【作者】 陈渊；

【导师】 潘明章； 边桂彬；

【作者基本信息】 广西大学 ， 机械（专业学位）， 2023， 硕士

【摘要】 机器人辅助骨盆骨折闭合复位技术还处于起步阶段。目前,脱位骨块的自动复位规划仅局限于线性规划,复杂的骨折复位仍需医生亲自规划,影响了手术的时效性和避障的彻底性,且医生规划并未考虑路径长度和肌肉阻力对手术安全性的影响。因此,如何解决上述问题成为机器人辅助骨盆骨折闭合复位的重要研究方向。本研究旨在开发一种智能的路径规划算法用于机器人辅助骨盆骨折闭合复位,即:在软、硬组织无碰撞的约束下,以最小肌肉阻力为目标,完成机器人辅助骨盆骨折闭合复位手术,提高手术系统的安全性。论文的主要内容和创新点如下:(1)针对骨盆牵引夹具通用性和刚度低的问题,设计了5自由度的骨盆牵引夹具,该夹具可调整各关节的伸缩量或旋转量以夹持不同尺寸的骨盆。分析了夹具系统在常规位置和极限位置处的应力应变,探索了满足骨盆骨折复位手术强度的夹具配置和材料。结果表明,12 mm的不锈钢髋臼上横针夹具组合在骨表面应力、牵引针应力、夹具应力、最大位移和极限牵引力五个方面性能最优。(2)针对传统骨盆骨折复位规划中存在二次碰撞的问题,提出结合空间重叠检测和交叉包围盒技术的碰撞检测方法。该方法基于八叉树空间划分理论将静态对象网格化,利用点与矩形和矩形与矩形的相交测试进行碰撞检测。骨盆体外模拟复位实验结果表明,所提出的碰撞检测方法能有效避免二次碰撞的发生,且可以推广应用到其他骨折复位规划算法中进行碰撞检测。(3)针对骨盆骨折姿态复位前后肌肉力陡升的问题,提出了骨折骨块的姿态规划策略(Orientation Planning Strategy,OPS),该策略使得骨折骨块可以按照设定的姿态变量逐渐调整姿态,解决了传统复位规划中骨折骨块一次性姿态复位而导致肌肉阻力陡增的弊端。结果表明,基于OPS的路径规划方法相比于传统的方法可以降低49.4%的肌肉阻力。(4)针对骨盆骨折复位路径缺乏肌肉力约束的问题,提出了一种动态肌肉阻力计算方法。该方法基于OpemSim 4.0平台搭建了一个骨盆骨折的肌肉骨骼模型文件,该模型文件可用于二次开发以计算特定肌肉拉伸状态下的肌肉力,最后将肌肉力数值作为影响因素纳入路径搜索算法的启发函数中,搜索肌肉阻力最小的骨折复位路径。结果表明,基于该肌肉力约束方法的复位路径可进一步降低12.8%的肌肉阻力。更多还原

【Abstract】 The robot-assisted pelvic fracture closed reduction technology is in its infancy.Currently,automatic fracture fragment reduction planning is only limited to linear planning,and complex fracture reduction still requires the surgeon’s planning,which affects the timeliness of surgery and the thoroughness of obstacle avoidance,and the surgeon’s planning does not consider the influence of path length and muscle resistance on the safety of surgery.Therefore,how to solve the above problems has become an important research direction for robot-assisted pelvic fracture closed reduction.This study aims to develop an intelligent path planning algorithm for robot-assisted pelvic fracture closed reduction: to complete robot-assisted pelvic fracture closed reduction surgery under the constraint of collision-free of soft and hard tissues with minimum muscle resistance,and to improve the safety of the surgical system.The main contents and innovations of the paper are as follows:(1)To address the problems of low versatility and stiffness of the pelvic traction clamp,a 5-degree-of-freedom pelvic traction clamp was designed,which can be adjusted for the amount of extension or rotation of each joint to clamp different sizes of the pelvis.The stress-strain of the clamp system at the conventional and ultimate positions was analyzed,and the clamp configuration and material to meet the strength of pelvic fracture reduction surgery were explored.The results showed that the 12-mm stainless steel supra-acetabular transverse pin clamp combination performed optimally in five aspects: bone surface stress,traction pin stress,clamp stress,maximum displacement,and ultimate traction force.(2)To address the problem of secondary collision in traditional pelvic fracture reduction planning,a collision detection method combining spatial overlap detection and cross-bounding box technology is proposed.The method is based on the spatial partitioning theory of octree to grid static objects,and collision detection can be performed by using the intersection test of pointsrectangles and rectangles-rectangles.The experimental results of in vitro simulated pelvic reduction show that the proposed collision detection method can effectively avoid the occurrence of secondary collisions and can be extended and applied to other fracture reduction planning algorithms for collision detection.(3)To address the problem of steep increase in muscle force before and after orientation reduction of pelvic fractures,an Orientation Planning Strategy(OPS)for fracture bone fragments was proposed,which allows the fracture fragments to gradually adjust their orientation according to the set orientation variables and solves the drawback of steep increase in muscle resistance due to one-time orientation reduction of fracture fragments in traditional reduction planning.The results show that the OPS-based path planning method can reduce the muscle resistance by 49.4% compared with the conventional method.(4)To address the lack of muscle force constraints on the pelvic fracture reduction path,a dynamic muscle resistance calculation method is proposed.The method builds a musculoskeletal model file of pelvic fracture based on OpemSim 4.0 platform,which can be used for secondary development to calculate the muscle force in a specific muscle stretch state,and finally incorporates the muscle force value as an influencing factor in the heuristic function of the path search algorithm to search for the fracture reduction path with the least muscle resistance.The results show that the reduction path based on this muscle force constraint method can further reduce the muscle resistance by 12.8%.更多还原