User Defined Assembly Features and Pattern Recognition From STEP AP203

2014 ◽  
Author(s):  
Prabath Vemulapalli ◽  
Prashant Mohan ◽  
Jami J. Shah ◽  
Joseph K. Davidson
Keyword(s):  
Pattern Recognition ◽  
Feature Recognition ◽  
Point Of View ◽  
Tolerance Allocation ◽  
Output File ◽  
Assembly Features ◽  
Assembly Feature

Tolerance allocation is important aspect in designing as well as manufacturing. Mating features in an assembly are important from the tolerance point of view and govern the tolerance schema. Presence of patterns within these features also plays an important role in the allocation of different tolerance classes. Identification of these assembly features and patterns are previously done manually. This research is aimed at automating these processes. The automation starts with the recognition of the assembly features in the assembly. The algorithms for feature recognition are designed such that they can handle any user defined assembly feature. The input for feature recognition is a STEP file containing information of the assembly. And the output file contains information of the recognized assembly features. Then patterns are identified from these assembly features. This paper discusses these two processes in detail. Also to facilitate the user, define new assembly features an alternate system called assembly feature tutor is developed. This paper also explains the working of this tutor.

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

Toward Automatic Tolerancing of Mechanical Assemblies: Assembly Analyses

2014 ◽  
Vol 14 (4) ◽  
Author(s):  
Prashant Mohan ◽  
Payam Haghighi ◽  
Prabath Vemulapalli ◽  
Nathan Kalish ◽  
Jami J. Shah ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Feature Recognition ◽  
Tolerance Analysis ◽  
Tolerance Allocation ◽  
Geometric Dimensioning And Tolerancing ◽  
Mechanical Assemblies ◽  
Loop Detection ◽  
Assembly Feature ◽  
Aided Design ◽  
Assembly Analysis

Generating geometric dimensioning and tolerancing (GD&T) specifications for mechanical assemblies is a complex and tedious task, an expertise that few mechanical engineers possess. The task is often done by trial and error. While there are commercial systems to facilitate tolerance analysis, there is little support for tolerance synthesis. This paper presents a systematic approach toward collecting part and assembly characteristics in support of automating GD&T schema development and tolerance allocation for mechanical assemblies represented as neutral B-Rep. First, assembly characteristics are determined, then a tentative schema is determined and tolerances allocated. This is followed by adaptive iterations of analyses and refinement to achieve desired goals. This paper will present the preprocessing steps for assembly analysis needed for tolerance schema generation and allocation. Assembly analysis consists of four main tasks: assembly feature recognition (AFR), pattern detection, directions of control, and loop detection. This paper starts with identifying mating features in an assembly using the computer-aided design (CAD) file. Once the features are identified, patterns are determined among those features. Next, different directions of control for each part are identified and lastly, using all this information, all the possible loops existing in an assembly are searched.

Toward Automatic Tolerancing of Mechanical Assemblies: First-Order GD&T Schema Development and Tolerance Allocation

2015 ◽  
Vol 15 (4) ◽  
Author(s):  
Payam Haghighi ◽  
Prashant Mohan ◽  
Nathan Kalish ◽  
Prabath Vemulapalli ◽  
Jami J. Shah ◽  
...  
Keyword(s):  
Feature Recognition ◽  
Reference Frames ◽  
Geometric Analysis ◽  
Tolerance Allocation ◽  
First Order ◽  
Geometric Dimensioning And Tolerancing ◽  
Mechanical Assemblies ◽  
Schema Development ◽  
Design Function ◽  
Acceptance Rates

Geometric and dimensional tolerances must be determined not only to ensure proper achievement of design function but also for manufacturability and assemblability of mechanical assemblies. We are investigating the degree to which it is possible to automate tolerance assignment on mechanical assemblies received only as STEP AP 203 (nominal) geometry files. In a previous paper, we reported on the preprocessing steps required: assembly feature recognition, pattern recognition, and extraction of both constraints and directions of control (DoC) for assembly. In this paper, we discuss first-order tolerance schema development, based purely on assemblability conditions. This includes selecting features to be toleranced, tolerance types, datums, and datum reference frames (DRFs), and tolerance value allocation. The approach described here is a combination of geometric analysis and heuristics. The assumption is that this initial geometric dimensioning and tolerancing (GD&T) specification will be sent to a stack analysis module and iterated upon until satisfactory results, such as desired acceptance rates, are reached. The paper also touches upon issues related to second-order schema development, one that takes intended design function into account.

scholarly journals ALGORITHM FOR ISO 14649 (STEP-NC) FEATURE RECOGNITION

2013 ◽  
Vol 4 (4) ◽  
pp. 50-58 ◽  
Author(s):  
Janusz Pobożniak
Keyword(s):  
Feature Recognition ◽  
Point Of View ◽  
Final Part ◽  
Future Research ◽  
The Future ◽  
Manufacturing Features

Abstract The paper focuses on the algorithm for the recognition of manufacturing features defined in ISO 14649 (STEP-NC). First, the features defined in STEP-NC standard are discussed and then commonly used feature recognition methods are presented. Then the developed algorithm for recognition is presented in details starting with the discussion of STEP-NC features from the point of view of their recognition. The steps of the algorithm responsible for the recognition of profile based, transition and group features are presented. The software developed to verify the algorithm is also described. The final part includes the directions for the future research works. This paper adds to the works aimed to strengthen the position and use the full benefits of this new ISO 14649 standard.

scholarly journals Automated handwriting analysis based on pattern recognition: a survey

2021 ◽  
Vol 22 (1) ◽  
pp. 196
Author(s):  
Samsuryadi Samsuryadi ◽  
Rudi Kurniawan ◽  
Fatma Susilawati Mohamad
Keyword(s):  
Pattern Recognition ◽  
Feature Extraction ◽  
Medical Diagnosis ◽  
Forensic Psychology ◽  
Recognition System ◽  
Processing Technique ◽  
Point Of View ◽  
Personality Characteristics ◽  
Classification Model ◽  
Handwriting Analysis

<span>Handwriting analysis has wide scopes include recruitment, medical diagnosis, forensic, psychology, and human-computer interaction. Computerized handwriting analysis makes it easy to recognize human personality and can help graphologists to understand and identify it. The features of handwriting use as input to classify a person’s personality traits. This paper discusses a pattern recognition point of view, in which different stages are described. The stages of study are data collection and pre-processing technique, feature extraction with associated personality characteristics, and the classification model. Therefore, the purpose of this paper is to present a review of the methods and their achievements used in various stages of a pattern recognition system. </span>

OAM+: An Assembly Data Model for Legacy Systems Engineering

2007 ◽  
Author(s):  
S. M. Mahbub Murshed ◽  
Jami J. Shah ◽  
Vadivel Jagasivamani ◽  
Ayman Wasfy ◽  
David W. Hislop
Keyword(s):  
Systems Engineering ◽  
Data Model ◽  
Detailed Comparison ◽  
Legacy Systems ◽  
Engineering System ◽  
Assembly Model ◽  
Assembly Features ◽  
Technical Function ◽  
Feature Based ◽  
Assembly Feature

This paper presents a new assembly model named open assembly model plus (OAM+) to support legacy systems engineering (LSE). LSE is a collection of technologies for prolonging the life of old mechanical systems. Rapid Re-Engineering System (RRES), a subsystem of LSE is geared towards the fast production of redesigned parts customized to the manufacturing capability available. RRES requires the extraction of initial part geometry, parameters, interfacing constraints, kinematic constraints, and technical function. These specifications need to be imprinted on the CAD model before iterative redesign. A CAD data model is needed that can carry all the functional constraints. A detailed comparison of all the available assembly model shows that none of them can provide all these requirements in one place. Assembly feature based, object oriented assembly model OAM+ is developed to meet these requirements in one model. OAM+ can be used to perform kinematic analysis, force analysis and can exchange feature data using N-Rep feature definition language between different modules of RRES. OAM+ is based on part and assembly features in N-Rep.

Object-oriented design of product assembly feature data requirements in advanced assembly planning

2018 ◽  
Vol 38 (1) ◽  
pp. 97-112 ◽  
Author(s):  
Mahmood Reza Khabbazi ◽  
Jan Wikander ◽  
Mauro Onori ◽  
Antonio Maffei
Keyword(s):  
Product Design ◽  
Object Oriented ◽  
3D Models ◽  
Assembly Planning ◽  
Content Type ◽  
Assembly Design ◽  
Assembly Features ◽  
Assembly Feature ◽  
Product Assembly ◽  
Data Requirements

Purpose This paper introduces a schema for the product assembly feature data in an object-oriented and module-based format using Unified Modeling Language (UML). To link production with product design, it is essential to determine at an early stage which entities of product design and development are involved and used at the automated assembly planning and operations. To this end, it is absolutely reasonable to assign meaningful attributes to the parts’ design entities (assembly features) in a systematic and structured way. As such, this approach empowers processes such as motion planning and sequence planning in assembly design. Design/methodology/approach The assembly feature data requirements are studied and definitions are analyzed and redefined. Using object-oriented techniques, the assembly feature data structure and relationships are modeled based on the identified requirements as five UML packages (Part, three-dimensional (3D) models, Mating, Joint and Handling). All geometric and non-geometric design data entities endorsed with assembly design perspective are extracted or assigned from 3D models and realized through the featured entity interface class. The featured entities are then associated (used) with the mating, handling and joints features. The AssemblyFeature interface is realized through mating, handling and joint packages related to the assembly and part classes. Each package contains all relevant classes which further classify the important attributes of the main class. Findings This paper sets out to provide an explanatory approach using object-oriented techniques to model the schema of assembly features association and artifacts at the product design level, all of which are essential in several subsequent and parallel steps of the assembly planning process, as well as assembly feature entity assignments in design improvement cycle. Practical implications The practical implication based on the identified advantages can be classified in three main features: module-based design, comprehensive classification, integration. These features help the automation and solution development processes based on the proposed models much easier and systematic. Originality/value The proposed schema’s comprehensiveness and reliability are verified through comparisons with other works and the advantages are discussed in detail.

Robust Design by Tolerance Allocation Considering Quality and Manufacturing Cost

1994 ◽  
Author(s):  
Rikard Söderberg
Keyword(s):  
Critical Parameter ◽  
Point Of View ◽  
Total Loss ◽  
Tolerance Allocation ◽  
Manufacturing Cost ◽  
Total Quality ◽  
Tolerance Limits ◽  
Component Price ◽  
Customer Values

Abstract Involving customer values in the design process is necessary to improve the total quality of a product. The purpose of this work is to establish a theoretical base for tolerance allocation which allows both quality and manufacturing cost to be considered. The paper addresses functional tolerance chains, i.e. tolerance chains that involve a dimension important for the function of the product or component. The total loss to customer is determined as the sum of two tolerance dependent properties; the functionality loss and the component price. The functionality loss represents the customer’s economical loss due to poor functionality. The optimal tolerance limits are found by minimizing the total loss to customer. These are the limits that represent the best trade-off between cost and quality, from the customer’s point of view. This work specially emphasizes a method for treating asymmetrical functionality loss, i.e. when the design is more sensitive to a deviation of a critical parameter in one direction than in the other. By moving the manufacturing target in a direction away from the most sensitive part, the total loss to customer can be reduced. This paper describes how the optimal manufacturing target and corresponding symmetrical tolerance band are found. This method thus increases the robustness of the design. The method may be used for single tolerances or any resulting tolerance of a tolerance chain.

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