【作者】 胡海燕；

【导师】 孙立宁；

【作者基本信息】 哈尔滨工业大学 ， 机械电子工程， 2011， 博士

【摘要】 随着社会工业化的发展,环境污染、饮食结构改变、精神压力等因素对人类的健康产生了消极影响,许多人遭受肠道炎、肠道肿瘤以及肠道癌等肠道疾病的困扰。作为定性诊断和治疗结肠疾病的医疗器械,结肠内窥镜在人体结肠肿瘤性病变的诊断方面具有重要价值。然而,传统结肠内窥镜只有其前端的导向段具有可控转向功能,其余部分通过利用与肠道壁接触所产生的挤压力而被动弯曲,故容易在肠道弯曲部位发生镜体“堆积”和“结襻”现象而无法通过、损伤肠道组织甚至出现“穿孔”事故,造成病人不适和痛苦。针对传统结肠内窥镜的缺点,本文研制了一种新型的结肠内窥镜机器人。该内窥镜机器人采用多关节段连续体型仿生结构,具有10自由度主动弯曲能力。在由操作者控制其前进运动的同时,内窥镜机器人根据所建立的成人结肠弯曲模型和传感器力反馈信息主动而柔顺地改变自身的形状以适应结肠的弯曲状况,实现在肠腔非结构环境内的半自主运动。本文主要在半自主式结肠内窥镜机器人的仿生结构设计、运动学分析、在结肠肠腔环境下的通过性和柔顺控制方面开展研究。在对人体结肠的解剖学特征和连续体型机器人的仿生原理进行分析的基础上,设计了具有多关节段连续体型结构的结肠内窥镜机器人。机器人分为5段,每段各具有2个自由度,通过绳索驱动方式实现对各关节段的运动控制。针对传统D-H方法不适用于连续体型机器人运动学分析的问题,提出了一种高效并具有良好实时性的连续体型机器人运动学分析方法,利用该分析方法对内窥镜机器人单关节段和多关节段的驱动空间、关节空间以及操作空间三者的位置映射关系进行了研究,并进行了运动学仿真分析。在机械结构和运动学层面为内窥镜机器人的通过性和柔顺控制研究奠定了基础。根据成人结肠解剖学弯曲特征,构建了人体结肠的三维弯曲模型,该模型具有简练而不失一般性的特点。为了使内窥镜机器人在工作空间受限的肠腔环境内具有良好的通过性,针对结肠内窥镜机器人的多关节段连续体型结构,提出了一种基于端点重合思想的多关节段结肠内窥镜机器人肠腔环境下的半自主通过控制策略。研究了结肠内窥镜机器人在乙状结肠段和降结肠段二维结肠环境下以及横结肠段三维结肠环境下半自主通过控制策略的实现方法,并进行了通过性仿真分析,验证了通过控制策略和实现方法的可行性。研究了人体结肠组织的生物力学特性,确立了结肠内窥镜机器人与结肠壁接触压力的安全阈值,为半自主式结肠内窥镜机器人对结肠肠腔环境的柔顺控制研究提供了依据。设计了用于测量机器人关节段与肠道壁接触压力的压力传感器,并分析其力学特性。针对半自主式结肠内窥镜机器人在肠腔内部非结构环境下的适应性问题,提出了一种基于肠腔环境生物力学特性的内窥镜机器人柔顺控制策略。该控制策略不需要对机器人复杂动力学模型进行求解,因而具有较高的实时性和可行性。最后搭建了半自主式结肠内窥镜机器人原理样机实验系统,介绍了原理样机所采用的两级分布式控制系统的硬件和软件构成,对内窥镜机器人单关节段和多关节段的弯曲能力分别进行了实验,验证了所提出的多关节段连续体型机器人运动学算法的正确性。开展了刚性模拟肠道环境下机器人的通过性实验研究,验证了半自主通过控制策略的有效性。对内窥镜机器人在医用结肠模型内的柔顺运动进行了实验,结果表明内窥镜机器人对柔性肠道模型具有良好的适应性,机器人与肠道壁的接触压力可控制在安全压力阈值以内,验证了所提出的柔顺控制方法的有效性。更多还原

【Abstract】 Due to environmental pollution, changes in the diets and mental stress, many people suffer from intestinal diseases. These diseases include inflammatory bowel diseases, intestinal tumor and intestinal cancers. As a direct tool, the colonoscope is a reliable and thus important for diagnosis and treatment of intestinal diseases. However, only a very short distal tip of the colonoscope can be controlled to bend actively, the bend of other sections is realized passively by the pressure between the tube and the colon wall. Consequently, the colonoscope usually changes the bending shape of colon and thus causes the patient a great deal of pain and taking a risk of perforation.Aimed at the disadvantages of traditional colonoscope, a novel semi-autonomous colonoscopic robot is presented in this paper. The robot consists of 5 continuum sections which is inspired by snake, elephant trunk or octopus tentacle, and has a total of 10 degrees of freedom (DOF). The robot moves in colon tract with a kind of semi-automous mode: it moves forward by the control of manipulator, and bends actively and compliantly according to the bending model of adult colon and the feedback of pressure sensors. The research of this paper includes bionic structure design and kinematics analysis of colonoscopic robot, trafficability analysis and compliance control in the unconstructed environment of colon tract.Based on the analysis of the anatomical characteristics of human colon and the bionic principle of continuum robot, a colonoscopic robot with multi-sections continuum structure is proposed. The robot is composed of five sections, each has two DOF and driven by cables. As the standard D-H method can’t be used to realize the kinematics analysis of continuum robot, a kinematics analysis method which is concise and real-time is presented. The relationship among drive space, section space and operation space of single section and multi-sections is studied respectively, and then validated by simulation. The structure design and kinematics analysis laid the foundation for trafficability analysis and adaptability analysis in the unconstructed environment of colon tract.According to the anatomical characteristics of human colon, the bend model of adult colon is constructed which is concise and without loss of generality. Aimed at the multi-section continuum structure of colonoscopic robot, a semi-autonomous control strategy for the motion of colonoscopic robot in the unconstructed environment of colon tract is proposed. The implementation of control strategy in the two-dimensional colon model which includes sigmoid flexure and descending colon and the three-dimensional colon model which includes transverse colon is studied respectively, and validated by simulation.The biomechanical property of human colon tissue is analyzed, and the safety threshold of pressure between the colonoscopic robot and colon tract is derived. These studies provide a basis for the compliance control of colonoscopic robot in colon tract. A pressure sensor which is used to measure the pressure between the colonoscopic robot and colon tract is designed and the mechanical characteristics is analyzed. Aimed at the adaptability of colonoscopic robot in the unstructured environment of colon tract, a compliance control method is proposed based on the biomechanical property of colon tissue. This method avoids computing the complicated dynamics of colonoscopic robot and thus features high real-time and feasibility.Finally, the prototype experiment system of semi-autonomous colonoscopic robot is built. The hardware and software of distribute control system for colonoscopic robot are introduced. The bending experiments of single section and multi-sections are carried out respectively, which validate the kinematics of continuum robot. In order to test the effectiveness of semi-autonomous control strategy for the motion of colonoscopic robot in colon tract, the trafficability experiment in rigid colon model is performed. The result of compliance control experiment in medical colon model shows that the pressure between colonoscopic robot and colon tract is within the threshold, which validates the effectiveness of the compliance control method in the unstructured environment of colon tract.更多还原