Showing papers in "IEEE Transactions on Instrumentation and Measurement in 2003"

Modeling of high power automotive batteries by the use of an automated test system

Abstract: In order to estimate the field of application for an electrical energy storage, its performance at different operating conditions has to be measured and evaluated. An automated test system has been designed to speed up measurement and to ensure reproducible measurement conditions. This paper focuses on the performance of this test system and on measured data. Based on this data, a battery model of a NiMH cell is parameterized and the obtained results are discussed.

A method for dead reckoning parameter correction in pedestrian navigation system

Abstract: This paper presents a method for correcting dead reckoning parameters, which are heading and step size, for a pedestrian navigation system. In this method, the compass bias error and the step size error can be estimated during the period that the Global Positioning System (GPS) signal is available. The errors are used for correcting those parameters to improve the accuracy of position determination using only the dead reckoning system when the GPS signal is not available. The results show that the parameters can be estimated with reasonable accuracy. Moreover, the method also helps to increase the positioning accuracy when the GPS signal is available.

Behavior-based neuro-fuzzy controller for mobile robot navigation

Abstract: This paper discusses a neuro-fuzzy controller for sensor-based mobile robot navigation in indoor environments. The control system consists of a hierarchy of robot behaviors.

Digital watermarking-based DCT and JPEG model

Abstract: In recent years, digital watermarking techniques have been proposed to protect the copyright of multimedia data. Different watermarking schemes have been suggested for images. The goal of this paper is to develop a watermarking algorithm based on the discrete cosine transform (DCT) and image segmentation. The image is first segmented in different portions based on the Voronoi diagram and features extraction points. Then, a pseudorandom sequence of real numbers is embedded in the DCT domain of each image segment. Different experiments are conducted to show the performance of the scheme under different types of attacks. The results show that our proposed watermark scheme is robust to common signal distortions, including geometric manipulations. The robustness against Joint Photographic Experts Group (JPEG) compression is achieved for a compression ratio of up to 45, and robustness against average, median, and Wiener filters is shown for the 3/spl times/3 up to 9/spl times/9 pixel neighborhood. It is observed that robustness against scaling was achieved when the watermarked image size is scaled down to 0.4% of its original size.

On-line heart beat recognition using Hermite polynomials and neuro-fuzzy network

Abstract: This paper presents a neuro-fuzzy approach to the recognition and classification of heart rhythms on the basis of ECG waveforms. The important part in recognition fulfills the Hermite characterization of the QRS complexes. The Hermite coefficients serve as the features of the process. These features are applied to a fuzzy neural network for recognition. The results of numerical experiments have confirmed very good performance of such a solution.

A few methods for fitting circles to data

Abstract: Five methods are discussed to fit circles to data. Two of the methods are shown to be highly sensitive to measurement error. The other three are shown to be quite stable in this regard. Of the stable methods, two have the advantage of having closed form solutions. A positive aspect of all of these models is that they are coordinate free in the sense that the same estimating circles are produced no matter where the axes of the coordinate system are located nor how they are oriented. A natural extension to fitting spheres to points in 3-space is also given.

Application of electrical capacitance tomography to the void fraction measurement of two-phase flow

Abstract: Based on the electrical capacitance tomography technique, a new method for the void fraction measurement of two-phase flow is proposed. A 12-electrode void fraction measurement system is established. A mathematical model of image reconstruction of electrical capacitance tomography is developed. To obtain the quantitative information of two-phase flow, combining the Tikhonov regularization principle and the algebraic reconstruction technique algorithm, a new image reconstruction algorithm is presented. The experimental results show that the accuracy of void fraction measurement is satisfactory. The proposed method is suitable for the void fraction measurement of many kinds of two-phase flow.

A displacement-measuring instrument utilizing self-mixing interferometry

Abstract: We develop a self-mixing laser interferometer for the measurement of displacements on a generic target surface. The measurement is based on the bright-speckle tracking, a technique we have recently proposed to solve amplitude fading associated with the speckle statistics when the displacement to be covered is well in excess of the speckle longitudinal size. We implement the dynamical tracking of speckle maxima with piezo actuators and a phase-sensing loop. Also, we use an automatic gain control, based on a liquid crystal attenuator, to improve the amplitude statistics. Details of digital signal acquisition with adaptive signal processing through a field programmable gate array are discussed. The resulting instrument offers sub-/spl mu/m resolution in the measurement of displacement up to 500 mm of total shift, has virtually no need for alignment, and has very relaxed target-surface requisites, yet works with a very simple and inexpensive set-up.

A method for estimation and filtering of Gaussian noise in images

Abstract: A new approach to the restoration of images corrupted by Gaussian noise is presented. The proposed method combines a nonlinear algorithm for detail preserving smoothing of noisy data and a technique for automatic parameter tuning based on noise estimation. As a key feature, the method does not require any a priori knowledge about the amount of noise corruption. Experimental results show that the filtering performance of the proposed approach is very satisfactory.

Data glove with a force sensor

Abstract: This paper presents a data glove equipped with a force sensor. The construction and the electronic circuit are also described. The glove is selected to be a rubber-coated cotton glove. The sensors are firmly attached to the rubber-coated glove using cyanoacrilic glue. The force sensor is made of a steel plate substrate where the commercial strain gauges are attached. The plate is attached on the thumb. The strain gauge bridge is powered by a digital current source. A digital sine is produced by a microcontroller and a DAC with current output. At the peak, the microcontroller produces a digital output signal. This signal triggers the data acquisition system. The force sensor presents a linear response and a resolution of 0.38 N with a sensitivity of 0.05 V/N. The combination can be used in robotics, telecheric applications, biomechanics and virtual reality applications.

Wavelet transform with spectral post-processing for enhanced feature extraction [machine condition monitoring]

Abstract: The quality of machine condition monitoring techniques and their applicability in the industry are determined by the effectiveness and efficiency, with which characteristic signal features are extracted and identified. Because of the weak amplitude and short duration of structural defect signals at the incipient stage, it is generally difficult to extract hidden features from the data measured using conventional spectral techniques. A new approach, based on a combined wavelet and Fourier transformation, is presented in this paper. Experimental studies on a rolling bearing with a localized point defect of 0.25 mm diameter have shown that this new technique provides significantly improved feature extraction capability over the spectral technique.

ReMLab: a Java-based remote, didactic measurement laboratory

Abstract: The availability of didactic experimental laboratories is of utmost importance for technical schools, mainly the engineering faculties. Experimental laboratories, however, represent a great investment, both in term of required money and space, that may become unbearable to the schools, especially when the number of students and the number of subjects that require lab classes increase. Remote laboratories are a very cost-effective solution to this problem, provided that they allow the students to access real instruments from any site connected to Internet without any need for buying commercial software. This paper shows how this goal has been achieved by implementing a Java-based client-server architecture that is presently used as a subsidiary laboratory for the measurement subjects in the Electrical Engineering curriculum at the Politecnico di Milano.

Improved recursive Newton-type algorithm for frequency and spectra estimation in power systems

Abstract: In this paper, a new improved recursive Newton-type algorithm suitable for various measurement applications in electric power systems is presented. It is used for the power system frequency and spectra estimation. The recursive algorithm form is improved with a strategy of sequential tuning of the forgetting factor. By this, the algorithm convergence and accuracy are significantly improved. To show the main algorithm features, the results of computer simulation, laboratory testing (load rejection and unsuccessful synchronization tests) and field data processing are given.

Chaotic pulse position modulation to improve the efficiency of sonar sensors

Abstract: Ultrasonic devices are widely used in robotics as exteroceptive sensors for ranging measurements. Robotic applications often involve a large number of sonars operating concurrently, giving rise to the phenomenon of crosstalk. In this work, the problem of improving performance of ultrasonic devices in the presence of crosstalk and noise is addressed. In order for each device to discriminate its own echo, chaos is exploited to create unique firing sequences. In particular, the firing scheme described in this work is inspired to a modulation scheme used in chaotic communications, called chaotic pulse position modulation (CPPM). The evaluation of the time of flight is performed by a detection filter. The experimental setup consists of a Polaroid 600 electrostatic transducer driven by a continuous CPPM modulator. Experimental results confirm the suitability of the approach.

On-line sensor fault detection, isolation, and accommodation in automotive engines

Abstract: This paper describes the hybrid solution, based on artificial neural networks (ANNs), and the production rule adopted in the realization of an instrument fault detection, isolation, and accommodation scheme for automotive applications. Details on ANN architectures and training are given together with diagnostic and dynamic performance of the scheme.

Digital measurement station for power quality analysis in distributed environments

Abstract: Today there is a wide application of different electronic apparatus that both produce electromagnetic disturbances on the supply power system and are sensitive to them. Power disturbances present on typical electric utility distribution systems degrade product quality, increase process downtime, and dissatisfy commercial customers. For these reasons, the monitoring of the quality of the supply networks has become an issue of international interest. To monitor power quality, in this paper, we propose a digital measurement station. Its main features are remote data transmission capability and reduced cost. It is a PC-based virtual instrument that offers the flexibility due to the high-level programming language, the familiar working environment of Windows, and the low cost of a widely used computer. The local area network or a modem card allows the measurement system to be controlled via a transmission control protocol/Internet protocol network, implementing in this way a distributed power quality evaluation system.

Using run-time reconfiguration for fault injection applications

Abstract: The probability of faults occurring in the field increases with the evolution of the CMOS technologies. It becomes, therefore, increasingly important to analyze the potential consequences of such faults on the applications. Fault injection techniques have been used for years to validate the dependability level of circuits and systems, and approaches have been proposed to analyze very early in the design process the functional consequences of faults. These approaches are based on the high-level description of the circuit or system and classically use simulation. Recently, hardware emulation on FPGA-based systems has been proposed to accelerate the experiments; in that case, an important characteristic is the time to reconfigure the hardware, including re-synthesis, place and route, and bitstream downloading. In this paper, an alternative approach is proposed, based on hardware emulation and run-time reconfiguration. Fault injection is carried out by direct modifications in the bitstream, so that re-synthesizing the description can be avoided. Moreover, with some FPGA families (e.g., Virtex or AT6000), it is possible to reconfigure the hardware partially at run-time. Important time-savings can be achieved when taking advantage of these features, since the injection of a fault necessitates the reconfiguration of only a few resources of the device. The injection process is detailed for several types of faults and experimental results are discussed.

The NIST microforce realization and measurement project

Abstract: The National Institute of Standards and Technology (NIST) has launched a five-year Microforce Realization and Measurement Project focusing on the development of an instrument and laboratory capable of realizing and measuring the SI unit of force below 5/spl times/10/sup -6/ N using the electrical units as the link to the International System of Units (SI). As a proof of principle, a prototype electromechanical balance has been developed to allow comparisons between mechanically and electrically derived forces up to 300 /spl mu/N with a resolution of 15 nN. Results from force comparisons using 1-, 10-, and 20-mg deadweights are presented.

Design rules for robust capacitive sensors

Abstract: Capacitive technologies play an increasingly important role in the fields of industrial and automotive sensors. The noncontact working principle, on the one hand, is the main advantage of this technology; on the other hand, the sensor is thus sensitive to electromagnetic disturbances. This paper describes methods to successfully develop capacitive sensors, which can reliably be operated in harsh industrial and automotive environments. A carrier frequency system combined with a ratiometric evaluation algorithm and a frequency hopping strategy can guarantee safe operation of capacitive sensors.

Fully automated spectral analysis of periodic signals

Abstract: In this paper, we propose a method that allows to make a fully automated spectral analysis of a periodic signal, including a noise analysis, without any user interaction. The only action required from the user is to provide a data record that contains more than two periods of the signal (no integer number of periods is required). No synchronization between the generator and the data acquisition is needed, and different sampling rates are allowed (no integer number of samples/period is required).

Calibration for time domain propagation constant measurements on power cables

Abstract: A method has been developed for characterizing the wave propagation properties of medium voltage (MV) power cables. It delivers the complex propagation constant of lossy cable transmission lines as a function of frequency. The technique is based on time domain measurements and frequency domain analysis of short pulse propagation. Particular attention is paid to the calibration, as samples with arbitrary characteristic impedances can cause multiple reflections in the test setup. The influence of numerical artefacts is also investigated. The developed technique is demonstrated on MV crosslinked polyethylene (XLPE) cables. The results are verified by comparison with frequency domain measurements of the cable S-parameters.

3-D motion system ("data-gloves"): application for Parkinson's disease

Abstract: In this application, three-dimensional electromagnetic sensors have been integrated into a data-glove to accurately model and capture the motion of the human hand. By modeling the movement of the human hand, this system has been shown to accurately measure the tremor evident in subjects with Parkinson's disease (PD). It was found that 11 sensors were sufficient to model the human hand including all the phalanges. A capture rate of 10 measurements/s was achieved. A discrete Fourier analysis has been applied to extract the tremor frequency from the sensor data time series. Further, an analysis of the instantaneous speed of hand motion has been used to extract clinically significant diagnosis. The technique described is seen to provide an objective and quantitative method for the analysis of clinic conditions, such as PD and essential tremor, as a way to assess the effect of therapeutic interventions.

A high precision 24-GHz FMCW radar based on a fractional-N ramp-PLL

Abstract: A 24-GHz FMCW radar system is presented using a fractional-N phase-locked loop ramp generator. This fractional-N ramp generator achieves relative ramp nonlinearities below 10/sup -8/. Among others linear frequency ramps are important tools in high precision FMCW radar systems. Highly linear frequency ramps make post measurement error correction feasible. Other important aspects of the high performance FMCW radar system are the design of the microwave circuit and the digital signal processing of the IF signals. Furthermore, a large RF bandwidth of more than 3 GHz obtained by thorough simulations results in a high range resolution and a good potential measurement accuracy. To maintain this high potential accuracy, a phase slope algorithm is used to calculate the precise range value leading to a significantly better precision with absolute range errors below 0.8 mm, compared to the commonly used spectral center algorithm.

Measurement of current variations for the estimation of software-related power consumption [embedded processing circuits]

Abstract: A current measurement configuration for the estimation of the power consumption of processing systems is presented in this work The problem addressed is to measure the variations of the power supply current of digital circuits (and especially of embedded processing circuits) and to calculate from these measurements the energy consumption variations associated with certain tasks performed by the system software Accurate monitoring of the instantaneous variations of the power supply current provides the appropriate information for the estimation of the power consumption at different operating situations of the processor (core) and of the overall processing system, as well (consumption of peripheral units) The proposed instantaneous current measuring approach, along with the execution of special test programs for analysis of inter-instruction effects, is expected to provide clear information of the power behavior of single-chip processing systems for low-power applications

On the use of intensity optical pumping and coherent population trapping techniques in the implementation of atomic frequency standards

Abstract: The paper summarizes the relative advantages and disadvantages of coherent population trapping (CPT) or intensity optical pumping (IOP) for the implementation of a passive atomic frequency standard using the isotope /sup 87/Rb. This paper outlines the basic principles common to both CPT and IOP when using laser optical pumping, and makes explicit their similarities and their differences. This paper describes experimental results obtained in the same cell on the characteristics of the CPT and IOP /sup 87/Rb-hyperfine-resonance line. The measurements showed that the signal contrast is larger in CPT than in IOP for the same resulting line width; the light shift is smaller in CPT than in IOP, and is easier to control; in principle, a passive frequency standard based on CPT has a smaller size than that based on IOP, due to the absence of a microwave cavity. Conclusions on overall expectations for the future of such frequency standards are drawn.

A quantitative method for evaluating the performances of hyperspectral image fusion

Abstract: Hyperspectral image fusion is a key technique of hyperspectral data processing. In recent years, many fusion methods have been proposed, but there is little work concerning evaluation of the performances of different image fusion methods. In this paper, a method called quantitative correlation analysis (QCA) is proposed, which provides a quantitative measure of the information transferred by an image fusion technique into the output image. Using the proposed method, the performances of different image fusion methods can be compared and analyzed directly based on the images of before and after performing the fusion. The correlation information entropy, based on the developed QCA, is also proposed and testified by numerical simulations. Typical hyperspectral data are applied to the proposed method. The results show that the method is effective, and its conclusions agree with the classification results in applications.

Classification of audio radar signals using radial basis function neural networks

Abstract: Radial basis function (RBF) neural networks are used to classify real-life audio radar signals that are collected by a ground surveillance radar mounted on a tank. Currently, a human operator is required to operate the radar system to discern among signals bouncing off tanks, vehicles, planes, and so on. The objective of this project is to investigate the possibility of using a neural network to perform this target recognition task, with the aim of reducing the number of personnel required in a tank. Different signal classification methods in the neural net literature are considered. The first method employs a linear autoregressive (AR) model to extract linear features of the audio data, and then perform classification on these features, i.e, the AR coefficients. AR coefficient estimations based on least squares and higher order statistics are considered in this study. The second approach uses nonlinear predictors to model the audio data and then classifies the signals according to the prediction errors. The real-life audio radar data set used here was collected by an AN/PPS-15 ground surveillance radar and consists of 13 different target classes, which include men marching, a man walking, airplanes, a man crawling, and boats, etc. It is found that each classification method has some classes which are difficult to classify. Overall, the AR feature extraction approach is most effective and has a correct classification rate of 88% for the training data and 67% for data not used for training.

A traceable precision current source for currents between 100 aA and 10 pA

Abstract: A new calibration setup for picoamperemeters is presented. Owing to the use of a novel voltage ramp generator with increased linearity, the useful measuring time is increased to about 35 min, which reduces the calibration uncertainty of picomaperemeters with long time constants.

Wavelet-based power quantification approaches

Abstract: This paper presents alternative computing methods for power-related quantities using wavelet transforms. First, two alternatives for classical reactive power quantities based on the real wavelet transform are given, having advantages over the methods published in the literature for the calculation of reactive power. They are based on the implementation of a time delay in the wavelet domain and on a method splitting the current into an active and reactive component. Second, a totally different method is presented using complex wavelet transforms, allowing the formulation of power definitions in the time-frequency domain itself, similar to Fourier-based power definitions, but theoretically yielding continuously varying power quantities. All approaches are illustrated with examples.

Material characterization using a quasi-optical measurement system

Abstract: The application of a quasi-optical apparatus in the determination of the relative permittivity of low-loss dielectric materials is presented in this paper. A description of the measurement system and its components is provided. Correction terms are introduced to remove errors due to the position tolerance of the sample and the calibration procedure. Two numerical methods are used to determine the relative permittivity from reflection and transmission coefficients. Good agreement was observed between corrected results obtained with the quasi-optical measurement system and measurements performed by an independent standards testing organization.