【作者】 梁东；

【导师】 万淑敏； 张国华；

【作者基本信息】 天津大学 ， 机械工程（专业学位）， 2017， 硕士

【摘要】 本文研究了在近距离放射治疗中,采用人工势能场法进行人体复杂环境下的柔性针路径规划的问题,针对由于针与软组织交互引起靶点移位进行分析,针对人工势能场算法自身的缺陷提出改进方法,针对人体实体器官外廓信息的提取进行研究,并结合柔性针操控算法进行实验验证。研究结果有助于医生术前预测靶点位移,并准确、快速完成术前路径规划,对手术的顺利进行有重大意义。本文主要研究内容如下所述:首先,分析了引起靶点移位的原因—柔性针挠曲和软组织变形。建立了柔性针挠曲模型,数值模拟得到其变形量。研究了自制仿生材料的参数,结合柔性针挠曲模型,提出了组织变形仿真方法,通过穿刺实验验证仿真方法的准确性,从而为预测靶点移位提供一种简便方法。其次,分析了传统人工势能场算法理论及其优缺点,提出了改进算法。研究了核磁图像手动分割、盆腔器官信息获取方法,对人体复杂环境下障碍物信息进行提取,利用改进人工势能场算法在该环境下对柔性针进行路径规划,仿真结果可以躲避障碍物并且保留了算法的高效性,能够解决机器人陷入最小势能阱问题,并能成功逃逸。最后,研究了柔性针操控的占空比算法,搭建了针操控实验台及针尖点追踪识别实验台,进行了相关穿刺验证实验。比较了仿真结果与实验结果,分析了产生误差的可能原因,并给出了解决方案。更多还原

【Abstract】 The paper takes the robot-assisted percutaneous surgery as the object of study.The trajectory planning of flexible needle in the complex environment of human body is researched extensively in this thesis.Therein an improved algorithm for the defects of the algorithm is proposed.We also study the extraction of human organ information.In addition,the target displacement caused by the interaction between the needle and the soft tissue is analyzed.The flexible needle puncture experiments are conducted combined with the flexible needle steering algorithm.The results of the study will help doctors to predict the target displacement,and complete the preoperative path planning accurately and quickly.This research has great significance to the success of the operation.Firstly,we analyze the causes of the target displacement including flexible needle deflection and soft tissue deformation.The flexible needle deflection model is established,and its deformation is obtained by numerical simulation.The material parameters of the biomimetic tissue made by ourselves are studied as the input of the finite element analysis and combined with the flexible needle deflection to research the deformation of the tissue,so as to provide a simple method for predicting the target displacement.Secondly,the traditional artificial potential field algorithm and its advantages and disadvantages are analyzed,and an improved algorithm is proposed.According to the information of obstacles in the complex environment of the human body,this paper studies the manual segmentation and the method of extracting the information of the pelvic organs.The extracted information is visualized and the path planning of the flexible needle is carried out in this environment by using the improved artificial potential field algorithm.The planning results show that the trajectory can avoid the obstacles and the improved method can keep the efficiency of the algorithm.The experimental results prove that the improved algorithm can solve the problem that the robot trapped in the minimum potential energy well,and can escape successfully under the premise of preserving the advantages of the original method.Finally,the duty cycle algorithm of flexible needle steering has been studied and the needle steering experiment table and point identification tracking test table are established.By comparing the simulation results with the experimental results,the possible reasons for the errors are analyzed and the solutions are given.更多还原