Feature-based Product Model Research Articles

Partial encryption of feature-based product models for collaborative development

Abstract Feature-based product systems have been predominantly adopted for product development. To facilitate product development collaboration, product models need to be effectively shared among co-developers. However, in a shared model, it is challenging to preserving confidential features pertaining to intellectual property originating from the initial developer. To address the challenge, this paper presents a novel approach of partially encrypting feature-based product models to support effective collaboration. In the approach, collaborative features to support co-development, and confidential features to specify intellectual property information, are defined in a shared model. An innovative Encryption Transformation Matrix (ETM) is then designed to encode confidential features parametrically and synchronized with collaborative features as a partially encrypted product model. Finally, the approach is validated via complex case studies to demonstrate its effectiveness in industrial applications. The novelty of the approach is based on the innovative ETM design, which makes encryption processes parametric, randomized and self-adaptive. In detail, zooming and transformation variables are devised in ETM to facilitate users to manage encryption processes in a parametric means. Random probability is embedded into ETM to achieve security effectiveness in encrypted models. A self-adaptive mechanism is integrated into ETM to ensure the geometrical validity of encrypted models. The research in this paper, which supports collaborative design on real-world product models, presents a disruptive innovative potential for industrial applications.

Feature-based product modelling: an ontological approach

ABSTRACTFeature-based modelling is the leading approach for computer-based product design. The development of knowledge-based information systems brought to represent features in formalised ontologies. The lack of a clear ontological analysis of how features are understood in engineering led to formal models that treat features in an ambiguous manner, or reduce them to pure geometric elements. The purpose of the paper is to present a modular ontological architecture to support the explicit and machine treatment of features’ semantic. Differently from the state of art, we provide a general framework where features are contextualised within a larger system for product knowledge representation. We focus on the fundamental (ontological) properties that features satisfy independently from specific applications and contexts of usage. The paper presents modelling case studies where the proposed ontologies are used to represent and (automatically) reason over product knowledge, and to analyse, compare, and integrate existing features classifications.

Constraint-based adaptive shape deformation technology for customised product development

Customised agile product shape development requires intelligent integration of multiple designers’ inputs to fit various customer preferences. This study proposes a robust feature-based product modelling architecture for design customisation, which represents the product modelling processes as constrained morphing of relatively constant base feature with customised defined working features by subjecting to corresponding boundary constraints. The deformation on the surface patches of working features is adaptively controlled by the proposed energy-based solid mechanics surface model. The techniques on the construction of surface control network of springs, model segmentation, displacement computation of network nodes, as well as surface morphing processes are introduced in detail. The shape deformation process is uniformed across the surface control network, maintaining the shape being similar to its imported source pattern. This paper discusses examples and case study in footwear industry. The proposed method could be applied for customised product development in other related industries.

A feature ontology to support construction cost estimating

Construction cost estimators are confronted with the challenging task of estimating the cost of constructing one of a kind facilities. They must first recognize the design conditions of the facility design that are important (i.e., incur a cost) and then determine how the design conditions affect the cost of construction. Current product models of facility designs explicitly represent components, attributes of components, and relationships between components. These designer-focused product models do not represent many of the cost-driving features of building product models, such as penetrations and component similarity. Previous research efforts identify many of the different features that affect construction costs, but they do not provide a formal and general way for practitioners to represent the features they care about according to their preferences. This paper presents the formal ontology we developed to represent construction knowledge about the cost-driving features of building product models. The ontology formalizes three classes of features, defines the attributes and functions of each feature type, and represents the relationships between the features explicitly. The descriptive semantics of the model allow estimators to represent their varied preferences for naming features, specifying features that result from component intersections and the similarity of components, and grouping features that affect a specific construction domain. A software prototype that implements the ontology enables estimators to transform designer-focused product models into estimator-focused, feature-based product models. Our tests show that estimators are able to generate and maintain cost estimates more accurately, consistently, and expeditiously with feature-based product models than with industry standard product models.

A generic feature-driven activity-based cost estimation process

Understanding how the building design influences construction costs is a challenging task for estimators. Estimators must recognize the design conditions that affect construction costs and customize the cost estimate accordingly. Estimators have different preferences for how and when to adjust a project's activities, resources, and resource productivity rates that form the basis of a cost estimate. Current tools and methodologies lack ways to help estimators customize construction cost information according to their preferences and the particular features in a given design. This paper describes the process we formalized to customize a project's activities, resources, and resource productivity rates based on a project-independent representation of estimators' rationale and a project-specific feature-based product model. The formal process creates an integrated model that explicitly relates features, activities, resources, costs and the estimator's rationale. Our tests show that this process enables a software prototype to generate and maintain cost estimates quickly, consistently, and accurately for feature-based product models.

A Generative Feature-Based CAPP/CNC System for Hydraulic Manifold Blocks

A generative CAPP/CNC system for hydraulic manifold blocks is proposed to generate the process plan and the NC codes automatically by interfacing with a feature-based product model. A backward recursive method is used to determine the process operations for features, and an optimal searching algorithm is generated for sequencing the process operations. The sequenced process operations can be translated into the appropriate NC codes that can be recognised by a numerical control (NC) machine. In addition, a visual simulation for machining is built to check both the reliability of the NC codes and the feasibility of the design and manufacturing processes. The software is built using an object-oriented approach and it can be run under the Windows environment.

Assembly features in modeling and planning

In recent years, features have been introduced in modeling and planning for manufacturing of parts. Such features combine geometric and functional information. Here it is shown that the feature concept is also useful in assembly modeling and planning. For modeling and planning of both single parts and assemblies, an integrated object-oriented product model is introduced. For specific assembly-related information, assembly features are used. Handling features contain information for handling components, connection features information on connections between components. A prototype modeling environment has been developed. The product model has been successfully verified within several analyses and planning modules, in particular stability analyses, grip planning, motion planning and assembly sequence planning. Altogether, feature-based product models for assembly can considerably help in both assembly modeling and planning, on the one hand by integrating single-part and assembly modeling, and on the other hand by integrating modeling and planning.

Feature Representation and Database Schema of an Object-Oriented Feature-Based Product Model for Hydraulic Manifold Blocks

A feature-based hydraulic valve block model is built using an object-oriented method to integrate the information for CAD and CAM. Features are predefined in a feature library and can be instantiated and managed to form a hydraulic valve block. The block model is a dynamic database and can be updated at any stage of CAD/CAM, and has a user-friendly interface to different applications, such as design, evaluation, and CAPP. The model is developed with C++ in a Windows environment.

Flexible planning logic for technology planning

The ever-rising expectations of customers regarding quality and diversity of products require new products to be launched with a minimum of upheaval and consequently rapid, defect-free and economical processes. These goals can be attained and guaranteed in the planning departments of businesses through the sharing of secure and up-to-date planning data, leading to a high degree of flexibility and a minimum of interruptions in the production processes. In terms of technology planning, this results in a demand for economic methods of planning and NC programming, leading in turn to continuous, systematic acquisition of specialised in-house technological knowledge. However, most of the applications on the market are unsatisfactory in terms of acquisition of specialised knowledge of technology, only allowing specialised planning knowledge to be gathered or entered through costly procedures and for it to be organised statically. For rational processing and evaluation of planning knowledge, it is therefore sensible to systematically record technological discoveries made in the course of the planning and running-in process and to make them available for future planning processes. This processing of empirical knowledge along with rational and safe technology planning is supported by the use of DP systems, thus enabling planning knowledge to be kept constantly up-to-date, growing along with the data specific to the enterprise. For this purpose, a suitable information model must be devised that represents the integration point within the NC process chain. Using a feature-based product model introduced in the design departments as a starting point, the model is extended to take in a production-orientated view. The model should be designed in such a way that, above all, the technological interconnections are represented and that the technology planning, NC programming and running-in process are integrated through the model. In order to evaluate and process empirical knowledge, methods are applied from machine learning from Bayesian belief networks. This enables a costly human acquisition of the empirical knowledge of technology to be avoided and a rapid and rational decision-support system tailored to the particular problem to be developed. Also, by using suitable Bayesian belief networks, planning knowledge can be condensed, the numerous different planning conditions can be automatically diverted and the decision-base kept extremely up-to-date.

Integration of functional and feature-based product modelling — the IMS/GNOSIS experience

This article describes collaborative research carried out in the project GNOSIS, one of the six test cases of the proposed international research programme IMS. A joint demonstration combining tools and methods from several partners was created to experiment supporting the flow of models and processes involved in the various stages of product realization including design, manufacturing preparation, and manufacturing. The article discusses the product modelling part of the joint demonstration. The process covered begins from a creative design state where a functional product description is created using the SYSFUND system of the University of Tokyo. The functional structure is passed on to the MCOES, system of the Helsinki University of Technology; in MCOES, the functional model is mapped to a physical structure for creating an assembly family. The most interesting result of the demonstration is the experience on the information flow and the gaps between these two systems.

CAD-directed automatic assembly sequence planning

SUMMARY CAD-directed assembly sequence planning is an essential component of automated robotic assembly task planning. Many research attempts have been made in the past to integrate computer-aided design (CAD) and robot task planning to increase the efficiency and effectiveness of robotic assembly automation. This paper presents a graph-based heuristic approach for automatic generation of assembly sequences from a feature-based data base. A feature-based representation is used to model product assembly. The automatic assembly sequence planning system utilizes four major stages to generate assembly sequences without any user intervention:(1) creates connective graphs based on the product feature representation; (2) decomposes an assembly into sub-groups using the connective graphs; (3) generates the disassembly sequence for each sub-group formed at stage 2; and (4) merges the disassembly sequences of the sub-groups into a complete disassembly sequence, and converts the disassembly sequence into the final assembly sequence. The assembly planning system associated with the feature-based product model has been implemented in Smalltalk-an object-oriented programming language. Several examples are included to illustrate the approach and the heuristic algorithms. The results show that the approach can be used to automatically generate assembly sequences for robot assembly task planning directly from the feature-based database.

The Application of Features in Airframe Component Design and Manufacturing

This paper discusses recent results obtained from the development of a CAD/CAM application, which supports the generation of the manufacturing information for airframe components, which are produced using the rubber pad pressing technique. It describes the design module, which has been developed to generate feature based product models. The feature based approach guides the designer in creating product models according to company rules. These models represent the input for the subsequent modules for manufacturability analysis and tool design. The features are implemented as extensions to the data structure of a commercial geometric modeler. The functionality of the manufacturability and tool design modules are briefly discussed to clarify the demands these modules put on the product model. It is shown how high level design modifications can be supported using the proposed product model.

An integrated CAD/CAPP/CAM system based on form feature oriented product model

Form feature based product modelling technique is the basis of integration of CIMS information system. On this basis, an integrated CAD/CAPP/CAM prototype system called HFCIM has been developed by authors. Some main principles used in this system will be discussed. At first, the structure of product model is described in section 2. In section 3, The feature based product modelling system is described. A prototype process planning expert system is described in section 4. The principles of automatic NC programming system based on product model is described in section 5.

RA-IQSE: a system for on-line quality support for the designer of machined parts and products

Work carried out under the auspices of the ESPRIT RA-IQSE project, which aims to design and implement an intelligent revision advisor for mechanical product designers, is detailed. The system philosophy relies on the use of detailed feature-based product model, and the data structures employed in the definition of such models are explained. The system architecture is broken into three main parts: a front end design module; a product evaluator; and a back end user interface providing feedback. The role of the system in the various stages of manufacture, from customer enquiry to series production, is described in detail and the principal benefits of its implementation are anticipated.