Research On Physical Simulation And Interaction In Virtual Reality Environment

Immersion and interactivity are the most important characteristics of Virtual Reality. Virtual Reality can create a kind of virtual environment which is dynamic and interactive. The key techniques of Virtual reality include real-time rendering, visual simulation, three-dimensioned modeling, real-time physical simulation, computer control and so on. It involves the disciplines of computer graphics, computational geometry, physics, and automations. Virtual Reality has Broad application prospects, and has been producing a great amount of social and economic benefits.Bridge crane simulator is a kind of application of Virtual Reality in simulated driving training. Driving simulator based on Virtual Reality can make the crane driver get immersed in the virtual driving environment. The driver can operate the crane by the joystick, making the crane hook swing according to the real force condition. That is the aim of the simulated driving training. So the simulation of the crane's motion and its hook's swing are the key aspects for this thesis.The technique of physical simulation in Virtual Reality can well simulate the crane's motion and its hook's swing in real operation. The three-dimensioned graphics engine, OpenSceneGraph (OSG), is adopted here as a tool for visual simulation and real-time rendering. At the beginning of this thesis, the related techniques of OSG are studied, including the following parts: the principles of scene management and scene graph, the drawing program framework and the methods and framework of revising the drawing program while realizing animation and interactive program, principles of realizing virtual camera and the method of its operation, principle of the class PositionAttitudeTransform in OSG, techniques of basic geometries drawing and the principle of deformed shapes drawing.The thesis researches mainly on the techniques of physical simulation, including the dynamic equations and its matrix expressions of particles and rigid bodies, the method of numerical calculation specialized for dynamics simulation and the design of software solver. For the part of collision detection, several kinds of bounding box techniques are analyzed, including the work on the realizing of AABB bounding box collision detection algorithm, collision detection of basic geometries and the principles of collision's response. While analyzing the dynamics simulation library ODE, the thesis depicts the deign method of the integration layer class between ODE and OSG, analyzes the mechanisms and loads of the crane, develops the physical model of the crane-hook system and finally realizes the interactive simulation of the crane's motion and its hook's swing.