Tendon-Actuated Galvanometer Robot (TAGR) Towards Minimally Invasive Hybrid Surgical Laser Steering

Abstract

Surgical lasers are becoming increasingly prevalent in minimally invasive procedures, as laser fibers are thin and flexible, allowing for precise targeting. The use of surgical lasers spans tissue manipulation, energy delivery (in laser interstitial thermal therapy), imaging (optical coherence tomography), and tumor identification. There are two primary methods for steering surgical lasers: fiber steering and free-beam steering using galvanometers. In practice, however, lasers must first traverse through complex anatomical structures, then the laser must be steered with high precision while the tool body avoids critical anatomy. In this paper, we develop a steerable surgical tool that combines both fiber and free-beam steering, the Tendon-Actuated Galvanometer Robot (TAGR). The proposed ball-chain (BC) robot can bend in 3D space, then utilizes a 2-DoF tendon-actuated galvanometer (TAG) at the end-effector to steer the laser on a surface while the robot body is static. Both BC kinematics and 2-DoF TAG laser kinematics models are presented and validated. Closed-loop PID control is implemented in both robot and laser steering, resulting in RMSE values of less than 2.5 mm and 3.7 mm for independent and hybrid steering, respectively. The novel hybrid laser steering system is then demonstrated within a phantom rib-cage model to showcase how novel hybrid laser steering can impact minimally invasive laser surgery.