The preparation of a VR scene mainly includes the preparation of geometrical model and the simulation/behaviour model. Although the CAD model of a product can be imported in many available VR software to prepare the geometrical model, but there is no direct method to import the simulation or behaviour into VR. The currently available solutions make use of programming to build the simulation or behaviour models for the objects in VR. Such solutions are time-consuming, application specific and offer very limited reusability. Therefore, we focus on a new idea of dividing the complete VR model into sub-models i.e. product, actor and environment.

Division in submodels

Division in submodels

Sub-model approach

Dividing the complete model can allow the reuse of the VR models or parts of it. However, this division can impose new requirements i.e. the sub-models should be described independently and their interaction should be described as well. In order to describe these sub-models and their interaction, we focus on a Model Based Systems Engineering (MBSE) approach instead of programming of the complete scene in advance. Systems Modeling Language (SysML) is implementation language for MBSE approaches and fulfils the requirements associated with the sub-models. Therefore, the behaviour of sub-models and their interactions in described in SysML.

Example behaviour model in SysML

Example behaviour model in SysML

Physics engine with SysML models

The behaviour of sub-models can be described in SysML using the behaviour modelling diagrams. However, SysML does not facilitate the calculation of physical behaviour (e.g. calculation of collision detection between objects). Some of the available VR software can perform the physical calculation of virtual objects, however, it usually works by programming the objects inside VR software. This can again make the method application specific e.g.  the behaviour model prepared for CAVE type VR system may not work in the HMD. This leads us to integrate an extra physics engine with SysML models and was performed by using Virtual Robot Experimentation Platform (V-REP). V-REP has the exact representation of the objects in VR scene, but in a form on which physical calculation can be performed.

VR scene replica in physics engine (V-Rep)

VR scene replica in physics engine (V-Rep)

The overall method can be summed up as described in the below picture.

Information flow during VR simulation

Information flow during VR simulation