Octree Based Recognition of Assembly Features

2000 ◽  
Author(s):  
Raymond C. W. Sung ◽  
Jonathan R. Corney ◽  
Doug E. R. Clark
Keyword(s):  
Geometric Reasoning ◽  
Wide Range ◽  
Assembly Features ◽  
Form Features ◽  
Octree Representation

Abstract This paper reviews the nature and use of assembly features. One of the conclusions drawn from this survey is that the majority of assembly features involve sets of spatially adjacent faces. Two principle types of adjacency relationships are identified and an algorithm is presented for identifying assembly features, these are features which arise from these “spatial” and “contact” face adjacency relationships (known as s- and c-adjacency respectively). The algorithm uses an octree representation of a B-rep model to support the geometric reasoning required to locate assembly features on disjoint bodies. Once all the adjacent faces which form features have been located, they are used to partition the original faces of the assembly into adjacent and non-adjacent portions. The resulting system can locate and partition spatially adjacent faces in a wide range of situations and at different resolutions. By way of illustration, the algorithm is applied to a trial component.

Automatic Assembly Feature Recognition and Disassembly Sequence Generation

2001 ◽  
Vol 1 (4) ◽  
pp. 291-299 ◽  
Author(s):  
Raymond C. W. Sung ◽  
Jonathan R. Corney ◽  
Doug E. R. Clark
Keyword(s):  
Feature Recognition ◽  
Automatic Recognition ◽  
Automatic Assembly ◽  
Sequence Generation ◽  
Disassembly Sequence ◽  
Wide Range ◽  
Assembly Features ◽  
Assembly Feature ◽  
State Tree ◽  
Octree Representation

This paper describes a system for the automatic recognition of assembly features and the generation of disassembly sequences. The paper starts by reviewing the nature and use of assembly features. One of the conclusions drawn from this survey is that the majority of assembly features involve sets of spatially adjacent faces. Two principle types of adjacency relationships are identified and an algorithm is presented for identifying assembly features which arise from “spatial” and “contact” face adjacency relationships (known as s-adjacency and c-adjacency respectively). The algorithm uses an octree representation of a B-rep model to support the geometric reasoning required to locate assembly features on disjoint bodies. A pointerless octree representation is generated by recursively sub-dividing the assembly model’s bounding box into octants which are used to locate: 1. Those portions of faces which are c-adjacent (i.e. they effectively touch within the tolerance of the octree). 2. Those portions of faces which are s-adjacent to a nominated face. The resulting system can locate and partition spatially adjacent faces in a wide range of situations and at different resolutions. The assembly features located are recorded as attributes in the B-rep model and are then used to generate a disassembly sequence plan for the assembly. This sequence plan is represented by a transition state tree which incorporates knowledge of the availability of feasible gripping features. By way of illustration, the algorithm is applied to several trial components

A Generalized Method for the Classification and Extraction of Form Features

1996 ◽  
Author(s):  
A. Z. Qamhiyah ◽  
R. D. Venter ◽  
B. Benhabib
Keyword(s):  
Feature Extraction ◽  
Sequential Extraction ◽  
Feature Recognition ◽  
Boundary Elements ◽  
Geometric Reasoning ◽  
Extraction Techniques ◽  
Planar Surfaces ◽  
Cad Models ◽  
Extraction Stage ◽  
Form Features

Abstract Feature-extraction techniques address the primary limitation of feature-recognition approaches, namely their lack of generalization. This paper presents a boundary-based procedure for the classification and sequential extraction of form features from the CAD models of objects with planar surfaces. Form features are first classified based on their effect on the boundary elements of a basic shape. Geometric reasoning is then used to obtain generalized properties of the form-features’ classes. Finally, form-features’ classes are sequentially extracted based on the recognized properties. At the onset of each extraction stage, the object is viewed as an initial basic shape that has been iteratively altered through the introduction of form features.

The Spinning Ellipse Speed Illusion

2017 ◽  
Author(s):  
Gideon Paul Caplovitz ◽  
Po-Jang Hsieh ◽  
Peter J. Kohler ◽  
Katharine B. Porter
Keyword(s):  
Aspect Ratio ◽  
Relative Motion ◽  
Characteristic Form ◽  
Low Aspect Ratio ◽  
Wide Range ◽  
Form Features ◽  
Illusory Percept ◽  
Perceived Speed ◽  
Contour Curvature

The Spinning Ellipse Speed Illusion is an illusion of perceived speed in which a low-aspect ratio “fat” ellipse will appear to rotate more slowly than a higher-aspect ratio “skinny” ellipse that is rotating at the same speed. This illusory percept can be observed when the ellipses are defined by luminance, color, relative motion, and dotted contours and across a wide range of rotational speeds and eccentricities. The illusion is not limited to rotating ellipses and can be observed with different-shaped contours as well. The Spinning Ellipse Speed Illusion illustrates that the perceived speed of a rotating object depends in part on the form and form features of the object. Objects without characteristic form features such as regions of high or discontinuous contour curvature will appear to rotate more slowly than objects that have these features.

An approach to concurrent engineering

1998 ◽  
Vol 212 (1) ◽  
pp. 13-27 ◽  
Author(s):  
D T Pham ◽  
S S Dimov
Keyword(s):  
Carrying Capacity ◽  
Concurrent Engineering ◽  
Deductive Reasoning ◽  
Design Models ◽  
New Approach ◽  
Wide Range ◽  
Manufacturing Information ◽  
Form Features ◽  
The Given ◽  
Natural Way

This paper presents a new approach to concurrent engineering, focusing on simultaneous product design and process planning. The key elements in this approach are (a) a framework for structuring manufacturing information and maximizing the information-carrying capacity of the design models, (b) a procedure for intelligently mapping form features on to pertinent manufacturing considerations and (c) a procedure for utilizing the available manufacturing information about components already machined within the given manufacturing environment. The proposed approach provides a natural way for conveying manufacturing information to the designer. Its distinguishing feature is the application of a wide range of artificial intelligence techniques for knowledge acquisition and deductive reasoning.

Feature-Based Assembly Mating Reasoning

1996 ◽  
Author(s):  
Eric Wang ◽  
Yong Se Kim
Keyword(s):  
Flexible Manufacturing ◽  
Backtracking Search ◽  
Part Geometry ◽  
Assembly Features ◽  
Feature Based ◽  
Computer Based ◽  
Boundary Representations ◽  
Form Features ◽  
Component Assembly ◽  
Assembly Operations

Abstract It is desirable to provide computer-based tools to assist designers and manufacturing engineers in the difficult task of geometric reasoning to achieve fast product development and flexible manufacturing. In the domain of assembly reasoning and planning, numerous methods have been developed to analyze a user-specified assembly configuration of parts. Fewer efforts have been made to systematically obtain the assembly configuration itself from underlying information. As a step in this direction, we present an assembly mating reasoning method that determines feasible assembly configurations directly from part geometry. Our method recognizes form features from the boundary representations of the components, then treats the form features as assembly features and identifies mating relations between them. Assembly configurations are constructed by using Boolean operations on the components to simulate the assembly process. A heuristic backtracking search is used to traverse the space of feasible component assembly operations. The result of the search is an enumeration of feasible assembly configurations.

Geometric reasoning for the extraction of form features

1996 ◽  
Vol 28 (11) ◽  
pp. 887-903 ◽  
Author(s):  
A.Z. Qamhiyah ◽  
R.D. Venter ◽  
B Benhabib
Keyword(s):  
Geometric Reasoning ◽  
Form Features

An Object-Oriented Formalism for Geometric Reasoning in Engineering Design and Manufacture

1993 ◽  
Author(s):  
Ravisrinivas Navaneethakrishnan ◽  
Kristin L. Wood ◽  
Richard H. Crawford
Keyword(s):  
Data Model ◽  
Mechanical Design ◽  
Object Oriented ◽  
Geometric Reasoning ◽  
Levels Of Abstraction ◽  
Modeling Technology ◽  
Design And Manufacturing ◽  
Form Features ◽  
Abstraction Levels ◽  
Design And Manufacture

Abstract Geometry is a language for representing and communicating mechanical design information. To enhance the integration of design and manufacturing tasks, a representation of product geometry at appropriate levels of abstraction for geometric reasoning is necessary. In addition, a mechanism to perform reasoning with the representation is needed. This paper describes a computational formalism for representing and manipulating geometry at different abstraction levels. Geometry is abstracted in terms of form features. Spatial relationships between features, which are important components for geometric reasoning, are represented using a modification of a previously developed technique — the intermediate geometry language (IGL). To enable geometric reasoning, information abstracted using features and the IGL is transformed into a data model based on object-oriented modeling technology. An object algebra is defined to query the data model for information.

Assemblability Evaluation Method Based on an Assembly Model and an Assembly Process Model

1991 ◽  
Author(s):  
Akira Okano
Keyword(s):  
Process Model ◽  
Evaluation Method ◽  
Design Phase ◽  
Assembly Process ◽  
Assembly Model ◽  
Process Plan ◽  
Assembly Features ◽  
Form Features ◽  
Assembly Operations ◽  
Early Design Phase

Abstract An evaluation of assemblability at an early design phase leads to a better product and a better assembly process plan. This paper proposes a method for computerized evaluation of assemblability, based on an assembly model and an assembly process model, which are also proposed in the paper. An assembly model consists of form features, assembly features, and constraints among those features. An AND/OR graph is used to represent all the assembly processes. A node has the direction of access to a subassembly as an attribute. This make it possible to create an actual assembly process plan. To generate a graph efficiently, the system interacts with the user and acquires knowledge about order of precedence of operations. In the evaluation of assemblability, consideration is given to factors such as assembly operations and direction of access. These are calculated from the assembly model. The assembly process model is then used to calculate the best assembly process.

A Neutral Framework for Feature Definition and a Generic Algorithm for Feature Recognition

2014 ◽  
Vol 988 ◽  
pp. 530-539
Author(s):  
De Biao Zeng ◽  
Shi Ming Wan ◽  
Chun Ling Zeng ◽  
Guo Lei Zheng ◽  
Dong Ming Li
Keyword(s):  
Feature Recognition ◽  
Recognition Algorithm ◽  
Generic Algorithm ◽  
Wide Range ◽  
Form Features ◽  
Interacting Features ◽  
Form Feature

Traditional feature recognition approaches predefine features which can be recognized in systems. Feature definitions and recognitions are characterized by the domains which the approaches are applied to. Therefore, these approaches are not generic. In order to fulfill various feature recognition requirements of different users in different domains, this paper proposes an application independent framework for form feature definition and a generic algorithm for feature recognition based on the framework. Users in different domains can define their own features following the rules of the feature definition framework according to their tasks and user-defined features can be recognized by the uniform recognition algorithm. Hence, the system is flexible and can recognize a wide range of form features in different domains. The testing results show that this approach is effective in defining and recognizing isolated features as well as interacting features.

Recent Applications of High Resolution Electron Microscopy to Crystalline Arrays of Virus Particles

1978 ◽  
Vol 36 (3) ◽  
pp. 470-482 ◽  
Author(s):  
R.W. Horne
Keyword(s):  
Electron Microscopy ◽  
Image Processing ◽  
Analytical Techniques ◽  
Staining Technique ◽  
High Resolution Electron Microscopy ◽  
Optical Diffraction ◽  
Full Potential ◽  
Virus Particles ◽  
Resolution Electron ◽  
Wide Range

The technique of surrounding virus particles with a neutralised electron dense stain was described at the Fourth International Congress on Electron Microscopy, Berlin 1958 (see Home & Brenner, 1960, p. 625). For many years the negative staining technique in one form or another, has been applied to a wide range of biological materials. However, the full potential of the method has only recently been explored following the development and applications of optical diffraction and computer image analytical techniques to electron micrographs (cf. De Hosier & Klug, 1968; Markham 1968; Crowther et al., 1970; Home & Markham, 1973; Klug & Berger, 1974; Crowther & Klug, 1975). These image processing procedures have allowed a more precise and quantitative approach to be made concerning the interpretation, measurement and reconstruction of repeating features in certain biological systems.

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