面向机器人辅助穿刺手术的新型柔性针驱动-传感系统创成与针-组织复合操控方法研究

Flexible needle insertion can provide "non-straight trajectory" due to the flexibility of the needle body, which can be implemented in the surgeries involving critical anatomical structures, so it shows high potential in the applications of diagnostic biopsy, drug delivery and radioactive therapy etc. However, currently it is not widely employed in clinical applications, since this technique is still limited by some crucial issues, e.g. the accuracy of the needle axial rotation, real-time monitoring information of the needle path trajectory and the onefold control mode of the needle manipulation. In this proposal, it will be attempted to breakthrough the limits of the past concepts and achieve innovative design and results in the actuation, sensing, and control etc. Several key research issues are involved in this proposed research, i.e. the creation of flexible needle mechatronics system based on piezoelectric actuation, the stick-slip motion model of the flexible needle actuation under the tissue disturbance, active sensing and state identification of flexible needle based on preoperative path planning, modeling of needle path trajectory in inhomogeneous tissues induced by needle-tissue combined manipulation, and motion planning optimization and control decision under the combined manipulation mode. This proposed research is attempting to solve several critical scientific issues and technique bottlenecks, which will provide detailed references and solid fundamentals to the research of novel robot-assisted needle insertion systems with "actuation-sensing-control" integration features.

柔性针穿刺能够利用针体的柔性实现"非直线进针"轨迹，使得涉及重要解剖结构的穿刺手术得以实施，在活体切片、靶向注射、短程放射性治疗等方面有着极为重要的潜在应用价值。但受到诸如针体轴向转动精度低、穿刺路径实时监测信息少、柔性针操控方式单一等问题的制约，始终没有得到广泛的应用。本课题将从驱动、传感、控制三个方面着手，尝试突破传统思路上的限制，获得创新性设计和突破性结果。本课题的主要关键技术涉及：基于压电驱动的柔性针机电系统创成；组织扰动下柔性针驱动粘滑运动模型研究；基于穿刺术前路径规划的柔性针主动传感与状态辨识；针-组织复合操控下的非均匀介质穿刺数学模型建立；基于针-组织复合的穿刺路径优化与控制决策。本课题研究的开展能够解决目前基于柔性针的机器人辅助穿刺手术系统研究的若干理论瓶颈问题，为新型"驱动-传感-控制"一体化的柔性针系统应用，提供详实的理论依据和技术基础。

经皮穿刺术是微创介入手术中一种重要的方法。传统的经皮穿刺术使用刚性针作为穿刺工具，但刚性针通常难以满足穿刺过程中的避障要求，由此产生斜角柔性针。本课题从柔性针穿刺过程的力学模型、结构创新设计、轨迹规划和针-组织控制等方面做了深入的研究。力学模型方面，建立了柔性针穿刺过程中的摩擦和切割数学模型，减小了针轨迹预测误差，同时通过模型可以推算出针轴推进所需的轴向力。为了从根本上消除因针轴摩擦带来的轨迹偏差，提出了基于压电陶瓷驱动的针尖针体分离的斜角柔性针创新设计。并且对柔性针在均匀介质中的轨迹规划做了研究。受刚性针穿刺技术中组织控制的启发，课题组提出了基于柔性针的“针-组织”操控技术，对针在非均匀组织中的轨迹特征做了理论分析，并且利用压电应变片研究了一套重建柔性针曲线形状的方法。针对人体组织的无先验知识特性，分析并实现了一种基于无标定视觉伺服的柔性组织变形控制算法。提出了通过对柔性针进行轨迹规划，逆向推导出柔性组织靶点位移的变形控制方案。