面向软组织微创手术交互力学及柔性器械操控的关键问题研究

Image-guided robot-assisted minimally invasive percutaneous puncture surgery is an important medicine measure in biopsy and local target treatment. In order to reach the target region, long and thin flexible needle is used to insert into the soft tissue which has larger deformation property. Security and accuracy are the key problems to influence the detection results and curative effect. In view of this, the main focus of this project is to study the trajectory planning, needle steering, and the interactive-mechanism including force modeling and deformation between needle and soft tissue during the percutaneous puncture which is the main technology of image-guided robot-assisted system. First of all, through the comprehensive analysis of mechanical property of flexible needle and soft tissue characteristics, take into full consideration on anisotropy, viscoelasticity, and superelasticity of biological tissue, establish an interaction mechanical model between the flexible needle and soft tissue. Secondly, investigate the interaction mechanism of deformation between the flexible needle and soft tissue; settle the prediction of nonlinear deformation of soft tissue and deflection of needle and realize the compensation of the puncture position error. Finally combine the researches described above, and then establish the algorithm of obstacle avoidance and path planning theory in three-dimensional space; investigate robot-assisted high precision control strategy of flexible needle during percutaneous puncture surgery. Integrate the theoretical research and intraoperative practical application and achieve the purpose of obstacle avoidance and accurate puncture.

机器人辅助经皮微创手术是肿瘤疾病中活检、局部靶区治疗的重要医疗手段。经皮穿刺介入术需细长柔性针刺入具有大变形特性的软组织到达靶点，进行活检或治疗，而该手术的安全性及精准性是影响检测结果及疗效的关键问题。鉴于此，本课题以图像导航机器人辅助的经皮穿刺软组织手术为主要研究对象，针对该手术中的交互力学模型、变形的误差补偿、轨迹规划及针体操控等关键技术问题展开研究。首先，通过对柔性手术针及软组织的力学特性等影响因素的综合分析，充分考虑生物组织的各向异性、粘弹性及超弹性特点，确立完善的柔性手术针与软组织交互力学模型。其次，探究柔性针与软组织交互变形机理，解决穿刺针与软组织交互的非线性变形预测，实现对穿刺位置误差的实时补偿。最后，结合上述研究建立柔性针体末端空间避障及轨迹规划算法，探究机器人辅助经皮微创穿刺术可控柔性针的高精度操控策略，将理论研究与实际应用相结合，实现术中避障及精准穿刺的目的。

经皮穿刺是临床中用于癌症诊断和治疗的一种常见的微创手术。机器人辅助穿刺手术对于提高诊疗效果具有重大意义。该课题旨在通过对力觉、视觉等多种信息的处理分析，实现精准安全的穿刺操作，达到理想诊疗效果。本研究面向机器人辅助穿刺手术的交互力学机理及操控策略开展深入研究：.（1）引入断裂力学理论，建立接触变形过程中的硬度力模型。基于单向纤维增强材料力学理论及张量变换原理推导组织内切割力模型。通过肌肉组织多角度穿刺实验，验证了模型能够准确的描述针与纤维结构软组织的穿刺力。.（2）根据穿刺力模型，基于温克尔梁理论和瑞利里兹法，建立穿刺针在横观各向同性软组织中的非线性变形模型。分别以单层肌肉和肌肉-肝脏双层组织为例验证了模型的有效性。.（3）引入代价地图概念，结合人工势能场理论，建立基于穿刺风险代价评估的穿刺路径规划算法。以肝脏活检手术为例，进行了算法的模拟，获得了个性化生理解剖环境中的活检穿刺路径。.（4）基于方向依赖的交互力学分析及变形模型，确定针在各向异性、异质性组织中的有效操控方式。根据穿刺任务，采用模拟退火算法设计操控策略优化器。提出了基于模型预测控制理论的穿刺针智能控制算法。.（5）开发了超声导航下的智能穿刺系统。通过静态、动态靶向穿刺、路径追踪等多任务自动穿刺实验，得到穿刺误差约为1mm，验证了系统可满足临床需求的穿刺精度。.本研究对于推进机器人辅助微创癌症诊疗技术的发展、提高穿刺手术的成功率与安全性具有重要理论意义和应用价值。