Compensation for encoder geometry and shaft speed variation in time interval torsional vibration measurement

Resor, Brian Ray; Trethewey, Martin W.; Maynard, Kenneth P.

doi:10.1016/j.jsv.2004.10.044

Cited by 54 publications

(35 citation statements)

References 9 publications

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“…The method is derived and then tested against simulated and laboratory experiments. The results indicate that the proposed method is capable of accurately determining the shaft encoder geometry for any shaft speed profile.1 The term 'zero-crossing time' is sometimes used exclusively to indicate the exact time a signal changes sign, like a sine wave passing through 0 V. For the purposes of this article and related literature [6], the term 'zero-crossing time' is used to indicate the exact time a signal has passed a prescribed threshold value (2.5 V in the case of TTL signals).…”

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confidence: 90%

Online shaft encoder geometry compensation for arbitrary shaft speed profiles using Bayesian regression

Diamond

Heyns

Oberholster

2016

Mechanical Systems and Signal Processing

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The measurement of instantaneous angular speed is being increasingly investigated for its use in a wide range of condition monitoring and prognostic applications. Central to many measurement techniques are incremental shaft encoders recording the arrival times of shaft angular increments. The conventional approach to processing these signals assumes that the angular increments are equidistant. This assumption is generally incorrect when working with toothed wheels and especially zebra tape encoders and has been shown to introduce errors in the estimated shaft speed. There are some proposed methods in literature that aim to compensate for this geometric irregularity. Some of the methods require the shaft speed to be perfectly constant for calibration, something rarely achieved in practice. Other methods assume the shaft speed to be nearly constant with minor deviations. Therefore existing methods cannot calibrate the entire shaft encoder geometry for arbitrary shaft speeds.The present article presents a method to calculate the shaft encoder geometry for arbitrary shaft speed profiles. The method uses Bayesian linear regression to calculate the encoder increment distances. The method is derived and then tested against simulated and laboratory experiments. The results indicate that the proposed method is capable of accurately determining the shaft encoder geometry for any shaft speed profile.1 The term 'zero-crossing time' is sometimes used exclusively to indicate the exact time a signal changes sign, like a sine wave passing through 0 V. For the purposes of this article and related literature [6], the term 'zero-crossing time' is used to indicate the exact time a signal has passed a prescribed threshold value (2.5 V in the case of TTL signals).

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confidence: 90%

Online shaft encoder geometry compensation for arbitrary shaft speed profiles using Bayesian regression

Diamond

Heyns

Oberholster

2016

Mechanical Systems and Signal Processing

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“…Since the spacing pattern repeats itself after each revolution, the error manifests itself as high-level content at integer multiples of the shaft running speed. It is possible to use the synchronous averaged encoder passage times to correct for the uneven encoder spacing [Resor, et al -2005]. These errors are unavoidable, but the production standards are very high and great precision can be obtained.…”

Section: Mhz F Count 80mentioning

confidence: 99%

Instantaneous Angular Speed: Encoder-Counter Estimation Compared with Vibration Data

Spagnol

Bregant

2013

Lecture Notes in Mechanical Engineering

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In rotating machinery, actions of the moving parts take place at specific angular positions rather than at specific times. For this reason, having a geometrical reference, such as the one provided by an encoder, and studying the Instantaneous Angular Speed (IAS) variations can provide a large amount of information about the health status of the machine. In fact, from the variation of the IAS during the machine loads' cycle it is possible to identify defects and faults. The current work focuses on the estimation of the IAS through the Elapsed Time (ET) method, using a counter in order to measure the time elapsed between the pulses of an encoder. Both IAS and vibration measurement are conducted on an asynchronous four poles electrical motor driven by 50Hz line current, without load. The study compares the order analysis of both signals. The bearing's Fundamental Train Frequency is detected using IAS estimation.

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“…A number of similar TIMS concepts have been developed since this one was first published in 1986. See [14] for examples. The method gets more attractive with the advancement of the capability of computers and data acquisition hardware.…”

Section: Time-interval Measurement Systemsmentioning

confidence: 99%

Torsional Vibration

2010

Machinery Vibration and Rotordynamics

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Compensation for encoder geometry and shaft speed variation in time interval torsional vibration measurement

Cited by 54 publications

References 9 publications

Online shaft encoder geometry compensation for arbitrary shaft speed profiles using Bayesian regression

Online shaft encoder geometry compensation for arbitrary shaft speed profiles using Bayesian regression

Instantaneous Angular Speed: Encoder-Counter Estimation Compared with Vibration Data

Torsional Vibration

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