que apresentou valor médio de 5,1 micronaire.bitstream/CNPA/19898/1/BOLETIM82.pd