血管介入手术机器人系统力反馈的模糊融合

为完善主从式血管介入手术机器人系统,构建了力反馈回路.通过集成两个微型力传感器,实现了对导管前端和侧壁与血管接触力的同时测量.鉴于主从模式与传统手动操作的不同,在进行力觉交互时,为保证医生成熟的手术经验继续发挥作用,采用模糊推理中的双输入–单输出模型完成两路数据的融合.通过标定隶属度函数和制定融合规则表,将积累的手术经验转化为数字化的力反馈策略,不但改善了低采集频率下的力反馈效果,更在准确表征介入状态的同时,针对不同的接触状态实现了不同的反馈分辨率,从而进一步保证了机器人手术系统的适应性、安全性和操作效率.     

微创血管介入手术机器人的主从交互控制方法与实现

微创血管介入手术是治疗冠心病的重要治疗手段, 手术中要求对导管、导丝等介入器械高精度递送.得益于机器人技术的高精度、可远程操作等特点, 血管介入手术机器人的研制受到了极大关注.在微创血管介入手术中, 按导管或导丝远端所处血管部位, 将介入器械递送过程分为三个阶段: 1) 主动脉阶段:导丝或导管远端位于主动脉, 需快速前送, 以减少X射线和造影剂的使用; 2) 冠脉入口阶段:导丝或导管远端进入冠脉, 此时需选择相应的病变冠脉分支; 3) 冠脉病变阶段:导丝或导管远端位于狭窄病变部位, 需要高精度操作才能使导丝或导管穿过狭窄病变.针对器械递送的不同阶段, 提出具有运动缩放的主从控制方法, 通过改变血管介入手术机器人主端和从端之间的运动缩放关系, 实现机器人从端对主端操作的放大、缩小或等比例复现.通过在微创血管介入手术机器人平台实验, 验证了机器人从端对主端操作缩放的可行性和有效性.通过操作时间和操作精度对比分析得到:在缩放因子为4时操作时间减少39.9%;在缩放因子为1/4时, 平移和旋转操作精度分别提高72.9%和77.1%.     

主从式胃镜介入机器人系统

针对胃镜操作难度高、医生工作强度大、消化液污染以及X射线辐射等问题,提出了主从式胃镜辅助介入机器人系统.在充分分析医生手动操作胃镜特点的基础上,将机器人分为镜体输送机械臂与镜体操作机械臂两部分.镜体输送机械臂调整镜体相对于病人口部的位姿,并完成插镜动作;对镜体输送被动臂进行逆运动学分析,确定各关节参数与基座位置;对输送器与镜体间作用力进行分析以确定输送电动机输出力矩.镜体操作机械臂控制操作部完成镜体旋转、操作部跟随、末端弯曲以及送气送水和抽吸功能.采用手柄实现对胃镜介入操作的主从控制,完成手柄与镜体在动作上的直观映射.在体外测试实验之后,进行活体动物实验发现机器人系统可完成对镜体的各项操作且未发现对组织造成损伤.实验结果表明,本文提出的胃镜辅助介入机器人系统可直观有效地完成胃镜介入,降低了操作难度,符合人类工程学设计.     

基于导管机器人的变论域模糊PID控制研究

在微创血管介入手术中,当操作者通过主手给出期望位置后,要求导管机器人能够控制导管快速稳定并精确到达目标位置。但由于导管机器人的电机响应迟滞以及血管内的复杂环境因素,传统的模糊PID控制已经不能满足血管介入手术对导管机器人快速性、精确性、强鲁棒性的要求。通过对导管建模,导管机器人运动学、手术坐标空间变换分析,采用变论域模糊PID控制,并运用Matlab进行仿真。仿真结果证明,所设计的变论域模糊PID控制器能够提高导管机器人的响应速度、定位精度与稳定性,为血管介入手术导管机器人的控制提供良好的理论依据。     

微创手术导管机器人系统变论域模糊PID控制

在微创血管手术导管机器人系统控制机器人送导管问题的研究中,为克服手动送管的缺陷,要求导管机器人系统能够快速响应、抗干扰能力强以及对目标轨迹的实时跟踪.传统模糊PID控制由于其精度与响应速度之间的矛盾,限制了在微创手术中的应用.提出采用变论域模糊PID控制,引入伸缩因子,在不降低响应速度的前提下改善模糊PID控制精度,进一步改善系统位置跟踪精度以及在主从微创手术中的实用性.仿真结果表明,所提出的变论域模糊PID控制对系统具有快速准确的跟踪性能和较强的鲁棒性能,证实了变论域模糊PID控制在主从微刨手术中的优越性与实用性.     

微创介入机器人系统设计与精度分析

针对微创介入手术对医生的身体危害性及难操作性等问题,设计了一种辅助医生手术操作的新型介入手术机器人系统,并详细阐述了模仿医生实际夹持与旋捻导管动作的仿生手指的设计理念以及基于神经网络的PID控制系统的设计过程。利用所研制出的血管介入机器人样机,开展了推进机构的精度实验,实验测试的各项精度结果证明所开发的推进机构满足精度的设计要求。通过对机构精度和误差来源的分析,给出提高精度的3条可行措施。本介入手术机器人满足设计要求,为同类产品的设计和改进提供了参考依据。     

基于中心线匹配的导管三维重建技术

针对工业领域中导管的三维重建效率低的问题,提出了一种基于中心线匹配的导管三维重建方法.该方法首先通过导管的平面灰度图像提取出中心线和边缘线,根据立体视觉原理,以非均匀有理 B样条(Non-uniform rational B-spline, NURBS)曲线作为导管中心线的描述工具和匹配基元,利用其透视投影不变性,重建导管的空间中心线,并通过边缘线计算导管的外径,最后利用三维建模技术重建导管的CAD模型.相对于现有导管三维重建方法,该方法具有测量效率高,操作简单的特点.实验结果表明,该方法的导管三维重建时间可控制在1分钟内,重投影误差为0.284像素,导管两端面中心点的测量误差为0.242mm,外径测量误差为0.158mm.     

用机器人修复心脏

1998年5月是医学史上一个值得纪念的日子,医生成功地用机器人完成了一例心脏瓣膜修复手术,其中包括对病人心脏瓣膜的修整和再造。这个手术之所以不寻常,并不是因为手术本身,而是因为这个手术的特殊做法。在整个复杂的手术过程中,医生根本没有接触病人的身体,实际上医生根本没有上手术台。手术的每一个精细的步骤都是由医生控制着先进的外科手术系统完成的。手术过程中,一个有经验的心脏外科专家在距手术台几米远的控制台上遥控着工具。手术工具通过一个小孔插入人体并通过另一个也插入病人体内的三维视觉成像系统观察手术的过程。医生通过机器人巧妙精确地完成如此复杂的手术,这在以前是不可能的。     

手术机器人夹持力检测技术进展

夹持力检测是医疗机器人进行手术的必要手段。在手术过程中,通过检测夹钳的夹持力,然后反馈给医疗机器人控制系统进行调整操作,可避免因夹持力过大对患者人体组织造成不必要的损伤。本文回顾了近6年有关医疗机器人夹持力检测方面的研究情况,总结了目前6种医疗机器人夹持动作力检测的实现技术,并对其原理、性能、应用前景进行了对比,最后对手术机器人未来的发展做了展望。     

一套研究双向控制实验系统的实现

主要介绍了一套单自由度主从式力觉临场感遥操作的实验平台,该实验平台具有操作简单和直观的特点,操作者可两手同时接触主端和从端的操作器,通过控制主手运动,使从手跟踪其运动,并且能够同时正面地感受到主从两端操作器的力反馈情况。文中对硬件和软件方面的设计分别进行了分析,最后针对某一算法进行有时延和无时延的力觉临场感实验,并进行研究。该套实验系统的设计目的是为了进行遥操作中双向控制算法的研究,实验结果表明该套实验系统能够有效地实现控制算法,从而证明其有效性。     

Catheter manipulation training system based on quantitative measurement of catheter insertion and rotation

How to preserve the catheter without any modifications and improve the precision of manipulation in the catheter-based endovascular intervention remains a challenge for quantitative training and evaluation. This paper presents an optical sensor unit to measure catheter motions based on the working principle of Laser Doppler, which allows for catheter motion measurement with non-contact detection and supports medical training and evaluation without modifications on the catheter. Then, calibrate this sensor unit and implement recording of catheter motion. Next, propose a training system by tracking the reference trajectory based on an expert’s skill, and provide visual feedback to improve the precision of catheter manipulation. Eight subjects were trained for catheter manipulation with this system. Among them, six subjects improved their catheter manipulation of linear motion, and seven improved the catheter rotational motion.     

A modeling approach for robotic catheters: effects of nonlinear internal device friction

Recently, robotic surgery systems using passive flexible catheters have been developed for minimally invasive surgical applications – such as in the treatment of atrial fibrillation – where catheter control in the open chamber of the heart is required. The soft, atraumatic construction of these devices help reduce injury to delicate cardiac structures while providing a means of tool placement and control. To provide kinematic and control relationships, various models of continuous catheters have been developed. However, these approaches cannot explain the nonlinear behavior of the catheter when the effect of internal friction is considered. In this paper, we describe a lumped-parameter modeling approach which directly accounts for the effects of internal device friction. The nonlinear model is validated against experimental results from a prototype robotic catheter and is shown to correctly predict the variations in curvature and path-dependent instantaneous behavior observed. Finally, the validated model is used to investigate and describe a set of non-ideal catheter motions observed in practice.     

导管操作系统中力觉传感器信息的获取与控制研究

针对导管操作系统中力觉传感器反馈力的获取与控制进行了研究,导管前端采用光纤力传感器测量导管的顶端力;导管侧壁采用基于PVDF材料开发的微力传感器来测量导管的侧壁力。该导管操作系统对力觉传感器的输出信息进行了监测,实现了一种带有受力信息监测的主—从模式的新型导管操作系统。实验结果表明:该系统能够较好地实现受力信息的反馈。     

Design and performance evaluation of a novel robotic catheter system for vascular interventional surgery

Vascular interventional surgery (VIS) is an effective treatment method for vascular diseases. However, there are many problems in traditional VIS, such as surgeons are radiated by X-ray, the lack of well skilled surgeons, the security of the surgery will be reduced due to the Surgeons’ fatigue, high risk of the surgery. To solve these problems, a robotic catheter system is needed to protect the surgeons and enhance the safety of the surgery. In this paper, a novel robotic catheter system with master–slave structure for VIS has been developed. This system is designed with the consideration of the operation method in traditional VIS, which allows the surgeon to operate a real catheter on the master side, then the surgeon make full use of the natural catheter manipulation experience and skills obtained in conventional catheter operation. The salve manipulator operates the catheter insert into the blood vessel with following the operation of the surgeon, and the operating force of the salve manipulator is detected. On the master side, a novel damper-based magnetorheological (MR) fluid is designed to realize the force feedback, which is also used to reappear the operation force from the salve manipulator. The damper connected directly with real catheter is a piston structure using the MR fluid to realize the force feedback. It can transmit the feedback force to surgeon’s hand through the operating catheter connected with damper, which seems that the surgeon operates the catheter beside the patient. The operating transparency of the developed system has been enhanced. The mechanism of the developed system has been introduced in detail. Performance evaluation experiments for the developed robotic catheter system have been done. The experimental results indicated that the developed robotic catheter system is fit for VIS.     

Laser-machined shape memory alloy sensors for position feedback in active catheters

Catheter-based interventions are a form of minimally invasive surgery that can decrease hospitalization time and greatly lower patient morbidity compared to traditional methods. However, percutaneous catheter procedures are hindered by a lack of precise tip manipulation when actuation forces are transmitted over the length of the catheter. Active catheters with local shape memory alloy (SMA) actuation can potentially provide the desired manipulation of a catheter tip, but hysteresis makes it difficult to control the actuators. A method to integrate small-volume, compliant sensors on an active catheter to provide position feedback for control would greatly improve the viability of SMA-based active catheters. In this work, we describe the design, fabrication, and performance of resistance-based position sensors that are laser-machined from superelastic SMA tubing. Combining simple material models and rapid prototyping, we can develop sensors of appropriate stiffness and sensitivity with simple modifications in sensor geometry. The sensors exhibit excellent linearity over the operating range and are designed to be easily integrated onto an active catheter substrate.     

A geometric approach to the modeling of the catheter-heart interaction for VR simulation of intra-cardiac intervention

Cardiac intervention is a minimally invasive diagnostic and therapeutic procedure used to treat cardiac diseases. The mapping of heart geometry with minimal visual assistance presents a technical challenge for interventional cardiologists attempting catheter navigation. This paper presents a geometric approach to modeling the catheter-heart interaction for VR simulations of catheter navigation within a heart chamber. Three types of modeling are used to model the interaction between the catheter and the heart wall: non-slip, pseudo-slip and slip modeling. A two-step shape memory process that minimizes the bending of and strain on the catheter is designed for catheter deformation for non-slip or pseudo-slip contact, and a progressive group linkage bending process that constrains the catheter curvature and position within the volume enclosure is designed for catheter deformation for slip contact. The proposed model is consistent with the observations made during the experiment. The model is able to deform the catheter in any free-state shape within the volume enclosure and is independent of local motion increment. Thus, it presents advantages in terms of complexity and real-time requirements.     

Autonomous Image-Guided Robot-Assisted Active Catheter Insertion

Interventional cardiologists are at great risk from radiation exposure due to lengthy procedures performed under X-ray radiations. Angioplasty is one such procedure wherein the clinician guides a catheter into the femoral artery under X-rays and the procedure often extends to over 50 min. A clinician performs several hundred such procedures over his/her lifetime, leading to an accumulation of the total radiation he/she is exposed to. In this paper, we investigate autonomous robot-assisted insertion of an active catheter instrumented with Shape Memory Alloy (SMA) actuators using image guidance. The tip of the active catheter is tracked in real time to provide information on the location of the catheter that determines the optimal stroke length of insertion for the robot and the necessary bending angle for the active catheter. The catheter is autonomously guided from the point of entry to the site of plaque buildup, thereby shielding the clinician from harmful radiation due to the X-rays used for imaging and providing a more ergonomic approach for catheter insertion. Experimental results are given to illustrate the robot-assisted catheter insertion procedure using image guidance.      

A multilink active catheter with polyimide-based integrated CMOSinterface circuits

This paper describes an active catheter with flexible polyimide-based integrated CMOS interface circuits for communication and control (C&C IC) to be used for applications in biomedicine. The active catheter has a multilink structure. Distributed micro shape memory alloy (SMA) coils are utilized as actuators for multidegree of freedom movement. The C&C IC's, which are incorporated on the links, require three common lead wires to address all the links and control the selected SMA actuators in the active catheter. An MOS transistor with large channel width is used for switching the SMA actuator. To reduce the system size and simplify the assembly work, the C&C circuit and three lead wires are fabricated on the same substrate using CMOS-compatible polyimide-based process. The outer diameter of the fabricated active catheter is approximately 2.0 mm. The fabricated active catheter has a four-link structure and six degrees of freedom of movement per one link. A simple bending model of one unit is presented and compared with the experiments. The fabricated C&C IC measures 1.0 mm×3.35 mm×0.2 mm. The link addressing and the actuator switching functions of the fabricated chip were confirmed. The minimum access time for addressing and actuating a single unit was 6.4 μs. The active catheter was actuated by the fabricated C&C IC chip with flexible interconnect leads in response to the C&C signals from the outside controller     

心内膜几何模型的计算机三维重建技术

心内膜标测系统中,三维心内膜几何模型的构建是一个重大进步,在手术中导航导管起着关键的作用。本文介绍了一种利用凸包算法,从心腔内导管电极的位置信息中提取建模数据的方法。并用Matlab仿真,证明该法可以筛除心腔内的数据点,而提取心内膜表面上的点,构建心腔舒张期的三维心内膜模型。