Enhanced Speed and Current Control of PMSM Drives by Perfect Tracking Algorithms

Abstract-Speed and current closed loops control represent the heart of any advanced AC servo drive. These inner loops usually feature high-dynamic feedback control, with possible axes decoupling and a straight feedforward action of the backelectromotive force (back-EMF). More sophisticated techniques as single-rate or multi-rate control could be exploited for both speed and current closed loops, and their performances compared to that of the classic cascade feedback controllers. This represents the goal of the present work, focusing on permanent magnet synchronous motor (PMSM) drives

Meniscal femoral and tibial surfaces characterization in the swine model.

Menisci are wedge-like structures interposed, in the knee joint, between the femoral and the tibial articular heads (Kohn et al. 1995; Greis et al. 2002). Improving the articular surface, the cellular nutrition and the articular lubrication, they are essential structures for the prevention of gonarthrosis (Proctor et al.1989; Makris et al. 2011). This study is focused upon the relationship between the contact forces at the femoral and tibial surfaces and the corresponding structure of these meniscal surfaces. For this purpose, 20 adult (~9 months old) female pigs (Landrace x Large white, average weight 75–90 kg; n=80 meniscal samples) were obtained from a local slaughterhouse and dissected to isolate the menisci. Swine meniscal samples were evaluated from morphological (Safranin-O, Sirius Red and collagen type I and II) (Di Giancamillo et al. 2014), biochemical (DNA and glycosaminoglycans, or GAGs, contents) and biomechanical (compression and traction tests) points of view at the level of femoral and tibial meniscal surfaces. Results revealed a characterization of the meniscus which is biomechanical-dependent.  The femoral surface, morphologically characterized by the interposition of radial and oblique fibers and biomechanically by the femoral condyles compression, sliding and rolling forces, shows a higher compressive modulus (p<0.05) and a greater amount of cells and GAGs deposition (p<0.01 for each analysis). On the other hand, results from traction test revealed a higher tensile modulus (p<0.05) in the tibial surface, characterized by a circumferential arrangement of the fibers and a poorer GAGs deposition and cellular distribution (p<0.01). Results (summarized in the figure 1) from this work suggest that a biphasic “femoral-to-tibial” scaffold that mimic the different behavior and composition of the two meniscal surfaces could be useful in the light of meniscal replacement.

Zgodnji gigantocelični arteritis

Gigantocelični arteritis (GCA) je najpogostejši primarni sistemski vaskulitis pri odraslih po 50. letu starosti v Evropi. Prizadene velike in srednje velike arterije in vnetni proces, ki zožuje ali popolnoma zapre svetlino žile, lahko dovede do hudih/trajnih ishemičnih zapletov kot so oslepitev, možganska kap ali miokardni infarkt. V zadnjem desetletju se je z vključitvijo slikovnih preiskav v diagnostični postopek pomembno skrajšal čas do prepoznave bolezni (t.i. zgodnji GCA). Pospešena obravnava bolnikov (ang. “fast track clinic”) je vodila v zmanjšanje pojavnosti najresnejših ishemičnih zapletov bolezni in znižanje stroškov zdravljenja. Vendar pa bolezen praviloma poteka kronično, s poslabšanji, kar skupaj s kroničnim glukokortikoidnem zdravljenjem vodi v kopičenje okvar organov in tkiv. Prav zato se intenzivno preučuje patogeneza bolezni, z možnostjo implementacije izsledkov kot so sodobne molekularno in celično usmerjene tarčne terapije. Glavni cilji našega preglednega članka so bili: a) analiza raziskav z navedenim časom trajanja od začetka simptomov do postavitve diagnoze, b) raziskava obetavnih molekularnih tarč za zdravljenje GCA in c) prepoznava klinično pomembnih celičnih podtipov. Najbolj obetavne tarčne molekule za tarčno zdravljenje so IL-6, IL-12/IL-23 in citototoksični z limfociti T povezan protein 4, medtem ko terapija z zaviralci TNF-α ni bila uspešna. Kliničnih raziskav z učinkovinami, usmerjenimi proti IL-17, še ni. V prispevku pa smo se dotaknili tudi drugih potencialnih terapevtskih tarč, vključno z molekulami, ki sodelujejujo v signalnih poteh

Production of He-4 and (4) in Pb-Pb collisions at root(NN)-N-S=2.76 TeV at the LHC

Results on the production of He-4 and (4) nuclei in Pb-Pb collisions at root(NN)-N-S = 2.76 TeV in the rapidity range vertical bar y vertical bar <1, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be dN/dy4(He) = (0.8 +/- 0.4 (stat) +/- 0.3 (syst)) x 10(-6) and dN/dy4 = (1.1 +/- 0.4 (stat) +/- 0.2 (syst)) x 10(-6), respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature (T-chem = 156 MeV) as for light hadrons. The measured ratio of (4)/He-4 is 1.4 +/- 0.8 (stat) +/- 0.5 (syst). (C) 2018 Published by Elsevier B.V.Peer reviewe

A Force feedback System for Steer-by-Wire Applications Based on Low-Cost MR Fluids

In the automotive research scenario, the main purpose of a steer-by-wire system is the elimination of all mechanical connections between wheels and the steering wheel. The driver gets just a virtual and configurable feedback through the steering wheel, which becomes a stand-alone component. Among the emerging alternatives, magnetorheological (MR) fluids exhibit interesting properties that could well fit for safe and reliable force feedback systems. Through the collected data, this paper offers the essential information for the realisation of a force feedback device for steer-by-wire application. The paper includes the design and test of a pre-industrialised system, exploited for the measurements of low-cost, homemade MR fluids. Experimental results and their discussion conclude the paper

Identification of mechanical load for electrical drive commissioning - labelling machine case study

The paper presents a result of the system identification theory applied to an industrial machine. The case study was a labelling machine driven by a permanent magnet synchronous motor drive. The identified system model has been used to tune the closed-loop speed control of the drive. A brief recall of the basic principles of power spectral density applied to model identification, hints for the practical implementation and experimental results are included in the paperQC 20181001</p

Combined current/voltage model with inductance mismatch compensation for on-line estimation of flux linkages in permanent magnet and synchronous reluctance motor drives

A flux linkage estimator for synchronous machines which combines a voltage and a current model is analysed, based on an original scheme with some modifications. The proposed schemes assure convergence at steady-state and better transient performances. Simulation and experimental results were performed for different combinations of control schemes and flux linkage estimators, validating the discussed theory.QC 20180921</p

Automatic procedure for induction motors parameters estimation at standstill

The paper presents a self-commissioning procedure for the automatic parameter estimation of three-phase induction motor drives. The procedure consists of a step-by-step approach with different test signals to obtain the parameter values, while maintaining the motor at standstill. The actual implementation is capable of mapping both inverter and motor parameters non-linearities, providing accurate data for the tuning of common current regulators and for advanced sensorless drives as well. Theoretical and experimental results are provided, proving the effectiveness of the procedure.QC 20180920</p

A force feedback system for steer-by-wire applications based on low-cost MR fluids - design hints

In the automotive research scenario, the main purpose of a steer-by-wire system is the elimination of all mechanical connections between wheels and the steering wheel. The driver gets just a virtual and configurable feedback through the steering wheel, which becomes a stand-alone component. Among the emerging alternatives, magnetorheological (MR) fluids exhibit interesting properties that could well fit for safe and reliable force feedback systems. Through the collected data, this paper offers the essential information for the realisation of a force feedback device for steer-by-wire application. The paper includes the design and test of a pre-industrialised system, exploited for the measurements of low-cost, homemade MR.QC 20180914</p