Uncertainty in measurement for x-ray-computed tomography using calibrated work pieces

Schmitt, Robert; Niggemann, Christian

doi:10.1088/0957-0233/21/5/054008

Cited by 60 publications

(30 citation statements)

References 11 publications

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“…They developed an equation characterizing the measurement CT process and calculated the measurement uncertainty according to the GUM. In [15], the authors calculated the measurement uncertainty using experimental methods. In particular, they followed ISO 15530-3 describing the use of calibrated workpieces.…”

Section: Introductionmentioning

confidence: 99%

A study on evaluation strategies in dimensional X-ray computed tomography by estimation of measurement uncertainties

Müller

Hiller

Cantatore

et al. 2012

Int. J. Metrol. Qual. Eng.

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Abstract.Computed tomography has entered the industrial world in 1980's as a technique for nondestructive testing and has nowadays become a revolutionary tool for dimensional metrology, suitable for actual/nominal comparison and verification of geometrical and dimensional tolerances. This paper evaluates measurement results using different measuring strategies applied in different inspection software packages for volume and surface data analysis. The strategy influence is determined by calculating the measurement uncertainty. This investigation includes measurements of two industrial items, an aluminium pipe connector and a plastic toggle, a hearing aid component. These are measured using a commercial CT scanner. Traceability is transferred using tactile and optical coordinate measuring machines, which are used to produce reference measurements. Results show that measurements of diameter for both parts resulted in smaller systematic errors compared to distance and height measurements. It was found that uncertainties of all measurands evaluated on surface data were generally greater compared to measurements performed on volume data.

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Section: Introductionmentioning

confidence: 99%

A study on evaluation strategies in dimensional X-ray computed tomography by estimation of measurement uncertainties

Müller

Hiller

Cantatore

et al. 2012

Int. J. Metrol. Qual. Eng.

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“…Three main different applied procedures to estimate the measurement uncertainty exist and are classified as follows [ 9 , 17 , 18 ]:…”

Section: Measurement Uncertainty Assessment Using Ct: a Reviewmentioning

confidence: 99%

“…Despite the high number of repeated experiments necessary for statistical validation, this procedure is currently regarded by many authors as the most accepted for CT measurements. Several articles consider and apply the ISO 15530-3 standard [ 17 , 18 , 29 , 30 ] and the VDI/VDE 2630-2.1 version [ 31 ]. However, the VDI standard in its current version only considers geometries accessible from outside the workpiece, not considering the measurement characterization capability of internal features that is the most distinguishing advantage of CT and µCT metrological systems.…”

Section: Measurement Uncertainty Assessment Using Ct: a Reviewmentioning

confidence: 99%

Experimental Approach for the Uncertainty Assessment of 3D Complex Geometry Dimensional Measurements Using Computed Tomography at the mm and Sub-mm Scales

Jiménez

Torralba

Yagüe‐Fabra

et al. 2017

Sensors

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The dimensional verification of miniaturized components with 3D complex geometries is particularly challenging. Computed Tomography (CT) can represent a suitable alternative solution to micro metrology tools based on optical and tactile techniques. However, the establishment of CT systems’ traceability when measuring 3D complex geometries is still an open issue. In this work, an alternative method for the measurement uncertainty assessment of 3D complex geometries by using CT is presented. The method is based on the micro-CT system Maximum Permissible Error (MPE) estimation, determined experimentally by using several calibrated reference artefacts. The main advantage of the presented method is that a previous calibration of the component by a more accurate Coordinate Measuring System (CMS) is not needed. In fact, such CMS would still hold all the typical limitations of optical and tactile techniques, particularly when measuring miniaturized components with complex 3D geometries and their inability to measure inner parts. To validate the presented method, the most accepted standard currently available for CT sensors, the Verein Deutscher Ingenieure/Verband Deutscher Elektrotechniker (VDI/VDE) guideline 2630-2.1 is applied. Considering the high number of influence factors in CT and their impact on the measuring result, two different techniques for surface extraction are also considered to obtain a realistic determination of the influence of data processing on uncertainty. The uncertainty assessment of a workpiece used for micro mechanical material testing is firstly used to confirm the method, due to its feasible calibration by an optical CMS. Secondly, the measurement of a miniaturized dental file with 3D complex geometry is carried out. The estimated uncertainties are eventually compared with the component’s calibration and the micro manufacturing tolerances to demonstrate the suitability of the presented CT calibration procedure. The 2U/T ratios resulting from the validation workpiece are, respectively, 0.27 (VDI) and 0.35 (MPE), by assuring tolerances in the range of ± 20–30 µm. For the dental file, the EN < 1 value analysis is favorable in the majority of the cases (70.4%) and 2U/T is equal to 0.31 for sub-mm measurands (L < 1 mm and tolerance intervals of ± 40–80 µm).

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“…15,16 A reference workpiece similar to the actual measurement objects has to be calibrated using a high point density almost similar to the one used during the CT measurements. Different operators measure this calibrated workpiece repeatedly.…”

Section: Measurement Uncertaintymentioning

confidence: 99%

Computed tomography in quality control: chances and challenges

Weckenmann

Krämer

2013

Proceedings of the Institution of Mechanical Engineers, Part B:

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Since the first applications of computed tomography for medical diagnostics in the 1970s, the technology has been rapidly adopted for non-destructive testing of casted workpieces or complex assemblies. In 2005, the first coordinate measuring machine with computed tomography sensor has been presented for manufacturing metrology and quality control. Today, there exist numerous different manufacturers as the benefits for metrology are convincing. Computed tomography offers the possibility to acquire a measurement object holistically, that is, the whole volume of the object, not only the surface, with a very high point density of typically several millions of points. Current research and development activities are focused on several different aspects of computed tomography. First, the machine components are analysed and improved with respect to application in metrology. Larger detectors with better resolution or X-ray tubes with smaller focal spots may help in improving the machine's accuracy. Second, algorithms for reconstruction and artefact reduction are developed, especially for metrological purpose. As technical measurement objects feature a greater variety of material properties than in medical diagnostics, different strategies have to be investigated. The most crucial point is that not only the image quality of the radiographies or the reconstructed data is important but also the measurement accuracy plays the decisive role. Finding the interrelation between image quality and measurement accuracy is an important research topic. Third, from a metrological point view, the determination of measurement accuracy and measurement uncertainty for computed tomography measurements is an important task. Methods for experimental and simulationbased uncertainty determination are developed at the time being.

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Uncertainty in measurement for x-ray-computed tomography using calibrated work pieces

Cited by 60 publications

References 11 publications

A study on evaluation strategies in dimensional X-ray computed tomography by estimation of measurement uncertainties

A study on evaluation strategies in dimensional X-ray computed tomography by estimation of measurement uncertainties

Experimental Approach for the Uncertainty Assessment of 3D Complex Geometry Dimensional Measurements Using Computed Tomography at the mm and Sub-mm Scales

Computed tomography in quality control: chances and challenges

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