Steps and grooves, which have typical directional characteristic, are two main functional structures of MEMS (MicroElectro-Mechanical Systems). This paper proposes a method for analysis and evaluation of MEMS steps and grooves based on finite radon transform (FRAT) and lifting wavelet. The method consists of three steps. Firstly, FRAT is adopted to detect the directional characteristic of a MEM...

A semantic tolerance modeling scheme based on generalized intervals was recently proposed to allow for embedding more tolerancing intents in specifications with a combination of numerical intervals and logical quantifiers. By differentiating a priori and a posteriori tolerances, the logic relationships among variables can be interpreted, which is useful to verify completeness and soundness of n...

In this paper we study the problem of computing the smallest-width annulus for a convex polytope in R d. This generalizes a topic from tolerancing metrology to higher dimensions, of which the planar case has been investigated by Swanson, Lee and Wu. We show this problem to be equivalent to the problem of computing diierent variants of Hausdorr-minimal spheres. We can formulate the latter proble...

Abstract Many tolerancing problems on mechanical assemblies involve a functional requirement depending chain of parallel dimensions individual parts. In these one-dimensional cases, simple methods are available for the analysis and allocation dimensional tolerances. However, they difficult to extend geometric tolerances, which must be translated into equivalent tolerances; this allows but makes...

The CAD software seeks to represent the syntax of the geometric tolerances, i.e. their writing on the drawings. We propose to represent their semantics, i.e. their meaning with respect to the part. We show that the meaning of the geometric tolerances can be defined thanks to a model of virtual gauges. These gauges concern geometrical entities of the part which are represented on the three-dimen...

A semantic tolerance modeling scheme based on generalized intervals was recently proposed to allow for embedding more tolerancing intents in specifications with a combination of numerical intervals and logical quantifiers. By differentiating a priori and a posteriori tolerances, the logic relationships among variables can be interpreted, which is useful to verify completeness and soundness of n...

The tolerance study is one of the most critical and neglected issues in sheet metal assembly manufacturing research. The fundamental shortcoming of currently existing tolerancing methods is the lack of physical significance of the model. This paper presents a new tolerance analysis methodology for sheet metal assembly based on physical/functional modeling of the fabrication error using the deve...

This paper describes the Linear Parametric Model of Geometric Uncertainty (LPMGU). The model, based on our previous work on shape and position uncertainties, describes the worst-case first-order approximations of the uncertainty zones of basic geometric entities. It is general and expressive, allows for parameter dependencies typical of tolerance specifications, and can be uniformly used to stu...