Vector Based Datum Transformation Scheme for Computer Aided Measurement

Lai, Danny

doi:10.3722/cadaps.2012.289-305

Cited by 2 publications

(1 citation statement)

References 15 publications

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“…To synthesize adequate GD&T these stacks should be analyzed and qualified within a confidence limit. Lai and Yeun [9] developed a vector based transformation scheme.…”

Section: Automated Loop Detectionmentioning

confidence: 99%

Automated Iterative Tolerance Value Allocation and Analysis

Biswas

Venkiteswaran

Hejazi

et al. 2016

Volume 2B: 42nd Design Automation Conference

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Tolerance specification for manufacturing components from 3D models is a tedious task and often requires expertise of "detailers". The work presented here is a part of a larger ongoing project aimed at automating tolerance specification to aid less experienced designers by producing consistent geometric dimensioning and tolerancing (GD&T). Tolerance specification can be separated into two major tasks; tolerance schema generation and tolerance value specification. This thesis will focus on the latter part of automated tolerance specification, namely tolerance value allocation and analysis. The tolerance schema (sans values) required prior to these tasks have already been generated by the auto-tolerancing software. This information is communicated through a constraint tolerance feature graph file developed previously at Design Automation Lab (DAL) and is consistent with ASME Y14.5 standard.The objective of this research is to allocate tolerance values to ensure that the assemblability conditions are satisfied. Assemblability refers to "the ability to assemble/fit a set of parts in specified configuration given a nominal geometry and its corresponding tolerances". Assemblability is determined by the clearances between the mating features. These clearances are affected by accumulation of tolerances in tolerance loops and hence, the tolerance loops are extracted first. Once tolerance loops have been identified initial tolerance values are allocated to the contributors in these loops. It is highly unlikely that the initial allocation would satisfice assemblability requirements. Overlapping loops have to be simultaneously satisfied progressively.ii Hence, tolerances will need to be re-allocated iteratively. This is done with the help of tolerance analysis module.The tolerance allocation and analysis module receives the constraint graph which contains all basic dimensions and mating constraints from the generated schema. The

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“…To synthesize adequate GD&T these stacks should be analyzed and qualified within a confidence limit. Lai and Yeun [9] developed a vector based transformation scheme.…”

Section: Automated Loop Detectionmentioning

confidence: 99%

Automated Iterative Tolerance Value Allocation and Analysis

Biswas

Venkiteswaran

Hejazi

et al. 2016

Volume 2B: 42nd Design Automation Conference

View full text Add to dashboard Cite

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The Strategy of Datum Reference Frame Selection Based on Statistical Learning

Cao

Zhao

Liu

et al. 2018

Journal of Computing and Information Science in Engineering

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A datum selection strategy based on statistical learning is proposed. The datum selection is an important part of tolerance specification which is the base of geometric tolerance selection and tolerance principle selection. The problem of datum selection is to deduce the datum reference frame (DRF) based on geometrical, contact, and positioning characteristics. Currently, heuristic rules are used for DRF selection, leading to suboptimal choice of DRF in many cases. The proposed strategy formulates normalized vectors computed from the geometric, contact, and positioning characteristics of surfaces. The surfaces of different parts can be compared by their normalized vectors. Then the statistical learning method is used for building a classifier which can discriminate datum feature vectors based on training samples. Finally, a case study is given to verify the strategy and the different algorithms are compared and discussed.

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Vector Based Datum Transformation Scheme for Computer Aided Measurement

Cited by 2 publications

References 15 publications

Automated Iterative Tolerance Value Allocation and Analysis

Automated Iterative Tolerance Value Allocation and Analysis

The Strategy of Datum Reference Frame Selection Based on Statistical Learning

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