FLEXIBLE MULTIBODY DYNAMICS EXPLICIT SOLVER FOR REAL-TIME SIMULATION OF AN ONLINE VIRTUAL DYNAMICS LAB

摘要

A high-fidelity online virtual video-game-like Newtonian dynamics lab that can be used as a teaching lab for university freshman physics and sophomore engineering dynamics courses is presented in this paper. The lab is driven using a virtual-reality display engine with an integrated flexible multibody dynamics finite element explicit real-time solver. The hierarchical "scene-graph" representation of the lab that is used in the virtual-reality display engine is also used in the solver. The multibody system includes rigid bodies, flexible bodies, joints, frictional contact constraints, actuators and controllers. Flexible bodies are modeled using spring, truss and beam elements. A penalty technique is used to impose joint/contact constraints. An asperity-based friction model is used to model joint/contact friction. A bounding box binary tree contact search algorithm is used to allow fast contact detection between finite elements and other elements as well as general triangular/quadrilateral rigid-body surfaces. The following experiments are modeled: mass-spring systems, pendulums, pulley-rope-mass systems, air-hockey, billiards, 1D and 2D frictional and frictionless motion with and without gravity, roller-coasters, planetary motion, gears, cams, robotic manipulators and linkages.