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Non-intrusive torque measurement for rotating shafts using optical sensing of zebra-tapes

Zappalá, D.; Bezziccheri, M.; Crabtree, C.J.; Paone, N.

Non-intrusive torque measurement for rotating shafts using optical sensing of zebra-tapes Thumbnail


D. Zappalá

M. Bezziccheri

N. Paone


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 cross-correlation approaches, respectively. Statistical simulations performed by the Monte Carlo method have provided, in the worst case, an expanded uncertainty of ±1.19 %.


Zappalá, D., Bezziccheri, M., Crabtree, C., & Paone, N. (2018). Non-intrusive torque measurement for rotating shafts using optical sensing of zebra-tapes. Measurement Science and Technology, 29(6), Article 065207.

Journal Article Type Article
Acceptance Date Mar 16, 2018
Online Publication Date May 10, 2018
Publication Date Jun 1, 2018
Deposit Date May 22, 2017
Publicly Available Date Mar 19, 2018
Journal Measurement Science and Technology
Print ISSN 0957-0233
Electronic ISSN 1361-6501
Publisher IOP Publishing
Peer Reviewed Peer Reviewed
Volume 29
Issue 6
Article Number 065207


Accepted Journal Article (1.8 Mb)

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Copyright Statement
As the Version of Record of this article is going to be/has been published on a gold open access basis under a CC BY 3.0 licence, this Accepted Manuscript is available for reuse under a CC BY 3.0 licence immediately.

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