ROBOTS CONTROL BY ADAPTIVE GAIN SMOOTH SLIDING OBSERVER-CONTROLLER AND PARAMETER IDENTIFICATION

An adaptive gain, smooth sliding observer-controller are developed to control uncertain parameters, -degree of freedom rigid robotic manipulators. Furthermore, an on-line, closed loop identification scheme, for time-varying parameters is proposed in order to obtain useful information despite loads, external disturbances and faults detection. In order to reduce the chattering, a smooth switching function (parameterised tangent hyperbolic function) is used instead of pure relay one, into the observer and the controller. The gains of the switching functions are adaptively updated, depending on the estimation error and tracking error, respectively. By using adaptive gains, the transient and tracking responses are improved. Simulation results with a two degree of freedom (DOF) robot manipulator are presented to show the interest of the approach

Flexible Joints Robotic Manipulator Control By Adaptive Gain Smooth Sliding Observer-Controller

An adaptive gain sliding observer for uncertain parameter nonlinear systems together with an adaptive gain sliding controller is proposed in this paper. It considered nonlinear, SISO affine systems, with uncertainties in steady-state functions and parameters. A further parameter term, adaptively updated, has been introduced in steady state space model of the controlled system, in order to obtain useful information despite fault detection and isolation. By using of the sliding observer with adaptive gain, the robustness to uncertainties is increased and the parameters adaptively updated can provide useful information in fault detection. Also, the state estimation error is bounded accordingly with bound limits of the uncertainties. The both of them, the sliding adaptive observer and sliding controller are designed to fulfill the attractiveness condition of its corresponding switching surface. An application to a single arm with flexible joint robot is presented. In order to alleviate chattering, a parameterized tangent hyperbolic has been used as switching function, instead of pure relay one, to the observer and the controller. Also, the gains of the switching functions, to the sliding observer and sliding controller are adaptively updated depending of estimation error and tracking error, respectively. By the using adaptive gains, the transient and tracking response can be improved

Growth and characterizations of nanostructured tungsten oxides

Tungsten oxide (WO3) as nanostructured thin film is an attractive compound to be used for sensors applications. We report on WO3 nanostructured thin films deposited by radio-frequency plasma assisted laser ablation technique. A tungsten oxide ceramic target was irradiated at 193 nm wavelength; the depositions have been carried out in a gas mixture of oxygen and argon on heated substrates (corning glass and silicon) up to 600°C. The gas pressure varied between 1 Pa and 10 Pa. The influence of the substrate temperature, gas pressure and RF power on properties of the obtained nanostructures was investigated by Atomic Force Microscopy, Raman spectroscopy, Secondary Ion Mass Spectrometry and spectro-ellipsometry

Exploring the multi-humped fission barrier of 238U via sub-barrier photofission

The photofission cross-section of 238U was measured at sub-barrier energies as a function of the gamma-ray energy using, for the first time, a monochromatic, high-brilliance, Compton-backscattered gamma-ray beam. The experiment was performed at the High Intensity gamma-ray Source (HIgS) facility at beam energies between E=4.7 MeV and 6.0 MeV and with ~3% energy resolution. Indications of transmission resonances have been observed at gamma-ray beam energies of E=5.1 MeV and 5.6 MeV with moderate amplitudes. The triple-humped fission barrier parameters of 238U have been determined by fitting EMPIRE-3.1 nuclear reaction code calculations to the experimental photofission cross section.Comment: 5 pages, 3 figure

Anaesthesiology trainees and their needs: a Romanian perspective. Results from a European survey

Anaesthesiology training is going through continuous transformations worldwide. Recent data from a European Survey on anaesthesiology postgraduate trainees and their concerns have been published for the first time, following an initiative by the European Society of Anaesthesiology. Among the responders of this survey, 10.8% were represented by Romanian trainees. The main needs of the Romanian anaesthesiology trainees who completed the questionnaire were, in descending order educational contents/EDAIC, technical skills, exchange programmes, residency workload, residency costs and autonomy transition. Another observation coming from the analysed data is that Romanian anaesthesiologists in training are highly concerned and interested in the field of intensive care medicine. The results also pinpoint to the high costs associated with continuous medical education, leading to a high incentive for workforce migration.info:eu-repo/semantics/publishedVersio

Nuclear photonics at ultra-high counting rates and higher multipole excitations

Next-generation gamma beams beams from laser Compton-backscattering facilities like ELI-NP (Bucharest)] or MEGa-Ray (Livermore) will drastically exceed the photon flux presently available at existing facilities, reaching or even exceeding 10^13 gamma/sec. The beam structure as presently foreseen for MEGa-Ray and ELI-NP builds upon a structure of macro-pulses (~120 Hz) for the electron beam, accelerated with X-band technology at 11.5 GHz, resulting in a micro structure of 87 ps distance between the electron pulses acting as mirrors for a counterpropagating intense laser. In total each 8.3 ms a gamma pulse series with a duration of about 100 ns will impinge on the target, resulting in an instantaneous photon flux of about 10^18 gamma/s, thus introducing major challenges in view of pile-up. Novel gamma optics will be applied to monochromatize the gamma beam to ultimately Delta E/E~10^-6. Thus level-selective spectroscopy of higher multipole excitations will become accessible with good contrast for the first time. Fast responding gamma detectors, e.g. based on advanced scintillator technology (e.g. LaBr3(Ce)) allow for measurements with count rates as high as 10^6-10^7 gamma/s without significant drop of performance. Data handling adapted to the beam conditions could be performed by fast digitizing electronics, able to sample data traces during the micro-pulse duration, while the subsequent macro-pulse gap of ca. 8 ms leaves ample time for data readout. A ball of LaBr3 detectors with digital readout appears to best suited for this novel type of nuclear photonics at ultra-high counting rates.Comment: 4 pages, 1 figure, 1 tabl

Optical Properties of TiO 2 Thin Films Grown by PLD

Abstract Titanium dioxide thin …lms have been grown by pulsed laser deposition (PLD) under a …ne tuning of the deposition parameters, such as the substrate temperature, gas pressure, or the application of special treatments, e.g. RF-plasma assistance conditions. The main concern during the deposition process/treatments has been to obtain a high reproducibility and well de…ned optical and topographic properties. The emerging TiO 2 thin …lms have been analyzed with respect to the above mentioned properties by Atomic Force Microscopy (AFM) and Spectroscopic Ellipsometry (SE)

Computer Aided Model for an Off-grid Photovoltaic System Using Batteries Only

This article will present an off-grid photovoltaic energy system based on a photovoltaic element (PV), or a group of PVs, integrated in a solar battery (SB), directly connected to an electrical battery (EB) having no DC-DC adapter (use of adapters is the most common solution existing now on in this domain). This SB must be properly adjusted to the EB, not only as voltage, but it must provide also the same amount of energy as the system when operating at its classically detected maximum power operating point. This proposed technical solution is more economically justified, compared to the classic one: SB+DC-DC+EB, due to the simple fact that the DC-DC converter is no longer required at all. A simple mathematical model for the current-voltage characteristics is also presented, followed by a comparison between the classic DC-DC converter-based solution and the newly proposed one, without DC-DC converter

Computer Aided Model for a Low Voltage Varistor with Increased Thermal Stability

Metal Oxide Varistors are a very common power electronic device, applied for efficient overvoltage protection at any voltage level. This piece of equipment has a high non-linear current response function of the applied voltage, and, it provides a relatively high heat absorption capacity in case of accidental overvoltage pulse (shock)s. The crossing response current is clearly activated by temperature of that device, and, by consequent, overheating could be disastrous. Actual researches must be carried out both for a new more performant material as well as for new technical solutions for the design of all equipment integrating them, by studying heat extraction and heat transfer inside a new complex varistor device. Our article proposes a totally new device, used basically for low voltage applications, having a supplementary metal mass added to the body of that varistor, shaped as small disk. It actions like a heat pump immediately after the voltage pulse (shock) and as additional radiators at the end of the heating process caused by a transitory overvoltage. A CAD solution combined with a finite element model, followed by some experimental results are also presented, for confirming the performance of that newly design. By placing additional metal alloy masses inside a new varistor structure it will have a higher heat pumping and dissipation capability, in order to reduce temperature stress and all aging effects