A Controller to Impose a RCM for Hands-on Robotic-Assisted Minimally Invasive Surgery

Abstract

In Robotic-Assisted Minimally Invasive Surgery a long and thin instrument attached to the robotic arm enters the human body through a tiny incision. To ensure that no injury occurs when the surgeon is manipulating the instrument, the incision point must be a remote center of motion (RCM) for the instrument. For this purpose, a novel target admittance model is designed in the joint space for hands-on procedures that can be applied in all commercially available general-purpose manipulators with six or more degrees of freedom. It is proved that the joint reference trajectories generated by the proposed target admittance model under the exertion of a human force are stable and satisfy the RCM constraint. The measurements of the human force and the robot's forward kinematic model are only required. Its use spans all hands-on surgical procedures. The proposed model can be easily extended to achieve additional objectives. Simulation results validate the theoretical findings and experimental results utilizing a KUKA LWR4+ demonstrate that trocar displacements are less than 1mm.