Robot-Enabled Uterus Manipulator for Laparoscopic Hysterectomy With Soft RCM Constraints: Design, Control, and Evaluation

Laparoscopic hysterectomy is a common minimally invasive gynecologic surgery in which an assistant is required to manipulate the uterus during the procedure according to the verbal commands of the primary surgeon. However, uterus manipulation is a lengthy and laborious task, where human fatigue may lower operating safety. This paper presents a novel robot-enabled uterus manipulation system that provides accurate, tireless, and direct uterus manipulation. The system consists primarily of a 7-DoF robotic arm tailored for uterus manipulation in laparoscopic hysterectomy. The primary surgeon can directly control the robot using a footswitch pedal to move within the constraint of the Remote Center of Motion (RCM) via software and achieve the desired range of pitch and yaw motion. An additional rotational motion around the instrument axis is provided for twisting the uterus to enhance the exposure of the ligaments and peritoneum for resection. In addition, the robot arm consists of 7 compact modular actuators that provide the target payload for holding the uterus while maintaining a small footprint in a constrained operating environment. To facilitate operation, a passive mobile base is provided for supporting and positioning the robot. A 6-D force sensor is equipped that allows the assistant to quickly guide the robot into the work area and move the robot under RCM constraint using an admittance control approach. The uterus manipulation rod can be easily detached from the robot body by a quick pluggable mechanism for preoperative sterilization. A quick pluggable mechanism was proposed for easy separation and mounting of the uterus manipulation rod from the robot body for preoperative sterilization. Experiments were performed to measure the performance of the modular joints, RCM repeatability, and evaluate the feasibility of the robot in the simulated laparoscopic hysterectomy.