Development of a Dual-Handed Haptic Assembly System: SHARP Abhishek Seth Ph.D. Department of Mechanical Engineering, Virtual Reality Applications Center, Iowa State University, Ames, IA 50011 e-mail: abhiseth@vrac.iastate.edu Hai-Jun Su Ph.D. Department of Mechanical Engineering, University of Maryland, Baltimore County, Baltimore, MD 21250 e-mail: haijun@umbc.edu Judy M. Vance Ph.D. Fellow ASME Department of Mechanical Engineering, Virtual Reality Applications Center, Iowa State University, Ames, IA 50011 e-mail: jmvance@iastate.edu Virtual reality (VR) technology holds promise as a virtual proto- typing (VP) tool for mechanical assembly; however, several de- velopmental challenges still need to be addressed before VP ap- plications can successfully be integrated into the product realization process. This paper describes the development of Sys- tem for Haptic Assembly and Realistic Prototyping (SHARP), a portable virtual assembly system. SHARP uses physics-based modeling for simulating realistic part-to-part and hand-to-part interactions in virtual environments. A dual-handed haptic inter- face for a realistic part interaction using the PHANToM ® haptic devices is presented. The capability of creating subassemblies en- hances the application’s ability to handle a wide variety of assem- bly scenarios at the part level as well as at the subassembly level. 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, resulting in faster product development, faster identification of assembly and design issues, and a more efficient and less costly product design process. DOI: 10.1115/1.3006306 Keywords: haptics, virtual reality, virtual prototyping, human- computer interaction, virtual assembly, swept volumes, physics- based modeling 1 Introduction VR technology is gaining popularity as an engineering design tool and is increasingly used as a digital test-bed for early proto- types. VR simulations are used as a tool during the product design process to evaluate design alternatives for assembly, manufactur- ability, maintainability, etc. However, in order to use digital prod- uct models for advanced evaluations, a virtual prototype must exhibit a behavior that is very similar to physical models. For instance, the digital environment should provide the same level of human/product interaction, allow for similar testing scenarios, and accurately reflect the evaluations obtained when using physical models. Sensory evaluations such as visual, haptic force feed- back, and auditory feedback are also important to accurately evaluate product performance. VR techniques are used throughout the design process to simulate different stages of product realiza- tion, i.e., evaluating multiple design concepts, manufacturing pro- cesses, assembly process planning, plant layout, maintenance evaluations, etc. A virtual assembly VA system as proposed in this paper will empower future engineers with a platform that will allow them to visualize and realistically interact with multiple design alterna- tives during conceptual stages before physical prototypes are built. Such a system will facilitate identification of product/ process design errors during early stages of product development where major changes are still feasible. Thus, it will reduce unfore- seen problems that arise during later stages of the product life cycle, consequently saving both time and money while improving product quality. 2 Research Challenges During the past two decades, VR technology has evolved to a level where immersive virtual walkthroughs and data visualization simulations have become commonplace. Prototyping assembly/ disassembly processes in virtual environments present a much more challenging problem because they require frequent, direct, and intuitive human interactions with virtual product models. To simulate simple real world assembly tasks in a virtual environ- ment, a VA system must include the following features Table 1: graphical visualization, which provides visual feedback; object behavior modeling, which simulates the physical interaction dy- namics, collision, and friction between part-part and hand-part; haptic force feedback, which allows the worker to feel contacts that occur between parts; and dual-handed assembly. In addition, capabilities such as subassembly creation, part joining methods, and interaction with tools and fixtures also form core components of the simulation. Prominent challenges in this field are classified into four categories and are elaborated below. 2.1 Graphic Visualization. Immersive and realistic graphical visualization is important for tasks such as part picking and place- ment, which require understanding 3D spatial relationships among computer-aided design CAD models. Stereo visualization and high level-of-detail LOD product models are critical in provid- ing an accurate representation of the real world assembly sce- narios. CAD assemblies containing thousands of parts present problems for interactive visualization due to the “excessive num- ber of polygons and number of objects that are created” 1. 2.2 Collision Detection. Another critical challenge in creat- ing VA simulations is accurately modeling the physical behavior of parts. Collision detection algorithms are frequently used to pre- vent part interpenetration during assembly. Mechanical assembly scenarios demand an accurate collision detection among arbi- trarily complex nonconvex CAD geometries. In VA simulations where real-time update rates are critical, performing a fast and accurate collision detection among dynamic objects is a challeng- ing problem. Contributed by the Engineering Simulation and Visualization Committee for pub- lication in the JOURNAL OF COMPUTING AND INFORMATION SCIENCE IN ENGINEERING. Manuscript received November 2, 2007; final manuscript received September 1, 2008; published online November 7, 2008. Guest Editors: J. Oliver, M. Omalley, and K. Kesavadas. Journal of Computing and Information Science in Engineering DECEMBER 2008, Vol. 8 / 044502-1 Copyright © 2008 by ASME Downloaded From: http://computingengineering.asmedigitalcollection.asme.org/ on 04/22/2014 Terms of Use: http://asme.org/terms