离体软组织力学参数测量及其在虚拟手术系统中的应用

发布时间：2018-03-20 12:43

本文选题：虚拟手术系统　切入点：物理建模　出处：《哈尔滨工程大学》2016年硕士论文　论文类型：学位论文

【摘要】：虚拟现实技术的进步,使得建立虚拟手术系统从可能变成现实。医生通过力触觉交互设备在虚拟环境下模拟手术过程,获得逼真的力触觉和视觉反馈。在虚拟手术系统的物理建模过程中,软组织的力学性能参数已成为制约虚拟器官物理模型效果的瓶颈。测量软组织器官真实的力学性能参数,对提升虚拟手术系统的力触觉反馈,具有极大的意义。在国内外关于软组织力学参数测量研究的基础上,本课题将要搭建一种新型软组织力学参数测量平台,通过实验测量肝脏力学参数,并将其应用到虚拟手术系统当中,使操作者获得更贴近真实的力反馈效果。主要研究内容有:搭建虚拟手术系统软件环境。利用OpenGL在虚拟环境下重绘肝脏和手术器械的几何模型,通过建立包围盒方式,提高碰撞检测速度;通过分析软组织力学特性,进而利用三参量模型描述软组织的粘弹性;建立质点-弹簧模型,进而明确虚拟肝脏物理模型所需的核心力学参数:肝脏的弹性系数k、黏性系数η和外层组织的破坏力阀值Fm。搭建一种全新的软组织力学参数测量平台,提出将Phantom Omni机器人的功能扩展,应用到软组织形变信息的测量中。采用球面算法,利用Matlab拟合测量平台的“杆长L”,使用D-H法进行正运动学建模,获得末端点的坐标。编写M文件,分析末端点工作空间。设计装夹机构和支架机构,用于辅助实验操作。设计算法,计算力传感器的末端重量补偿和接触力阀值。结合编程软件,测量肝脏形变量和形变力。设计单轴压缩实验,采用分段拟合弹性系数方法,拟合不同形变阶段肝脏的弹性系数k ;设计应力松弛实验,拟合肝脏的黏性系数η;设计穿刺实验,分析肝脏外层组织被刺破瞬间的形变力峰值,即肝脏外层组织的破坏力阀值Fm。将肝脏的力学性能参数应用到虚拟手术系统中。通过Phantom Omni力触觉设备,对虚拟肝脏进行压缩和拉伸操作,获得虚拟环境下的力反馈。设计真实肝脏整体的压缩实验,测量真实整体肝脏在被压缩状态下的形变力位关系,将此力位关系与虚拟环境下的形变力位关系进行对比,验证虚拟手术系统的正确性,进一步说明真实肝脏的力学参数可以提高虚拟手术系统的力触觉体验。本课题建立一个基于真实肝脏力学性能参数的虚拟手术系统,为操作者提供较为完善的力触觉和视觉上的体验。
[Abstract]:Advances in virtual reality technology have made it possible to build virtual surgery systems. Doctors use force-tactile interactive devices to simulate the process of surgery in a virtual environment. In the process of physical modeling of virtual surgery system, the mechanical performance parameters of soft tissue have become the bottleneck restricting the effect of physical model of virtual organ. The real mechanical performance parameters of soft tissue organ are measured. It is of great significance to enhance the force-tactile feedback of virtual surgery system. Based on the research of soft tissue mechanics parameter measurement at home and abroad, this paper will build a new soft tissue mechanics parameter measurement platform. The parameters of liver mechanics were measured experimentally and applied to the virtual surgery system. The main research contents are as follows: setting up the software environment of virtual surgery system, redrawing the geometry model of liver and surgical instruments by using OpenGL in virtual environment, and establishing the bounding box method. Improve the speed of collision detection, analyze the mechanical properties of soft tissue, then describe the viscoelasticity of soft tissue by using three parameter model, establish mass-spring model, Furthermore, the core mechanical parameters needed for the virtual liver physical model are defined: the elastic coefficient of the liver k, the viscosity coefficient 畏 and the destructive power threshold value Fm of the outer tissue. A new platform for measuring the mechanical parameters of soft tissue is built. In this paper, the function of Phantom Omni robot is extended and applied to the measurement of soft tissue deformation information. The spherical algorithm is used to fit the "bar length L" of the measuring platform with Matlab, and the D-H method is used to model the forward kinematics. Get the coordinates of the terminal point. Write M file, analyze the workspace of the end point. Design the clamping mechanism and support mechanism to assist the experimental operation. The end weight compensation and contact force threshold of the force sensor are calculated. Combined with the programming software, the liver shape variables and deformation forces are measured. The uniaxial compression experiment is designed, and the method of piecewise fitting elastic coefficient is adopted. Fitting the elastic coefficient k of the liver at different deformation stages; designing stress relaxation experiments to fit the viscosity coefficient 畏 of the liver; designing puncture experiments to analyze the peak deformation force at the moment of the puncture of the outer layer of the liver, That is, the damage threshold of the outer layer of the liver, Fm. The mechanical properties of the liver are applied to the virtual surgery system. The virtual liver is compressed and stretched by the Phantom Omni force tactile device. Force feedback under virtual environment is obtained. The compression experiment of real liver is designed to measure the deformed force position relationship of real whole liver under compression state, and the force position relationship is compared with that under virtual environment. The validity of the virtual surgery system is verified, and it is further proved that the mechanical parameters of the real liver can improve the force-tactile experience of the virtual surgery system. In this paper, a virtual surgery system based on the parameters of the real liver mechanical performance is established. To provide operators with a more complete sense of force and visual experience.
【学位授予单位】：哈尔滨工程大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：R61;TP391.9

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