The Experts below are selected from a list of 237 Experts worldwide ranked by ideXlab platform
R.c. Kavanagh - One of the best experts on this subject based on the ideXlab platform.
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Performance analysis and compensation of M/T-type digital Tachometers
IEEE Transactions on Instrumentation and Measurement, 2001Co-Authors: R.c. KavanaghAbstract:New analyses are presented of the widely used M/T-type digital Tachometer. This device incorporates accurate time measurement with pulse counting. It is shown that the accuracy of velocity measurement in real implementations is significantly poorer than indicated previously. Encoder nonidealities are found to introduce a bias in the measured velocity output. A significant rms output error can also result. The insensitivity of the error to the form of the encoder noise model is demonstrated, and two analyses of differing complexity are presented. These permit calculation of the Tachometer error measures, based on a knowledge of the magnitude of the error characteristics of the encoder. This facilitates the implementation of a compensation function that will reduce the influence of the bias. Experimental results are presented which demonstrate the existence of the bias, verify the validity of the derived formulae, and show the benefit to be gained by compensation.
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Performance analysis of M/T-type digital Tachometers
Proceedings of the 17th IEEE Instrumentation and Measurement Technology Conference [Cat. No. 00CH37066], 2000Co-Authors: R.c. KavanaghAbstract:New analyses are presented of the widely used M/T-type digital Tachometer. This device incorporates accurate time measurement with pulse counting. It is shown that the accuracy of velocity measurement in real implementations is significantly poorer than indicated previously. Encoder nonidealities are found to introduce a bias in the measured velocity output. A significant rms output error can also result. The insensitivity of the error to the form of the encoder noise model is demonstrated and two analyses of differing complexity are presented. These permit calculation of the Tachometer error measures, based on a knowledge of the magnitude of the error characteristics of the encoder. This facilitates the implementation of a compensation function that will reduce the influence of the bias. Experimental results are presented which demonstrate the existence of the bias and verify the validity of the derived formulae.
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Improved digital Tachometer with reduced sensitivity to sensor nonideality
IEEE Transactions on Industrial Electronics, 2000Co-Authors: R.c. KavanaghAbstract:A constant sample-time digital Tachometer, similar to Ohmae's "M/T" method, is described. This system is capable of accurate determination of shaft velocity, based on the outputs of an incremental encoder. Previous error analyses of such devices which consider only the asynchronous nature of counter operation are shown to be specious. It is highlighted that sensor nonidealities, including variations in the transition locations from their nominal values and phasing errors between encoder channels, can produce much larger Tachometer errors. An estimate is made of the actual RMS output error, based on a simple encoder model and simplified analysis. It is shown that the error can be significantly reduced by operating four sub-circuits in parallel, each dealing with either a low-to-high or high-to-low transition of a single incremental encoder signal. A field-programmable-gate-array/digital-signal processor-based practical implementation is described. Both simulation and experimental results are presented which confirm the utility of the enhanced digital Tachometer.
N. P. Cheragin - One of the best experts on this subject based on the ideXlab platform.
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A Fabry-Pérot etalon as fourier Tachometer
Solar Physics, 1996Co-Authors: I. E. Kozhevatov, E. H. Kulikova, N. P. CheraginAbstract:A Tachometer for measuring the displacements of the center of gravity of spectral line profiles is developed. The implementation of the device, basically a Fabry-Pérot etalon, is given. The spectral shifts are determined, using the frequency of a laser as reference.
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A Fabry-Pérot etalon as fourier Tachometer
Solar Physics, 1996Co-Authors: I. E. Kozhevatov, E. H. Kulikova, N. P. CheraginAbstract:A Tachometer for measuring the displacements of the center of gravity of spectral line profiles is developed. The implementation of the device, basically a Fabry-Perot etalon, is given. The spectral shifts are determined, using the frequency of a laser as reference.
I. E. Kozhevatov - One of the best experts on this subject based on the ideXlab platform.
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A Fabry-Pérot etalon as fourier Tachometer
Solar Physics, 1996Co-Authors: I. E. Kozhevatov, E. H. Kulikova, N. P. CheraginAbstract:A Tachometer for measuring the displacements of the center of gravity of spectral line profiles is developed. The implementation of the device, basically a Fabry-Pérot etalon, is given. The spectral shifts are determined, using the frequency of a laser as reference.
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A Fabry-Pérot etalon as fourier Tachometer
Solar Physics, 1996Co-Authors: I. E. Kozhevatov, E. H. Kulikova, N. P. CheraginAbstract:A Tachometer for measuring the displacements of the center of gravity of spectral line profiles is developed. The implementation of the device, basically a Fabry-Perot etalon, is given. The spectral shifts are determined, using the frequency of a laser as reference.
John Snyder - One of the best experts on this subject based on the ideXlab platform.
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novel method for rolling element bearing health assessment a Tachometer less synchronously averaged envelope feature extraction technique
Mechanical Systems and Signal Processing, 2012Co-Authors: David Siegel, Hassan Alatat, Vishwesh Shauche, Linxia Liao, John SnyderAbstract:Abstract The assessment and diagnosis of bearing health using vibration data has been a research topic of interest for many years and includes developments in an assortment of signal processing methods and classification algorithms. This paper investigates detecting bearing degradation at different levels of damage, in that estimating the bearing health at the various stages of degradation is important for predicting failure as well as making maintenance decisions. The proposed technique does not require a measure of the rotational shaft speed or bearing cage speed, which makes it very suitable in certain applications in which it is very difficult or not cost effective to measure the rotational speed. To effectively estimate the bearing health state, a novel Tachometer-less synchronously averaged envelope (TLSAE) signal processing and feature extraction technique for rolling element bearing is proposed. The Tachometer-Less Synchronous Averaged Envelope (TLSAE) method consists of first using a narrow band pass filter around a calculated bearing fault frequency of interest and using the derivative of the phase of the Hilbert Transform of this narrow band signal to generate a synthesized Tachometer signal that is representative of the impact due to a bearing defect. This synthesized Tachometer signal is combined with the high frequency envelope method to perform synchronous averaging on the envelope signal, resulting in a defect synchronous envelope spectrum in which the frequency content is in terms of the fault frequency orders. The proposed method is further compared and evaluated with other existing methods, in particular to the traditional Fourier Transform technique, the bearing envelope analysis technique, and the empirical mode decomposition signal processing methods on the basis of whether each method provides an enhanced level of indication that can determine the health of rolling element bearings. Data from a bearing test-rig is used to facilitate the comparison and evaluation of the signal processing methods. Vibration data was collected from the test-rig for bearings with different levels of degradation. The calculated vibration features from the Tachometer-less synchronously averaged envelope (TLSAE) technique are compared to the other feature extraction techniques; with the synchronous average method providing a set of bearing vibration features that can distinguish all three levels of damage on the outer race of the rolling element bearing. Future work looks to further investigate this proposed technique for data collected during a run to failure test in order to consider its merits for early detection of incipient bearing damage and whether it provides a consistent monotonic trend from spall initiation to bearing failure.
Eusebio Bernabeu - One of the best experts on this subject based on the ideXlab platform.
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A magneto-optical Tachometer for anti-lock braking systems using plastic optical fibre
Measurement Science and Technology, 1994Co-Authors: H. Guerrero, J. L. Escudero, Eusebio BernabeuAbstract:A magneto-optical Tachometer specially designed for an automotive anti-lock braking system is described. It employs a plastic optical fibre for the bidirectional data transmission and its transducing mechanism is magneto-optical. It uses a Bi-substituted iron garnet as sensor element and a ferromagnetic tooth gear, which produces 46 pulses per turn. Owing to its compact design and its constitutive materials it is suitable for withstanding all the environmental hazards present in the car. The Tachometer can measure car speeds of 0-400 km h-1 with a signal variation less than 0.6 dB throughout the whole range.
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Magneto-optical Tachometer using plastic optical fibre
Measurement Science and Technology, 1993Co-Authors: H. Guerrero, J. L. Escudero, Eusebio BernabeuAbstract:A magneto-optical Tachometer using plastic optical fibre is described. This was specially designed for an automotive ABS braking device (antilock braking system). It uses a plate of polycrystalline CdMnTe developed by the authors as sensor element. Due to its compact design and its constitutive materials it is suitable for withstanding all the environmental hazards present in the car. The Tachometer can measure wheel speed from 0 to 300 km h-1 with a signal variation less than 11 dB throughout the whole range.
