微创手术机器人机械臂结构设计与工作空间分析

Structure Design and Workspace Analysis of Robotic Arm for Minimally Invasive Surgical Robot

目的现有双平行四边形机构设计的机械臂需要串联一个伸缩自由度机构,导致机械臂体积增大,运动灵活性降低,持镜臂与持器械臂发生干涉。针对这一问题,提出一种新型机械臂结构,增强运动灵活性、减小机械臂的体积。方法采用5连杆机构、滑块与滑轨的低副机构和丝传动机构设计机械臂,实现末端执行器的伸缩运动,建立机械臂的运动学模型,以MATLAB为仿真工具验证零位关节角D-H参数的正确性,求解出机械臂的运动方程;同时运用蒙特卡洛算法,得到末端执行器的三维工作空间范围,并对3条机械臂作术前动物实验规划;最后,在猪体内进行胆囊切除等操作,验证机械臂的双5连杆2自由度设计的合理性和可操作性。结果蒙特卡洛算法在MATLAB环境下得到的工作空间范围为:-650.4 mm<x<649 mm,163.8 mm<y<1 202 mm,-254.6 mm<z<829.8 mm,并成功完成16例猪的胆囊切除实验,平均操作时间为51 min。结论新型设计的双5连杆2自由度机械臂在猪体内成功完成胆囊切除等操作,且猪术后无其他不良症状,机械臂之间的运动无干涉,充分验证了所提出的微创手术机器人机械臂设计方案的可行性。

Objective The current manipulator with double parallel quadrilateral mechanism should be connected in series with a flexible degree of freedom(DOF)mechanism,which increases the volume of the manipulator,decreases the motion flexibility and creates the interference between the mechanical arms that hold the mirror and the device.Aimed at solving this problem,a novel mechanical arm was put forward to enhance the motion flexibility and reduce the volume of the manipulator.Methods The mechanical arm was designed by using the mechanism of five-link,slider and slide rail lower pair and wire transmission to realize the telescopic movement of the end effector.The kinematics model of the manipulator was established,and the MATLAB was used as the simulation tool to verify the correctness of the D-H parameters under the specific zero joint angle,and the motion equation of the manipulator was solved.Meanwhile,the three-dimensional workspace of the end effector was obtained by using Monte Carlo algorithm,and the preoperative plan of animal experiment for 3 arms was per-formed.Finally,cholecystectomy and other operations were acted in pigs,to verify the rationality and maneuverability of the design of double 5-link 2-DOF manipulator.Results The working space of Monte Carlo algorithm under MATLAB environment was-650.4 mm<x<649 mm,163.8 mm<y<1 202 mm and-254.6 mm<z<829.8 mm.Sixteen cases of pig cholecystectomy were successfully completed,with an average operation time of 51 minutes.Conclusions The novel double 5-link 2-DOF manipulator could successfully complete cholecystectomy and other operations in pigs,which had no other symptoms after the operation.There was no interference between the mechanical arms,which fully verified the feasibility of the design scheme of the robot manipulator for minimally invasive surgery.