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

Abstract

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%.

Data Measuring System for Torque Measurement on Running Shafts Based on a Non-Contact Torsional Dynamometer

“…Torsional dynamometers are divided into strain-gauge [3,[5][6][7][10][11][12] and torque [4,8,9,[13][14][15][16][17][18]. Work process of the torsional torque dynamometer, in contrast to the torsional strain-gauge dynamometer, is based on direct or indirect measurement of a twisting angle of the torsional shaft.…”

“…Devices designed to measure the torque can be divided into four classes according to the principle of operation: cradle dynamometers, torsional indicators, transmission dynamometers and transducers for measuring by extrinsic parameters . Torsion dynamometers are usually inertialess instruments and perform only the measuring function, enabling to record both the time averages and ever-varying values of the engine torque during its operation in any modes [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”

Investigating wind turbine dynamic transient loads using contactless shaft torque measurements

“…The contactless torque meter proposed in this research consists of two black and white striped codes, with equal stripe pairs, directly glued around the shaft scanned by two optical sensors mounted on non‐rotating supports. The operating principle of the contactless torque meter has been described in details in [14]. As schematically shown in Fig.…”

“…The calibration curve shows an R 2 value of 0.999, indicating a good fit of the experimental data by the regression line. The statistical analysis of the residuals of the calibration data has provided an expanded measurement uncertainty, with respect to the system full‐scale torque, of ±0.3% [14].…”

A Self-Powered and Battery-Free Vibrational Energy to Time Converter for Wireless Vibration Monitoring

“…A non-contact vibration monitoring technique employing WSNs could prove especially advantageous in this scenario over more conventional methods involving contact between the sensor and control system. Non-contact techniques to date have been based on magnetostrictive sensors [13,14] and optical sensors [15]. Such non-contact sensors, however, are limited in their dependence on external battery sources and sensitivity to harsh operating environments [16].…”