A virtual prototyping system for rapid product development

This paper describes a virtual prototyping (VP) system that integrates virtual reality with rapid prototyping (RP) to create virtual or digital prototypes to facilitate product development. The proposed VP system incorporates two new simulation methodologies, namely the dexel-based and the layer-based fabrication approaches, to simulate the powder-based and the laminated sheet-based RP processes, respectively. The dexel-based approach deposits arrays of solid strips to form a layer, while the layer-based approach directly forms a complete layer by extruding the slice contours. The layer is subsequently stacked up to fabricate a virtual prototype. The simulation approaches resemble the physical fabrication processes of most RP systems, and are therefore capable of accurately representing the geometrical characteristics of prototypes. In addition to numerical quantification of the simulation results, the system also provides stereoscopic visualisation of the product design and its prototype for detailed analyses. Indeed, the original product design may be superimposed on its virtual prototype, so that areas with dimensional errors beyond design limits may be clearly highlighted to facilitate point-to-point analysis of the surface texture and the dimensional accuracy of the prototype. Hence, the key control parameters of an RP process, such as part orientation, layer thickness and hatch space, may be effectively tuned up for optimal fabrication of physical prototypes in subsequent product development. Furthermore, the virtual prototypes can be transmitted via the Internet to customers to facilitate global manufacturing. As a result, both the lead-time and the product development costs can be significantly reduced.     

A multi-material virtual prototyping system

This paper proposes a multi-material virtual prototyping system for digital fabrication of heterogeneous prototypes. It consists mainly of a topological hierarchy-sorting algorithm for processing slice contours, and a virtual simulation system for visualisation and optimisation of multi-material layered manufacturing (MMLM) processes. The topological hierarchy-sorting algorithm processes the hierarchy relationship of complex slice contours. It builds a parent-and-child list that defines the containment relationship of the slice contours, and subsequently arranges the contours in an appropriate sequence, which facilitates toolpath planning for MMLM by avoiding redundant tool movements. The virtual simulation system simulates MMLM processes and provides stereoscopic visualisation of the resulting multi-material prototypes for quality analysis and optimisation of the processes.     

Concept design for quality in virtual environment

The early identification of the optimal concept is a critical task of the design process in order to increase the chances of satisfying customers. The challenging aspect of the approach proposed in this work relies in the quality evaluation of virtual prototypes of new industrial products (i.e. concept designs) by adopting a statistical procedure previously applied to service industries. Following this approach, the optimal concept design is defined at the end of a process consisting of five phases: identification of the quality elements of the concept design, classification of the quality elements, generation and quality evaluation of product concepts and, finally, definition of the optimal concept. Currently, virtual reality (VR) environment offers the opportunity to evaluate the characteristics of different virtual prototypes by involving experts and/or customers, overcoming the need for several physical prototypes. On the other side, the dynamics of simulation and the stereoscopic visualization in VR environment provides a more realistic and impressive interaction with virtual prototypes than in CAD environment.

The proposed methodology is fully exploited through two case studies: the choice of the optimal design for a traditional Neapolitan coffee maker, addressed by the Italian designer Riccardo Dalisi, and for a subassembly of a new minicar.     

A virtual prototyping system with reconfigurable actuators for multi-material layered manufacturing

Proliferation of layered manufacturing (LM) in various sectors has been calling for fabrication of large, complex products with more materials and efficiency. We address this issue by integrating reconfigurable manufacturing (RM) with LM. This paper first analyses the benefits of such integration, and then presents a virtual prototyping system with reconfigurable actuators (VPRA) that can increase the number of materials, speed, and build volume to improve the efficiency and flexibility of multi-material layered manufacturing (MMLM). The VPRA system offers a test bed for design, visualization, and validation of MMLM facilities and processes. It takes advantage of the convenient graphics platform of SolidWorks™ for constructing a virtual MMLM facility by selecting reconfigurable actuators from predefined templates. The characteristics, including the dimensions and relative spatial constraints, of the actuators can be conveniently configured to suit design requirements. The mechanism and the operation process of the resulting MMLM facility can then be simulated and validated through digital fabrication of complex objects. Case studies are presented to demonstrate some possible applications of the VPRA system. Overall, the VPRA system gives insights into the characteristics of a reconfigurable MMLM system, which can be subsequently materialized for physical fabrication of multi-material objects. This approach highlights a possible direction for development of MMLM technology.     

A dynamic priority-based approach to concurrent toolpath planning for multi-material layered manufacturing

This paper presents an approach to concurrent toolpath planning for multi-material layered manufacturing (MMLM) to improve the fabrication efficiency of relatively complex prototypes. The approach is based on decoupled motion planning for multiple moving objects, in which the toolpaths of a set of tools are independently planned and then coordinated to deposit materials concurrently. Relative tool positions are monitored and potential tool collisions detected at a predefined rate. When a potential collision between a pair of tools is detected, a dynamic priority scheme is applied to assign motion priorities of tools. The traverse speeds of tools along the x-axis are compared, and a higher priority is assigned to the tool at a higher traverse speed. A tool with a higher priority continues to deposit material along its original path, while the one with a lower priority gives way by pausing at a suitable point until the potential collision is eliminated. Moreover, the deposition speeds of tools can be adjusted to suit different material properties and fabrication requirements. The proposed approach has been incorporated in a multi-material virtual prototyping (MMVP) system. Digital fabrication of prototypes shows that it can substantially shorten the fabrication time of relatively complex multi-material objects. The approach can be adapted for process control of MMLM when appropriate hardware becomes available. It is expected to benefit various applications, such as advanced product manufacturing and biomedical fabrication.     

A topological hierarchy-based approach to toolpath planning for multi-material layered manufacturing

This paper proposes a topological hierarchy-based approach to toolpath planning for multi-material layered manufacturing (MMLM) of heterogeneous prototypes. The approach facilitates control of MMLM and increases the fabrication efficiency of complex objects by generating multi-toolpaths that avoid redundant tool movements and potential collisions. It uses a topological hierarchy-sorting algorithm to group complex multi-material slice contours into families connected by a parent-and-child relationship. Subsequently, a sequential toolpath planning algorithm generates multi-toolpaths for sequential deposition of materials without redundant tool movements. To reduce build time further, a concurrent toolpath planning algorithm generates collision-free multi-toolpaths to control the tools that deposit materials concurrently. It uses parametric polygons to construct tool envelopes for contour families of the same material property to simplify detection of tool collisions. The tightness of polygons can be controlled to suit the processing speed and the optimality of the resulting concurrent toolpaths. The proposed approach has been implemented as an integral part of a multi-material virtual prototyping (MMVP) system that can process complex slice contours for planning, stereoscopic simulation, and validation of multi-toolpaths. It may be adapted for subsequent control of MMLM processes.     

Virtual prototyping of automated manufacturing systems with Geometry-driven Petri nets

The design process of automated manufacturing systems typically involves physical prototypes to validate the interactions between hardware and software components. However, physical prototyping is expensive and time consuming, which often leads to insufficient opportunities for testing early during the development cycle. Our objective is to improve this situation by providing a method to develop realistic prototypes using virtual reality technology that can be applied during earlier development stages. Our approach combines a virtual reality engine capable of enacting the laws of rigid body physics with a new hybrid software modelling language to control the simulated hardware using virtual sensors and actuators as they would be present in a physical prototype. The new modelling language is called Geometry-driven Petri nets (GPN) and combines a class of timed, high-level Petri nets with data structures used in state-of-the-art VR environments. This article describes the new GPN approach, applies it to a case study of an automated manufacturing line, and compares it with related approaches.     

Design evaluation and modification of mechanical systems in virtual environments

Design is one of the most important stages in the manufacturing cycle and influences all the subsequent stages of product development. In the context of today’s iterative design methodology, the modification of any design is a process involving many evaluations and improvements to the solutions chosen in earlier stages. For this purpose, in the most recent decade, 3D computer simulations have become common tools used within industry. Whilst virtual reality (VR) technology is seen as the interaction technology of the future, much of the current research in this area is carried out to explore the potential benefits and added value brought by the integration of this into standard software technologies currently used at various stages in manufacturing life cycle. A lot of attention has been given to exploring the usability and benefits of interactive VR for assembly planning, knowledge elicitation and design and simulation. However, little research has focussed on the analytical aspects of the design process, for example in the use of VR as an interface for simulation software in finite element methods and multi-body systems. This paper introduces research focussing on applications of virtual environments (VEs) for interactive design evaluation and modification adapted and used with standard simulation software. The use of such interactive visualisation offers the engineer more realistic real-time representations of the design and advanced facilities to interact with the model during the design process. While design evaluation is based mainly on visualisation; design modification requires interactive changes of the model during the simulation, and the interfaces described here highlights such applications. In this work, two software prototypes have been developed using VR technology. First, a software tool called design evaluation in virtual environments is presented together with an application in civil engineering to illustrate the mode of operation and added value of the use of an interactive visualisation environment. Linking the simulation software with the VE provides real time bi-directional communication of graphical information which can be successfully achieved even within the limits of current computer technology. The tool includes a suite of software modules and a user interface to facilitate the link between the simulation results and the VE. The second tool facilitates the design modification in virtual environments system by providing real time dynamic simulation. Two dynamic approaches are investigated in order to study the real time simulation issues in the context of design modification and system performance: the classic approach based on rigid interconnected bodies, and a new and novel approach developed by the authors based on particles dynamics. Both implementations have been tested and compared on a mechanism application under the same computing conditions. The research applications presented demonstrate the practicality, flexibility and versatility of the visualisation in virtual environment in design evaluation and modification. However, the computer efficiency whilst carrying out real time dynamic simulation is limiting the range of applications to models of moderate size; however, this is an improvement on previous similar applications.     

Integrated manufacture: A role for virtual reality?

Virtual Reality (VR) is fast becoming an affordable technology with potentially wide-ranging applications in many professions including education, medicine and industry. Its advantages over existing technology are primarily that users can visualise, feel involvement and interact with virtual representations of real world activities in real time.

A recently completed study, funded by the EPSRC, examined the feasibility of VR as a tool for UK manufacturing industry. Of primary interest was whether manufacturers perceive a use for VR in their inudstry and, if so, what impact they envisage it will have within their company. A national survey was distributed to over 2,000 UK manufacturing companies randomly selected and interviews carried out with existing users of VR technology. A brief summary of these results is presented.

A demonstration application was developed in desktop VR representing the manufacture of a consumer product in which various stages of the manufacturing process were featured including initial design, manufacture, and testing. The demonstration application is described in detail and user assessments are presented. On the basis of these findings, the potential future role of VR in integrated manufacture is discussed. Relevance to industry

In only a short time, virtual environments have become a focus of serious consideration as a tool for manufacturing and other industry. In order that VR has greatest industrial utility we need to examine and develop its potential as a specialism-free integrating medium within a simultaneous engineering approach.     

Evaluation of customer impressions using virtual prototypes in the internet environment

This study aims to investigate a cost effective and efficient way of analyzing customer impressions on design alternatives by incorporating the benefits of virtual prototyping into the Internet-based experimental environment. It is hypothesized that the results of the Internet-based experiment using the images of virtual prototypes are comparable to those of the virtual reality-based environment using virtual prototypes. Two experiments were conducted. In the virtual reality environment, participants were employed to evaluate virtual prototypes while in the Internet environment participants evaluated images of the same virtual prototypes from their own places. For each experiment, 16 male participants were employed to evaluate 32 different virtual prototypes generated from the combination of 17 design elements of automobile interior. The results of the experiments indicated that there were no significant differences between the two experimental methods while the Internet environment-based method could save considerable time and efforts for experimentation. This study concludes that the Internet-based evaluation method using the images of virtual prototypes could be a cost effective and efficient way of analyzing customer impressions on design alternatives.

Relevance to Industry

This study showed that the results of the Internet-based evaluation method using the images of virtual prototypes are comparable to those of the virtual reality-based method using real virtual prototypes. The Internet-based evaluation method could be used as a cost effective and efficient way of collecting and analyzing various customers’ impressions on design alternatives at the early stage of product development process.     

一个基于Web的网络虚拟现实系统的设计与实现

虚拟现实技术发展很快,有广泛的工业和商业应用。网络虚拟现实技术已越来越为工业制造业所关注,虚拟制造环境(VME)的一个主要用途是在线可视化和对3D信息的协作控制,这需要实时数据传输的支持。为了满足基于Internet的VE通信需求,特别是为满足虚拟制造和协作设计和控制,该文设计并实现了一个支持网络虚拟设计和制造的网络虚拟现实系统,此系统用MMS协议实现VE通信,并将工业控制服务集成于基于Internet的虚拟环境中。     

虚拟样机技术及其在轻武器研制中的应用

给出了虚拟样机技术一个建议性的定义并论述了虚拟样机、虚拟现实及虚拟制造之间的区别.在新型单兵自卫武器的研制中引入虚拟样机技术.仿真评估结果表明：所建立的虚拟样机具有模拟物理样机的能力.这种虚拟样机应用的新方法在轻武器的研制中具有十分重要的意义.     

An integrated manufacturing system for rapid tooling based on rapid prototyping

To reduce the time and cost of moulds fabrication, a novel integrated developing and manufacturing system of rapid tooling (RT) based on rapid prototyping (RP) is proposed. The architecture of system which consists of four building blocks: digital prototype, virtual prototype (VP), physical prototype and RT system, is presented. A digital prototype can be established by 3D CAD software packages or reveres engineering technique. A VP is employed to guide in optimization of the mould design and manufacturing process planning. A physical prototype, which is built using RP technology, generally serves as a pattern for producing RT. By integrating these building blocks closely, the system can aid effectively in mould design, analysis, prototyping, simulating, and manufacturing process development. Three typical cases are discussed in detail to illustrate the application of the system. It has been shown from a number of case studies that the system has a high potential to reduce further the cycle and cost of die development while minimizing error introduction. As a result, the integrated system provides a feasible and useful tool for companies to speed up their product development.     

基于虚拟现实的塑料注塑成型系统场景可视化

虚拟现实,作为一门新型技术,已成功地应用于工程、设计和制造业领域.该文针对塑料注塑成型复杂的设计、制造、加工过程,将虚拟现实技术应用到塑料注塑成型过程中,并利用Delaunay三角剖分技术结合立体显示技术,开发了一种实用的虚拟场景.在此场景中可实现注射系统的全部设计和制造过程,并结合面向对象的编程技术和OpenGL图形库,实现注射成型系统在虚拟现实场景中的动态可视化,从而能够预先感知注射系统在设计、制造过程中可能出现的问题,并加以解决,实践证明了其可行性.     

Virtual factory approach for implementation of holonic control in industrial applications: A case study in die-casting industry

Design and implementation of holonic manufacturing control systems for the real industrial applications require risky, careful decisions to ensure that the manufacturing system will successfully satisfy the demands of an ever-changing market. This paper suggests a virtual reality (VR)-based methodology for enhancing the design and implementation process of holonic control systems in manufacturing practice. The major focus has been given to the implementation of holonic control into the small to medium size manufacturing enterprises (SMEs).     

A collaborative Design for Usability approach supported by Virtual Reality and a Multi-Agent System embedded in a PLM environment

This paper details a collaborative workstation design approach integrating knowledge based on engineering process, using a Multi-Agent System (MAS) on a Virtual Reality (VR) platform. The MAS supports R&D teams to extract and re-use engineering knowledge so as to improve their efficiency in developing new products. Our research targets the development of a knowledge engineering system integrated into a PLM-Product Life cycle Management-environment linked with virtual reality tools. A PLM is a strategic business approach with a consistent set of methodologies and software solutions. It is meant to promote collaborative creation, management, delivery and proper use of this life cycle definition and information product in multinational companies. This system is used by engineers to carry out projects in a collective way while conveying a defined process. The MAS allows capitalization, and to annotate knowledge according to the actions of the designers inside a PLM environment. Then, this knowledge is used by VR tools to analyze various aspects of the virtual prototype such as manufacturing, maintenance, reliability or ergonomics. Consequently, we use expert knowledge to pilot the design process of a virtual prototype inside a three-dimensional immersive virtual reality platform. In this context, our paper describes our knowledge management approach applied to improve ergonomics and collaborative design in industrial areas.     

Applications of virtual reality in maintenance during the industrial product lifecycle: A systematic review

As a state-of-the-art computer technology, virtual reality (VR) is considered to play an important role in helping manufacturing companies stay competitive in the international market. However, despite the achievements made in the field of VR, it is still an emerging technology that lacks deeper exploration and development in industrial application scenarios, especially in the coming fourth industrial revolution (Industry 4.0). This paper aims to systematically investigate the applications of VR in industrial maintenance to discover evidence of its values, limitations, and future directions so that VR can be guided to better serve manufacturing enterprises in remaining competitive in the coming Industry 4.0. A systematic literature review (SLR) methodology is adopted to review primary studies on this topic, by which 86 studies are ultimately included. The results show that VR has proved its value in benefiting maintenance issues through the product lifecycle. However, VR is still not an indispensable element for the lifecycle management of products regarding maintenance-related issues. Several key findings are concluded based on the analysis of the 86 studies. This review is valuable for researchers who are interested in the application of VR technology in maintainability design, maintenance training or maintenance task assistance.     

虚拟制造技术在电动工具设计中的应用

该文简要介绍了虚拟制造技术尤其是虚拟样机技术目前的发展状况，阐述了当前电动工具行业的一些发展趋势，指出对虚拟样机技术的需要，并结合实际提出了一种电动工具行业或轻型机械行业应用虚拟制造技术的原则、重点及方法，并利用虚拟样机技术对一电动射钉枪联动钢绳易断问题给出分析和解决方案。     

Context analysis to support development of virtual reality applications

To develop a usable Virtual Reality system, the prospective context of use of such a system may need to be considered in order to make sure it meets the requirements and restrictions of that context. In this paper, a contextual analysis is described for a virtual reality system to aid medical diagnosis and treatment planning of vascular disorders. Semi-structured interviews were coupled with observations in an ethnographic approach to requirements gathering in the daily work environment of (interventional) radiologists and vascular surgeons. The identified potential usability problems of a fully immersive prototype, coupled with the needs, requirements and real-life environment of the end-users lead to guidelines for the development of a VR application on a semi-immersive desktop environment. The findings lead us to believe that contextual analysis can be a powerful way to inform the design of a VR application by offering an understanding of the context of use and to inform developers of the most appropriate degree of immersiveness of the VR environment.     

浅谈人机工程分析软件在虚拟制造中的应用

在当前社会中,世界各地的企业之间竞争意识在增强,决定制造企业全球竞争能力的主要指标之一就是产品的开发时间、产品成本、产品质量以及产品应用.目前使用相对于广泛的就是“虚拟制造”技术,而人机工程分析则是虚拟制造”技术其中的一部分.为了适应目前市场的多变性质,减少企业成本和制作周期, “虚拟制造”技术逐渐成为最突出的一种.它能够在产品设计初期和开发的各个阶段有效的把握制造过程各个阶段的实际情况,同事也能有效的协调设计与制造各阶段之间的关系,以便使企业整体全局达到最优益.