北京生物医学工程

基于位置动力学的软组织建模研究

Research on soft tissue modeling based on position-based dynamics

作者：张禹李佳罗丹李基圣

单位：沈阳工业大学机械工程学院(沈阳 110870)

关键词：关键词虚拟手术; 软组织形变; 位置动力学; 四面体网格; 触觉交互

分类号：R318.04

出版年·卷·期（页码）：2020·39·4（344-349）

摘要：

目的为满足虚拟手术模拟实时性与真实性要求,本文采用位置动力学的算法建立虚拟手术系统的软组织形变模型。方法首先以人体软组织肝脏为例,对表面三角形网格进行四面体划分,用四面体网格来构造肝脏的形变模型;然后介绍位置动力学模型的算法原理并推导几何约束投影,赋予软组织形变模型距离约束和体积约束;提出手术器械拾取控制点的碰撞检测方法,并利用触觉交互设备搭建虚拟手术仿真平台;最后对肝脏等软组织进行形变模拟实验及时间效率分析,并与质点-弹簧模型对比? 结果位置动力学模型相比质点-弹簧模型形变效果更逼真,肝脏模型形变耗时仅为 3.07 ms,系统帧率达到 60 帧/ s 以上。结论基于位置动力学的软组织建模具有真实的变形模拟和较高的计算效率。

Objective In order to meet the real-time requirements of virtual surgery simulation, this paper adopts the algorithm based on position-based dynamics to establish the soft tissue deformation model of virtual surgery system Methods First of all, taking the human soft tissue liver as an example, the triangular mesh on the surface is divided into tetrahedron, and the tetrahedron mesh is used to construct the deformation model of the liver. Then, we introduce the algorithm principle of position dynamic model, deduce geometric constraint projection, and give the distance and volume constraints to the soft tissue deformation model. A collision detection method is proposed to pick up the control points of the surgical instruments, and a virtual surgery simulation platform is built by using the tactile interaction equipment. Finally, the deformation simulation experiment and time efficiency analysis of the liver and other soft tissues are carried out, and compared with the mass spring model.Results Compared with the mass spring model, the effect of the position-based dynamics model is more realistic.The deformation time of the liver model is only 3.07ms, and the frame rate of the system is more than 60 frames per second.Conclusions The soft tissue modeling based on position dynamics has the advantages of real deformation simulation and high computational efficiency.

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