Structure Design and Workspace Analysis of Robotic Arm for Minimally Invasive Surgical Robot / 医用生物力学

ABSTRACT

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 performed. 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.