861 research outputs found
Interactive Imitation Learning of Bimanual Movement Primitives
Performing bimanual tasks with dual robotic setups can drastically increase
the impact on industrial and daily life applications. However, performing a
bimanual task brings many challenges, like synchronization and coordination of
the single-arm policies. This article proposes the Safe, Interactive Movement
Primitives Learning (SIMPLe) algorithm, to teach and correct single or dual arm
impedance policies directly from human kinesthetic demonstrations. Moreover, it
proposes a novel graph encoding of the policy based on Gaussian Process
Regression (GPR) where the single-arm motion is guaranteed to converge close to
the trajectory and then towards the demonstrated goal. Regulation of the robot
stiffness according to the epistemic uncertainty of the policy allows for
easily reshaping the motion with human feedback and/or adapting to external
perturbations. We tested the SIMPLe algorithm on a real dual-arm setup where
the teacher gave separate single-arm demonstrations and then successfully
synchronized them only using kinesthetic feedback or where the original
bimanual demonstration was locally reshaped to pick a box at a different
height
Polish device for FOCCoS/PFS slit system
The Fiber Optical Cable and Connector System, FOCCoS, for the Prime Focus
Spectrograph, PFS, is responsible for transporting light from the Subaru
Telescope focal plane to a set of four spectrographs. Each spectrograph will be
fed by a convex curved slit with 616 optical fibers organized in a linear
arrangement. The slit frontal surface is covered with a special dark composite,
made with refractory oxide, which is able to sustain its properties with
minimum quantities of abrasives during the polishing process; this stability is
obtained This stability is obtained by the detachment of the refractory oxide
nanoparticles, which then gently reinforce gently the polishing process and
increase its the efficiency. The surface roughness measured in several samples
after high performance polishing was about 0.01 microns. Furthermore, the time
for obtaining a polished surface with this quality is about 10 times less than
the time required for polishing a brass, glass or ceramic surface of the same
size. In this paper, we describe the procedure developed for high quality
polishing of this type of slit. The cylindrical polishing described here, uses
cylindrical concave metal bases on which glass paper is based. The polishing
process consists to use grid sequences of 30 microns, 12 microns, 9 microns, 5
microns, 3 microns, 1 micron and, finally, a colloidal silica on a chemical
cloth. To obtain the maximum throughput, the surface of the fibers should be
polished in such a way that they are optically flat and free from scratches.
The optical fibers are inspected with a microscope at all stages of the
polishing process to ensure high quality. The efficiency of the process may be
improved by using a cylindrical concave composite base as a substrate suitable
for diamond liquid solutions. Despite this process being completely by hand,
the final result shows a very high quality
Economic burden of colorectal and breast cancers attributable to lack of physical activity in Brazil
Background: The increasing number of cancer patients has an escalating economic impact to public health systems (approximately, International dollars- Int = 2.1 reais) with hospitalization, chemotherapy and radiotherapy were obtained from the Hospital and Ambulatory Information Systems of the Brazilian SUS. Two counterfactual scenarios were considered: theoretical minimum risk exposure level (≥8000 MET-min/week) and physical activity guidelines (≥600 MET-min/week). Results: Annually, the Brazilian SUS expended Int 553 million due to colon and breast cancers. Direct costs related to colon and breast cancers attributable to lack of physical activity were Int 26.9 million, respectively. Achieving at least the physical activity guidelines would save Int 6.4 mi; breast, Int 50.3 million annually in direct costs related to colon and post-menopausal breast cancers. Population-wide interventions aiming to promote physical activity are needed to reduce the economic burden of cancer in Brazil
Interactive Imitation Learning in Robotics: A Survey
Interactive Imitation Learning (IIL) is a branch of Imitation Learning (IL)
where human feedback is provided intermittently during robot execution allowing
an online improvement of the robot's behavior. In recent years, IIL has
increasingly started to carve out its own space as a promising data-driven
alternative for solving complex robotic tasks. The advantages of IIL are its
data-efficient, as the human feedback guides the robot directly towards an
improved behavior, and its robustness, as the distribution mismatch between the
teacher and learner trajectories is minimized by providing feedback directly
over the learner's trajectories. Nevertheless, despite the opportunities that
IIL presents, its terminology, structure, and applicability are not clear nor
unified in the literature, slowing down its development and, therefore, the
research of innovative formulations and discoveries. In this article, we
attempt to facilitate research in IIL and lower entry barriers for new
practitioners by providing a survey of the field that unifies and structures
it. In addition, we aim to raise awareness of its potential, what has been
accomplished and what are still open research questions. We organize the most
relevant works in IIL in terms of human-robot interaction (i.e., types of
feedback), interfaces (i.e., means of providing feedback), learning (i.e.,
models learned from feedback and function approximators), user experience
(i.e., human perception about the learning process), applications, and
benchmarks. Furthermore, we analyze similarities and differences between IIL
and RL, providing a discussion on how the concepts offline, online, off-policy
and on-policy learning should be transferred to IIL from the RL literature. We
particularly focus on robotic applications in the real world and discuss their
implications, limitations, and promising future areas of research
Multi-fibers connectors systems for FOCCoS-PFS-Subaru
The Fiber Optical Cable and Connector System (FOCCoS), provides optical
connection between 2400 positioners and a set of spectrographs through optical
fibers cables as part of PFS instrument for Subaru telescope. The optical fiber
cable will be segmented in 3 parts along the route, cable A, cable B and cable
C, connected by a set of multi-fiber connectors. The company USCONEC produces
the multi-fiber connector under study. The USCONEC 32F model can connect 32
optical fibers in a 4 x 8 matrix arrangement. The ferrules are made of a
durable composite, Polyphenylene Sulfide (PPS) based thermoplastic. The
connections are held in place by a push-on/pull-off latch, and the connector
can also be distinguished by a pair of metal guide pins that protrude from the
front of the connector. Two fibers per connector will be used for monitoring
the connection procedure. It was found to be easy to polish and it is small
enough to be mounted in groups. Highly multiplexed instruments like PFS require
a fiber connector system that can deliver excellent optical performance and
reliability. PFS requires two different types of structures to organize the
connectors. The Tower Connector system, with 80 multi-fiber connectors, will be
a group of connectors for connecting cable B (Telescope Structure) with cable C
(Positioners Plate). The Gang Connector system is a group of 8 gang connectors,
each one with 12 multi-fibers connectors, for connecting cable B (Telescope
Structure) with cable A (Spectrograph). The bench tests with these connector
systems and the chosen fibers should measure the throughput of light and the
stability after many connections and disconnections. In this paper we describe
tests and procedures to evaluate the throughput and FRD increment. The lifetime
of the ferrules is also in evaluation
EVENTOS DE PRECIPITAÇÕES EXTREMAS NA AMAZÔNIA OCIDENTAL: RONDÔNIA - BRASIL
Este estudo objetivou analisar a ocorrência de eventos pluviométricos extremos a partir dos dados de precipitação das estações pluviométricas instaladas no estado de Rondônia. Utilizou-se 41 estações pluviométricas com séries históricas acima de 10 anos. Posteriormente tais dados foram analisados pela distribuição de Gumbel, sendo os mesmos relacionados, por meio da desagregação de chuva diária, para períodos de retorno compreendendo 2 a 100 anos e durações pluviométricas de 5 minutos a 24 horas. As séries históricas utilizadas revelaram que a média das chuvas máximas de “um dia”, no estado de Rondônia encontrou-se variando de aproximadamente 71,341 a 173,542 mm/dia, além disso, observou-se que possíveis atuações de fenômenos climáticos como o El Niño e La Niña na região analisada pode ter gerado, respectivamente, as reduções e aumentos na ocorrência de eventos pluviométricos extremos
Análise de chuvas intensas por meio da desagregação de precipitações diárias de Jaru e Machadinho d’Oeste – RO, Brasil
A precipitação pluviométrica, dentre os elementos hidrológicos, é o que mais interfere na vida humana, uma vez que, se configura como a principal entrada de água no sistema hidrológico. Atualmente uma das soluções para realizar a caracterização e estimativa das precipitações intensas é a utilização de curvas Intensidade-Duração-Frequência (IDF), as quais consistem em modelos matemáticos semi-empíricos que preveem a intensidade precipitada por meio da duração e distribuição temporal. Neste contexto, esse estudo objetiva estimar a função IDF para os municípios de Jaru e Machadinho d’Oeste, localizados no estado de Rondônia – Brasil, por meio da metodologia da desagregação de chuvas diárias, que gera séries sintéticas com duração em intervalos menores, por meio de coeficientes que transformam chuva de 24h em outras de menor duração, permitindo assim o desenvolvimento de curvas IDF. As equações geradas apresentaram um coeficiente de ajuste de aproximadamente 96% para o município de Jaru e 92,85% para Machadinho d’Oeste. Por fim, constatou-se que as equações propostas para a estimativa da intensidade das precipitações máximas são de grande aplicabilidade tanto para o município de Machadinho d’Oeste quanto para Jaru
Slit device for FOCCoS, PFS, Subaru
The Fiber Optical Cable and Connector System, FOCCoS, subsystem of the Prime
Focus Spectrograph, PFS, for Subaru telescope, is responsible to feed four
spectrographs with a set of optical fibers cables. The light injection for each
spectrograph is assured by a convex curved slit with a linear array of 616
optical fibers. In this paper we present a design of a slit that ensures the
right direction of the fibers by using masks of micro holes. This kind of mask
is made by a technique called electroforming, which is able to produce a nickel
plate with holes in a linear sequence. The precision error is around 1micron in
the diameter and 1 micron in the positions of the holes. This nickel plate may
be produced with a thickness between 50 and 200 microns, so it may be very
flexible. This flexibility allows the mask to be bent into the shape necessary
for a curved slit. The concept requires two masks, which we call Front Mask,
and Rear Mask, separated by a gap that defines the thickness of the slit. The
pitch and the diameter of the holes define the linear geometry of the slit; the
curvature of each mask defines the angular geometry of the slit. Obviously,
this assembly must be mounted inside a structure rigid and strong enough to be
supported inside the spectrograph. This structure must have a CTE optimized to
avoid displacement of the fibers or increased FRD of the fibers when the device
is submitted to temperatures around 3 degrees Celsius, the temperature of
operation of the spectrograph. We have produced two models. Both are mounted
inside a very compact Invar case, and both have their front surfaces covered by
a dark composite, to reduce stray light. Furthermore, we have conducted
experiments with two different internal structures to minimize effects caused
by temperature gradients
QUANTIFICATION OF RESIDUAL CLOVE OIL, BENZOCAINE AND TRICAINE IN FISH FILLETS USING SPE AND UPLC-DAD
Residual quantification of the anesthetics clove oil (CO) – isoeugenol (ISO), eugenol (EUG) and methyleugenol (MET) –,benzocaine (BZN) and tricaine (MS-222) was made in fillets of two fish species: Nile tilapia (Oreochromis niloticus) and acatfish hybrid, cachadia (Pseudoplatystoma reticulatum x Leiarius marmoratus). Samples (n=4) of each fish wereevaluated after submitted to anesthesia in five dosages defined based on the induction time of each species afterdepuration times (0h, 12h, 24h and 48h). Different methodologies of sample preparation were tested and selectedaccording to the better recovery. The quantification of anesthetics was performed by UPLC-DAD. The variance of residualmeans among anesthetics, dosages and fish species was compared. After anesthesia (0h) both species, tilapia andcachadia, presented residual anesthetics. Fishes depurated during 12h, 24h and 48h did not present detectable values, itmeans, values were below the limits of detection. BZN presented the highest mean residual concentration for tilapia andcachadia (p=0.01), while MS-222 presented the lowest residual amounts in tilapias and EUG in cachadias, what may berelated to the metabolism and carcass composition of each fish species. There were no significant differences among thefive dosages, except the lowest MS-222 concentration in tilapias that resulted in higher residual concentrations becauselow dosages increase the induction time and consequently the permanence of the fish in anesthesia. Ultimately, meanvalues of residues in cachadia were higher than in tilapia, and MS-222 and EUG presented the lowest residual values fortilapia and cachadia, respectively
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