Graduate Studies


First Advisor

Carl Nelson

Date of this Version

Summer 7-25-2017


Garay-Romero, R.G. Tool-Exchange System for a Two-Armed Laparo-Endoscopic Single-Site Surgery Robot (R-LESS) (2017).


A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Mechanical Engineering and Applied Mechanics, Under the Supervision of Professor Carl A. Nelson. Lincoln, Nebraska: August, 2017

Copyright (c) 2017 Raul Gonzalo Garay Romero


Laparoscopic surgery is a form of minimally invasive surgery (MIS) that has been an important advancement in modern medicine. MIS has been shown to reduce postoperative pain, recovery time, and has improved cosmetic outcomes. A naturally evolved form of laparoscopic surgery is laparo-endoscopic single-site (LESS) surgery where all the laparoscopic instruments are introduced through a single incision made at the patient’s navel.

Even though there are benefits, both present a steep learning curve for new surgeons. A response to these challenges is the application of surgical robotics. One robotic-LESS (R-LESS) platform is LouBot-1.0, a two-armed robot, developed in the Advanced Surgical Technologies Laboratory at the University of Nebraska-Lincoln. Although they ease surgical procedures, the robotic platforms themselves have their own set of limitations. One is the exchanging of surgical instruments. It is advantageous for the process to be as streamlined as possible during surgery to reduce errors and operating time.

This thesis explains the design of a tool-exchange system for LouBot-1.0. It uses a laparoscopic tool-exchanger that is inserted through a surgical trocar to [un]mount modular surgical tools. The laparoscopic tool-exchanger has a 0.57-inch (14.5-mm) outer diameter profile, an elbow, and a set of jaws to hold the modular surgical tools. Four modular surgical tools were developed: a grasper, a pair of scissors, a monopolar hook, and a bipolar grasper. The tools have a 3/8-inch outer diameter, are about 1.7 inches in length, and share the same modular base exterior. A modular robotic forearm was also designed to accept the surgical tools. It uses a push-to-connect mechanism to fix or release the surgical tools. Apart from rotating and actuating, the forearm also supplies electrical power to the tools to perform either monopolar or bipolar cautery if needed.

The thesis is structured to report on the design and bench-top results of the laparoscopic tool-exchanger first, then the modular surgical tools, and lastly the modular robotic forearm. Conclusions on the overall tool-exchange system are given at the end.

Advisor: Carl A. Nelson