1,721,088 research outputs found
Measurement errors in the scanning of piezoresistive sensors arrays
No full textArrays of piezoresistive sensors (PRS), which an often used for tactile sensing, suffer from crosstalk between adjacent elements that can alter the readings of the force applied. In this paper, the sources of errors, with specific reference to crosstalk and electronic circuitry used to scan the array, are examined. The solutions presented in the literature are discussed, evaluating their performance and errors. From this analysis, some guidelines can be derived for the use of scanning circuits. (C) 1999 Elsevier Science S.A. All rights reserved
Markeless systems for the analysis of movement
No full textMarkeless systems for the analysis of movemen
Extraction of the envelope from surface EMG signals
No full textThe envelope of a surface myoelectric signal has been historically related to the force exerted
by muscles during contraction. In fact, during isometric contractions, signal amplitude has
been shown to be linearly related to the force. This relationship is no longer valid when
myoelectric data are recorded during body movement.
In routine work, the envelope of the signal is extracted by means of a technique based on a
full-wave rectifier followed by an integrator (smoothing filter) giving rise to the so-called
Integrated ElectroMyography (IEMG). This technique presents some drawbacks that are
mainly related to the subjective choice of parameters and to the loss of adaptivity to signal
characteristics, which limit its use in dynamic protocols and affects the comparison of results
obtained by different experimenters.
New approaches are therefore needed. This paper presents a method which aims to improve
the quality of the estimation and the standardization of the results while, at the same time,
being suitable for signals recorded both in static and dynamic conditions.
The new approach is based on an adaptive iterative procedure which automatically sets and
dynamically changes (according to signal characteristics) the length of the smoothing filter
used for the estimation.
The estimation error is far lower than that given by classical estimators and approaches the
theoretical lower bound. Moreover, the automatic choice of filter length guarantees good
repeatability of the results and standardization in the processing approaches. This technique
can therefore help in analyzing myoelectric signals recorded during dynamic protocols, and
in studying the physiological mechanism driving muscular force during movement, and also
the evolution of muscular fatigue
Spectral analysis for non-stationary signals from mechanical measurements: A parametric approach
No full textNon-parametric time-frequency methods for spectral estimation are increasingly used in the analysis of non-stationary signals. However, neither have their performance and limits of application been completely investigated nor has a comparison with other methods, such as parametric ones, been clearly established. This paper deals with the analysis of nonstationary signals of interest in mechanics, and more specifically, the performance of some non-parametric methods widely used for this analysis will be discussed; an autoregressive time-varying method, improved with respect to the classical parametric implementation, will be presented and its potential in analysing signals coming from mechanical systems will be shown; the performance of parametric and non-parametric methods will be compared. (C) 1999 Academic Press
BioLab3 - Sito Web del Laboratorio di Ingegneria Biomedica del Dipartimento di Elettronica Applicata
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