Enabling a high fidelity dynamics simulation of cad assemblies in a virtual environment for machine design

This paper presents a software architecture that enables VRMDS (Virtual Reality Mechanism Design Studio) to simulate multi-body dynamics of computer-aided design (CAD) assemblies. VRMDS is a recently developed virtual environment dedicated to the conceptual design of mechanisms and machines. It allows users to build spatial or planar mechanisms through intuitive operations. In this paper, we develop Python's parsing modules that import CAD assembly models in either XML or MDL format files into VRMDS and visualize them through the use of WRL or OSG geometry files. CAD assembly models consist of parts as well as kinematic constraints among them. These parts and constraints can be translated into links and kinematic joints of mechanisms and machines. The dynamics simulation for the assembly is achieved by MATLAB SimMechanics solver that communicates with VRMDS through a dedicated Pymat interface and M-script files. Finally, two case studies are provided to demonstrate the feasibility and validity of using assembly models in this virtual reality system for mechanism design. The high fidelity of the SimMechanics dynamics solver makes the simulation justified scientifically. The result is a highly integrated virtual reality design environment that is dedicated to both the concept design and virtual prototyping of machines.