Design and Coordination Kinematics of an Insertable Robotic Effectors Platform for Single-Port Access Surgery

Single port access surgery (SPAS) presents surgeons with added challenges that require new surgical tools and surgical assistance systems with unique capabilities. To address these challenges, we designed and constructed a new insertable robotic end-effectors platform (IREP) for SPAS. The IREP can be inserted through a Ø15 mm trocar into the abdomen and it uses 21 actuated joints for controlling two dexterous arms and a stereo-vision module. Each dexterous arm has a hybrid mechanical architecture comprised of a two-segment continuum robot, a parallelogram mechanism for improved dual-arm triangulation, and a distal wrist for improved dexterity during suturing. The IREP is unique because of the combination of continuum arms with active and passive segments with rigid parallel kinematics mechanisms. This paper presents the clinical motivation, design considerations, kinematics, statics, and mechanical design of the IREP. The kinematics of coordination between the parallelogram mechanisms and the continuum arms is presented using the pseudo-rigid-body model of the beam representing the passive segment of each snake arm. Kinematic and static simulations and preliminary experiment results are presented in support of our design choices.

I. Introduction

Robotic assistance in minimally invasive surgery (MIS) extended the capabilities of surgeons via improved precision, dexterity, and computer assistance [1], [2]. Recently, novel single port access surgery (SPAS) and natural orifice transluminal endoscopic surgery (NOTES) have been investigated by the authors in [3]–[6] for their potential benefits in reducing patient trauma and shortening their recovery time compared to traditional multiport laparoscopic MIS. However, SPAS and NOTES also set strict requirements for instrument miniaturization, dexterity, and collision avoidance between surgical tools operating in confined spaces. Existing surgical robots for MIS cannot satisfy these requirements due to either dexterity deficiency or the size of their actuation mechanisms that prohibit a multitude of arms from operating through a single port. Therefore, to date, SPAS is still limited to a small number of academic centers using instruments that are not clinically proven to be able to facilitate SPAS [7]–[9].