Design, Modeling, and Control of a Coaxially Aligned Steerable (COAST) Guidewire Robot.

Manual navigation of a guidewire is the first step in endovascular interventions. However, this procedure is time consuming with uncertain results due to tortuous vascular anatomy. This paper introduces the design of a novel COaxially Aligned STeerable (COAST) guidewire robot that is 0.40 mm in diameter demonstrating variable curvature and independently controlled bending length of the distal end. The COAST design involves three coaxially aligned tubes with a single tendon running centrally through the length of robot. The outer tubes are made from micromachined nitinol allowing for tendon-driven bending of the robot at various segments of the robot, thereby enabling variable bending curvatures, while an inner stainless steel tube controls the bending length of the robot. By varying relative positions of the tubes and the tendon by insertion and retraction in the entire assembly, various joint lengths and curvatures can be achieved, which enables a follow-the-leader motion. We model the kinematics, statics, as well as the coupling within tubes of the COAST robot and develop a simple controller to control the distal tip of the robot. Finally, we experimentally demonstrate the ability of COAST guidewire to accurately navigate through phantom anatomical bifurcations and tortuous anatomy.