【作者】 张建鹏；

【导师】 姜杉； 王海涛；

【作者基本信息】 天津大学 ， 机械工程， 2018， 硕士

【摘要】 本文以柔性针在组织内旋转时的扭转变形为研究对象,推导了柔性针稳定状态下的角位移误差公式,进行了柔性针扭转变形及软组织变形的有限元仿真,完成了角位移误差补偿方法的实验验证。主要工作内容与研究结果如下:首先,测量了柔性针直线轨迹和弯曲轨迹下的摩擦扭矩,探究了不同因素对摩擦扭矩大小的影响。建立了稳定状态下的柔性针-组织交互扭转摩擦模型,得到了柔性针针尖与针尾的转动角位移误差公式。其次,采用有限元方法建立了柔性针和软组织模型,分析了柔性针扭转变形及引起的组织变形,得到了柔性针角位移的误差值及组织二维形变量。结合解剖学知识与三维重建技术将组织变形模拟扩展至三维盆腔器官群,计算出前列腺组织在柔性针转动状态下的变形量。最后,搭建了实验平台,进行了柔性针角位移误差补偿方法的实验验证。分析了柔性针退回距离的有效值,实验结果表明当柔性针退回距离为3 mm时,针体所受摩擦扭矩能够降低63.4%。推导了柔性针扭转动力学模型,将其与控制系统结合完成了角位移误差补偿实验,结果表明柔性针针尖偏移量降低了65%。研究结果有助于正确认识手术过程中柔性针角位移误差的产生机理与补偿方法,推动实现柔性针的精准操控,对医疗手术操作的误差控制及良好手术效果的获得具有重要意义。更多还原

【Abstract】 The research object of this paper is the torsional deformation during flexible needle twisting inside tissue.The angular displacement error formula of the flexible needle under a steady state is derived.The finite element simulation for the deformation of flexible needle and soft tissue are conducted.In addition,the experimental verifications of angular displacement error compensation methods are conducted.The detailed research contents and results of this paper are as follows:Firstly,the frictional torque is measured under needle straight trajectory and curving trajectory inside tissue,and the influence of various factors on frictional torque is analyzed.The torsional friction model is established when the needle is rotated under a steady state inside tissue,and the formula of angular displacement error between needle tip and needle base is derived.Secondly,the models of flexible needle and soft tissue are established in the finite element analysis.The needle twisting deformation and tissue deformation are analyzed,and the values of flexible needle angular displacement error and tissue two-dimensional deformation are obtained.The tissue deformation simulation is extended to three-dimensional pelvic organ groups by combining the anatomical knowledge with 3D reconstruction technique,and the deformation value of prostate under needle rotation is calculated.At last,the experimental platform is built,and the experimental verifications of angular displacement error compensation methods are conducted.The valid value of needle retraction distance is analyzed,and the experimental results show that the frictional torque can be reduced by 63.4% when the needle is retracted 3 mm.The torsional dynamic model of flexible needle is derived,and the angular displacement error compensation experiment is conducted by combing torsional dynamic model with control system.It turns out that the needle tip offset can be reduced by 65%.The research results are contributed to understand the mechanism and compensation method of the flexible needle angular displacement error during operation and promote the accuracy of flexible needle control.It is of great significance for the error control of medical operation and the acquisition of better surgical results.更多还原