Solution Approaches for Planning of Assembly Systems in Three-Dimensional Virtual Environments (original) (raw)
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OPTIMIZATION TECHNIQUES FOR ASSEMBLY PLANNING OF COMPLEX MODELS IN LARGE-SCALE VIRTUAL ENVIRONMENTS
International Journal of Image and Graphics, 2003
Evaluation and planning of assembly processes in virtual environments, especially largescale virtual environments, have attracted much attention in the engineering community. However, the planning of complex assemblies in virtual environments is still hindered by limitations like insufficient frame rates, unnatural user interaction, as well as deficiencies in the processing of assembly constraints. This paper discusses some optimization techniques for the assembly planning of complex assemblies in a large-scale virtual environment such as CAVE. Specifically, the real-time display of complex assemblies, the natural and intuitive assembly operations, and a real-time collision detection algorithm for the assembly applications are presented.
Experiments of Assembly Planning in Virtual Environment
This paper deals with the design of a 3D synthetic environment in which human operator can perform assembly operation in the same way as in real world (RW). The objective is to evaluate the product assemblability and refine the product design before launching its manufacture. The long term objective is to evaluate the product assembly/disassembly time, hence its cost at the design stage in order to support production planning and to determine the financial commitment associated with the product maintenance before its manufacture. To validate the virtual environment (VE) so that quantitative and qualitative information, such as relating to assembly planning activity can be derived from the interaction of the operator with virtual world, we suggest a validation technique based on the evaluation of the operator performance in terms of the generated assembly sequences in real and virtual environments.
Integrating Computerised Assembly Planning With Virtual Assembly Environment
Virtual Reality in Mechanical and Production Engineering (VR-Mech’01), November 22-24, 2001, Royal Military Academy, Brussels, Belgium , 2001
One of the important issues in assembly planning is to develop an efficient method to combine human and machine intelligence (Computer aided assembly planning system (CAAP)) to perform the planning of operations that cannot be done by either human or the automated system alone. The term " assembly " applies to some 20 different procedures. For a human operator equipped with adequate tools, none of these tasks is impossible. The human combines logic and perception of the environment, and has two sophisticated tools, the hands, to do the work. The problems facing automated CAAP systems are related to their limitation in the degree to which they prune down the combinatorial explosion of feasible sequences that is inevitably produced, they generally require human inputs (geometric constraint data) during the process of assembly sequence generation. Based on our newly developed Virtual Environment for Design and Assembly Planning (VEDAP), an approach integrating the interaction of human operator with virtual environment and a computerized assembly planning system is presented. The evaluation of the system's performance and results are described.
Engineering with Computers, 2000
Complex mechanical arrangements involve a large number of constraints referring to either properties of individual components (of the arrangement) or relationships between components. Current practices approximate these constraints with simplified 'dimensional constraints' aiming at formulating a system of (in)equalities to be solved automatically by a 'geometric constraint solver'. This paper identifies limitations in this approach, leading to inaccurate descriptions of problems that disallow development of a collaborative engineering environment. Our work focuses on complex plants and their conformity with operational constraints for performing, e.g. maintenance, repair and emergency operations. Current Virtual Reality techniques cannot solve this problem as, at best, they only significantly enhance visual perception of 3D plant models. A detailed analysis of required 'free-spaces' is presented on the basis of industrial data. The concept of 'virtual solid' is proposed for modeling free-spaces and related geometric modelling techniques are derived. An 'extended product model' is presented, also accommodating nongeometric properties of free-spaces, and thus leading to informationally-complete descriptions of plant-layout problems. Finally, an implementation in the AutoCAD environment is presented accompanied by realistic examples.
Volume 1: 23rd Computers and Information in Engineering Conference, Parts A and B, 2003
The aspects of adequate simulation of the flexible parts for path planning during the Assembly/Disassembly (A/D) operation simulation are discussed in this paper. An interactive system forming two complementary levels and incorporating mechanical models of flexible part is described. The approach proposed will be used as a basis to the simulation of flexible parts into a Virtual Reality (VR) environment for the A/D evaluation. First of all, the study of current assembly path planning systems is performed. Secondly, as an issue of the problems discussed, a new system integrating real-time and interactive mechanical simulation approaches is proposed. Finally, an example of the interactive mechanical behavior model applicable to flexible rods used into an A/D path planning context is presented. Numerical modeling focuses on typical boundary conditions. The present approach is considered as a proposal for a methodology used with VR environments during the product design process.
A new approach to virtual design for spatial configuration problems
Proceedings on Seventh International Conference on Information Visualization, 2003. IV 2003., 2003
In this paper, we present a new framework for the use of Virtual Reality (VR) in engineering design for configuration applications. Traditional VR systems support the visual exploration of a design solution but do not assist the user in exploring alternative solutions based on domain knowledge. Extending previous work in the area of Intelligent Virtual Environment, we propose an intelligent configuration system based on constraint logic programming (CLP), integrated in a real-time 3D graphic environment. This type of integration facilitates the expression of design knowledge in the VE and enables the user to interactively solve and/or refine a spatial configuration problem. In the system described in this paper, the user can visually explore configurations, but his interaction with objects of the configuration problem triggers new cycles of constraint propagation from the modified configuration to produce a new compatible solution. . The user refines a given configuration by reallocating an object. As a result of this, the environment reconfigures itself.
3D Visualization of Modular Building Assembly: from a Factory to Construction Site
Buildings are constructed using traditional on-site construction methods or industrialized (i.e. manufactured in components or modules). Modular building is the highest degree of industrialization of the building construction process. In this context, the manufacturing of buildings in a factory and their shipment in modules to the site, demands a new approach to scheduling and resource use. Because of their large geometric volumes, handling the modules especially on construction sites can be extremely challenging. As a result, 3D visualization tools are critical for precise planning since they allow one to resolve beforehand any spatial constraint such as collisions with existing obstructions and lifting paths feasibility. This paper addresses the two most important aspects of modular construction: 1) shop manufacturing and 2) on-site assembly. In this respect this contribution describes a methodology which integrates simulation models and post-simulation 3D-Visualization. The integration of these tools provides a framework allowing to gain a detailed insight into the dynamics of the manufacturing and assembly processes and also to gauge the risks related to the work-space and interference of modules with the surrounding obstacles. The proposed methodology is validated by a case study that involves the construction of five (5) student dormitories for Muhlenberg College, Pennsylvania, USA. The five (5) buildings are each 3-storeies consist of 18-modules, totaling 92-modules for all five buildings. The 92-modules were manufactured at Kullman (a modular manufacturer in New Jersey, USA).
A systematic approach for 3D VRML model-based assembly in Web-based product design
The International Journal of Advanced Manufacturing Technology, 2006
Collaborative virtual assembly design is often considered complicated and hardly achievable, for it requires high real-time performance, platform independence, and model synchronization. In order to satisfy all these requirements, a VRML-based virtual assembly solution is proposed. This paper first presents a synchronous moving-searching algorithm for retrieving information from the basic assembly model (BAM) and target assembly model (TAM) in order to give Internet-based collaborative assembly capabilities to these VRML files. Then, a set of assembly approaches for VRML models are systematically addressed to implement the assembly according to constraints of link relations. The advantages of the algorithm and assembly approaches are their high computational efficiency and ease of implementation, which enriches works of Anton and Gorazd (2003) and Qin et al. (2004) with respect to accessibility and maneuverability of VRML model-based assembly design. Moreover, the realization method of collaborative assembly over the Internet is introduced. Finally, some actual examples of collaborative virtual assemblies systems are provided to illustrate the application of these approaches.
Path planning for flexible components using a virtual reality environment
Proceedings of the IEEE International Symposium onAssembly and Task Planning, 2003.
Assembly/Dismsembly (MD) operation simulation during the product design is an important aspect to improve the performance and qualify of products. Current MD path planning approaches are based on models representing rigid parts. So. an important mpect is an adequate simulation of flexible parts for path planning. The approach proposed will be used as a basis to simulate flexible parts into a Virtual Reality (VRJ environment for the A/D evaluation. First of all, the study of current assembly path planning method is performed Secondly, as an issue of the problems discussed, a new system integrating real-time and interactive mechanical simulation approaches is proposed Finally, an example of the interactive mechanical model applicoble toflexible r o d used into an A/D path planning context for the VR simulation is presented The present approach is considered as apropasal for a methodologv used with VR environments during the product design process.
Combining physical constraints with geometric constraint-based modeling for virtual assembly
Virtual reality (VR) technology holds promise as a virtual prototyping (VP) tool for mechanical assembly; however, several developmental challenges still need to be addressed before virtual prototyping applications can successfully be integrated into the product realization process. This paper categorizes and elaborates these challenges and then describes how SHARP (System for Haptic Assembly & Realistic Prototyping), addresses them for virtual assembly. SHARP uses physics-based modeling for simulating realistic part-to-part and hand-to-part interactions in virtual environments. A dual handed haptic interface is presented for realistic hand-part interaction. Additional modules are added to utilize the system to provide answers for maintenance issues, virtual training 50 applications and collaborative design. Swept volumes are implemented for addressing maintainability issues and a network module is added for communicating with different VR systems at dispersed geographic locations. Support for various types of VR systems allows an easy integration of SHARP into the product realization process. This has the potential to result in faster product development, faster identification of assembly and design issues and a more efficient and less costly product design process.