Configuration of drive mechanisms with fewer wires in a surgical robot considering operation trajectory and delay

Abstract

Surgical robots have contributed greatly to the development of minimally invasive surgery.Surgical robots mostly use a wire cable drive mechanism because wire has high responsiveness, however, the wires often loosen or break, resulting in high maintenance costs.In contrast, flexible-shaft, timingbelt, and pneumatic-actuator mechanisms have low maintenance costs but lengthen the mechanical delay.In this study, we derived an appropriate configurations of drive mechanisms with fewer wires for each joint of a surgical robot, considering the delay of the mechanisms.We assumed the configuration of the four drive mechanisms at six joints of the surgical robot.Using a virtual surgical simulator, we measured the operation trajectory of a robot in virtual space without delay.From this operation trajectory, the trajectory of the robot's tip was calculated by simulating the delay for 4096 configurations of the drive mechanisms.We compared the suturing accuracy of the robot with and without delay for all combinations and determined the four configurations whose accuracy was within requirements.Finally, we conducted a verification experiment to compare theoretical and experimental values.The small relative errors validate the feasibility of the method proposed for designing the configuration of drive mechanisms in a surgical robot.