Surgical Robotic Manipulator Based on Local Magnetic Actuation

Magnetic coupling is a strategy to transmit actuation forces across a physical barrier. This approach can be applied to remotely control and manipulate robotic instruments in minimally invasive surgery (MIS) [1]. Interrupting the mechanical continuity of such system by having surgical instruments and laparoscopic camera magnetically coupled across the abdominal wall greatly enhances both the workspace of operation and triangulation without the need for multiple abdominal incisions [2]. On the other hand, continuum robots are able to provide a large amount of mechanical power to accomplish surgical tasks [3]. Focusing on the typical surgical task of suturing a tissue, 1 N of force in any direction and 180 deg per second rotational speed must be achieved throughout a 50 50 50 mm workspace [3]. In Ref. [4], the authors introduced the concept of local magnetic actuation (LMA), where mechanical power is transmitted across the patient abdomen by specific magnetic couplings to drive the degrees of freedom (DOF) of the robotic surgical instrument. This approach removes the need for electromagnetic motors on board and wired connections. The LMA-based surgical retractor presented in Ref. [5] combines two pairs of magnets, one providing anchoring and the other transferring motion to the internal mechanism actuating a single DOF. This study shows the feasibility for the LMA approach to transfer a relevant amount of mechanical power to produce forces of up to 5 N. Previous papers, such as Ref. [6], have proposed the use of cable-driven mechanism in surgical applications. Major advantages of cable-actuation are the light weight, small size, transmission of force to hard-to-reach location, and high bending radii. The design presented in this paper aims to develop a surgical manipulator for MIS able to perform surgical tasks combining mechanical power transmission based on LMA and cable-driven actuation of a novel design of spherical parallel wrist. 2 Methods