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手术模拟器中的触力觉交互技术研究
郝剑龙
学位类型工学博士
导师侯增广
2017-05-26
学位授予单位中国科学院大学
学位授予地点北京
关键词触力觉交互设备 力反馈 手术模拟器 无源性与稳定性 多模式交互
摘要随着科学技术的发展,神经系统疾病的诊断和治疗也日益完善。但是,复杂的手术操作对神经外科医生的手术技能提出了很高的要求。传统的培训方式成本高,周期长,特别是年轻医生在手术室的临床操作学习延长了患者的手术时间,增加了手术风险。基于虚拟现实技术的手术模拟器为外科医生提供了无风险、可重复的操作平台,能够为医生提供虚拟的手术场景。近年来,触力觉交互技术在手术模拟器中的应用已经成为一项研究热点。本文在国家863计划项目“基于混合现实的脑与脊髓及其比邻结构微创手术训练与实时决策系统”(2013AA013803)支持下,针对当前内镜经鼻入路手术模拟器中触力觉交互技术存在的问题,围绕触力觉交互系统的设计、控制以及多模式交互环境的构建展开研究。本文的主要工作和创新点如下:
(1)通用型七自由度触力觉交互设备的设计与控制。针对手术器械形态差异大、操作方式多变的特点,本文设计了一款通用型多自由度的触力觉交互设备,并提出了一种基于模型的重力补偿算法,该设备空间分辨率小于0.3 mm,旋转关节分辨率0.18度,轴向最大反馈力6.0 N。该设备机械结构设计为串并联混联的构型,在机械结构上实现了平移和旋转的解耦。基于机构运动学和动力学分析,设计了带重力补偿的阻抗控制器,实现了三个平动自由度和一个夹持自由度的力反馈功能,通过重力补偿实验,验证了重力补偿算法的有效性。通过评估实验分析,测定了设备的输入输出特性曲线和反馈力动态跟踪性能,实验结果表明,设备能够精确实现反馈力的输出。
(2)面向经鼻入路手术的专用型三自由度触力觉交互设备的设计与控制。针对内镜经鼻入路手术,本文设计了一款专用型三自由度触力觉交互设备,空间位置分辨率小于0.5 mm,最大反馈力6.2 N。为了模拟鼻孔对手术器械的约束,该设备采用并联型基座实现俯仰和偏转两个旋转自由度,固定在基座上的导轨滑块模型实现径向伸缩。基于结构的运动学和力传递分析,完成了阻抗控制器的设计与开发,实现了空间三个自由度的力反馈功能。与商业化的通用型力反馈设备相比,该设备不仅在活动自由度和工作空间上与真实手术相匹配,而且具有惯性小、反馈力大的特点。通过评估实验分析,测定了设备的输入输出特性曲线和反馈力的动态跟踪性能,实验结果表明,设备具有良好的力反馈特性。
(3)触力觉交互控制系统的无源性及稳定性分析。针对触力觉交互系统的稳定性问题,本文论证了阻抗云虚拟环境下系统的无源边界条件和稳定边界条件,将二维空间(K-B)的边界条件扩展到了三维空间(K-B-M)。首先,通过对操作者、触力觉交互设备以及虚拟环境三部分动力学特性的分析,构建了三种典型的触力觉交互控制系统模型。其次,本文根据无源性理论,研究了系统可渲染的最大阻抗,给出了阻抗云虚拟环境下系统无源的边界条件。根据稳定性理论对非耦合系统进行了稳定性分析,求解出系统稳定时可渲染的最大阻抗,并分析了虚拟质量对系统稳定性的影响。最后,针对虚拟手术中的振动触觉,本文提出了一种基于事件的触觉渲染算法,实现了触力觉交互设备的振动触觉反馈。
(4)基于多模式交互的虚拟手术系统设计。针对传统虚拟现实完全依赖视觉交互造成的交互沉浸感差、训练效率低等问题,本文提出了一种基于视觉、触觉和听觉的多模式交互框架。首先,分析了多模式交互的三个组成部分:数据模型、渲染算法和接口设备,研究了利用患者术前影像资料构建个性化虚拟手术环境的方法。其次,采用自主设计的三自由度触力觉交互设备,集成了一款具备多模式交互功能的内镜经鼻入路手术模拟器。最后,通过虚拟骨质结构的磨削实验,验证了多模式交互的可行性。
其他摘要With the rapid development of technology, the diagnoses and treats of neurological diseases have been increasingly improved. However, neurosurgeons are faced with the challenge of performing complex surgical procedures in which there is little room for error due to the critical vessels, nerves and other brain tissues. Training in the operating room can prolong a patient's operation time and in the worst-case scenario can cause permanent damage or death. Virtual reality based surgical simulator creates a no-risk environment where skills can be gained through harmless repetition. Except for vision, haptics is the second important cue for surgeons making decisions. Research has shown that the performance can be improved with haptic cue in the virtual training tasks. Supported by the National Hi-Tech R \& D Program (863) of China (Grant 2013AA013803), this research focuses on the design and control of the haptic interface for surgical simulator, aiming to solve the problems in the current haptic interaction for EEA (Endoscopic Endonasal Approach) surgery simulator. The main contributions and innovations of this research are as follows:
  1. The design and control of a 7-DOF general-purpose haptic interface.  A 7-DOF haptic interface is proposed in consideration of a variety of configurations of surgical tools. The mechanism is a series-parallel hybrid architecture,which benefits from its low inertia and the decoupling between translation and rotation. Based on the kinematics and dynamics analysis, an impedance controller with gravity compensation is designed and implemented. The evaluation experiments validate the effectiveness of gravity compensation algorithm and the performance of force feedback.
  2. The design and control of a 3-DOF customized haptic interface for EEA surgery simulation.} A 3-DOF customized haptic interface is proposed because the motion of surgical tools is constrained by the narrow nostril with limited DOFs and workspace in EEA surgery. Based on the kinematics and force transmission analysis, an impedance controller is designed to realize the force feedback in 3D space. Characterized by low inertia, high resolution and large feedback force, the customized haptic interface maintains as much fidelity of tool handling in the surgical training as in a real operation. The input-output characteristics and the force tracking capability are validated in the evaluation experiments.
  3. The passivity and stability analysis for haptic systems. The passivity and stability boundaries for impedance cloud rendering are demonstrated. According to the passivity theory, the passivity boundary for impedance cloud rendering is deduced. However, the passivity boundary is too conservative compared to the stability boundary. The stability boundary of uncoupled system is researched and the effect of virtual mass rendering on the stability is analyzed. Besides, an event-based haptic rendering algorithm is proposed to realize the vibration feedback.
  4. The design of a multi-modal interactive surgery simulator.  A multi-modal interactive system for EEA surgery simulator with visual, haptic and audio feedback is proposed. First, the multi-modal interaction framework is introduced and the virtual surgical environment is built based on patient-specific pro-operative medical image data set. Second, a multi-modal interactive system for EEA surgery simulation is integrated with the customized 3-DOF haptic interface. Third, a virtual bone drilling task is performed and the experiment results suggest that the multi-modal interactive mode is practicable.
文献类型学位论文
条目标识符http://ir.ia.ac.cn/handle/173211/14695
专题毕业生_博士学位论文
推荐引用方式
GB/T 7714
郝剑龙. 手术模拟器中的触力觉交互技术研究[D]. 北京. 中国科学院大学,2017.
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