A practical generative design method

A generative CAD based design exploration method is proposed. It is suitable for complex multi-criteria design problems where important performance criteria are uncomputable. The method is based on building a genotype of the design within a history based parametric CAD system and then, varying its parameters randomly within pre-defined limits to generate a set of distinctive designs. The generated designs are then filtered through various constraint envelopes representing geometric viability, manufacturability, cost and other performance related constraints, thus reducing the vast design space into a smaller viable design space represented by a set of distinctive designs. These designs may then be further developed by the designer. The proposed generative design method makes minimal imposition on the designer’s work process and maintains both flexibility and fluidity that is required for creative design exploration. Its ability to work seamlessly with current CAD based design practices from early conceptual to detailed design is demonstrated. The design philosophy behind this generative method and the key steps involved in its implementation are presented with examples.     

SplineLearner: Generative learning system of design constraints for models represented using B-spline surfaces

Product design involves a computer-aided design (CAD) model with its design (dimensional) parameters. A generative design (GD) system can then be utilized to generate new designs by modifying these parameters. There is a need for a GD system to determine the visual validity of a design that is obtained after parametric modification. In this context, this paper introduces an approach to learn visual (i.e., design) constraints of a CAD model (represented using B-spline surfaces) by means of user feedbacks. A deformation technique (utilizing modification and limit curves) for B-spline surfaces is first introduced, which involves a few design (deformation) parameters. Via a generative learning process, the proposed system, SplineLearner, generates random designs, which are shown to user(s) for visual validity classifications. In a machine learning step, a mathematical model is computed that can perform prediction for a design to be valid or not. The mathematical model is also integrated into SplineLearner (after some user interactions) to prevent imbalances between the numbers of valid and invalid designs. As a proof of concept, B-spline surface models of a car body parts (hood, roof, side and trunk) are utilized, and two user studies are conducted to demonstrate the efficacy of the proposed method.     

Constructing a hybrid Kansei engineering system based on multiple affective responses: Application to product form design

This study proposes an expert system, which is called hybrid Kansei engineering system (HKES) based on multiple affective responses (MARs), to facilitate the development of product form design. HKES is consists of two sub-systems, namely forward Kansei engineering system (FKES) and backward Kansei engineering system (BKES). FKES is utilized to generate product alternatives and BKES is utilized to predict affective response of new product designs. Although the idea of HKES and similar hybrid systems have already been applied in various fields, such as product design, engineering design, and system optimization, most of existing methodologies are limited by searching optimal design solutions using single-objective optimization (SOO), instead of multi-objective optimization (MOO). Hence the applicability of HKES is limited while adapting to real-world problems, such as product form design discussed in this paper. To overcome this shortcoming, this study integrates the methodologies of support vector regression (SVR) and multi-objective genetic algorithm (MOGA) into the scheme of HEKS. BKES was constructed by training SVR prediction model of every single affective response (SAR). The form features of these product samples were treated as input data while the average utility scores obtained from all the consumers were used as output values. FKES generates optimal design alternatives using the MOGA-based searching method according to MARs specified by a product designer as the system supervisor. A case study of mobile phone design was given to demonstrate the analysis results. The proposed HKES based on MARs can be applied to a wide variety of product design problems, as well as other MOO problems involving with subjective human perceptions.     

Reverse innovative design — an integrated product design methodology

Today’s product designer is being asked to develop high quality, innovative products at an ever increasing pace. To meet this need, an intensive search is underway for advanced design methodologies that facilitate the acquisition of design knowledge and creative ideas for later reuse. Additionally, designers are embracing a wide range of 3D digital design applications, such as 3D digitization, 3D CAD and CAID, reverse engineering (RE), CAE analysis and rapid prototyping (RP). In this paper, we propose a reverse engineering innovative design methodology called Reverse Innovative Design (RID). The RID methodology facilitates design and knowledge reuse by leveraging 3D digital design applications. The core of our RID methodology is the definition and construction of feature-based parametric solid models from scanned data. The solid model is constructed with feature data to allow for design modification and iteration. Such a construction is well suited for downstream analysis and rapid prototyping. In this paper, we will review the commercial availability and technological developments of some relevant 3D digital design applications. We will then introduce three RE modelling strategies: an autosurfacing strategy for organic shapes; a solid modelling strategy with feature recognition and surface fitting for analytical models; and a curve-based modelling strategy for accurate reverse modelling. Freeform shapes are appearing with more frequency in product development. Since their “natural” parameters are hard to define and extract, we propose construction of a feature skeleton based upon industrial or regional standards or by user interaction. Global and local product definition parameters are then linked to the feature skeleton. Design modification is performed by solving a constrained optimization problem. A RID platform has been developed and the main RE strategies and core algorithms have been integrated into SolidWorks as an add-in product called ScanTo3D. We will use this system to demonstrate our RID methodology on a collection of innovative consumer product design examples.     

A new design optimization framework based on immune algorithm and Taguchi's method

This paper describes an innovative optimization approach that offers significant improvements in performance over existing methods to solve shape optimization problems. The new approach is based on two-stages which are (1) Taguchi's robust design approach to find appropriate interval levels of design parameters (2) Immune algorithm to generate optimal solutions using refined intervals from the previous stage. A benchmark test problem is first used to illustrate the effectiveness and efficiency of the approach. Finally, it is applied to the shape design optimization of a vehicle component to illustrate how the present approach can be applied for solving shape design optimization problems. The results show that the proposed approach not only can find optimal but also can obtain both better and more robust results than the existing algorithm reported recently in the literature.     

Data-driven generative design for mass customization: A case study

Generative design provides a promising algorithmic solution for mass customization of products, improving both product variety and design efficiency. However, the current designer-driven generative design formulates the automated program in a manual manner and has insufficient ability to satisfy the diverse needs of individuals. In this work, we propose a data-driven generative design framework by integrating multiple types of data to improve the automation level and performance of detail design to boost design efficiency and improve user satisfaction. A computational workflow including automated shape synthesis and structure design methods is established. More specifically, existing designs selected based on user preferences are utilized in the shape synthesis for creating generative models. For structural design, user-product interaction data gathered by sensors are used as inputs for controlling the spatial distributions of heterogeneous lattice structures. Finally, the proposed concept and workflow are demonstrated with a bike saddle design with a personalized shape and inner structures to be manufactured with additive manufacturing.     

The shared expertise model for teaching interactive design assistants

The growing complexity of contemporary engineering designs requires the use of sophisticated computer-based design tools. Such tools increase productivity in drafting, configuration and calculations. However, the current generation of design tools plays a rather passive role in the entire design process. Recent progress in knowledge-based engineering design, machine learning and knowledge acquisition allows the development of knowledge-based design assistants which could behave as active partners to human designers, rather than as passive graphical or computational tools. This paper presents the shared expertise model (SEM) of interaction between a human designer and a knowledge-based design assistant, in which the design assistant behaves as an apprentice and a collaborator in the design process. The human designer and his computer-based assistant create designs together, with the assistant proposing routine or even innovative designs, and the human designer correcting and finalizing these design, as well as specifying creative designs. In this process, the assistant also learns from the human designer, constantly extending and improving its knowledge base, and becoming a better design assistant. This is achieved by employing apprenticeship multistrategy learning based on a plausible version space representation. Within the SEM framework, a human designer with limited programming capabilities can directly develop and maintain a personalized knowledge-based design assistant. The use of SEM leads to increased capabilities of the expert-assistant design team. In this paper, some of the main features of the SEM model, as well as its implementation with the Disciple toolkit, are illustrated within the domain of computer workstation configuration.     

An integrated web-based CAD/CAPP/CAM system for the remote design and manufacture of feature-based cylindrical parts

This work describes the implementation of an integrated web-based CAD/CAPP/CAM system for the remote design and manufacture of feature-based cylindrical parts. This system, called WebMachining (), was developed in an e-manufacturing context, and the use of features allows the integration among the activities of collaborative design (WebCADbyFeatures), generative process planning (WebCAPP) and manufacturing (WebTurning). Through the WebCADby Features agent-based collaborative design module, cylindrical parts are modeled based on the synthesis of design features, in a Concurrent Engineering context. The WebCAPP generative CAPP module maps design features into machining features (including turning, milling, and drilling), and the mapping considers the setup, geometry, and operation. It uses a data structure similar to STEP-NC, and the generated process plans are nonlinear (i.e. they have alternatives). The WebTurning module performs the remote manufacture of the part, and it is based on a client–server architecture, where: (a) the servers are represented by the programs located at a workstation (Linux platform), which are connected to the machine tool through an Ethernet network interface; (b) the client is represented by a Java Applet. Some examples are provided in this paper, illustrating the remote design, process planning and manufacture of parts in a CNC turning center.     

CAD tools for aesthetic engineering

The role of computers and of computer-aided design tools for the creation of geometrical shapes that will be judged primarily by aesthetic considerations is reviewed. Examples are the procedural generation of abstract geometrical sculpture or the shape optimization of constrained curves and surfaces with some global ‘cost’ functional. Different possibilities for such ‘beauty functionals’ are discussed. Moreover, rapid prototyping tools based on layered manufacturing now add a new dimension to the visualization of emerging designs. Finally, true interactivity of the CAD tools allows a more effective exploration of larger parts of the design space and can thereby result in an actual amplification of the creative process.     

A conceptual approach for the die structure design

A large number of decisions are made during the conceptual design stage which is characterized by a lack of complete geometric information. While existing CAD systems supporting the geometric aspects of design have had little impact at the conceptual design stage. To support the conceptual die design and the top–down design process, a new concept called conceptual assembly modeling framework (CAMF) is presented in this paper. Firstly, the framework employs the zigzag function-symbol mapping to implement the function design of the die. From the easily understood analytical results of the function-symbol mapping matrix, the designer can evaluate the quality of a proposed die concept. Secondly, a new method—logic assembly modeling is proposed using logic components in this framework to satisfy the characteristic of the conceptual die design. Representing shapes and spatial relations in logic can provide a natural, intuitive method of developing complete computer systems for reasoning about die construction design at the conceptual stage. The logic assembly which consists of logic components is an innovative representation that provides a natural link between the function design of the die and the detailed geometric design.     

Mountain railway alignment optimization using stepwise & hybrid particle swarm optimization incorporating genetic operators

Optimizing railway alignments is a quite complex and time-consuming engineering problem. The huge continuous search space, complex constraints, implicit objective function and infinite potential alternatives of this problem pose many challenges. Especially in mountainous regions, finding a near-optimal alignment for extremely complex terrain and constraints is a most arduous task, which cannot be solved satisfactorily with most existing methods. In this study, a stepwise & hybrid particle swarm-genetic algorithm is developed for railway alignment optimization in mountainous regions. It is a continuous search method suitable for railway alignment design. A stepwise horizontal–vertical–integral approach which defines the horizontal and vertical alignments as two kinds of particles, is proposed to solve the three-dimensional railway alignment optimization problem. To enhance the initial diversity and momentum, butterfly-shaped areas are preset on a path generated with a bidirectional distance transform for initializing horizontal particles. For the solution method, specific genetic operators, including roulette wheel selection, four crossovers and two mutations are integrated into the stepwise particle swarm method to address parameter-dependent performance and avoid premature convergence. In addition, a cubic polynomial weight update strategy is employed for thoroughly searching the problem space. This synthesis method has been applied to a real-world case in a very mountainous region. The detailed data analyses demonstrate that it can offer more promising solutions compared with alternatives designed by experienced designers and those generated with a genetic algorithm or non-stepwise particle swarm algorithm.     

Using interactive evolutionary computation to generate creative building designs

In this paper we describe how we have exploited Evolutionary Computation (EC) to generate creative building designs. The algorithm has been implemented to create a design tool for architects called Design Inspiration system (DIS). The interactive design inspiration tool is able to generate initial design concepts of architectural plans. Our approach illustrates what we regard as an ideal strategy towards an organic architecture that is inspired from living organisms and not concerned with architectural style. The current capabilities of the system are demonstrated by the example of designing a library building. The paper ends by describing a comprehensive experiment with a total of 28 volunteer architects as a cognitive performance measurement tool, capable of accurately positioning participants’ performance using the design system. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Using HCA and TOPSIS approaches in personal digital assistant menu–icon interface design

Mobile electronic products have recently become very popular because of their portable convenience and versatile functions. The personal digital assistant (PDA) can even access the Internet. However, there is still plenty of room for improvement in the PDA interface. This research proposes a systematic approach to analyze, generate and evaluate a PDA integrated menu–icon interface design for the DigitHub Company based on customer requirements.Hierarchical clustering analysis (HCA) is incorporated with the analytic hierarchy process (AHP) to identify and categorize functional PDA menus and their corresponding icons. We evaluate the importance of each of the different functional menus and categories. We generate five PDA menu–icon interface design alternatives that meet the proposed design guidelines, and we evaluate each for their respective feasibilities. The technique for order preference by similarity to ideal solution (TOPSIS) method is applied to measure the overall operating performance of the five PDA menu–icon interface design alternatives. The evaluation results show that the preferred design is option PDA₅, a hierarchical and separated menu–icon layout style that features a two-layer menu structure.We expect that the proposed development procedure for the generation and evaluation of PDA menu–icon design alternatives based on customer requirements will be of interest to interface designers who wish to focus on mobile products.

Relevance to industry

This paper proposes an integrated procedure for designing PDA menu–icon interfaces. Our methodology should help in the creation and optimization of screen layouts for mobile phones, global positioning system (GPS) navigation devices, digital cameras and related screen interfaces.     

Automated database design for document stores with multicriteria optimization

Document stores have gained popularity among NoSQL systems mainly due to the semi-structured data storage structure and the enhanced query capabilities. The database design in document stores expands beyond the first normal form by encouraging de-normalization through nesting. This hinders the process, as the number of alternatives grows exponentially with multiple choices in nesting (including different levels) and referencing (including the direction of the reference). Due to this complexity, document store data design is mostly carried out in trial-and-error or ad-hoc rule-based approaches. However, the choices affect multiple, often conflicting, aspects such as query performance, storage space, and complexity of the documents. To overcome these issues, in this paper, we apply multicriteria optimization. Our approach is driven by a query workload and a set of optimization objectives. First, we formalize a canonical model to represent alternative designs and introduce an algebra of transformations that can systematically modify a design. Then, using these transformations, we implement a local search algorithm driven by a loss function that can propose near-optimal designs with high probability. Finally, we compare our prototype against an existing document store data design solution purely driven by query cost, where our proposed designs have better performance and are more compact with less redundancy.

     

A new decomposition based evolutionary algorithm with uniform designs for many-objective optimization

For many-objective optimization problems, how to get a set of solutions with good convergence and diversity is a difficult and challenging work. In this paper, a new decomposition based evolutionary algorithm with uniform designs is proposed to achieve the goal. The proposed algorithm adopts the uniform design method to set the weight vectors which are uniformly distributed over the design space, and the size of the weight vectors neither increases nonlinearly with the number of objectives nor considers a formulaic setting. A crossover operator based on the uniform design method is constructed to enhance the search capacity of the proposed algorithm. Moreover, in order to improve the convergence performance of the algorithm, a sub-population strategy is used to optimize each sub-problem. Comparing with some efficient state-of-the-art algorithms, e.g., NSGAII-CE, MOEA/D and HypE, on six benchmark functions, the proposed algorithm is able to find a set of solutions with better diversity and convergence.     

Addressing Constraints Creatively: How New Design Software Helps Solve the Dilemma of Originality and Feasibility

Are designers doomed to sacrifice creativity when integrating new product development processes? Although many studies highlight the need to produce original and innovative designs, maintaining creativity in the design process continues to be difficult due to industrial constraints. Thus, creativity is restricted to phases in the ‘fuzzy front end’ to avoid those constraints that might effectively kill it. However, constraints are also acknowledged as a resource for creativity, as has previously been shown with artists and engineers. Thus, we pose the following research question: In which cases can a constraint be a resource for creativity? To answer this question, we investigate different types of computer‐aided design (CAD) software. Relying on an experimental method, we compare the performance of those types of software at the so‐called design gap where design sketches are transformed into digital models. We show that some CAD software enables designers to work under additional constraints, be more creative and avoid the trade‐off between robustness and creativity, and that understanding this performance means appreciating that such software enables designers to play with the embedded constraints to reveal associated fixations and to design models that follow the constraint but overcome the fixation. Constraints and creativity are linked by two competing processes: constraints decrease the degree of freedom and, as a result, creative possibilities, but embedding constraints increases the awareness of fixations and therefore the capacity to design original models. Today, new CAD tools more effectively support the second process, which leads to ‘acquired originality’ in design.     

Cross-validation based single response adaptive design of experiments for Kriging metamodeling of deterministic computer simulations

A new approach for single response adaptive design of deterministic computer experiments is presented. The approach is called SFCVT, for Space-Filling Cross-Validation Tradeoff. SFCVT uses metamodeling to obtain an estimate of cross-validation errors, which are maximized subject to a constraint on space filling to determine sample points in the design space. The proposed method is compared, using a test suite of forty four numerical examples, with three DOE methods from the literature. The numerical test examples can be classified into symmetric and asymmetric functions. Symmetric examples refer to functions for which the extreme points are located symmetrically in the design space and asymmetric examples are those for which the extreme regions are not located in a symmetric fashion in the design space. Based upon the comparison results for the numerical examples, it is shown that SFCVT performs better than an existing adaptive and a non-adaptive DOE method for asymmetric multimodal functions with high nonlinearity near the boundary, and is comparable for symmetric multimodal functions and other test problems. The proposed approach is integrated with a multi-scale heat exchanger optimization tool to reduce the computational effort involved in the design of novel air-to-water heat exchangers. The resulting designs are shown to be significantly more compact than mainstream heat exchanger designs.     

建筑空间创意设计研究

近几年,随着旧屋再利用的兴起,建筑空间创意设计也有了更广阔的发展空间。尤其对于一些小型老旧建筑来说,空间创意设计是整个建筑设计工作的一个延升,赋予建筑新的生命。创意空间设计与传统室内设计不同,它将创意结合使用的可能性完全融入到建筑当中。文章以予舍工作室空间改造为例,将对建筑室内空间的再利用进行研究,对空间的创意设计提出一些建议。     

Creative conceptual design: Extending the scope by infused design

Many methods that support human creativity by manual or computational means have been proposed in the past. They rely on the assumption that following a certain process of reasoning might lead to generating ideas considered creative. We start by defining creativity as a capability that enables the creation of systems that are patentable. We review the state-of-the-art of creative conceptual design and organize it with a framework. Subsequently, we present a method called infused design that guarantees the generation of design solutions by transforming systems and methods from remote disciplines. In many cases, these solutions would be deemed creative. Finding these systems and their transformations is done through a process based on the underlying discrete mathematical representation. This process is partially supported by a computer tool.We describe the method of infused design and illustrate its operation through part of the results achieved until now, including designing a new active torque amplifier system. We further demonstrate its benefits through other examples. We discuss the relation of infused design with other creativity or design methods and conclude with future developments of the method.“A well-directed imagination is the source of great deeds.”Chinese proverb