The internal representation of the solid modeller provides a description of parts which when used directly is useful for automation of the process planning function. So that the CAD model can be used to provide the information required for manufacturing, techniques to improve machine understanding of the part as required for manufacturing are needed. This paper presents the development of the concept attributed adjacency graph (AAG) for the recognition of machined features from a 3D boundary representation of a solid. Current implementation of the feature recogniser is limited to polyhedral features such as pockets, slots, steps, blind steps, blind slots, and polyhedral holes. Sample results that show the capabilities of the system are presented.

Graph-based heuristics for recognition of machined features from a 3D solid model

This paper presents a comparative study and survey of model-based object-recognition algorithms for robot vision. The goal of these algorithms is to recognize the identity, position, and orientation of randomly oriented industrial parts. In one form this is commonly referred to as the "bin-picking" problem, in which the parts to be recognized are presented in a jumbled bin. The paper is organized according to 2-D, 2½-D, and 3-D object representations, which are used as the basis for the recognition algorithms. Three central issues common to each category, namely, feature extraction, modeling, and matching, are examined in detail. An evaluation and comparison of existing industrial part-recognition systems and algorithms is given, providing insights for progress toward future robot vision systems.

Model-based recognition in robot vision

SUMMARY Computer Aided Process Planning (CAPP) has been recognized as playing a key role in Computer Integrated Manufacturing (CIM). In the last two decades, a tremendous effort has been made in developing CAPP systems. However, the benefits of CAPP in the real industrial environment are still to be seen. In this paper, a comprehensive summary on the state-of-the-art and projection of future trends in CAPP is presented to help make decisions concerning CAPP implementation today and to aid in guiding research for tomorrow. We systematically overview the historical background of the development of CAPP and discuss the current techniques which includes the implementation approaches, GT technology, application of AI techniques, programming languages, etc., for implementation CAPP systems. About 14 well-known CAPP systems, which are based on the variant, generative or semi-generative approach, are briefly introduced in this paper. In total about 156 currently existing CAPP systems are listed in Table 1 in the ...

Computer Aided Process Planning: the state-of-the-art survey

Features encapsulate the engineering significance of portions of the geometry of a part or assembly, and, as such, are important in product design, product definition, and reasoning, for a variety of applications. Feature-based systems have demonstrated some potential in creating attractive design environments and in automating the geometric reasoning required in applications such as process planning and manufacturability evaluation. The paper reviews the major concepts and approaches that are in use in feature-based modelling. Several methodologies are prevalent for creating feature models and databases. These fall broadly into the categories of interactive definition, automatic recognition/extraction, and design by features. Within each, there are several subcategories, which are discussed and compared in the paper. Also presented are several schemes popular for representing features. They include augmented graphs, syntactic strings in grammars, and objects in object-oriented programming. Feature interactions and validation issues are outlined. Attempts at developing feature taxonomies are also summarized.

Assessment of features technology

A discourse on geometric feature recognition from CAD models

In the paper a general purpose parts description language is presented. This language seems to be particularly adequate for the automatic processing of the CAD/CAM system. The description method of machine parts, developed in the paper, is associated not only with individual parts but also with their classes. Each of these classes is created by parts of “similar shapes.” This similarity is determined by the “structure” (configuration) of primitives in contours describing machine parts. This structure is defined in a syntactic manner by means of a formal language generated by the extended context-free grammar (ECFg for short). The right hand sides of the production rules of ECFg are regular expressions over the terminal and non-terminal symbols. It appears quite natural to assume that ECFg generating contours (which uniquely determine machine parts) is in the so-called chain form. ECFGg in the chain form is a modification of the simple chain grammar which has been introduced and investigated by Ni...

Ryszard Jakubowski

Papers

Syntactic characterization of machine parts shapes

A structural representation of shape and its features

Decomposition of complex shapes for their structural recognition