Hybrid Approach to Minimally Invasive Surgery (MIS): Universal Hand Tool Adapter for Robotically Controlled Laparoscopic Surgery

J Opfermann, MS, B Azizi Koutenaei, MS, A Shademan, PhD, S Leonard, PhD, A Krieger, PhD, PCW Kim, MD, PhD. Sheikh Zayed Institute for Pediatric Surgical Innovation, Children’s National Health System, Washington, D.C..

Objective: Despite clear benefits, broader adoption of MIS remains delayed because of technical and economic reasons.  With the robotic approach, improved ergonomics and tool dexterity is often offset by reduced surgical intimacy, high tool cost, and lengthened procedure times. In contrast, manual laparoscopic tools provide physical feedback and maneuverability across all quadrants in the abdomen, but lack the dexterity of robotic tools.  Manual multi degree of freedom (DOF) tools are not readily adopted due to poor ergonomics.

We present an innovative collaborative hybrid approach that enables adoption of laparoscopic hand tools into robotic control by addressing these technical and ergonomic challenges.  We propose the design and use of a novel universal tool adapter (UTA) capable of mechanizing modular laparoscopic tools in a robotic platform.  This paradigm enables surgeons to readily use manual tools, while selectively engaging robotic control.  Our hypothesis is that mechanized disposable tools are robust enough to perform surgical tasks, providing an inexpensive but effective toolset for robotically controlled laparoscopy.

Description: The UTA integrates with existing modular hand tools, and has the flexibility to control one and two DOF end effectors.  Presently, the system is configured to interface with modified two DOF (rotation and articulation) hand tools (Covidien), and mounts to a seven axes LWR positioning robot (Kuka).  EPOS2 motor controllers (Maxon Motors) control the tool axes via CAN interface.  The Mantis Duo (Mimic Technologies) is used for teleoperation whereby pinching and wrist translation control tool grasping and articulation.  It is intended that when a surgeon performing MIS becomes fatigued or precise control is required, they can transition manual tools to robotic control by removing the tool handle (Figure 1a) and placing the end effector within the UTA (Figure 1b).    

Results: Our team designed, built and teleoperated a prototype UTA (Figure 1c).  Once mechanized, the UTA has articulation resolution of 0.002°, and can be flexed up to 80°, as compared to two ±90° articulation joints of the da Vinci surgical tools. The UTA was manipulated within the 20cm x 20cm x10cm workspace necessary to perform a peg transfer task, and was measured to have a maximum grasping pressure of 111kPA, exceeding the clinical requirement for bowel MIS.  The rotational DOF of the modified hand tool was successfully implemented using the wrist joint of the LWR robot.

Conclusions: To the best of our knowledge, the UTA demonstrates the first platform capable of mechanizing and robotically controlling laparoscopic hand tools.  Preliminary results indicate control of two DOF end effectors is robust enough to perform simple surgical tasks.  Clinical feasibility will be addressed in a comparison study between the UTA and da Vinci systems to quantify effectiveness while performing the Fundamentals of Laparoscopic Surgery tasks.  While additional development and testing is necessary, the UTA shows promise in expanding the capacity of robotic laparoscopic surgeries. 

                   (a)                                       (b)                               (c)
Figure 1: Removing the end effector from a laparoscopic hand tool (a).  Inserting the end effector into the universal tool adapter (b).  Teleoperating the universal tool adapter with the LWR positioning robot (c).

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