Search results for "Adaptive filter"
showing 10 items of 30 documents
In-process tool-failure detection by means of AR models
1997
The present paper proposes a cutting tool breaking and chipping detection system for continuous and interrupted cutting, based on the analysis of the cutting force componentsFx andFy. A multifactorial experimental design has been carried out, to take account of the variability of the force signal. An adaptive signal processing algorithm is proposed, which detects catastrophic failure when at least one component deviates outside an estimated oscillation band for a time duration longer than a prefixed interval. The algorithm has been implemented on a four-microprocessor transputer board. Several tests confirmed the validity of the approach for detecting breaking and chipping phenomena in a fe…
A Novel Approach to Introducing Adaptive Filters Based on the LMS Algorithm and Its Variants
2004
This paper presents a new approach to introducing adaptive filters based on the least-mean-square (LMS) algorithm and its variants in an undergraduate course on digital signal processing. Unlike other filters currently taught to undergraduate students, these filters are nonlinear and time variant. This proposal introduces adaptive filtering in the context of a linear time-invariant system using a real problem. In this way, introducing adaptive filters using concepts already familiar to the students motivates their interest through practical application. The key point for this simplification is that the input to the filter is constant so that the adaptive filter becomes linear. Therefore, a …
A Hybrid Frequency-Space Approach for Shape Measurement by Shadow Moiré Technique with Carrier Fringe Pattern
2006
In this paper, a novel methodology to process fringe pattern is presented. The core of the signal processing technique is the use of the direction information, a modulo 2pi quantity that locally informs about the direction along which fringes grow with maximum rate. By using this information, it was possible to perform adaptive, direction- and orientation-based operations on fringe images in order to remove unwanted effects, to enhance the contrast and to extract the phase information encoded. The method has been applied on shadow moire interferograms with carrier fringes in order to measure the surface of small objects. The developed algorithm allows to process fringes whose phase informat…
A Direction/Orientation-Based Method for Shape Measurement by Shadow MoirÉ
2008
In this paper, a methodology to process fringe patterns is presented. The core of the signal processing technique is the use of the direction information, which is a modulo quantity that locally indicates the direction along which fringes grow at a maximum rate. By using this information, it was possible to perform adaptive and direction/orientation-based operations on fringe images to remove unwanted effects (mainly distortions at the image borders), to enhance the contrast, and to extract the phase information encoded. The method has been applied on shadow-moire interferograms with carrier fringes in order to measure the surface of small objects. The developed algorithm allows processing …
Adaptive Metropolis algorithm using variational Bayesian adaptive Kalman filter
2013
Markov chain Monte Carlo (MCMC) methods are powerful computational tools for analysis of complex statistical problems. However, their computational efficiency is highly dependent on the chosen proposal distribution, which is generally difficult to find. One way to solve this problem is to use adaptive MCMC algorithms which automatically tune the statistics of a proposal distribution during the MCMC run. A new adaptive MCMC algorithm, called the variational Bayesian adaptive Metropolis (VBAM) algorithm, is developed. The VBAM algorithm updates the proposal covariance matrix using the variational Bayesian adaptive Kalman filter (VB-AKF). A strong law of large numbers for the VBAM algorithm is…
Steady-state and tracking analysis of a robust adaptive filter with low computational cost
2007
This paper analyses a new adaptive algorithm that is robust to impulse noise and has a low computational load [E. Soria, J.D. Martin, A.J. Serrano, J. Calpe, and J. Chambers, A new robust adaptive algorithm with low computacional cost, Electron. Lett. 42 (1) (2006) 60-62]. The algorithm is based on two premises: the use of the cost function often used in independent component analysis and a fuzzy modelling of the hyperbolic tangent function. The steady-state error and tracking capability of the algorithm are analysed using conservation methods [A. Sayed, Fundamentals of Adaptive Filtering, Wiley, New York, 2003], thus verifying the correspondence between theory and experimental results.
Sensor Fusion Combining 3-D and 2-D for Depth Data Enhancement
2012
Time-of-Flight (ToF) cameras are known to be cost-efficient 3-D sensing systems capable of providing full scene depth information at a high frame rate. Among many other advantages, ToF cameras are able to provide distance information regardless of the illumination conditions and with no texture dependency, which makes them very suitable for computer vision and robotic applications where reliable distance measurements are required. However, the resolution of the given depth maps is far below the resolution given by standard 2-D video cameras which, indeed, restricts the use of ToF cameras in real applications such as those for safety and surveillance. In this thesis, we therefore investigate…
Binarization of a super-resolving graytone pupil filter by digital halftoning
1995
— Six digital-halftoning procedures, including one algorithm proposed by us, are compared to determine which one is best suited to binarization of a parabolic super-resolving pupil filter. The procedures we deal with include iterative, error-diffusion, error-convergence, and 1-pixel algorithms. We carry out a numerically simulated experiment in which an object that consists of either one point source or two coherent point sources is imaged in a 4f imaging system with either a continuous super-resolving parabolic filter or one of its six different binary versions. The performance of binary filters is examined in terms of two parameters: the resemblance of their amplitude impulse response (AI…
Experimental study on the effects of physical training on the defibrillation threshold
2011
Background: Chest compression artifacts during cardiopulmonary resuscitation (CPR) deteriorate the rhythm diagnosis of automated external defibrillators (AED). Cardiopulmonary resuscitation must therefore be interrupted for a reliable shock/no-shock decision. However, these hands-off intervals adversely affect the defibrillation success, and, in addition, pauses in chest compressions compromise circulation. An accurate diagnosis of the rhythmwhile performing CPR is therefore needed to minimize these hands-off intervals. Methods: The characteristics of the CPR artifact are very variable, and the artifact presents an important spectral overlap with human cardiac arrest rhythms. Consequently, …
A software receiver adaptive phase lock loop method
2009
The aim of this paper is to introduce a new and relatively simple algorithm which is capable to tune the parameters of the loop filter in a phase lock loop, like the one that can be found in a global navigation satellite system receiver. The parameters are chosen while the system is running, in order to make the bandwidth of the filter adaptive with respect to the signal dynamic and strength. A wider bandwidth is obtained to make the filter more reactive when searching the carrier, while the bandwidth gets narrower when the system is in the tracking state, in order to cut off as much noise as possible. The algorithm is based on the observation of the estimated variance of the phase lock loo…