Rapid Interaction Specification in DHM-Included VE to Support Virtual Design Ergonomic Evaluation

Abstract

Virtual design ergonomic evaluation is useful at early design stage where the physical design mock up is not available but human-centred design must be considered. The interactive virtual ergonomics evaluation approach integrates a digital human model (DHM) with a product’s digital mock up to form a DHM-included virtual environment (VE). The DHM is interactively puppeteered by a human player who wears motion capture devices. Posture data recorded by the motion capture devices are sent to ergonomics programs for evaluation. The DHM-included VE developed by previous research suffers from two problems. First, the DHM can only touch or reach the virtual objects but can not grab nor manipulate them. As such the range of posture data that could be acquired is limited. Secondly, the domain experts, who are usually non VR experts, have to resort to VR engineers to specify the interactions between DHM and virtual objects, which make the virtual evaluation process inconvenient and inefficient. This paper discusses an interactive VE in which the DHM could grab objects and manipulate them. A two-level Petri-net (PN) is proposed as a high-level, graphical representation that allows domain experts to quickly and easily define the interactions between the DHM and the virtual object. The first-level PN monitors the object-grabbing status whereas the second-level PN monitors the hand-grabbing status and hand coordination. If the object-grabbing status or the hand-grabbing status is wrong, the PN will stop the posture data recording process, reset the object to its original position, and notice the human player to re-do the operation so that correct posture data could be acquired. A case study is presented in which the proposed method is applied to generate an interactive VE to acquire posture data for evaluating ergonomics problems associated in operating and maintaining a control console in a ship control room.