scholarly journals Analysis and Realization of Sampling Strategy in Coordinate Metrology

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Syed Hammad Mian ◽  
Abdulrahman Al-Ahmari ◽  
Hisham Alkhalefah
Keyword(s):  
Grid Point ◽  
Coordinate Measuring Machine ◽  
Sampling Strategy ◽  
Surface Characteristics ◽  
Optimization Techniques ◽  
Point Distribution ◽  
Solution Approach ◽  
Coordinate Metrology ◽  
Measuring Machine ◽  
Distribution Algorithms

The stringent customer demands and competitive market emphasize the importance of efficient and effective inspection in industrial metrology. Therefore, the implementation of an appropriate sampling strategy, i.e., the number of points and their distribution, has become very important in the inspection process using a coordinate measuring machine. Moreover, the quality of inspection results has frequently been influenced by sampling plan as well as workpiece size and surface characteristics. It has been an indispensable problem in the present-day measurement processes. Thus, this paper investigates various sample sizes and different point distribution algorithms that can be employed in the evaluation of form error. The effect of specimen size and surface quality on the sampling strategy has also been investigated. Furthermore, this work employs a fuzzy based Technique for Order Performance by Similarity to Ideal Solution approach to realize the best sampling strategy. The results have demonstrated the significance of robust optimization techniques as well as the importance of a suitable sampling strategy in coordinate metrology. This study has also established that Poisson point distribution achieved the best accuracy and the Grid point distribution had taken the least measurement time.

Application of the sampling strategies in the inspection process

2017 ◽  
Vol 231 (4) ◽  
pp. 565-575 ◽  
Author(s):  
Syed Hammad Mian ◽  
Abdulrahman M Al-Ahmari
Keyword(s):  
Sample Size ◽  
Adaptive Sampling ◽  
Sampling Methods ◽  
Fundamental Problem ◽  
Coordinate Measuring Machine ◽  
Sampling Strategy ◽  
Point Distribution ◽  
Coordinate Metrology ◽  
Inspection Process ◽  
Measuring Machine

The selection of appropriate sample size and point distribution on the measuring surface has been a fundamental problem in the contemporary coordinate metrology. It is usually resolved by the users depending on their instinct or prior experience. As a result, inspection results have to be compromised between accuracy and measurement time. However, to deliver quality products in minimum time, effort, and cost, a reliable and an efficient sampling plan is mandatory. Although there have been a remarkable progress due to the development of various procedures for computing the sample size and selecting the appropriate point distribution, still users are inconversant with the characteristics and applications of the available sampling methods due to the absence of a proper review. Accordingly, a systematic review, giving insight into the various strategies available for the sample size and the point distribution, is presented. In this article, different algorithms and their application in the estimation of sample size and point distribution have been reviewed comprehensively. The classification of sampling methods and the importance of adaptive sampling have also been described. It has been concluded that the effectiveness of inspection process or the performance of coordinate measuring machine can be escalated through the application of a suitable sampling strategy. Therefore, the metrologists should either develop an effective method for defining sampling strategy or select the most suitable method from the available resources before carrying out the inspection process.

Evaluation of Actual Geometric Tolerances Using Coordinate Measuring Machine Data

1989 ◽  
Author(s):  
W. H. ElMaraghy ◽  
Z. Wu ◽  
H. A. ElMaraghy
Keyword(s):  
Three Dimensional ◽  
Measurement Data ◽  
Simulated Data ◽  
Coordinate Measuring Machine ◽  
Optimization Techniques ◽  
Test Cases ◽  
Tolerance Zone ◽  
Geometric Tolerances ◽  
Measuring Machine

Abstract This paper focuses on the development of a procedure and algorithms for the systematic comparison of geometric variations of measured features with their specified geometric tolerances. To automate the inspection of mechanical parts, it is necessary to analyze the measurement data captured by coordinate measuring machines (CMM) in order to detect out-of-tolerance conditions. A procedure for determining the geometric tolerances from the measured three dimensional coordinates on the surface of a cylindrical feature is presented. This procedure follows the definitions of the geometric tolerances used in the current Standards, and is capable of determining the value of each geometric tolerance from the composite 3-D data. The developed algorithms adopt the minimum tolerance zone criterion. Nonlinear numerical optimization techniques are used to fit the data to the minimum tolerance zone. Two test cases are given in the paper which demonstrate the successful determination of geometric tolerances from given simulated data.

Computer-Aided Coordinate Metrology

1993 ◽  
Author(s):  
Hong-Tzong Yau ◽  
Chia-Hsiang Menq
Keyword(s):  
Three Dimensional ◽  
Coordinate Measuring Machine ◽  
Computer Integrated Manufacturing ◽  
Integrated Manufacturing ◽  
Coordinate Metrology ◽  
Cad Cam ◽  
Measuring Machine ◽  
Three Dimensional Coordinate ◽  
Inspection Machine ◽  
Accuracy And Repeatability

Abstract Three-dimensional coordinate metrology has gained much attention in recent years. On one hand, the accuracy and repeatability of a coordinate measuring machine (CMM) are approaching the sub-micron level. On the other hand, there is hardly any part that exists of which the dimensions cannot be measured with a CMM. This paper presents the recent development and applications in three-dimensional coordinate metrology. The emphasis has been placed in the utilization of computers and integration with CAD/CAM systems. Three important technologies, namely, CAD-directed inspection, three-dimensional optimal match, and reverse engineering are presented and discussed. With computers and CAD/CAM support, three-dimensional coordinate metrology has become an active part of the computer-integrated manufacturing (CIM). Its versatility and high degree of automation have made the CMM a universal inspection machine for quality control of manufactured parts in computer integrated manufacturing.

CMM Measurement Uncertainty Reduction via Sampling Strategy Optimization

2008 ◽  
Author(s):  
Giovanni Moroni ◽  
Stefano Petro`
Keyword(s):  
Measurement Uncertainty ◽  
Measurement Errors ◽  
Coordinate Measuring Machine ◽  
Sampling Strategy ◽  
Uncertainty Reduction ◽  
Repeated Measurements ◽  
Trade Off ◽  
Geometrical Error ◽  
Measuring Machine

Uncertainty is a key concept in any environment which involves measurements to ensure process quality: a trade-off has to be found between measurement costs, which increase as uncertainty lowers, and costs related to measurement errors. In mechanics, geometrical conformance is a common requirement. Two similar standards series deal with the problem of uncertainty in geometrical error estimate: ASME B89.7.3 and ISO 14253. Geometrical inspection is often performed by means of a “Coordinate Measuring Machine” (CMM). For a CMM, a trade off between measurement and errors costs may be found by optimizing the sampling strategy. In this work a cost function will be proposed as support for finding a trade-off between measurement uncertainty and costs. This function may be optimized by means of an heuristic algorithm. The method will involve repeated measurements of calibrated parts to evaluate uncertainty (like in ISO/TS 15330-3). A case study will be proposed.

scholarly journals Optimum design of reference points distribution in three-dimensional reconstruction of dental model in intercuspal position

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yujia Wu ◽  
Zhewen Hu ◽  
Xinyue Zhang ◽  
Hefei Bai ◽  
Yuchun Sun ◽  
...  
Keyword(s):  
Reference Point ◽  
Three Dimensional ◽  
Coordinate Measuring Machine ◽  
Distribution Patterns ◽  
Accurate Method ◽  
Reference Points ◽  
Rigid Fixation ◽  
Point Distribution ◽  
Dental Models ◽  
Measuring Machine

Abstract Purpose The scanning of plaster models for three-dimensional (3D) construction requires their rigid fixation in the intercuspal position. Factors such as installation, motion, and scanning procedures influenced the accuracy of this method, which ultimately influence the results. Therefore, the present study attempted to provide an optimal and accurate method with less complex procedures and a more accessible equipment for determining the intercuspal relation in the 3D occlusal construction of dental models. Methods A pair of plastic mounting plates that could be directly attached to a mechanical articulator was designed and 3D printed. Nine axial hemispherical concaves were introduced on the axial surface of each plate. The rigidly fixed maxillary and mandibular dental models were scanned directly. The distances DR between nine pairs of concaves on both mounting plates adhered to the maxillary and mandibular sections of the articulator were measured using the three-coordinate measuring machine Faro Edge as the reference. The present study comprised seven test groups varying in number and location. Assessing the reference points from each of the seven groups performed the 3D construction. The Geomagic Studio software was used to construct the concaves of digital casts, and the distances DM between the pairs of concaves were measured as test values. Variable differences between DR and DM were analyzed. Results An optimum distribution scheme was obtained for reference point registration by quantitatively evaluating accuracy levels of the 3D constructions of different reference point distribution patterns. This scheme can serve as a reference for related studies and dental clinic operations. Conclusions Three-dimensional construction of the intercuspal relation during scanning of the maxillary and mandibular models with an accuracy of 0.046 mm ± 0.009 mm can be achieved using the improved design of mounting plates.

scholarly journals Prognosis and Multiobjective Optimization of the Sampling Plan for Cylindricity Evaluation

2020 ◽  
Vol 2020 ◽  
pp. 1-24
Author(s):  
Syed Hammad Mian ◽  
Usama Umer ◽  
Osama Abdulhameed ◽  
Hisham Alkhalefah
Keyword(s):  
Machine Learning ◽  
Mean Squared Error ◽  
Sampling Strategy ◽  
Sampling Plan ◽  
Machine Learning Algorithms ◽  
Inspection Time ◽  
Support Vector ◽  
Point Distribution ◽  
Measuring Machine

The actualization of the befitting sampling strategy and the application of an appropriate evaluation algorithm have been elementary issues in the coordinate metrology. The decisions regarding their choice for a given geometrical feature customarily rely upon the user’s instinct or experience. As a consequence, the measurement results have to be accommodated between the accuracy and the inspection time. Certainly, a reliable and efficient sampling plan is imperative to accomplish a dependable inspection in minimal time, effort, and cost. This paper deals with the determination of an optimal sampling plan that minimizes the inspection cost, while still promising a measurement quality. A cylindrical-shaped component has been utilized in this work to achieve the desired objective. The inspection quality of the cylinder using a coordinate measuring machine (CMM) can be enhanced by controlling the three main parameters, which are used as input variables in the data file, namely, point distribution schemes, total number of points, and form evaluation algorithms. These factors affect the inspection output, in terms of cylindricity and measurement time, which are considered as target variables. The dataset, which comprises input and intended parameters, has been acquired through experimentation on the CMM machine. This work has utilized state-of-the-art machine learning algorithms to establish predictive models, which can predict the inspection output. The different algorithms have been examined and compared to seek for the most relevant machine learning regression method. The best performance has been observed using the support vector regression for cylindricity, with a mean absolute error of 0.000508 mm and a root-mean-squared error of 0.000885 mm. Likewise, the best prediction performance for measuring time has been demonstrated by the decision trees. Finally, the optimal parameters are estimated by employing the grey relational analysis (GRA) and the fuzzy technique for order performance by similarity to ideal solution (FTOPSIS). It has been approved that the values obtained from GRA are comparable with those of the FTOPSIS. Moreover, the quality of the optimal results is bettered by incorporating the measurement uncertainty in the outcome.

scholarly journals Recent developments on an interferometric multilateration measurement system for large volume coordinate metrology

2021 ◽  
Author(s):  
Eva Katharina Rafeld ◽  
Nils Koppert ◽  
Matthias Franke ◽  
Frank Keller ◽  
Daniel Heißelmann ◽  
...  
Keyword(s):  
Measurement System ◽  
Large Volume ◽  
Coordinate Measuring Machine ◽  
Mathematical Background ◽  
Large Complex ◽  
Complex Shapes ◽  
Coordinate Metrology ◽  
Recent Developments ◽  
Measuring Machine ◽  
Propagation Of Uncertainties

Abstract A mobile multilateration measurement system developed at the Physikalisch-Technische Bundesanstalt (PTB) around 2010 has been thoroughly investigated and refined to gain better performance with smaller uncertainties even when applied to the calibration of large complex workpieces. The mathematical background of multilateration and the propagation of uncertainties for the algorithms involved is explained in detail. Using the example of simple 1D and 2D measuring tasks, the influence of certain parameters characterizing the setup of the measurement system on the overall uncertainty is quantified. A strategy is developed to incorporate multi-stylus measurements which are often inevitable when workpieces feature complex shapes. The findings are verified on a large involute gear which is 2 m in diameter. All measurements are performed on PTB's large coordinate measuring machine with a working range of 5 m x 4 m x 2 m.

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