Development of Remote Center of Motion Mechanism for Biportal Endoscopic Spine Surgery Robot

Abstract

Remote Center of Motion (RCM) mechanism is widely used in surgical robots for Minimally Invasive Surgery (MIS). For endoscopic spine surgery, the surgical robot requires RCM mechanism with sufficient stiffness and compact end effector to manipulate hard tissues while avoiding interference with other instruments. This paper presents a modified belt-driven RCM mechanism designed to meet these specific requirements of the endoscopic spine surgery. Gearboxes were incorporated to the belt-driven Remote Center of Motion (RCM) mechanism to reduce belt tension and resulting elastic deformation, while the RCM constraint is maintained through a specific relationship between gearbox reduction ratios. The prismatic joint for instrument insertion is relocated to the base to reduce the size of the end effector. Prototype of a surgical robot with the presented RCM mechanism achieved an RCM point accuracy of 0.56 mm, repeatability of 0.019 mm, and stiffness of 11.676, 12.435, and 5.341 N/mm in the X, Y, and Z directions, respectively. Feasibility of the robot was validated through simulated BESS on a spine phantom.