1,720,990 research outputs found
Performance comparison of advanced techniques for voltage dip detection
No full textSeveral different approaches for the detection of voltage dips in electic power systems have been proposed in the literature to overcome the limits of the procedure proposed by the International Standard, based on the voltage root mean square. In this paper the most promising of these approaches are compared, by computer simulations, in terms of both statistical performance and response time, which is a critical issue for the development of real-time compensation systems
A distributed data acquisition architecture for magnetic positioning systems
No full textWe illustrate a devised and implemented data acquisition system (DAQ) for a magnetic positioning system (MPS) that is currently under development. This system aims to track position and attitude of an active transmitting coil (TX) supplied with a sinusoidal current, whose generated magnetic field induces tensions on an array of passive receiving coils (RX). The DAQ system has to acquire voltages at all RX coils. These signals are then processed to estimate the TX coordinates, according to a mathematical model in order. In order to track the TX in real-time with a good resolution, voltages have to be measured simultaneously on all RXs. To this aim, we opted for a distributed architecture of microcontroller units (MCU). Each selected MCU has four analog-to-digital converters (ADC) that can work in parallel. Moreover multiple MCUs can be triggered simultaneously by a single MCU in a master-slave configuration. We used MCUs with a fast dual-core CPU. Each unit can directly process its own acquired signals. Then all data are sent to the master MCU, which estimates the coordinates of the TX. According to a preliminary analisys, this tracking system should achieve more than fifty coordinates measurements per second
MagIK: A Hand-Tracking Magnetic Positioning System Based on a Kinematic Model of the Hand
No full textIn this article, we present a hand-tracking system based on magnetic positioning. A single magnetic node is mounted on each fingertip and two magnetic nodes on the back side of the hand. A fixed array of receiving coils is used to detect the magnetic field, from which it is possible to infer the position and orientation of each magnetic node. A kinematic model of the whole hand has been developed. Starting from the positioning data of each magnetic node, the kinematic model can be used to calculate the position and flexion angle of each finger joint, plus the position and orientation of the hand in space. Relying on magnetic fields, the hand-tracking system can work also in non-line-of-sight conditions. The gesture reconstruction is validated by comparing it with a commercial hand-tracking system based on a depth camera. The system requires a small number of electronics to be mounted on the hand. This would allow building a light and comfortable data glove that could be used for several purposes: human-machine interface, sign language recognition, diagnostics, and rehabilitation
Training Gaussian process regression through data augmentation for battery SOC estimation
No full textEstimating the state of charge of a battery is generally a challenging operation, as it depends non-linearly on the parameters that describe the internal state of the battery under test. Electrochemical impedance spectroscopy provides useful data for estimating state of charge, however, there is no simple relation between impedance spectra and state of charge. This relationship can be determined through the use of Machine Learning techniques. In particular, Gaussian process regression is used in this work. For the method to be efficient, the training ensemble must be quite large, but spectroscopy measurements can be time-consuming. A Monte Carlo ensemble generated from a limited set of experimental data was then used to train the model. Two sets of input features were used for the Gaussian process: components of the impedance spectrum, and equivalent circuit parameters. Both features give the same accuracy in estimating the state of charge, even of batteries whose impedance spectra are not included in the training set. The first set of features has the advantage of not requiring model fitting. The second feature set has a significantly shorter training time
Validation and comparison of circular coils’ inductive coupling models
No full textIn this paper, modeling of inductive coupling between circular coils is analyzed. We present a system for measuring the mutual inductance and the magnetic flux between resonant coils. We investigate the accuracy and precision against data obtained through the FastHenry2 simulation software and through experiments, when these are available (Pasku et al., 2017). The theoretical background is discussed, theoretical models are presented, and their properties are compared to those of other published models. A practical implementation is illustrated and employed to validate the considered numerical models. Obtained results demonstrate that the proposed modeling and experimental setup provide high-accuracy measurements of the induced voltage. Field measurements validate the considered numerical models with a discrepancy of less than 10% with respect to measurement results
A multi-node magnetic positioning system with a distributed data acquisition architecture
No full textWe present a short-range magnetic positioning system that can track in real-time both the position and attitude (i.e., the orientation of the principal axes of an object in space) of up to six moving nodes. Moving nodes are small solenoids coupled with a capacitor (resonant circuit) and supplied with an oscillating voltage. Active moving nodes are detected by measuring the voltage that they induce on a three-dimensional matrix of passive coils. Data on each receiving coil are acquired simultaneously by a distributed data-acquisition architecture. Then, they are sent to a computer that calculates the position and attitude of each moving node. The entire process is run in real-time: the system can perform 62 position and attitude measurements per second when tracking six nodes simultaneously and up to 124 measurements per second when tracking one node only. Different active nodes are identified using a frequency-division multiple access technique. The position and angular resolution of the system have been experimentally estimated by tracking active nodes along a reference trajectory traced by a robotic arm. The factors limiting the viability of upscaling the system with more than six active nodes are discussed
Accurate Fitting Techniques for QCM-D Response Analysis
No full textIn this work we propose use of three advanced digital fitting algorithms for the extraction of frequency and time constant of QCM-D response signals. The proposed algorithms provide very low estimation errors so to reach the challenging resolution and accuracy required in QCM applications. The algorithms' performance was characterized using simulated, emulated, and experimental datasets. The paper analyzes the dependence of the estimation accuracy both on the noise level and on the measurement conditions in terms of mechanical load. It is shown that with a smart selection of the initial conditions for the fitting algorithms, an estimation error lower than 5 Hz is reached for the series frequency in the presence of typical noise levels, even in the presence of large mechanical loads
Statistical Properties of Voltage Dip Detectors
No full textIn this paper, some statistical properties of procedures defined to detect voltage dips in electric power systems are discussed. First, a theoretical model of the root-mean-square based test proposed in the IEC 61000-4-30 is provided and validated.
Then, an alternative detection algorithm, based on the Generalized Likelihood Ratio Test (GLRT), is proposed, and compared to the 61000-4-30 test. It is shown that the GLRT may provide competitive performance, in terms of Receiver Operating Characteristic (ROC), if compared to the standardized procedure
Digital impedance emulator for battery measurement system calibration
No full textMeaningful information on the internal state of a battery can be derived by measuring its impedance. Accordingly, battery management systems based on electrochemical impedance spectroscopy are now recognized as a feasible solutions for online battery control and diagnostic. Since the impedance of a battery is always changing along with its state of charge and aging effects, it is important to have a stable impedance reference in order to calibrate and test a battery management system. In this work we propose a programmable impedance emulator that in principle could be used for the calibration of any battery management system based on electrochemical impedance spectroscopy. A digital finite-impulse-response filter is implemented, whose frequency response is programmed so as to reproduce exactly the impedance of a real battery in the frequency domain. The whole design process of the filter is presented in detail. An analytical expression for the impedance of real battery in the frequency domain is derived from an equivalent circuit model. The model is validated both through numerical simulations and experimental tests. In particular, the filter is implemented on a low-cost microcontroller unit, and the emulated impedance is measured by means of a custom-made electrochemical impedance spectroscopy measuring system, and verified by using standard commercial bench instruments. Results on this prototype show the feasibility of using the proposed emulator as a fully controllable and low-cost reference for calibrating battery impedance measurement systems
A multi-frequency approach to mitigate the performance degradation of a magnetic positioning system under CW disturbance conditions
No full textMagnetic localization in 3D space is a challenging but promising task in those indoor applications where low costs and limited range are key requirements as in industrial and in some medical clinics’ frameworks. In such cases, the localization system generally operates in disturbed environments where, in the worst case, continuous-wave disturbances could permanently affect the system performance. Therefore, the evaluation of its susceptibility to external disturbances is an issue to be assessed, before deploying the most suitable solution. Therefore, it is important to accomplish for two tasks: (i) to quantify the disturbance effect on the system performance and (ii) to propose robustness solutions to minimize the disturbance effect, thus allowing the system to behave as in regular mode. In this paper, concerning with continuous wave conducted disturbances, which act as the most impacting external disturbing sources, both the tasks are addressed by considering both analytical modeling and experimental validations
- …
