596 research outputs found
Dynamic Active Constraints for Surgical Robots using Vector Field Inequalities
Robotic assistance allows surgeons to perform dexterous and tremor-free
procedures, but robotic aid is still underrepresented in procedures with
constrained workspaces, such as deep brain neurosurgery and endonasal surgery.
In these procedures, surgeons have restricted vision to areas near the surgical
tooltips, which increases the risk of unexpected collisions between the shafts
of the instruments and their surroundings. In this work, our
vector-field-inequalities method is extended to provide dynamic
active-constraints to any number of robots and moving objects sharing the same
workspace. The method is evaluated with experiments and simulations in which
robot tools have to avoid collisions autonomously and in real-time, in a
constrained endonasal surgical environment. Simulations show that with our
method the combined trajectory error of two robotic systems is optimal.
Experiments using a real robotic system show that the method can autonomously
prevent collisions between the moving robots themselves and between the robots
and the environment. Moreover, the framework is also successfully verified
under teleoperation with tool-tissue interactions.Comment: Accepted on T-RO 2019, 19 Page
Autonomous Coordinated Control of the Light Guide for Positioning in Vitreoretinal Surgery
Vitreoretinal surgery is challenging even for expert surgeons owing to the
delicate target tissues and the diminutive workspace in the retina. In addition
to improved dexterity and accuracy, robot assistance allows for (partial) task
automation. In this work, we propose a strategy to automate the motion of the
light guide with respect to the surgical instrument. This automation allows the
instrument's shadow to always be inside the microscopic view, which is an
important cue for the accurate positioning of the instrument in the retina. We
show simulations and experiments demonstrating that the proposed strategy is
effective in a 700-point grid in the retina of a surgical phantom. Furthermore,
we integrated the proposed strategy with image processing and succeeded in
positioning the surgical instrument's tip in the retina, relying on only the
robot's geometric information and microscopic images.Comment: Accepted on T-MRB 2022, 16 page
Single-Shot Pose Estimation of Surgical Robot Instruments' Shafts from Monocular Endoscopic Images
Surgical robots are used to perform minimally invasive surgery and alleviate
much of the burden imposed on surgeons. Our group has developed a surgical
robot to aid in the removal of tumors at the base of the skull via access
through the nostrils. To avoid injuring the patients, a collision-avoidance
algorithm that depends on having an accurate model for the poses of the
instruments' shafts is used. Given that the model's parameters can change over
time owing to interactions between instruments and other disturbances, the
online estimation of the poses of the instrument's shaft is essential. In this
work, we propose a new method to estimate the pose of the surgical instruments'
shafts using a monocular endoscope. Our method is based on the use of an
automatically annotated training dataset and an improved pose-estimation
deep-learning architecture. In preliminary experiments, we show that our method
can surpass state of the art vision-based marker-less pose estimation
techniques (providing an error decrease of 55% in position estimation, 64% in
pitch, and 69% in yaw) by using artificial images.Comment: Accepted on ICRA 2020, 7 page
Active Constraints using Vector Field Inequalities for Surgical Robots
Robotic assistance allows surgeons to perform dexterous and tremor-free
procedures, but is still underrepresented in deep brain neurosurgery and
endonasal surgery where the workspace is constrained. In these conditions, the
vision of surgeons is restricted to areas near the surgical tool tips, which
increases the risk of unexpected collisions between the shafts of the
instruments and their surroundings, in particular in areas outside the surgical
field-of-view. Active constraints can be used to prevent the tools from
entering restricted zones and thus avoid collisions. In this paper, a vector
field inequality is proposed that guarantees that tools do not enter restricted
zones. Moreover, in contrast with early techniques, the proposed method limits
the tool approach velocity in the direction of the forbidden zone boundary,
guaranteeing a smooth behavior and that tangential velocities will not be
disturbed. The proposed method is evaluated in simulations featuring two eight
degrees-of-freedom manipulators that were custom-designed for deep
neurosurgery. The results show that both manipulator-manipulator and
manipulator-boundary collisions can be avoided using the vector field
inequalities.Comment: Accepted on ICRA 2018, 8 page
Impacto del orden canónico de constituyentes y la animacidad en el procesamiento de oraciones en español
Trabajo de investigaciónEstudia el impacto del orden canónico de constituyentes y la animacidad en el procesamiento de oraciones en español. Para ello realizó una réplica del estudio de Casado et al. (2005). El presente experimento es de tipo conductual y emplea a técnica de lectura autoadministrada (Self Paced Reading). La comparación de tiempos de lectura de oraciones SVO y OVS muestra que las oraciones OVS requieren un mayor costo de procesamiento. Además, los resultados indican que la animacidad del objeto dificulta el procesamiento oracional en español. La novedad de la investigación es que estudio el procesamiento de oraciones transitivas; además, empleo la técnica conductual de lectura autoadministrada.Trabajo de investigació
Soft X-ray Energy Spectra in the Wide-Field Galactic Disk Area Revealed with HaloSat
We analyzed data from HaloSat observations for five fields in the Galactic
disk located far away from the Galactic center (135
254) to understand the nature of soft X-ray energy emission in the
Galactic disk. The fields have 14 diameter and were selected to
contain no significant high-flux X-ray sources. All five HaloSat soft X-ray
energy spectra (0.4--7 keV with energy resolution of 100 eV below 1 keV)
show a possibility of the presence of unresolved high-temperature plasma in the
Galactic disk (UHTPGD) with a temperature of 0.8--1.0 keV and an emission
measure of (8--11) in addition to the soft X-ray
diffuse background components mainly studied at higher galactic latitudes
(solar wind charge exchange emission, local hot bubble, Milky Way halo
emission, and the cosmic X-ray background). This suggests that the UHTPGD is
present across the whole Galactic disk. We also observed UHTPGD emission in a
region with no bright sources in an {\it XMM-Newton} field contained within one
of the {\it HaloSat} fields. The temperature and emission measure are
consistent with those measured with {\it HaloSat}. Moreover, the stacked
spectra of the X-ray point-like sources and NIR-identified point sources such
as stars in the {\it XMM-Newton} field also show a spectral feature similar to
the UHTPGD emission. This suggests that the UHTPGD may partly originate from
point-like sources such as stars.Comment: Accepted for publication in ApJ. 11 pages and 4 figure
Interstellar Gas and X-rays toward the Young Supernova Remnant RCW 86; Pursuit of the Origin of the Thermal and Non-Thermal X-ray
We have analyzed the atomic and molecular gas using the 21 cm HI and 2.6/1.3
mm CO emissions toward the young supernova remnant (SNR) RCW 86 in order to
identify the interstellar medium with which the shock waves of the SNR
interact. We have found an HI intensity depression in the velocity range
between and km s toward the SNR, suggesting a cavity in the
interstellar medium. The HI cavity coincides with the thermal and non-thermal
emitting X-ray shell. The thermal X-rays are coincident with the edge of the HI
distribution, which indicates a strong density gradient, while the non-thermal
X-rays are found toward the less dense, inner part of the HI cavity. The most
significant non-thermal X-rays are seen toward the southwestern part of the
shell where the HI gas traces the dense and cold component. We also identified
CO clouds which are likely interacting with the SNR shock waves in the same
velocity range as the HI, although the CO clouds are distributed only in a
limited part of the SNR shell. The most massive cloud is located in the
southeastern part of the shell, showing detailed correspondence with the
thermal X-rays. These CO clouds show an enhanced CO = 2-1/1-0 intensity
ratio, suggesting heating/compression by the shock front. We interpret that the
shock-cloud interaction enhances non-thermal X-rays in the southwest and the
thermal X-rays are emitted by the shock-heated gas of density 10-100 cm.
Moreover, we can clearly see an HI envelope around the CO cloud, suggesting
that the progenitor had a weaker wind than the massive progenitor of the
core-collapse SNR RX J1713.73949. It seems likely that the progenitor of RCW
86 was a system consisting of a white dwarf and a low-mass star with
low-velocity accretion winds.Comment: 19 pages, 15 figures, 4 tables, accepted for publication in Journal
of High Energy Astrophysics (JHEAp
A Chandra observation of the ultraluminous infrared galaxy IRAS 19254--7245 (the Superantennae): X-ray emission from the Compton-thick AGN and the diffuse starburst
We present a {\it Chandra} observation of IRAS 19254--7245, a nearby ULIRG
also known as {\it the Superantennae}. The high spatial resolution of {\it
Chandra} allows us to disentangle for the first time the diffuse starburst
emission from the embedded Compton-thick AGN. The 2-10 keV spectrum of the AGN
emission is fitted by a flat power-law ) and a He-like Fe K
line with EW1.5 keV, consistent with previous observations. The Fe
K line profile could be resolved as a blend of a neutral 6.4 keV line
and an ionized 6.7 keV (He-like) or 6.9 keV (H-like) line. Variability is
detected compared with the previous {\it XMM-Newton} and {\it suzaku}
observations, demonstrating the compact size of the iron line emission. We fit
the spectrum of the galaxy-scale extended emission excluding the AGN and other
bright point sources with a soft thermal component with kT~0.8 keV. The
luminosity of the extended emission is about one order of magnitude lower than
that of the AGN. The basic physical and structural properties of the extended
emission are fully consistent with a galactic wind being driven by the
starburst (no contribution to the feedback by the AGN is required). A candidate
ultra-luminous X-ray source is detected 8\arcsec\ south of the southern
nucleus. The 0.3-10 keV luminosity of this off-nuclear point source is
~ erg s if the emission is isotropic and the source is
associated with the Superantennae.Comment: 31 pages, 10 figures, submitted to Ap
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