Conically shaped remote center-of-motion mechanism for single-incision surgery

In this paper, we introduce a remote center-of-motion (RCM) mechanism with a conical shape for laparoscopic surgeries that involve a single incision. The mechanism, which has two revolute joints and one prismatic joint, is designed to maintain a stationary point at the apex of the conical shape. By aligning the stationary point with the incision area, the mechanism allows a surgical instrument to explore the abdominal area through a small incision point. We have previously analyzed the reachable workspace of this mechanism. Here, we arrange two RCM mechanisms on a single conical structure but separated in space to avoid mutual interference, so as to enable the entire system to manipulate two surgical instruments through a single incision point without colliding. We describe the operational principle of this system, in addition to comparisons of various RCM mechanisms and the kinematics for parameter design and motion control. Finally, we describe preliminary experiments on peg transfer and suture motion by using the proposed RCM mechanism.