Consolatina Liguori

A DSP-based FFT-analyzer for the fault diagnosis of rotating machine based on vibration analysis

A DSP-based measurement system dedicated to the vibration analysis on rotating machines was designed and realized. Vibration signals are on-line acquired and processed to obtain a continuous monitoring of the machine status. In case of fault, the system is capable of isolating the fault with a high reliability. The paper describes in detail the approach followed to built up fault and unfault models together with the chosen hardware and software solutions. A number of tests carried out on small-size three-phase asynchronous motors highlights high promptness in detecting faults, low false alarm rate, and very good diagnostic performance.

An automatic measurement system for the evaluation of carotid intima-media thickness

This paper presents an automatic system for the measurement of carotid intima-media thickness (IMT) that is based on the digital processing of ultrasound images. The measurement technique is described in detail, highlighting the advantages compared to other methods and, reporting some experimental results. Finally, an analytical approach is used to estimate the intrinsic accuracy of the system.

Propagation of uncertainty in a discrete Fourier transform algorithm

Abstract The problem of evaluating the uncertainty that characterises discrete Fourier transform output data is dealt with, using a method based on a ‘white box’ theoretical approach. The main sources of uncertainty (quantization, time jitter, microprocessor finite wordlength) are analysed obtaining equations useful to evaluate the uncertainty in both module and phase output values, for any hardware configuration and for any algorithm operating condition. The theoretical results, verified by both simulation and experimental tests, can be particularly useful for any designer and user of DFT-based instruments, since they allow the measurement configuration to be optimised with respect to the final uncertainty.

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

The paper describes the hybrid solution, based on Artificial Neural Networks, ANNs, and production rule adopted in the realization of an Instrument Fault Detection, Isolation, and Accommodation scheme for automotive applications. Details on the ANN architectures and training are given together with diagnostic and dynamic performance of the scheme.

On-line fault detection and diagnosis obtained by implementing neural algorithms on a digital signal processor

A measurement instrument for on-line fault detection and diagnosis is proposed. It is based on the implementation of a neural network algorithm on a processor specialized in digital signal processing and provided with suitable data acquisition and generation units. Two specific implementations are detailed. The former uses the neural-network to simulate on-line the correct system behavior, thus allowing the fault detection to be achieved by comparing the neural network output with the measured one. The latter uses the neural network to classify on-line the system as correct or faulty, thus allowing the fault detection and diagnosis to be achieved simultaneously. These two implementations are applied to detect on-line and diagnose faults on a real system in order to point out different fields of application and to highlight the performance of the measurement apparatus.

Estimation of signal parameters in the frequency domain in the presence of harmonic interference: a comparative analysis

In this paper, a novel method for the estimation of the parameters of the spectral components of a signal, also in the case of harmonic interference, is characterized and compared to other methods proposed in literature. The comparison criteria include the evaluation of residual errors and uncertainties on estimated parameters for different multicomponent signals.

Analytical redundancy for sensor fault isolation and accommodation in public transportation vehicles

The paper discusses an instrument fault detection, isolation, and accommodation procedure for public transportation vehicles. After a brief introduction to the topic, the rule set implementing the procedure with reference to the kinds of sensors usually installed on public transportation vehicles is widely discussed. Particular attention is paid to the description of the rules aimed at allowing the vehicle to continue working regularly even after a sensor fault develops. Finally, both the estimated diagnostic and dynamic performances in the off-line processing of the data acquired in several drive tests are then analyzed and commented upon.

An intelligent FFT-analyzer

An intelligent FFT analyzer capable of adapting its operating parameters on the basis of the signal spectrum was set up and characterized. The realized instrument is based on a parameter optimization procedure which provides the instrument with auto-configuration capability. It was implemented on a multiple processor DSP architecture in order to achieve real-time behavior. The experimental tests carried out on a large number of signals highlight the instrument capability of correctly detecting tones with a good frequency resolution whatever the signal spectrum type.

Uncertainty evaluation in algorithms with conditional statement

A a t This paper proposes a methodology for the uncertainty evaluation of digifal signul processing algorithms including condifional insfructions (if-then-else satemenls). In agreement with fhe suggesfion of the IS0 Guide for the expression of uncerfainty in measurement, a probabilistic approach is proposed The application lo different algorifhms characterized by significanf decision phases is approached theoretically, verifiing fhe results also by suifable simulation The generality and suitability of fheproposed approach is fhenproved on a number of different real world applications.

An intelligent FFT-analyzer with harmonic interference effect correction and uncertainty evaluation

In the paper, the problem of the correction of harmonic interference effects on FFT results is discussed. A procedure for the effect evaluation and correction is proposed and implemented in an intelligent FFT-analyzer able also to provide the results with their uncertainty.