Estimation of Uncertainty for the Torque Transducer in MNm Range—Classical Approach and Fuzzy Sets

Abstract

The article provides an analysis of the metrological properties of a 5 MN·m torque transducer. The relative electrical signal (given in electrical units, mV/V) as a function of torque measured in both the clockwise and anticlockwise directions was monitored. To fit the data, the weighted method of least squares with both a straight-line and a cubic spline curve was used. The results of the analysis indicated that the straight-line fitting method produced smaller values of expanded uncertainty than the cubic spline fitting method. Additionally, the study confirmed the assumptions that the Monte Carlo method for propagating uncorrelated distributions was more accurate than the uncertainty propagation method, regardless of the type of curve fitting used. From the estimated uncertainty coverage corridor at selected measurement points, confidence intervals–expanded uncertainties were determined. Additionally, the fuzzy sets approach to the evaluation of uncertainty was presented, and the approximate value of the expanded uncertainty was calculated.

Keywords

• torque transducer
• reference torque standard machine
• measurement uncertainty
• calibration
• wind energy
• weighted least squares method