基于金属编织技术的柔性机械手结构设计与实验验证

Structural design and experimental verification of flexible manipulator based on metal weaving technology

目的开发一种应用于经自然腔道内镜手术(NOTES)机器人柔性机械手的骨架结构,以满足NOTES对手术执行器械的性能需求。方法基于金属编织技术设计一种柔性机械手结构及对应结构的控制策略。根据柔性机械手的机械结构特征推导几何关系公式。通过链式梁约束模型(CBCM)以及机械弹簧理论建立理论模型。对机械结构建立有限元模型并分析,验证理论模型的精度;并由金属编织结构的抗弯刚度验证柔性机械手的载荷能力。结果基于金属编织技术设计了一种柔性机械手结构及对应结构的控制策略。在设置恰当的约束条件后,金属圆环作为单个受力单元在受到0.5 N的轴向力驱动时,最大应变约为1.49%,处于线性弹性阶段。最大形变约为0.3089 mm,比理论值高3.26%。机械手骨架的最大应变约为0.21%,处于线性弹性阶段。最大总形变约为7.1355 mm,比理论值高6.30%。机械手骨架的抗弯刚度计算为3.19 N·mm^(2),与同量级尺寸形状记忆聚合物(SMPs)制成的柔性机械手相当。结论开发一种应用于NOTES机器人柔性机械手的骨架结构,符合执行NOTES手术任务的支撑刚度需求。

Objective To develop a skeleton structure for the flexible manipulator of a robotic system used in natural orifice transluminal endoscopic surgery(NOTES),meeting the performance requirements of surgical actuators.Methods A flexible manipulator structure and a control strategy for the corresponding structure were designed based on metal braiding technology.Geometric relationship formulas were derived according to the mechanical structure characteristics of the flexible manipulator.A theoretical model was established using the chained beam-constraint-model(CBCM)and mechanical spring theory.The finite element model of the mechanical structure was established,and simulation analysis was performed to verify the accuracy of the theoretical model.The bending stiffness of the metal-braided structure was tested to verify the load capacity of the flexible manipulator.Results A flexible manipulator structure and a control strategy for the corresponding structure were designed based on metal braiding technology.With proper constraints,the maximum strain of the metal ring as a single stressed unit was about 1.49%when subjected to an axial force of 0.5 N.At this time,the material was in the linear elastic phase and the maximum deformation was about 0.3089 mm,which was 3.26%higher than the theoretical value.The maximum strain of the manipulator skeleton was about 0.21%in the linear elastic phase.The maximum total deformation was about 7.1355 mm,which was 6.30% higher than the theoretical value.The flexural stiffness of the manipulator skeleton was calculated to be 3.19 N·mm^(2),which was comparable to a flexible manipulator made of shape memory polymers(SMPs)of the same magnitude and size.Conclusions A skeleton structure for application to NOTES robotic flexible manipulators is developed that meets the support stiffness requirements for performing NOTES surgical tasks.