基于视觉反馈的输尿管软镜机器人运动补偿策略  

Motion Compensation Strategy for Robot-Assisted Flexible Ureteroscopy Based on Visual Feedback

作　　者：李建民[1,2] 张增玉 赵建厂 苏赫[1,2] Li Jianmin;Zhang Zengyu;Zhao Jianchang;Su He(Key Laboratory of Mechanism Theory and Equipment Design of Ministry of Education,Tianjin University,Tianjin 300354,China;School of Mechanical Engineering,Tianjin University,Tianjin 300354,China)

机构地区：[1]天津大学机构理论与装备设计教育部重点实验室,天津300354 [2]天津大学机械工程学院,天津300354

出　　处：《天津大学学报（自然科学与工程技术版）》2021年第7期738-745,共8页Journal of Tianjin University：Science and Technology

基　　金：国家重点研发计划资助项目(2017YFB1302801);国家自然科学基金资助项目(51875394).

摘　　要：机器人辅助输尿管软镜术可以显著提高泌尿外科医生的手术执行能力.然而,由于人体自然腔道生理约束,导致输尿管软镜在手术过程中存在明显的末端运动偏差,影响手术效率,增加手术风险;同时输尿管软镜末端空间狭小,难以安装可检测末端运动偏差的传感器.针对以上问题,提出了一种基于视觉反馈的输尿管软镜末端运动补偿策略,以霍夫圆检测为基础,自动提取输尿管软镜的视野作为感兴趣区域,降低计算负担;同时,针对输尿管软镜的成像特点,对视野中特有的梳状结构干扰进行了频谱分析和消除.在此基础上,结合ORB算法提取图像信息,通过对前后两关键帧之间的空间关系进行几何描述并求解,得到输尿管软镜末端的角位移.该角位移与输入运动指令之差即为输尿管软镜末端运动偏差,并据此建立了输尿管软镜运动补偿策略.最后借助输尿管软镜机器人样机,利用实验手段对上述过程进行验证,结果显示,输尿管软镜末端的角位移平均计算时间约为21.32 ms,平均计算误差0.33°,最大计算误差1.90°.使用所提运动补偿策略前后输尿管软镜末端运动状态的对比实验结果表明,该运动补偿策略平均补偿误差约为2.17°,最大补偿误差为3.29°,可以显著减少输尿管软镜末端的运动偏差,并具有较好的实时性.Robot-assisted flexible ureteroscopy can significantly improve a urologist’s ability to perform surgery.However,due to physiological constraints of the natural orifice,the motion of a flexible ureteroscope’s tip has an obvious deviation,which consequently reduces the surgical efficiency and increases surgical risk.Installation of motion deviation sensors is difficult due to the narrow space at the tip of flexible ureteroscope.In response,a motion compensation strategy based on visual feedback is proposed.The circle Hoff transformation was used to automatically extract the visual field of flexible ureteroscope as the region of interest,reducing a computational burden.According to the imaging characteristics of the flexible ureteroscope,the characteristic comb structure in visual field was analyzed through the Fourier spectrum and was then eliminated.On this basis,the oriented FAST and rotated BRIEF algorithm was used to extract the image information and the angular displacement of the flexible ureteroscope’s tip was computed by solving the geometric relationship between the two key frames.The difference between the angular displacement and input movement instruction in the motion deviation of the flexible ureteroscope’s tip is analyzed and a motion compensation strategy is built.Finally,results using the proposed approach is verified with an experiment aided by a robot for flexible ureteroscope.Experimental results reveal that the average computation time of angular displacement is about 21.32 ms,the average error is 0.33°,and the maximal value is 1.90°.The average error of angular displacement achieved after the employment of the proposed compensation strategy is 2.17°with the maximum reaching 3.29°.This signifies that the proposed motion compensation strategy significantly reduces the motion deviation of the flexible ureteroscope’s tip and meets real-time requirement.

关 键 词：机器人辅助输尿管软镜术 视觉反馈 运动补偿策略 图像处理技术 

分 类 号：TP242.3[自动化与计算机技术—检测技术与自动化装置]