Sankar Jayaram

Virtual assembly using virtual reality techniques

Virtual reality is a technology which is often regarded as a natural extension to 3D computer graphics with advanced input and output devices. This technology has only recently matured enough to warrant serious engineering applications. The integration of this new technology with software systems for engineering, design, and manufacturing will provide a new boost to the field of computer-aided engineering. One aspect of design and manufacturing which may be significantly affected by virtual reality is design for assembly. This paper presents a research effort aimed at creating a virtual assembly design environment.

VADE: a Virtual Assembly Design Environment

Virtual Assembly Design Environment (VADE) resulted from a research and development project started in 1995, sponsored by the National Institute of Standards and Technology (NIST). The main purpose of this project was to explore the potential and the technical challenges in using VR technologies for design and manufacturing by creating a VE for assembly planning and evaluation. In this article, we describe the overall system, the important features, and examples of using VADE. We also discuss the benefits and limitations of virtual assembly systems. In addition, we compare virtual assembly and automated assembly planning systems.

A Virtual Assembly Design Environment

The Virtual Assembly Design Environment (VADE) is a virtual reality (VR) based engineering application which allows engineers to evaluate, analyze, and plan the assembly of mechanical systems. This system focuses on utilizing an immersive virtual environment tightly coupled with commercial computer aided design (CAD) systems. Salient features of VADE include: data integration (two-way) with a parametric CAD system; realistic interaction of the user with parts in the virtual environment; creation of valued design information in the virtual environment; reverse data transfer of design information back to the CAD system; significant interactivity in the virtual environment; collision detection; and physically-based modeling. This paper describes the functionality and applications of VADE. A discussion of the limitations of virtual assembly and a comparison with automated assembly planning systems are presented. Experiments conducted using real-world engineering models are also described.

Assessment of VR technology and its applications to engineering problems

Virtual reality applications are making valuable contributions to the field of product realization. This paper presents an assessment of the hardware and software capabilities of VR technology needed to support a meaningful integration of VR applications in the product life cycle analysis. Several examples of VR applications for the various stages of the product life cycle engineering are presented as case studies. These case studies describe research results, fielded systems, technical issues, and implementation issues in the areas of virtual design, virtual manufacturing, virtual assembly, engineering analysis, visualization of analysis results, and collaborative virtual environments. Current issues and problems related to the creation, use, and implementation of virtual environments for engineering design, analysis, and manufacturing are also discussed. @DOI: 10.1115/1.1353846#

Introducing quantitative analysis methods into virtual environments for real-time and continuous ergonomic evaluations

This paper presents our work on methods to link virtual environments (VE) and quantitative ergonomic analysis tools in real time for occupational ergonomic studies. We pursued two distinct approaches: (a) create methods to integrate the VE with commercially available ergonomic analysis tools for a synergistic use of functionalities and capabilities; (b) create a built-in ergonomic analysis module in the VE. The first approach provides the use of established, off-the shelf tools integrated with the VE to create a hybrid application. This integration is performed through the use of APIs provided by the software vendor and existing Internet and communications technologies. The commercial ergonomics tool and the VE run concurrently and integrate their capabilities. The second approach provides the capability to do ergonomic evaluations in a self-contained VE application. In this method, the required ergonomics calculations are built into the VE. Each approach has its own distinct advantages. The use of a commercially available ergonomics tool integrated with a VE provides significant more capability and should be used where detailed and complex ergonomics evaluations are required. However, the process of integration in this approach is more difficult and time consuming. The self-contained VE application is more suited for simple ergonomic evaluations or in cases where the ergonomics algorithms are readily accessible and easily implemented. The two integration strategies are methodically explained and demonstrated using case studies conducted with industry partners. This integrated capability facilitates integration of ergonomic issues early in the design and planning phases of workplace layouts. It provides functionality beyond the capabilities of current commercial off-the-shelf (COTS) solutions. In addition, it contributes to a new trend in the integration of different technology fields for synergistic use in industry.

Industry case studies in the use of immersive virtual assembly

In this paper, we report on two engineering case studies that have been conducted as part of a Virtual Assembly Technology Consortium. The objectives of the case studies were to determine if immersive virtual assembly capabilities allow industry assembly situations to be modelled and studied realistically, and to demonstrate the downstream value of the virtual assembly capabilities in areas such as ergonomics, assembly installation, process planning, installation, and serviceability. What is of special significance is that instead of modelling simplified problems or perceived representative situations, the case studies were constructed from actual assembly floor projects and situations encountered at industry member sites and with considerable participation from industry engineers and manufacturing shop floor personnel. Based on the success of the case studies, the consortium members inferred that virtual assembly methods are poised to move out of the realm of special projects and test scenarios to deployment in the actual design and manufacturing cycle. However, in order to be truly accepted in industry, there are still issues to be addressed in terms of ease of use, portability of the applications, and preparation of the models for the evaluations. Thus, the case studies added a new dimension to the exploration and understanding of how this new technology could be of practical value in industry.

Weight Sensation in Virtual Environments Using a Haptic Device With Air Jets

The research presented in this paper is the design and implementation of a force feedback hand master called AirGlove. The device uses six ports arranged in a Cartesian coordinate frame setting to apply a point force to the users hand. Compressed air is exhausted through the ports, creating thrust forces. The magnitude and direction of the resultant force are controlled by changing the flow rate of the air jets and by activating different ports. The AirGlove can apply an arbitrary point force to the users hand. However, the main goal of this research is to reflect gravitational forces to the user so that sensation of weight of a virtual object can be created. After introduction of the main concept of the AirGlove, the paper presents design and implementation details of the device. Integration of the AirGlove with a virtual assembly system called VADE is explained next. Finally, details of experiments with the device are presented and discussed. Results indicate that users wearing the AirGlove can feel a minimum mass of about 100 grams (~1N weight) and the device can create a fairly realistic weight sensation.

Participatory ergonomics using VR integrated with analysis tools

This paper presents our work on the integrated use of simulation tools in real time for participatory occupational ergonomic studies. The focus of this paper is a synergistic system that consists of an interactive immersive simulation tool that has been developed in-house and integrated with a commercial human modeling simulation system, Jack/spl trade/. The impetus of the real-time integration is to allow the complementary use of two powerful simulation tools by allowing the user to perform the task naturally in an immersive environment, while the body posture information is continuously and automatically passed to the human modeling system for a continuous (and not discrete) analysis of the participatory ergonomic issues under consideration. This facilitates integration of ergonomic issues early in the design and planning phases of workplace layouts, even where the physical facility does not exist. The proposed integration is demonstrated using a manufacturing example.

Methods and Algorithms for Constraint-based Virtual Assembly

Abstract:Constraint-based simulation is a fundamental concept used for assembly in a virtual environment. The constraints (axial, planer, etc.) are extracted from the assembly models in the CAD system and are simulated during the virtual assembly operation to represent the real world operations. In this paper, we present the analysis of ‘combinations’ and ‘order of application’ of axial and planar constraints used in assembly. Methods and algorithms for checking and applying the constraints in the assembly operation are provided. An object-oriented model for managing these constraints in the assembly operation is discussed.

Case Studies Using Immersive Virtual Assembly in Industry

The Virtual Assembly Technology Consortium is a university/government/industry consortium that seeks to investigate the application of virtual assembly methods in mechanical system assembly processes. In this paper we report three categories of engineering case studies that have been developed by the consortium members over the past two years, describe the overall methodology, and then proceed to feature specific details of two key case studies. An engineering case study has been defined as an account of an engineering activity, event or problem containing some of the background and complexities actually encountered by an engineer, with the objective of providing a medium for learning. The objective of the case studies was to assist consortium members in demonstrating and validating the use of immersive virtual assembly technologies and tools in the simulation of factory floor manufacturing processes. What is of special significance is that instead of modeling simplified problems or perceived representative situations, the case studies were constructed from actual assembly floor projects and situations encountered at industry member sites and with considerable participation from industry engineers and manufacturing shop floor personnel. Based on the success of the case studies, the consortium members inferred that virtual assembly methods are poised to move out of the realm of special projects and test scenarios to deployment in the actual design and manufacturing cycle. However, in order to be truly accepted in industry, there are still issues to be addressed in terms of ease of use, portability of the applications, and preparation of the models for the evaluations. Thus, the case studies added a new dimension to the exploration and understanding of how this new technology could be of practical value in industry.Copyright