【作者】 王震；

【导师】 左思洋；

【作者基本信息】 天津大学 ， 机械工程， 2020， 硕士

【摘要】 眼科手术是对医生技术水平要求最高的手术之一,目前大多数眼科手术还是依靠医生直接手持手术器械完成,医生手部的生理震颤、长时间手术造成的疲劳都影响着手术的安全性,特别是眼部组织及其脆弱,允许的器械-组织接触力极小,远低于人的感知能力极限,在眼科手术中施加过大的力可能会对眼球造成不可逆的损伤。针对这些问题,本文设计了基于力反馈的眼科手术机器人,包括手持式触觉反馈手术装置以及主从式力反馈手术机器人。手持式触觉反馈装置可以实现末端微小接触力的检测,并将力的大小与方向信息通过触觉信号反馈给操作者。主从式力反馈手术机器人可以实现医生操做端(主操作手)和手术执行端(从操作手)机器人的分离,通过信号处理和动作缩小等方法可以大大提高器械操作的稳定性与精确性,通过力反馈主手将操作端检测到的力信息反馈给操作者。具体内容如下:首先,设计了手持式触觉反馈手术装置,装置末端测力部分基于光纤布拉格光栅传感器(FBG)设计,可实现毫牛级别多自由度力的感测;触觉反馈利用旋转摩擦和平移运动实现,可对力的大小与方向信息进行反馈。同时对装置的力检测精度以及触觉反馈机构的有效性进行评估。其次分析了眼科手术的典型术式和手术中手术器械布局形式以及特有的器械运动自由度和运动范围,根据这些要求,基于远程运动中心(RCM)机构设计了新型的眼科手术机器人从操作手,针对现有研究的不足,设计了结构简单的手术器械快换机构,可以在短时间内实现从操作手末端携带的手术器械的快速手动更换;对现有的从操作手结构进行改进,可以实现其RCM的重新定位,进而实现手术前RCM与巩膜切入点的快速对准;基于之前的研究工作,将具有力检测功能的手术器械集成到从操作手末端,使其具有精准的力检测功能。在所设计的从操作手的基础上,对主操作手的设计要求进行了分析,基于对主从控制直观性的考虑,本文中的主操作手采用主从同构式设计;主操作手具备力反馈的功能,可将从操作手末端检测到的力实时反馈给操作者;主手同时设计了新型的并联机构,实现了两偏转自由度力反馈驱动器的固定布置,大大降低了主操作手的移动惯性。在完成手术机器人的设计后,分析了主从操作手的正运动学,建立了主从映射关系以及力反馈的对应关系。针对主从操作手中采用的传感器与驱动器的输入输出信号类型,选择了合适的控制器以完成主从控制与力反馈系统的搭建。然后,对完成装配的主从操作手进行初步实验验证,通过对比驱动器的输入运动与实际输出的运动实现了主从操作手运动精度的检验,结果表明从操作手各自由度运动误差均在0.5°以下,主操作手在空间中的运动误差在2 mm以下。对主操作手的力反馈性能进行了验证,结果表明主操作手在其各自由度上都有良好的反馈力控制性能,可以实现准确的力反馈。最后,利用主从机器人系统进行了更接近实际手术情况的主从操作过程(模拟血管注射以及鸡蛋壳膜剥离实验),以验证系统的整体性能,在主从控制的模式下完成了注射过程,同时在力反馈系统对于主从鸡蛋壳膜剥离过程的器械-组织接触力的控制有非常良好的效果(平均接触力与最大接触力均降低30%以上)。更多还原

【Abstract】 Ocular surgery is one of the most technically demanding surgery.At present,most ocular surgical procedures are performed manually by surgeons.The physiological hand tremor and the fatigue from prolonged operations affect the safety of the operation.Especially the eye tissue is fragile,the allowable tool-tissue contact force is extremely small,which is far below the limit of human perception ability.Excessive force may cause irreversible damage to the eyeball.To address these issues,this paper designs ocular surgical robots based on force feedback,including a hand-held haptic feedback surgical device and a master-slave force feedback surgical robot.The hand-held haptic feedback device can detect the contact force at the end,and indicate the magnitude and direction of the force to the operator through haptic signals.The master-slave force feedback surgical robot can realize the separation of the doctor’s operation end(master manipulator)and the operation execution end(slave manipulator)robots,and the stability and accuracy of the instrument operation can be realized through signal processing and motion downscaling.The forces detected by the force sensing part of the instrument is fed back to the operator through the force feedback master.The details are as follows:Firstly,a hand-held haptic feedback surgical device is designed.The force measurement at the end of the device is based on a fiber Bragg Grating(FBG)sensor design,which can achieve multi-degree-of-freedom(Do F)force sensing at the level of millinewton.Haptic feedback is realized by rotational friction and translation movement.The magnitude and direction of force can be presented.At the same time,the force detection accuracy of the device and the effectiveness of the haptic feedback mechanism were evaluated.Secondly,we analyze the typical surgical procedures of ocular surgery and the layout of surgical instruments during the operation.According to these requirements,a new slave manipulator is designed based on the remote center-of-motion(RCM)mechanism.In view of the shortcomings of the existing research,a surgical instrument quick-change mechanism is designed,which can realize the rapid manual change of the surgical instrument in a short time.The structure of slave manipulator is improved,which can realize the repositioning of its RCM.Hence,it can realize the rapid alignment of the RCM with the scleral entry point before the operation.Based on the previous work,the surgical instrument with force detection function is integrated with the slave manipulator.Based on the slave manipulator,the design requirements of the master manipulator are analyzed.Considering the intuitiveness of the master-slave control,the master manipulator adopts the isomorphic design with the slave manipulator.The master manipulator has the function of real time force feedback.The master manipulator also adopts a new type of parallel mechanism,which realizes the fixed arrangement of the force feedback actuators with two rotation Do Fs,which greatly reduces the inertia.After completing the design of the surgical robot,the kinematics of the master and slave manipulators were analyzed.The master-slave mapping and the corresponding relationship of force feedback were established.According to the types of the input and output signal of sensors and actuators in the robot system,a suitable controller was selected to complete the construction of the master-slave control and force feedback.Then,preliminary experiment was performed.The position accuracy of the master and slave manipulators was verified by comparing the input motion of the actuators with the actual output motion.Results showed that the movement error in each Do F of the slave manipulator was below 0.5°.The movement error of the master manipulator in the space is below 2 mm.The force feedback performance of the master manipulator was verified,the results showed that the master manipulator has good feedback force control performance,which can realize accurate force feedback.Finally,the master-slave robot system was controlled to perform master-slave operation processes(mimicking vessel injection and egg membrane peeling experiment)that were close to the actual surgical situation to verify the overall performance of the system.The injection process was completed under the master-slave control.At the same time,the force feedback system has a good effect on the control of the tool-tissue contact force during the peeling process(the average contact force and the maximum contact force are both reduced by more than 30%).更多还原