356 research outputs found
Elastomer-based visuotactile sensor for normality of robotic manufacturing systems
Modern aircrafts require the assembly of thousands of components with high accuracy and reliability. The normality of drilled holes is a critical geometrical tolerance that is required to be achieved in order to realize an efficient assembly process. Failure to achieve the required tolerance leads to structures prone to fatigue problems and assembly errors. Elastomer-based tactile sensors have been used to support robots in acquiring useful physical interaction information with the environments. However, current tactile sensors have not yet been developed to support robotic machining in achieving the tight tolerances of aerospace structures. In this paper, a novel elastomer-based tactile sensor was developed for cobot machining. Three commercial silicon-based elastomer materials were characterised using mechanical testing in order to select a material with the best deformability. A Finite element model was developed to simulate the deformation of the tactile sensor upon interacting with surfaces with different normalities. Additive manufacturing was employed to fabricate the tactile sensor mould, which was chemically etched to improve the surface quality. The tactile sensor was obtained by directly casting and curing the optimum elastomer material onto the additively manufactured mould. A machine learning approach was used to train the simulated and experimental data obtained from the sensor. The capability of the developed vision tactile sensor was evaluated using real-world experiments with various inclination angles, and achieved a mean perpendicularity tolerance of 0.34°. The developed sensor opens a new perspective on low-cost precision cobot machining
Removal of imidacloprid from polluted water using adsorption and membrane separation technologies
In this work, the stability of imidacloprid in fresh water and sludge was studied. The results
revealed that the pesticide is unstable in both media. In freshwater, it underwent hydrolysis
whereas a degradation to several metabolites has been observed in sludge. The rate constants for
the hydrolysis and degradation at 25°C were 0.0.0067 and 0.0.0099 dâ1, respectively. Monitoring
the degradation of imidacloprid in sludge by high-pressure liquid chromatography-mass spectrometry
(HPLC-MS) revealed that five metabolites have emerged during the study. These metabolites
include imidacloprid urea, imidacloprid-guanidine, 6-hydroxynicotinic acid, an olefin, and
5-hydroxy, 1-(6-chloro-3-pyridylmethyl)-2-(nitroimino)-imidazolidin-5-ol. The efficiency of Al-Quds
University Wastewater Treatment Plant towards the removal of imidacloprid indicates that the
ultrafiltration-hollow fiber unit was insufficient, whereas the ultrafiltration-spiral wound, activated
carbon, and reverse osmosis units were efficient for complete removal of the pesticide. Adsorption
experiments of imidacloprid using either activated charcoal or micelle-clay complex were found to
fit Langmuir isotherms better than Freundlich isotherm. The data demonstrate a higher Langmuir
Qmax value for the activated charcoal (126.6 mg gâ1) when compared to the micelle-clay complex
(11.76 mg gâ1). Filtration column experiments, conducted with mixed micelle-clay complex and sand
(using a ratio of 1/50 by mass) at a flow rate of 2 mL minâ1 and influent concentration of 50 mg Lâ1,
revealed that a sufficient removal of imidacloprid was achieved in the first fraction of 100 mL
elution. These findings indicate that the adsorption technology using the micelle-clay complex
provides efficient removal of imidacloprid in continuous flow mode
A novel vision-based multi-functional sensor for normality and position measurements in precise robotic manufacturing
Cobots play an essential role in the fourth industrial revolution and the automation of complex manufacturing processes. However, cobots still face challenges in achieving high precision, which obstructs their usage in precise applications such as the aerospace industry. Nonetheless, advances in perception systems unlock new cobot manufacturing capabilities. This paper presents a novel multi-functional sensor that combines visual and tactile feedback using a single optical sensor, featuring a moving gate mechanism. This work also marks the first integration of Vision-Based Tactile Sensing (VBTS) into a robotic machining end-effector. The sensor provides vision-based tactile perception capabilities for precise normality control and exteroceptive perception for robot localization and positioning. Its performance is experimentally demonstrated in a precise robotic deburring application, where the sensor achieves the high-precision requirements of the aerospace industry with a mean normality error of 0.13° and a mean positioning error of 0.2 mm. These results open a new paradigm for using vision-based sensing for precise robotic manufacturing, which surpasses conventional approaches in terms of precision, weight, size, and cost-effectiveness
Simulating International Shipments of Vegetable Oils: Focus on Quality Changes
This investigation evaluated the quality changes of commercial vegetable oils after
different simulated shipments. In particular, the oils were placed in containers with or
without thermal insulation and subjected to two simulated shipments, from Italy to Los
Angeles and to Quebec. The temperature profiles were monitored to simulate the real
shipments conditions in laboratory through properly developed climate chambers.
Different quality parameters were evaluated before and after the simulations, showing a
high degree of oxidation for samples shipped to Los Angeles in standard containers. In
this study, the thermal insulation container was effective in protecting samples from
potential oxidative damage during simulated shipping.The authors would like to thank Enhancement of the Palestinian University System (E- PLUS) for PhD scholarship grants
financed by the Italian Ministry of Foreign Affairs-Directorate General for Cooperation and Development (coordinated
by the University of Pavia)
Simulations and analysis tools for charge-exchange reactions in inverse kinematics with the AT-TPC
Charge-exchange reactions in inverse kinematics at
intermediate energies are a very promising method to investigate the
Gamow-Teller transition strength in unstable nuclei. A simulation and analysis
software based on the package was developed to
study these type of reactions with the active-target time projection chamber
(AT-TPC). The simulation routines provide a realistic detector response that
can be used to understand and benchmark experimental data. Analysis tools and
correction routines can be developed and tested from simulations in
, because they are processed in the same way as the
real data. In particular, we study the feasibility of using coincidences with
beam-like particles to unambiguously identify the
reaction channel, and to develop a kinematic fitting routine for future
applications. More technically, the impact of space-charge effects in the track
reconstruction, and a possible correction method are investigated in detail.
This analysis and simulation package constitutes an essential part of the
software development for the fast-beams program with the AT-TPC
The ASY-EOS experiment at GSI: investigating the symmetry energy at supra-saturation densities
The elliptic-flow ratio of neutrons with respect to protons in reactions of
neutron rich heavy-ions systems at intermediate energies has been proposed as
an observable sensitive to the strength of the symmetry term in the nuclear
Equation Of State (EOS) at supra-saturation densities. The recent results
obtained from the existing FOPI/LAND data for Au+Au collisions
at 400 MeV/nucleon in comparison with the UrQMD model allowed a first estimate
of the symmetry term of the EOS but suffer from a considerable statistical
uncertainty. In order to obtain an improved data set for Au+Au collisions and
to extend the study to other systems, a new experiment was carried out at the
GSI laboratory by the ASY-EOS collaboration in May 2011.Comment: Talk given by P. Russotto at the 11th International Conference on
Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1,
2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference
Series (JPCS
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