A feature-based reverse engineering system using artificial neural networks

Reverse Engineering (RE) is the process of reconstructing CAD models from scanned data of a physical part acquired using 3D scanners. RE has attracted a great deal of research interest over the last decade. However, a review of the literature reveals that most research work have focused on creation of free form surfaces from point cloud data. Representing geometry in terms of surface patches is adequate to represent positional information, but can not capture any of the higher level structure of the part. Reconstructing solid models is of importance since the resulting solid models can be directly imported into commercial solid modellers for various manufacturing activities such as process planning, integral property computation, assembly analysis, and other applications. This research discusses the novel methodology of extracting geometric features directly from a data set of 3D scanned points, which utilises the concepts of artificial neural networks (ANNs). In order to design and develop a generic feature-based RE system for prismatic parts, the following five main tasks were investigated. (1) point data processing algorithms; (2) edge detection strategies; (3) a feature recogniser using ANNs; (4) a feature extraction module; (5) a CAD model exchanger into other CAD/CAM systems via IGES. A key feature of this research is the incorporation of ANN in feature recognition. The use of ANN approach has enabled the development of a flexible feature-based RE methodology that can be trained to deal with new features. ANNs require parallel input patterns. In this research, four geometric attributes extracted from a point set are input to the ANN module for feature recognition: chain codes, convex/concave, circular/rectangular and open/closed attribute. Recognising each feature requires the determination of these attributes. New and robust algorithms are developed for determining these attributes for each of the features. This feature-based approach currently focuses on solving the feature recognition problem based on 2.5D shapes such as block pocket, step, slot, hole, and boss, which are common and crucial in mechanical engineering products. This approach is validated using a set of industrial components. The test results show that the strategy for recognising features is reliable

Rethinking of timber joinery in 21st-century architecture The computation of a timber joinery through complex geometry

Master of ScienceDepartment of ArchitectureMajor Professor Not ListedIn recent years, there has been a renewed interest in timber joinery in contemporary architecture. With the introduction of digital fabrication technologies and computational design, it is now possible to create complex timber structures with more complex shapes and designs. One of the critical advantages of timber as a building material is its ability to be combined in various ways. Timber joinery can create solid and durable connections between structural members while providing an aesthetically pleasing finish. In the 21st century, architects and designers are exploring new ways to use timber joinery to create unique and innovative structures. Computational design tools allow designers to create complex geometries that can be fabricated precisely using computer numerical control (CNC) machines and other digital fabrication technologies. Designers who are well-versed in programs like Rhino, Grasshopper, or Revit have the ability to utilize parametric modeling software that can calculate timber joinery that is based on intricate geometry. These tools allow designers to create 3D models of the structure and conduct experiments with different joinery options and configurations. Once the joinery is designed, it can be fabricated using CNC machines or other digital fabrication tools. It allows for high precision and accuracy in the fabrication process, ensuring the joint perfectly fits together. The use of complex timber joinery in contemporary architecture provides functional benefits and a unique aesthetic that cannot be achieved with other materials. By rethinking traditional joinery techniques and embracing digital technologies, architects and designers can create structures that push the boundaries of what is possible through timber construction. This thesis will investigate and explore the timber joinery system and fabrication methods, one of the old wooden structure techniques used in the age of digital technologies that rejuvenate the usage of conventional construction processes in timber buildings. The main aim of this thesis was to study computational design in creating complex wooden segmental base structures that rely on interlocking timber joints as the primary form of connection. This involved analyzing the role of wooden joinery and exploring complex systems made using this technique. The second objective was to create a digital model of several types of parametric wood joineries, such as halve and lap joint, Tenon and mortise joint, and finger joints. A digital model of a complex segmental plate structure with three fundamental parametric joints was also developed. The three basic types include finger, halve and lap clip, and Mortise and Tenon joints. The third objective is a structural and shape optimization of the basic mesh for specified complex geometry, which will be a digital model to evaluate the applicability of the generated joints, and will be determined because of this investigation

Fabricate

Bringing together pioneers in design and making within architecture, construction, engineering, manufacturing, materials technology and computation, Fabricate is a triennial international conference, now in its third year (ICD, University of Stuttgart, April 2017). Each year it produces a supporting publication, to date the only one of its kind specialising in Digital Fabrication. The 2017 edition features 32 illustrated articles on built projects and works in progress from academia and practice, including contributions from leading practices such as Foster + Partners, Zaha Hadid Architects, Arup, and Ron Arad, and from world-renowned institutions including ICD Stuttgart, Harvard, Yale, MIT, Princeton University, The Bartlett School of Architecture (UCL) and the Architectural Association

Plugin practice: recasting modularity for architects

Contemporary digital design practice is reframing a creative dialogue between design and making. Empowered by an increasingly seamless interface between data and material, the domain of the architect is expanding to engage diverse processes across design and fabrication. New practices of prototyping are emerging in which architects creatively extend opportunities for custom production, exploring relationships of form, material, fabrication, and aspects of performance. This research is driven by project work spanning such a broad domain across design and fabrication, through which I have developed a series of prototypes. In these projects I have created, used and appropriated numerous tools and techniques. In this dissertation, I focus on the ways in which I engage with such a diverse toolset, addressing the workflows of projects in order to frame a modularity of process. This modularity operates across multiple scales, from simple functions to more complex systems, and to varying degrees, from discrete elements to fuzzier arrangements. It is not derived from formulas for design but is instead grounded in expertise and experience. It emerges in response to specific demands for resilience and flexibility and frames a practice in which we plug together diverse processes to enable design and prototyping for architecture. The first contribution of this doctorate is to demonstrate a modularity of process and highlighting its role at multiple scales through a set of diagrams. Furthermore, I frame a series of implications of this modularity of process for architecture practice. Modularity is here more than just a means of organisation across design and fabrication. Nor is it employed to improve efficiency, as it is in some areas. Rather this modularity of process is important to enabling the generation and control differentiation, collaboration across fields of knowledge, and exploration of interdependent design criteria. These underpin a plugin practice in which designers can interrogate the ways we calibrate process and outcome, and create and reuse diverse forms of knowledg

CAD interface and framework for curve optimisation applications

Computer Aided Design is currently expanding its boundaries to include more design features in its processes. Design is identified as an iterative process converging to solutions satisfying a set of constraints. Its close relation with optimisation indicate that there is strong potential for the integration of optimisation and CAD. The problem addressed in this thesis lies in interfacing the geometric representation of design with other non-geometric aspects. The example of free-form curve modelling is taken to investigate such relationships. Assumptions are made that Optimisation is powered by Evolutionary Computing algorithms like Genetic Algorithms (GA). The geometric definition of curves is commonly supported by NURBS, whose construction constraints are defined locally at the data points. Here the NURBS formulation is used with GA in an attempt to provide complementary handles on the curves shape other than the usual data point coordinates and control points weights. Differential properties are used for optimising NURBS, Hermite interpolation allows for the definition of higher order constraints (tangent, normal, bi-normal) at data points. The assignment of parameter values at the data points, known as parameterisation also provides control of the curve’s shape. Curve optimisation is also performed at the geometric modelling level. Old mathematical theorems established by Frénet and further developed by other mathematicians provide means of defining a curve’s shape with it’s intrinsic equations. Such representation is possible by using Function Representation (F-rep) algebra available in the ACIS software. Frep allows more generic and exact means of interfacing with the curve’s geometry and new functionality for curve inspection and optimisation are proposed in this thesis. The integration of optimisation findings and CAD are documented in the definition of a framework. The framework architecture proposed reconstructs a new CAD environment from separate elements bolted together in a generic Application Programming Interface (API) named “Oli interface”. Functionality created to interface optimisation and CAD makes a requirement list of the work that both sides should undertake to achieve design optimisation in the CAD environment.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Fabricate 2020

Fabricate 2020 is the fourth title in the FABRICATE series on the theme of digital fabrication and published in conjunction with a triennial conference (London, April 2020). The book features cutting-edge built projects and work-in-progress from both academia and practice. It brings together pioneers in design and making from across the fields of architecture, construction, engineering, manufacturing, materials technology and computation. Fabricate 2020 includes 32 illustrated articles punctuated by four conversations between world-leading experts from design to engineering, discussing themes such as drawing-to-production, behavioural composites, robotic assembly, and digital craft

Fabricate 2017

Bringing together pioneers in design and making within architecture, construction, engineering, manufacturing, materials technology and computation, Fabricate is a triennial international conference, now in its third year (ICD, University of Stuttgart, April 2017). Each year it produces a supporting publication, to date the only one of its kind specialising in Digital Fabrication. The 2017 edition features 32 illustrated articles on built projects and works in progress from academia and practice, including contributions from leading practices such as Foster + Partners, Zaha Hadid Architects, Arup, and Ron Arad, and from world-renowned institutions including ICD Stuttgart, Harvard, Yale, MIT, Princeton University, The Bartlett School of Architecture (UCL) and the Architectural Association

A feature-based approach to the Computer-Aided Design of sculptured products

Computer-Aided Design systems offer considerable potential for improving design process efficiency. To reduce the 'ease of use' barrier hindering full realisation of this potential amongst general mechanical engineering industries, many commercial systems are adopting a Feature-Based Design (FBD) metaphor. Typically the user is allowed to define and manipulate the design model using interface elements that introduce and control parametric geometry clusters, with engineering meaning, representing specific product features (such as threaded holes, slots, pockets and bosses). Sculptured products, such as golf club heads, shoe lasts, crockery and sanitary ware, are poorly supported by current FBD systems and previous research, because their complex shapes cannot be accurately defined using the geometrically primitive feature sets implemented. Where sculptured surface regions are allowed for, the system interface, data model and functionality are little different from that already provided in many commercial surface modelling systems, and so offer very little improvement in ease of use, quality or efficiency. This thesis presents research to propose and develop an FBD methodology and system suitable for sculptured products. [Continues.