The MUSHA underactuated hand for robot-aided minimally invasive surgery.

BACKGROUND: Keyhole surgery is characterized by loss of dexterity of surgeon's movements due to the limited workspace, non-intuitive motor skills of the surgical systems and loss of tactile sensation that may lead to tissues damage and bad execution of the tasks.

METHODS: In this paper, a three-fingered underactuated miniature tool for robot-aided laparoscopic surgery is presented. The design is conceived to realize a closed-hand configuration allowing the insertion of the tool into the abdominal cavity through the trocar in one step, and to reach different grasping as well as pushing/holding configurations once in the cavity.

RESULTS: Aiming to replicate human-hand dexterity and versatility, different solutions for the kinematic structure of the hand are analyzed using quality indices to evaluate the manipulability and stability of the grasp. Furthermore, a first prototype of fingertip force sensor based on Fiber Bragg Grating (FBG) technology has been realized and tested. The design choices of the prototype are described and discussed with the aid of experiments.

CONCLUSIONS: The whole concept and the need for such anthropomorphic tool are discussed with surgeons to highlight constraints and potentials in surgical tasks. The feedback by expert surgeons is used to provide specifications and improvements to the kinematics and mechanical design. The investigations of different designs allow identifying the optimal solution to improve grasping and manipulation capabilities. The tests on FBG sensors led to the conclusion that this technology guarantees good performance and can be a good solution for applications in surgical robotics.