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一种基于手的力反馈虚拟现实系统的研究
Alternative TitleResearch on a kond of hand-based virtual reality system with haptic feedback
徐春
Subtype工学硕士
Thesis Advisor原魁
2003-06-01
Degree Grantor中国科学院研究生院
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力觉反馈 碰撞检测 Obb 物体变形 Nurbs曲面 Hpatic Feedback Collision Detection Obb Object Deformation Nurbs Surface
Abstract基于手的带有力觉反馈的虚拟现实系统在虚拟现实中还是一个比较新的研 究领域。本文的研究目标是,在保证系统一定真实程度的视觉反馈和力觉反馈 的同时,尽量减少计算复杂度,提高系统的实时性。其中,主要在虚拟手与物 体间的碰撞检测,以及柔软物体变形计算作了重点研究。本文主要包括如下几 个方面的工作: 1.提出了一种混合包围盒OBB—AABB计算虚拟手与刚体之间的碰撞检测。它继 承了OBB紧密性较好和AABB简单性较好的优点。可以在紧密性和简单性之 间达到一定的折衷。它为解决虚拟环境中复杂度相差较大的物体间的碰撞检 测问题,提供了一条有效途径。 2.提出了一种OBB与AABB之间的碰撞检测方法。这种方法选用改进的 Liang—Barsky线段裁减算法计算包围盒之间的相交情况。与目前最常用的 检测OBB间碰撞的分离轴理论算法相比,计算量小了很多。 3. 以中轴变换(MAT)理论为基础,结合NURBS曲面对柔软物体造型,并提出 一种简单有效的方法完成手作用点与柔软物体之间的单点碰撞检测。在运行 过程中先用运行前构造的物体的球包围盒排除不必要的检测,再用物体中轴 面计算手作用点与柔软物体的碰撞检测。 4.如果手的作用点与柔软物体相交,移动4个对于曲面上接触点最具影响力的 控制点来完成对曲面的修改。选用虚拟现实系统构造语言OpenGL APl中提 供的NURBS接口绘制变形结果,达到了较好的效果。 5.采取不同方法计算刚体与柔软物体的反馈作用力。对于刚体,直接对用户施 加适当的力,以避免手进入物体内部。对于柔软物体采用质点弹簧模型计算 反馈作用力。实验表明,用户可以得到实时且较真实的力的作用。 6. 以CAS-Grasp为人机交互接口构造了一个提供力觉反馈的虚拟现实系统,并 以此为应用背景验证了上述算法。系统视觉更新速度20Hz,力觉更新速度 1000Hz,可以满足交互的要求。
Other AbstractThe hand-based virtual reality system with haptic force feedback is a new field in VR research. The research target of the thesis is provide the realistic visual and haptic feedback of the system at the minimal cost, and improve the system's real-time property. The main research of the thesis is about collision detection between virtual hand and objects, and simulation of deformable objects. The main work and contribution are following: 1. A hybrid bounding box OBB-AABB is presented for collision detection between hand and rigid objects. It takes the advantages of OBB and AABB, and makes a compromise between tightfitting property and simplicity. It is an effective approach to detect the collisions between the models that differ greatly in their complexities. 2. A collision detection method based on OBB-AABB is presented. It uses the improved Liang-Barsky clipping line algorithm to test the overlap between OBB and AABB. Compared with Separating Axis Theory algorithm, the clipping line algorithm is more simple. 3. Deformable object model is based on MAT (medial axis transform), and is represented by NURBS surface. The thesis presents a simple-performed method for single-point collision detection of the user's position with the deformable objects. It first uses the sphere bounding box to discard some unnecessary computation, then uses the medial axis surface to detect the collision. 4. Reposition 4 most influenced control points of the surface to modify the shape, when the user's position enters the deformable object. The NURBS interface in OpenGL API is used to display the surfaces. The performance is satisfactory. 5. Different methods are used to compute the haptic feedback of rigid objects and deformable objects. A given force is exerted on the user as the rigid object's haptic force feedback. Mass-spring model is used to compute the haptic force feedback of deformable objects. The experiments show that the user can get a realistic feeling. 6. A virtual reality system with haptic force feedback is conducted interfaced with CAS-Grasp. The algorithms above are proved efficient with the background of the system. The visual interactive rate is 20Hz and the haptic interactive rate is 1000Hz. The system can provide the real-time interaction.
shelfnumXWLW696
Other Identifier696
Language中文
Document Type学位论文
Identifierhttp://ir.ia.ac.cn/handle/173211/6788
Collection毕业生_硕士学位论文
Recommended Citation
GB/T 7714
徐春. 一种基于手的力反馈虚拟现实系统的研究[D]. 中国科学院自动化研究所. 中国科学院研究生院,2003.
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