Integration of the STEP-based assembly model and XML schema with the fuzzy analytic hierarchy process (FAHP) for muti-agent based assembly evaluation

Assemblability analysis and evaluation plays a key role in assembly design, operation analysis and planning. In this paper, we propose an integrated intelligent approach and framework for evaluation of assemblability and assembly sequence for electro-mechanical assemblies (EMAs). The approach integrates the STEP (STandard for the Exchange of Product model data, officially ISO 10303)-based assembly model and XML schema with the fuzzy analytic hierarchy process for assembly evaluation. The evaluation structure covers not only the geometric and physical characteristics of the assembly parts but also the assembly operation data necessary to assemble the parts. The realization of the integration system is implemented through a multi-agent framework. Through integration with the STEP-based product modeling agent system, CAD agent system and assembly planning agent system, the developed assembly evaluation agent system can effectively incorporate, exchange, and share concurrent engineering knowledge into the preliminary design process so as to provide users with suggestions for improving a design and also helping obtain better design ideas. The applications show that the proposed approach and system are feasible. Received: July 2004 / Accepted: January 2006     

A spatiotemporal information management framework for product design and assembly process planning reconciliation

This paper introduces an innovative framework for product design and assembly process planning reconciliation. Nowadays, both product lifecycle phases are quasi concurrently performed in industry and this configuration has led to competitive gains in efficiency and flexibility by improving designers’ awareness and product quality. Despite these efforts, some limitations/barriers are still encountered regarding the lack of dynamical representation, information consistency and information flow continuity. It is due to the inherent nature of the information created and managed in both phases and the lack of interoperability between the related information systems. Product design and assembly process planning phases actually generate heterogeneous information, since the first one describes all information related to “what to be delivered” and the latter rationalises all information with regards to “how to be assembled”. In other words, the integration of assembly planning issue in product design requires reconciliation means with appropriate relationships of the architectural product definition in space with its assembly sequence in terms of time. Therefore, the main objective is to provide a spatiotemporal information management framework based on a strong semantic and logical foundation in product lifecycle management (PLM) systems, increasing therefore actors’ awareness, flexibility and efficiency with a better abstraction of the physical reality and appropriate information management procedures. A case study is presented to illustrate the relevance of the proposed framework and its hub-based implementation within PLM systems.     

Development of a CAD-based intelligent manufacturing system

This research proposes a CAD-based manufacturing system that embraces computer-aided design, design for manufacturing and assembly (DFMA), computer-aided process planning (CAPP), computer-aided assembly planning (CAAP), and vision-robot integration. The proposed system starts with the design of products using a commercial CAD software, Autocad. The design data is then extracted from the CAD database and organized into a standardized product model. Interface programs are used to translate the geometrical and topological information in the model into DFMA, CAPP, CAAP and vision image representations. Based on the results generated by the interface programs the applications using artificial intelligence techniques can automatically generate redesign advises, CNC part programs, assembly sequence and instructions for robots.     

A knowledge intensive multi-agent framework for cooperative/collaborative design modeling and decision support of assemblies

Multi-agent modeling has emerged as a promising discipline for dealing with decision making process in distributed information system applications. One of such applications is the modeling of distributed design or manufacturing processes which can link up various designs or manufacturing processes to form a virtual consortium on a global basis. This paper proposes a novel knowledge intensive multi-agent cooperative/collaborative framework for concurrent intelligent design and assembly planning, which integrates product design, design for assembly, assembly planning, assembly system design, and assembly simulation subjected to econo-technical evaluations. An AI protocol based method is proposed to facilitate the integration of intelligent agents for assembly design, planning, evaluation and simulation process. A unified class of knowledge intensive Petri nets is defined using the O-O knowledge-based Petri net approach and used as an AI protocol for handling both the integration and the negotiation problems among multi-agents. The detailed cooperative/collaborative mechanism and algorithms are given based on the knowledge objects cooperation formalisms. As such, the assembly-oriented design system can easily be implemented under the multi-agent-based knowledge-intensive Petri net framework with concurrent integration of multiple cooperative knowledge sources and software. Thus, product design and assembly planning can be carried out simultaneously and intelligently in an entirely computer-aided concurrent design and assembly planning system.     

Digital twin-based smart assembly process design and application framework for complex products and its case study

With rapid advances in new generation information technologies, digital twin (DT), and cyber-physical system, smart assembly has become a core focus for intelligent manufacturing in the fourth industrial evolution. Deep integration between information and physical worlds is a key phase to develop smart assembly process design that bridge the gap between product assembly design and manufacturing. This paper presents a digital twin reference model for smart assembly process design, and proposes an application framework for DT-based smart assembly with three layers. Product assembly station components are detailed in the physical space layer; two main modules, communication connection and data processing, are introduced in the interaction layer; and we discuss working mechanisms of assembly process planning, simulation, predication, and control management in the virtual space layer in detail. A case study shows the proposed approach application for an experimental simplified satellite assembly case using the DT-based assembly application system (DT-AAS) to verify the proposed application framework and method effectiveness.     

基于装配顺序的飞机装配容差信息建模

论文提出了基于装配顺序的装配容差信息建模方法,以装配仿真路径规划 的装配顺序为基础,提取装配体中各零件的特征约束关系及相关的关键特征,进而获取组成 环容差信息,建立装配容差信息模型。该模型考虑了装配顺序对装配误差累积过程的影响, 减少了人工容差信息建模繁琐的交互操作,提高了装配容差信息的建模质量。基于DELMIA 平台开发了飞机装配仿真系统。该系统已在工程上成功应用,提高了飞机装配仿真的效率, 减少了飞机实际装配生产中的出错率。     

A PDES/STEP-based model and system for concurrent integrated design and assembly planning

Product data exchange and interfacing between different CAD/CAM systems are of great importance to the development of concurrent integrated design environments and computer integrated manufacturing systems. This paper presents a STEP-based method and system for concurrent integrated design and assembly planning. An integrated object model for mechanical systems and assemblies is first defined by a hierarchy of structure, geometry and feature. The structure is represented as a component-connector or joint multi-level graph with both hierarchical functional and assembly relations. These hierarchical relation models are then used for uniformly describing their causal relations both for assembly level and feature based single part level. The generic product assembly model is organized according to STEP, using mostly the entities of integrated resources and partly self-defined entities, which are necessary for design and assembly planning. Based on the generic product assembly model, STEP-based strategies and agent concepts are used for agent-based concurrent integration of design and assembly planning. A prototype system, consisting of a CAD system, a product modeling system, an assembly planning system, and an assembly evaluation system is developed, in which product data can be exchanged between these subsystems. Details about the implementation of the system are addressed. The integrated design and assembly planning system can support the introduction of a new product. The results of assembly planning are feedback to the stage of assembly design to improve on the design. A case study is carried out for assembly-oriented design of a gearbox, to illustrate the proposed approach and to validate the developed system.     

Studies on visual scene process system of aircraft assembly

According to the aircraft assembly worksite scene process, the hierarchical data model based on PPR (product, process, resources) was got to achieve the conversion in various types of aircraft assembly process data model. At the same time, the lightweight technology and human–computer interactive scene control technology were researched to obtain the lightweight of three-dimensional (3D) model and site scene and the human–computer real-time interaction between people and virtual environment through the computer keyboard and mouse, respectively. And then, the visual assembly sequence planning algorithm based on the parallel binary-coded was suggested to complete the aircraft assembly sequence planning. On the basis of techniques mentioned above, we developed the assembly worksite scene process system, which can be integrated with PDM system. At last, an application case of aircraft nose assembly was given, and the result was proved to be effective.     

Development of a feature-based and object-oriented concurrent engineering system

Product information modeling is critical to the integration of mechanical CAD/CAM systems and to the implementation of a concurrent engineering system. This paper presents a recent development of a feature-based and object-oriented concurrent engineering system with its focus on a product information modeling technique implemented in the system. The technique was developed to capture product definition data including form features and their spatial relationships and to store them as an object-oriented information model during the design process. The paper also describes the implementation of the information modeling technique and its application to manufacturing process planning in an object-oriented environment.     

面向装配工序交叉的虚拟装配工艺信息模型

虚拟装配工艺规划中目前大都采用装配顺序描述装配过程,但尚无法表达装配工序交叉和设计中的安装布置'捌整等问题.考虑设计阶段和制造阶段的装配要求,建立了基于装配任务的装配工艺信息模型.该模型以多层次的装配进程表达产品装配工艺过程,通过任务对象的交叉安装表达工序交叉和安装布置凋整,并给出了装配调整策略;针对冗余装配任务提出了装配任务合并方法.最后通过实例验证了文中模型的正确性和有效性.     

Overview of entity-based integrated design product and process models

The development of computer-integrated systems for engineering design requires models to describe and organize the information and activities involved in design. A product model describes the information created during the design process, and a process model describes the associated design activities. Product and process models can be integrated into a single model. An entity-based approach is one way to carry out this integration. An entity-based integrated model uses product entities and process entities to represent design information and design activities, respectively. The relationships among these entities include organizational, interaction and sequence relationships. Organizational relationships organize entities into hierarchies, interaction relationships characterize the nature of entity interactions, and sequence relationships identify the sequences in which process entities are initiated during the design process. This paper presents an overview of the product and process entities, and the organizational, interaction and sequence relationships of entity-based integrated design product and process models. Formal concepts and notation used to represent these entities and relationships are described using a simple design example. © 1998 Published by Elsevier Science Limited. All rights reserved.     

An assembly oriented design framework for product structure engineering and assembly sequence planning

The paper describes a novel framework for an assembly-oriented design (AOD) approach as a new functional product lifecycle management (PLM) strategy, by considering product design and assembly sequence planning phases concurrently. Integration issues of product life cycle into the product development process have received much attention over the last two decades, especially at the detailed design stage. The main objective of the research is to define assembly sequence into preliminary design stages by introducing and applying assembly process knowledge in order to provide an assembly context knowledge to support life-oriented product development process, particularly for product structuring. The proposed framework highlights a novel algorithm based on a mathematical model integrating boundary conditions related to DFA rules, engineering decisions for assembly sequence and the product structure definition. This framework has been implemented in a new system called PEGASUS considered as an AOD module for a PLM system. A case study of applying the framework to a catalytic-converter and diesel particulate filter sub-system, belonging to an exhaust system from an industrial automotive supplier, is introduced to illustrate the efficiency of the proposed AOD methodology.     

Automatic assembly simulation of product in virtual environment based on interaction feature pair

In engineering practical implications, assembly simulation is a useful solution to test the planned assembly process and address assembly issues. However, it is usually carried out by time-consuming human–computer interaction, which causes a lot of unavoidable laborious work. Assembly simulation could exhibit the design intent in virtual environment through the interactions between parts. Unfortunately, the models which modeled with current constraint-based method cannot provide sufficient interaction information to support assembly simulation, and the needed information should be added by designers manually. To solve this problem, this paper introduces the concept of interaction feature pair (IFP) and presents an automatic assembly simulation method based on IFP. The proposed IFP provides a form that endues a part with the capability of knowing which part is going to interact with and how to interact. Based on IFP, the automatic assembly simulation is carried out in two steps: First, a graph-based method in presented to generate the interaction sequence, which provides the information that when and which feature should be mated during assembly. Then, the randomized motion planning is employed in the established C-space to find a collision-free path for each part, and the planning results in C-space are transferred into the movements of parts in simulation environment. With these two steps, the parts could interact with other parts under a certain interaction sequence, which automatically simulates the assembly of the product. Finally, an implementation sample is presented and the results show the effectiveness of the proposed method.     

An object-oriented knowledge based Petri net approach to intelligent integration of design and assembly planning

Artificial intelligence can play an important role in the reduction of manufacturing costs and the enhancement of production efficiency and product quality. In order to assist designers in the early stages of a product development this paper develops an intelligent methodology for integration of design and assembly planning processes, including product design, assembly evaluation and redesign, assembly process planning, design of assembly system and assembly simulation, subjected to both econo-technical and ergonomic evaluations. A new unified class of object-oriented knowledge based Petri nets called OOKPNs, incorporating knowledge based expert systems and fuzzy logic into ordinary place–transition Petri nets, is defined and used for the representation and modeling of the distributed design processes. A prototype intelligent integrated design and assembly planning system (IIDAP) is implemented through distributed blackboard structure with concurrent integration of multiple cooperative knowledge sources and software. It consists essentially of the networked agents and the meta-system, each of which is a knowledge Petri net system with the capabilities of problem solving, learning and conflict resolution, and can be obtained through the inheritance, polymorphism and dynamic binding of instances of OOKPNs. In IIDAP system, both C/C++ language and COOL (CLIPS object-oriented language) are used to incorporate a Petri net tool, a geometric modeling and design tool, a planner and simulator and an evaluation tool. By use of this system, product design and assembly planning can be carried out simultaneously and intelligently in an entirely computer-aided concurrent design and assembly planning system. The design of manufacturable, cost-effective, usable products can therefore be achieved rapidly and flexibly. The developed methodology and system have been successfully applied to assembly design and planning of a micro switch.     

面向并行设计的装配顺序规划研究

该文根据先进制造发展的特点,结合现代设计理论提出了适合敏捷制造的面向并行设计的装配顺序规划系统结构.针对在自动装配顺序规划过程中没有实际接触零件之间相互干涉这一难点问题,应用了虚接触原理,并给出了相应的虚接触生成规则.为了使设计人员和用户更有效地获得装配信息,提出了信息反馈规则.文中结合例子讨论了虚接触和信息反馈在生成可行装配顺序推理过程中的应用,证明了其可行性和有效性.最后讨论了在虚拟现实环境中进行装配仿真的优势和意义.     

Geometric skeleton computation enabling concurrent product engineering and assembly sequence planning

This paper introduces a novel modelling approach to geometric skeleton computation enabling concurrent product engineering and assembly sequence planning. Current engineering vision has recently moved towards new modelling and management paradigms to maintain competitive edges all along the product lifecycle. Consistent with concurrent engineering and design for X stakes, this recent shift promotes cross-X and knowledge-intensive philosophies in the product development process, principally focused on lifecycle engineering.The main objective of this research is to integrate assembly process engineering information and knowledge in the early phases of the product development process in a top-down and proactive manner, in order to provide a geometric skeleton-based assembly context for designers. The definition of the product and its related assembly sequence requires both the enhancement and the entire understanding of product relationships between the various product components, and its related assembly rationale. As a consequence, this new modelling approach highlights the need to integrate various stakeholders’ viewpoints involved in the beginning of the product lifecycle. In such a context, earlier work has achieved the early generation of an optimal assembly sequence in the product development process, before the product geometry is completely defined. As a result, previous research has made possible to control and bind the product modelling phase through an assembly oriented product structure.The aim of the proposed approach is to compute and define a geometric skeleton model based on product relational information and the early-defined assembly sequence. The proposed approach–called SKeLeton geometry-based Assembly Context Definition (SKL-ACD)–enables the control of the product modelling phase by introducing skeleton entities consistent with product relationships and assembly sequence planning information. A prototype application within a CAD tool has been developed for aiding geometric skeleton computation and generation. Lastly, an industrial case study is introduced to highlight the feasibility and the relevance of the proposed modelling approach.     

输送线设计仿真系统

针对目前输送线系统的设计开发中,在结构设计与布局方案规划、控制系统现场安装调试、规模较大系统的实时输送路径规划等环节普遍存在着工作繁琐、修改灵活性差、现场安装调试复杂等问题,本文设计研发了一种基于Unity3D的模块化输送线设计仿真系统,以模块化输送机Unity3D三维模型为基础,通过Winform人机交互实现设计方案的模块化快速拼装构建;采用软PLC技术和分布式控制器架构实现输送线控制系统的离线编程与现场快速安装;通过遗传算法规划物料运输最优路径,最终完成输送线系统的仿真运行,全面验证系统设计方案、控制编程与路径规划的有效性和正确性,为后续的输送线实物快速设计与现场安装奠定基础.     

基于Arcadia方法的民机信息系统架构设计

传统的基于文档的系统工程是目前民机研制的主要研制方法,存在需求获取不清晰、不同层级的需求与设计不一致、难以追溯以及设计方案更改难度大等问题。结合Arcadia方法和Capella建模工具,提出基于Arcadia的民机机载系统基于模型的系统工程研究方法。通过集成运行、系统、逻辑和物理的视景,构建了特定场景下的机载系统模型。研究表明,基于Arcadia的民机机载系统能够有效避免传统的基于文档式需求的风险和问题,保证了系统架构与需求分析的紧密融合。     

装配规划与方案评价集成系统的研究与开发

为了将装配顺序规划与方案评价有效集成,规划合理的装配顺序,检验装配过程中存在的干涉情况,提出了人机交互定义分层装配顺序主模型与自动生成子装配的两级装配顺序规划方法．该方法适用于大型装配模型的装配顺序规划场合;在原有的研究项目KMCAD3D基础之上,开发了一套实用的装配顺序规划与方案评价原型系统;通过对二级蜗轮减速器实例的装配顺序规划讨论,说明了该方法的可行性．