 
Zebra-tape torque measurement: Dataset

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 Funding:
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This work was funded as part of the UK EPSRC SUPERGEN Wind Hub, EP/L014106/1.

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 Related Publication:
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 Non-intrusive torque measurement for rotating shafts using optical sensing of zebra-tapes 
 D Zappal, M Bezziccheri, C J Crabtree and N Paone
 Measurement Science and Technology
 2018
 
 DOI: 10.1088/1361-6501/aab74a
 
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 Abstract:
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 Non-intrusive, reliable and precise torque measurement is critical to dynamic performance 
 monitoring, control and condition monitoring of rotating mechanical systems. This paper
 presents a novel, contactless torque measurement system consisting of two shaft-mounted
 zebra tapes and two optical sensors mounted on stationary rigid supports. Unlike conventional
 torque measurement methods, the proposed system does not require costly embedded
 sensors or shaft-mounted electronics. Moreover, its non-intrusive nature, adaptable design,
 simple installation and low cost make it suitable for a large variety of advanced engineering
 applications. Torque measurement is achieved by estimating the shaft twist angle through
 analysis of zebra tape pulse train time shifts. This paper presents and compares two signal
 processing methods for torque measurement: rising edge detection and cross-correlation. The
 performance of the proposed system has been proven experimentally under both static and
 variable conditions and both processing approaches show good agreement with reference
 measurements from an in-line, invasive torque transducer. Measurement uncertainty has
 been estimated according to the ISO GUM (Guide to the expression of uncertainty in
 measurement). Type A analysis of experimental data has provided an expanded uncertainty
 relative to the system full-scale torque of 0.30% and 0.86% for the rising edge and crosscorrelation
 approaches, respectively. Statistical simulations performed by the Monte Carlo
 method have provided, in the worst case, an expanded uncertainty of 1.19%.
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 Archive release: Copyright 2018 Donatella Zappal/ Christopher J Crabtree

 Department of Engineering
 Durham University
 Lower Mountjoy
 South Road, Durham
 DH1 3LE
 United Kingdom

 Email: donatella.zappala@durham.ac.uk
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There are three folders provided. Each of the folders contains the following:

A) Calibration_data
This folder contains two sub-folders: 1) Rising Edge_data and 2) Cross Correlation_data containing the torque (Magtrol)/twist (optical probes) data in .mat format. The algorithm results are based on these initial calibration data.

B) Steady state tests
This folder contains the results from the steady state tests @1700rpm and 4Nm and @1900rpm and 10Nm. For each case two .mat files are produced providing the speed and torque data.The files contains the reference torque transducer measurements and the torque measurments obtained from the zebra tapes by applying the rising edge and cross correlation algorithms.

C) Variable torque and speed tests
This folder contains the results from the variable torque and speed tests in .csv format. It conains two sub-folders: 1) Sharp step torque test and 2) Varying frequency test. In each case the files contain the reference torque transducer measurements and the torque measurments obtained from the zebra tapes by applying the rising edge and cross correlation algorithms.  

Zebra tape pulse train analysis has been implemented in LabView. The shaft rotational speed has been calculated by estimating the time per shaft revolution from the rising edges of the two pulse trains. The shaft absolute twist has been calculated by adopting the rising edge detection and the cross-correlation approaches. 

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For any questions please do not hesitate to contact me.