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虚拟现实在机器人领域的应用与虚拟环境计算理论的研究
刘铁成
Subtype工学硕士
Thesis Advisor欧阳秋
1999-06-01
Degree Grantor中国科学院自动化研究所
Place of Conferral中国科学院自动化研究所
Degree Discipline控制理论与控制工程
Keyword虚拟现实 机器人仿真 虚拟环境 网络简化 碰撞检测 Virtual Reality Robotics Simulation Virtual Environment Mesh Simplification Collision Detection
Abstract本文系统地研究了虚拟现实技术在机器人生产线设计与仿真中的应用,并 对虚拟环境计算理论中的两个问题:虚拟环境的多分辨率显示和虚拟环境中物 体间的碰撞检测算法进行了深入的探讨。 本文的第一部分工作是关于虚拟现实技术在机器人生产线布局与仿真中的 应用。本文采用基于WTK的虚拟现实开发技术,实现了机器人生产线的虚拟 现实系统。该系统能够生成机器人生产线的虚拟环境,进行机器人生产线的交 互式布局,设定机器人任务并进行运动仿真。采用虚拟现实技术,可以提高生 产线设计的直观性并加快设计进程。在机器人运动仿真中,本文采用了通用的 六自由度机器人逆运动学算法,对机器人运动轨迹中的奇异位姿进行了检测, 并提出了在奇异位姿附近进行插值计算的奇异值处理方法。 本文提出了一种虚拟环境的多分辨率模型生成算法,用于实现虚拟环境的 多分辨率显示。由于三角形网格是目前表达虚拟环境的最主要的方式,本文通 过三角形网格的简化操作实现了虚拟环境的不同细节层次表示。本文提出的新 算法的主要贡献在于:1、从数学的角度严格定义了网格简化的几何误差和拓扑 误差,并给出了计算这两种误差的方法;2、首次提出了采用顶点拉伸计算偏移 网格的方法,对于顶点拉伸方向给出了有效的计算方法;3、对偏移网格与简化 网格之间进行相交检测,保证了简化网格在两个偏移网格之间,从而将简化网 格限定在一定的几何误差范围之内;4、首次提出了通过局部二次曲面拟合的方 法计算曲面在一点附近的近似法向量和近似曲率,进而可以得到网格简化的拓 扑误差。5、采用了顶点合并的网格简化操作,在简化过程中保留了表征物体形 状的特征点。实验结果表明,本文的多分辨率模型生成算法是一种高效的算法, 在一定的误差范围内,可以取得较高的网格简化率,并能很好地保持物体的形 状。通过选取不同的简化误差,可以得到物体不同分辨率的模型。 碰撞检测在虚拟现实、计算机图形学、计算机仿真和机器人学等许多领域 都有着十分重要的意义。碰撞检测问题是一种典型的限时计算问题,对算法的 速度有较高的要求。本文提出一种虚拟环境中物体间的多级快速碰撞检测算法。 该算法采用物体长方体包围盒——物体的球树包围体——物体简化模型——物 体原始模型这样一个多级的碰撞检测体系结构。在进行物体间的碰撞检测时, 先从物体长方体包围盒的碰撞检测丌始,然后按照上述等级结构依次进入下一 级进行计算,从而可以得精
Other AbstractIn this thesis, the idea of applying VR technology to the design of product line with robotic workcells is proposed. Two problems related with virtual environment computing theory, level of detail representation of virtual environment and collision detection, are systematically studied. The first part of this thesis describes the implementation of ROBVR, a software system for design and simulation of product line with robotic workcells. The main goal of this project is to accelerate design process of product line. Based on WTK, the system provides full support fox" VR technology and implements many function, including generation of virtual environment, interactive layout of product line and robotics simulation. In the study of robotics kinematics simulation, this thesis provides a method to detect and avoid kinematic singularities in trajectory planing. This thesis also presents an algorithm for level of detail representation of virtual environment. This algorithm is built on mesh simplification techniques and then a new mesh simplification algorithm is presented in the thesis. The main contributions of the mesh simplification algorithm lie in several aspects: 1. Based on analysis of local theory of surface, geometry error and topology error between meshes are carefully defined, then an algorithm is presented to calculate these errors. 2. Using vertices offsetting method, we can produce offset mesh of original model. Simplified mesh is confined within the space between two offset meshes to avoid large geometry deviation. 3. In a local area, we use quadric surface to approximate original surface. By calculation the curvature of quadric surface, we can calculate topology error between two meshes. 4. In the process of mesh simplification, feature points are retained to keep the topology of original mesh. It is demonstrated by experiments that our algorithm is effective and has high triangle simplification rate. Fast and accurate collision detection between geometry models is a fundamental problem in computer graphics, robotics and virtual environments. In this thesis, we propose a multi-level collision detection algorithm based on hierarchy architecture. This algorithm uses a four-level collision detection strategy: bounding box, sphere octree, simplified meshes and original model. It can provide user-specified error collision detection. In practice, it can also accurately detect all the contacts between objects. Based on the hierarchy architecture above, the distance between two objects can be easily calculated. Experiments demonstrate that our multi-level collision detection algorithm is much faster than other collision detection algorithms.
shelfnumXWLW517
Other Identifier517
Language中文
Document Type学位论文
Identifierhttp://ir.ia.ac.cn/handle/173211/7264
Collection毕业生_硕士学位论文
Recommended Citation
GB/T 7714
刘铁成. 虚拟现实在机器人领域的应用与虚拟环境计算理论的研究[D]. 中国科学院自动化研究所. 中国科学院自动化研究所,1999.
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