Model layout optimization for solid ground curing rapid prototyping processes

Rapid prototyping technologies are capable of directly manufacturing physical objects from CAD models and have been increasingly used in product development, tool and die making and fabrication of functional parts. Solid ground curing (SGC) technology, one of the rapid prototyping technologies, is suitable of building multiple parts with different geometry and dimensions in batch production of rapid prototypes to minimize the cost of prototypes. However, the layout of CAD models in a graphic environment is time-consuming. Because of high cost of the resin, the layout of models in a batch is critical for the success of the SGC operations in any industrial environment. This paper presents the layout optimization using simulated annealing techniques. A software system was developed to assist Cubital operators to layout CAD models with various geometric shapes. The system accepts STL files from any solid modeling environment. Several examples are provided to illustrate the techniques and effectiveness of the approach.     

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.     

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.     

快速原型虚拟逼真设计原理及体系结构

在分析设计的特点和发展趋势的基础上,提出快速原型虚拟逼真设计,并对其特点和原理进行了讨论,快速原型虚拟逼真设计是面向并行工具,基于虚拟原型和虚拟环境仿真的设计,强调虚拟原型的快速生成和演化,在关键技术,原型系统以及开发环境三个层次上论述了快速原型虚拟逼真设计的研究,提出快速原型虚拟逼真设计模型以及基于该模型的体系结构。     

Simulation and computer-aided kinematic design of three-degree-of-freedom spherical parallel manipulators

Parallel robotic manipulators are complex mechanical systems that lead to involved kinematic and dynamic equations. Hence, the design of such systems is in general not intuitive, and advanced simulation and design tools specialized for this type of architecture are highly desirable. This article discusses the kinematic simulation and computer-aided design of three-degree-of-freedom spherical parallel manipulators with either prismatic or revolute actuators. The kinematic analysis of spherical parallel manipulators is first reviewed. Solutions for the direct and inverse kinematic problems are given, and the expressions for the singularity loci are then introduced. The determination of the workspace of this type of manipulator is also addressed. Finally, a computer package developed specifically for the CAD of spherical parallel manipulators is presented. This package allows the interactive analysis of manipulators of arbitrary architecture including the representation of the workspace, the representation of singularities, and the graphic animation of trajectories specified either by the direct or the inverse kinematic module. It can be used for the design of any spherical parallel three-degree-of-freedom actuated mechanism, which can find many applications in high-performance robotic systems. © 3995 John Wiley & Sons, Inc.     

基于虚拟原型的机械多体系统建模可视化

针对虚拟样机意义下的机械多体系统性能分析,提出一种直接从产品虚拟原型中的零件设计模型和装配模型获取多体系统物理性能属性和空间拓扑结构的理论和方法.将设计模型按照多体系统空间拓扑结构描述,直接映射为抽象的可视模型,并以此向求解模型过渡,从而最终获得对多体系统运动学和动力学的求解,使虚拟样机过程能在短时间内得以成功实施,达到整机动态性能分析的目的,获得满意的结果.最后,通过一个典型的机车车辆模型验证了文中方法的可行性.     

A process for solvent welded rapid prototype tooling

Rapid prototyping is widely seen as an effective tool for compressing time to market for new products. The typical process followed by industrial and mechanical design groups is to model a new product in a CAD system, rapidly prototype the component parts, use the parts as patterns for RTV silicone molds, and then cast polyurethane prototype parts from the molds. These prototype components are an integral part of the simultaneous engineering process. With prototype components, engineers are able to design, implement, test, and refine the assembly systems for a product while production tooling for the components is being made. In this paper, we describe an experimental rapid prototyping process, known as solvent welding freeform fabrication (SWIFT), that is very well suited to the production of short to medium run tooling. The advantage of the process is that it is very fast and inexpensive relative to the traditional RTV silicone mold making process. The process also produces ABS or polystyrene molds which last considerably longer than RTV silicone molds. Process development details are provided in the paper and its application to a power tool component is described.     

Microautonomous Robotic Ostraciiform (MARCO): Hydrodynamics, Design, and Fabrication

Boxfish with multiple fins can maneuver in confined spaces with a near zero turning radius, and it has been found that its unusual boxy shape is responsible for a self-correcting mechanism that makes its trajectories immune to water disturbances. The microautonomous robotic ostraciiform aims to apply these features in a novel underwater vehicle design. Miniature underwater vehicles with these characteristics have a variety of applications, such as environmental monitoring, ship wreck exploration, inline pipe inspection, forming sensor networks, etc. This paper presents the research leading to the design and fabrication of a robotic ostraciiform. Tail fin hydrodynamics have been investigated experimentally using robotic flapper mechanisms to arrive at a caudal fin shape with optimal-shape-induced flexibility. Fluid simulation studies were utilized to arrive at the body shape that can result in a self-correcting vorticity generation. Finally, the robotic ostraciiform prototype was designed based on the previous results. The ostracifform locomotion is implemented with a pair of 2 DOF pectoral fins and a single DOF tail fin. The finalized body shape of the robot is produced by 3-D prototyping two separate halves.     

A virtual prototyping approach to product disassembly reasoning

An important aspect of Design for the Life Cycle is assessing the disassemblability of products. After an artifact has completed its useful life, it must be disassembled then recycled, remanufactured or scrapped. Disassemblability of a product can be evaluated by performing disassembly activities on prototypes. Virtual prototyping (VP) is an alternative to hardware prototyping in which analysis of designs can be done without manufacturing physical samples. In recent years, disassembly processes have been generated either by using interactive or automated approaches, but these approaches have limitations. Interactive approaches require extensive user input usually in the form of answering questions, whereas automated approaches can only be used to generate disassembly processes for products with simple component configuration and geometry. In this paper automated and interactive techniques are combined, using VP, to generate complete disassembly processes of a product design. To support generation of disassembly processes of a product, a virtual environment and VP method were developed that will support disassembly activities performed by a designer. The product model of the virtual prototype is generated from the CAD model. The disassembly process model for the prototype is generated using automated reasoning techniques and is completed by interactively disassembling the product in the virtual environment. Extensions to automatic reasoning techniques to compute ranges of feasible directions of component removal were developed to facilitate the generation of the disassembly process. A scheme to represent the disassembly process for disassemblability evaluation was developed and implemented. In this paper a Chrysler LHS center console has been used to illustrate our approach of generating disassembly processes via VP.     

ProNoC: A low latency network-on-chip based many-core system-on-chip prototyping platform

Network-on-chip (NoC) is an emerging interconnect infrastructure to address the scalability limitation of conventional shared bus architecture for many-core system-on-chip (MCSoC). Current field-programmable gate arrays (FPGAs) have over million lookup tables, making it possible to prototype a complete NoC-based MCSoC on a single FPGA device. FPGA prototyping allows rapid system verification and optimum design parameters estimation. However, existing NoC-based MCSoC prototypes are usually adopting simple NoC architectural functionality. These NoC prototypes cannot represent a realistic projection of the state-of-the-art application-specific integrated circuit (ASIC) NoCs as these prototypes have limited overall system performance. This paper presents ProNoC, an integrated tool for rapid prototyping and validation of NoC-based MCSoC projects targeting FPGA devices. ProNoC adopts most advanced NoC features such as the support of virtual channel (VC), virtual network, low latency routing and different routing algorithms. Results show that NoC interconnect in ProNoC outperforms CONNECT, the most recent VC based prototype NoC with lower logic cell utilization, higher maximum operating frequency, higher average saturation throughput, and lower average communication latency. Moreover, ProNoC is equipped with graphical user interface to facilitate the development of MCSoC prototypes on FPGA platforms.     

The optimization of hybrid scaffold fabrication process in precision deposition system using design of experiments

In recent tissue engineering field, it is being reported that the fabrication of three-dimensional (3D) scaffolds having high porous and controlled internal/external architectures can give potential contributions in cell adhesion, proliferation and differentiation. To fabricate these scaffolds, various rapid prototyping technologies are being applied to. The rapid prototyping technology has made it possible to fabricate solid free-form 3D microstructures in layer-by-layer process. In this research, we introduce the development of precision deposition system, which is one of rapid prototyping technologies, and the fabrication result of scaffold using design of experiments (DOE) to optimize the deposition process. The precision deposition system required the combination of several technologies, including motion control, thermal control, pneumatic control, and CAD/CAM software. Through the organization of experimental approach using DOE, the fabrication process of hybrid scaffold, which is composed of blended poly-caprolactone, poly-lactic-co-glycolic acid and tricalcium phosphate, is established to get a uniform line width, line height and porosity efficiently.     

Interfacing geometric model data with rapid prototyping systems

The direct slicing of CAD models created in CADDS V to generate geometric data for rapid prototyping using fused feposition modeling technique (FDM) is presented in this paper. The report file from an explicit model is accessed for obtaining model data. Algorithms have been developed for determining the volumes of model material as well as support materials. New algorithms have been developed for filling the sheet solid. A simulation module has been developed to verify whether the filling is correctly done. Example of a model is manufactured using this approach is also presented in this paper.     

Using augmented reality to build digital twin for reconfigurable additive manufacturing system

The extrusion-based additive manufacturing (AM) processes are those where one or multiple tools (usually nozzles) are driven along predefined paths to deposit fabrication materials. They are usually inherently slow because solid contours have to be filled with mere single deposition lines of material. An intuitive way to improve the fabrication speed is to introduce multiple independent actuators for concurrent deposition of materials without collision among them. In this paper, a methodology of using augmented reality (AR) technique is presented to conveniently communicate the layout information between a reconfigurable AM system made of robotic arms and its corresponding digital twin for toolpath planning and simulation. A prototype system made of two desktops AM robotic arms is developed, and transformation matrices are derived to determine the spatial relation between different items in the system, including camera, markers, robotic arms and part substrate. Case studies are conducted to demonstrate the capability of this methodology in automatically retrieving layout information and assisting users to deploy pre-determined layout. The results show that the developed methodology enables rapid retrieval of position information from the physical system layout into the digital twin simulation and optimization and facilitates convenient deployment of an optimized layout determined in the digital twin into the physical system.     

Prototyping strategies for multisensory product experience engineering

The paper deals with prototyping strategies aimed at supporting engineers in the design of the multisensory experience of products. It is widely recognised that the most effective strategy to design it is to create working prototypes and analyse user’s reactions when interacting with them. Starting from this consciousness, we will discuss of how virtual reality (VR) technologies can support engineers to build prototypes suitable to this aim. Furthermore we will demonstrate how VR-based prototypes do not only represent a valid alternative to physical prototypes, but also a step forward thanks to the possibility of simulating and rendering multisensory and real-time modifiable interactions between the user and the prototype. These characteristics of VR-based prototypes enable engineers to rapidly test with users different variants and to optimise the multisensory experience perceived by them during the interaction. The discussion is supported both by examples available in literature and by case studies we have developed over the years on this topic. Specifically, in our research we have concentrated on what happens in the physical contact between the user and the product. Such contact strongly influences the user’s impression about the product.     

An object-oriented VLSI CAD framework

It is shown, in the context of an actual prototype VLSI CAD framework called Cbase, how concepts such as data abstraction, property and operation inheritance, object specialization/generalization, code reusability, and polymorphism offered by object-oriented database management systems (OODBMSs) support rapid prototyping. The work was conducted on Vbase, a commercially available OODBMS, but the results and conclusions apply to any database with comparable capabilities. To implement the prototype user interface, the X11 toolkit, a windowing package that is also built around the object paradigm, was used     

Nanofabrication using near-field optical probes

Nanofabrication using near-field optical probes is an established technique for rapid prototyping and automated maskless fabrication of nanostructured devices. In this review, we present the primary types of near-field probes and their physical processing mechanisms. Highlights of recent developments include improved resolution by optimizing the probe shape, incorporation of surface plasmonics in probe design, broader use in biological and magnetic storage applications, and increased throughput using probe arrays as well as high-speed writing and patterning.     

基于ADAMS的双足机器人建模与仿真

为了提高双足机器人的设计效率,可以通过虚拟样机技术对其进行设计与仿真。针对机器人设计双足行走步态,首先以实际的物理样机为原型,建立双足机器人的七连杆模型,并用解析法求得机器人的逆运动学模型;然后在ADAMS软件中建立参数化的虚拟样机模型,在Matlab软件中规划双足机器人在平地上的完整行走步态;最后将规划的步态导入ADAMS中,在虚拟样机上实现了双足机器人的行走仿真。仿真结果与规划的行走步态基本一致,验证了虚拟样机的有效性,从而为双足机器人的设计与步态规划提供了一种新的方法和可靠依据。     

UPE: Utah prototyping environment for robot manipulators

Developing an environment that enables optimal and flexible design of robot manipulators using reconfigurable links, joints, actuators, and sensors is an essential step for efficient robot design and prototyping. Such an environment should have the right mix of software and hardware components for designing the physical parts and the controllers, and for the algorithmic control of the robot modules (kinematics, inverse kinematics, dynamics, trajectory planning, analog control and digital computer control). Specifying object-based communications and catalog mechanisms between the software modules, controllers, physical parts, CAD designs, and actuator and sensor components is a necessary step in the prototyping activities.In this paper, we propose a flexible prototyping environment for robot manipulators with the required subsystems and interfaces between the different components of this environment. This environment provides a close tie between the design parameters of the robot manipulator by the different subsystems involved in the design process. The design and implementation of this environment along with the implementation of some of the subsystems are presented, and some examples that demonstrate the functionality of the environment are discussed. This work was supported in part by DARPA grant N00014-91-J-4123, NSF grant CDA 9024721, and a University of Utah Research Committee grant. All opinions, findings, conclusions or recommendations expressed in this document are those of the author and do not necessarily reflect the views of the sponsoring agencies.     

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.