Prototyping and design for assembly analysis using multimodal virtual environments

Abstract

The goal of this work is to investigate whether estimates of ease of part handling and part insertion can be provided by multimodal simulation using virtual environment (VE) technology, rather than by using conventional table-based methods such as Boothroyd and Dewhurst Charts. The long term goal is to extend cad systems to evaluate and compare alternative designs using Design for Assembly Analysis. A unified physically based model has been developed for modeling dynamic interactions among virtual objects and haptic interactions between the human designer and the virtual objects. This model is augmented with auditory events in a multimodal VE system called the Virtual Environment for Design for Assembly (VEDA). The designer sees a visual representation of the objects, hears collision sounds when objects hit each other and can feel and manipulate the objects through haptic interface devices with force feedback. Currently these models are 2D in order to preserve interactive update rates. Experiments were conducted with human subjects using two-dimensional peg-in-hole apparatus and a VEDA simulation of the same apparatus. The simulation duplicated as well as possible the weight, shape, size, peg-hole clearance, and frictional characteristics of the physical apparatus. The experiments showed that the Multimodal VE is able to replicate experimental results in which increased task completion times correlated with increasing task difficulty (measured as increased friction, increased handling distance combined with decreased peg-hole clearance). However, the Multimodal VE task completion times are approximately two times the physical apparatus completion times. A number of possible factors for this temporal discrepancy have been identified but their effect has not been quantified.