【作者】 张栋；

【导师】 刘宇；

【作者基本信息】 东北大学 ， 机械工程（专业学位）， 2020， 硕士

【摘要】 骨科疾病越来越被人们所关注,相比于传统骨科手术的笨拙和不安全,随着机器人技术的发展,CT扫描影像技术、计算机图像处理能力和导航系统等技术的日渐成熟,计算机辅助手术受到越来越多的关注和研究。在机器人骨科手术中,切削过程直接影响着手术的成功和术后恢复。在切削过程中,由于骨材料的各向异性和非均匀性,切削力时刻发生变化,而当刀具开始接触骨材料和离开骨材料时,切削力会突变并产生峰值极易造成刀具断裂,这些现象不仅会延长手术时间、影响表面质量、导致术后恢复效果大大降低,严重时还会对病人造成二次伤害。因此,本论文从骨材料性质出发,分析手术路径规划和刀具进给方向与骨单位接触夹角,通过切削力建模实现骨材料铣削切削力的离线预测与控制和路径点实时反馈。具体内容如下:(1)对机器人骨切削国内外研究现状进行了总结和概述。通过查阅大量文献,对国内外骨材料加工过程中切削力的产生和影响、切削过程中刀具磨损断裂和切削力控制以及金属加工过程中切削力控制等问题进行了总结和概述。在临床手术中,切削力的预测与控制是防止刀具断裂、缩短手术时间和提高表面质量的主要问题。(2)对骨科手术机器人及骨材料的特性进行了研究和概括。归纳整理了骨科手术机器人的类型及应用以及三种骨科机器人系统,介绍了骨科手术的流程步骤,并对骨材料的组成结构、生物特性、力学特性、几何特性和机械特性进行详细的分析。(3)研究了通过调节机器人进给速度百分比的方法实现对切削力的监测与控制。在骨材料铣削过程中,设置切削力阈值,当实时切削力超过阈值时,通过调节机器人进给速度的百分比,实现对切削力的控制。同时,对医用铣刀进行了有限元仿真,得出了刀具发生断裂时的受力情况和断裂部位;并对医用铣刀进行了断裂实验,将断裂实验数据与仿真结果进行对比分析。(4)建立了六维力传感器计算模型,实现了对机器人末端负载重力的补偿。基于六维力传感器的计算模型,利用坐标旋转变化和受力平衡等一系列关系求解出传感器的零点、重力负载和重心坐标,实现了机器人末端六维力传感器的负载重力补偿。(5)对骨材料铣削过程进行了分析。骨材料具有各向异性和非均匀性,在铣削过程中,随着刀具的移动和主轴的旋转,切削区域的性质会发生变化,直接影响切削力的改变。因此,首先分析了骨材料的各向异性和非均匀性对切削力的影响;其次,对手术路径规划和刀具进给方向与骨单位轴向方向接触夹角进行了研究;最后,分析了铣削过程中切削力的峰值,并对刀具受力断裂进行了静力学分析,提出一种新的判断刀具断裂的指标。(6)对骨材料铣削切削力进行了预测并对进给速度进行了优化。通过对切削力进行建模实现对切削力的离线预测,同时设置切削力阈值,优化了机器人的进给速度,实现对切削力的调节与控制。(7)对骨材料铣削过程进行了运动仿真。提出了骨科手术切削力预测与控制的实施方案并采用两种方法进行了运动仿真,实现了对骨材料铣削切削力的离线预测与控制和路径点的实时反馈。更多还原

【Abstract】 As the development of the robot technology,the image technology of the CT,the image processing capability of the computer and the navigation system are becoming more and more mature,Computer-assisted surgery has attracted more and more attention and research.In the robot orthopedic operation,the cutting process directly affects the success of the operation and the post-operation recovery.During the cutting process,the cutting force changes momentarily due to the anisotropy and non-uniformity of the bone material.When the tool starts to contact the bone material and leaves the bone material,the cutting force will abruptly change and the peak will easily cause the tool to break.The phenomenon will not only prolong the operation time,affect the surface quality,and cause the postoperative recovery effect to be greatly reduced.In severe cases,it will cause secondary damage to the patient.Therefore,based on the properties of bone materials,this paper analyzes the contact angle between surgical path planning and tool feed direction and bone unit,and realizes off-line prediction and control of cutting force and real-time feedback of path points through cutting force modeling.The details are as follows:(1)The research status of robot domestic cutting at home and abroad were summarized.Through reviewing a large number of literatures,the generation and influence of cutting force in the process of bone material processing at home and abroad,tool wear,fracture and cutting force control in cutting process and cutting force control in metal processing are summarized.In clinical surgery,the prediction and control of cutting force is a major problem in preventing tool breakage,shortening the operation time and improving the surface quality.(2)The characteristics of the orthopedic surgery robot and the bone material are studied and summarized.The type and application of the orthopaedic surgical robot and the three kinds of orthopaedic robot system are summarized.The procedure of the orthopedic operation is introduced,and the composition structure,biological characteristics,mechanical properties,geometric characteristics and mechanical properties of the bone material are analyzed in detail.(3)The monitoring and control of cutting force by adjusting the percentage of feed speed of robot is studied.During the milling of the bone material,the cutting force threshold is set.When the real-time cutting force exceeds the threshold,the cutting force is controlled by adjusting the percentage of the robot feed speed.At the same time,the finite element simulation of the medical milling cutter was carried out,and the force situation and fracture location of the tool when the fracture occurred were obtained.The fracture experiment of the medical milling cutter was carried out,and the fracture experimental data and simulation results were compared and analyzed.(4)A six-dimensional force sensor calculation model was established to compensate the weight of the robot’s end load.Based on the calculation model of the six-dimensional force sensor,a series of relationships such as coordinate rotation change and force balance are used to solve the zero point,gravity load and barycentric coordinates of the sensor,and the load gravity conpensation of the six-dimensional force sensor at the end of the robot is realized.(5)The milling process of bone material was analyzed.The bone material has anisotropy and non-uniformity.During the milling process,as the tool moves and the spindle rotates,the nature of the cutting area changes,directly affecting the change of the cutting force.Therefore,the influence of the anisotropy and non-uniformity of the bone material on the cutting force is first analyzed;Secondly,the surgical path planning and the contact angle between the tool feeding direction and the bone unit axial direction were studied.Finally,the milling was analyzed.Secondly,the surgical path planning and the contact angle between the tool feeding direction and the bone unit axial direction were studied.Finally,the milling was analyzed.(6)The milling and cutting force of bone material is predicted and the feed speed is optimized.Through modeling the cutting force,the off-line prediction of the cutting force is realized,and the threshold of the cutting force is set at the same time,the feed speed of the robot is optimized,and the adjustment and control of the cutting force are realized.(7)The motion simulation of bone milling process is carried out.The implementation scheme of cutting force prediction and control in orthopedic surgery is put forward and the motion simulation is carried out by two methods.The offline prediction and control of cutting force and the real-time feedback of path point are realized.更多还原