Accurate and Real-time Deformation in Haptic Virtual Reality

可变形物体的仿真是虚拟现实研究的核心。具有挑战性的任务是满足实时交互和准确性的相互冲突的需求。为了从虚拟现实中产生自然的“感觉”，视觉和触觉反馈分别需要30和1000赫兹？C的高刷新率。然而，任何物理上准确且逼真的虚拟对象建模在计算上都是昂贵的。本课题的研究目标如下。1)开发了实时精确变形大量顶点的非刚性虚拟物体的新算法。新的算法将改进有限元方法，它具有物理上精确的模型，但需要大量的计算。为了满足鲁棒性和满意的视觉效果的要求，所提出的模型将基于四面体网格结构来构建。将使用一个预处理阶段来计算模型的一组基本变形，以获得实时性能。为了在动态变形系统中模拟切割，需要对模型进行重新计算，去除与触觉接触处的四面体。2)实时虚拟现实应用中可变形物体的仿真。将开发两个模拟：用于医疗实践的针头插入皮肤；以及用于生物实验的从琼脂糖凝胶和聚丙烯酰胺凝胶中提取DNA。3)测试和评估变形以实现最佳模拟，这将由普渡大学Calumet(PUC)的工程学、生物学和护理专业的学生进行。该研究将提高触觉虚拟现实的基础知识，增强触觉虚拟现实的真实感和沉浸感。本研究的应用将对医学实践和生物实验有所裨益。模拟数据将被用作开发未来虚拟现实项目的基础。拟议研究的长期目标是1)推进最先进的虚拟现实技术，2)扩大虚拟现实在教育、医疗保健和制造等多个领域的应用，并在安全、时间、空间和设备以及成本效益等方面带来改进。课程的丰富和学生的参与将加强位于经济贫困地区的临时大学的工程学课程。

Simulation of deformable objects is central for progressing virtual reality research. The challenging task is to meet the conflicting demands of real-time interactions and accuracy. To generate natural 'feeling' from virtual reality, visual and haptic feedbacks require high refresh rates of 30 and 1000 Hz?C respectively. However, any physically accurate and realistic virtual object modeling is computationally expensive. The goals of this research project are as follows. 1) Development of new algorithms for accurate deformation of non-rigid virtual objects with a large number of vertices in real-time. The new algorithms will improve the Finite Element Method (FEM) which has physically accurate models but needs intensive computation. To meet the requirements of robustness and satisfactory visual results, the proposed model will be built based on a tetrahedral mesh structure. A preprocessing stage will be used to compute a set of elementary deformations of the model to obtain real-time performance. To simulate cutting in the dynamic deformation system, the model will be successively recomputed to remove the tetrahedron at the contacting places with haptics. 2) Simulation of deformable objects in real-time virtual reality applications. Two simulations will be developed: needle insertion into the skin for medical practices; and DNA extraction from agarose and polyacrylamide gels for biological experiments. 3) Testing and evaluating of the deformation to achieve optimal simulations, which will be performed by engineering, biology, and nursing students at Purdue University Calumet (PUC). The proposed research will improve the fundamental knowledge and enhance the realism and immersion of haptic virtual reality. The applications in this research will benefit medical practices and biological experiments. The simulation data will be used as a basis for developing future projects on virtual reality. The long term goals of the proposed research are to 1) advance the state-of-the-art virtual reality technologies, and 2) broaden the virtual reality applications in multiple areas such as education, health care, and manufacturing, as well as bring improvements in such issues as safety, time, space and equipment, and cost efficiency. Course enrichment and student involvement will enhance the engineering program at PUC, which is located in an economically disadvantaged region.