Design and Modeling of a Compact Advancement Mechanism for a Modified COAST Guidewire Robot

Peripheral vascular intervention remains a challenging procedure mainly due to the tortuosity of the vessels needing to be traversed by guidewires and catheters. In addition, handling long guidewires while navigating tortuous vasculature requires extensive time and skill from the surgeon. In this work, a compact guidewire advancement mechanism is proposed that is able to dispense guidewires up to 150 cm in length. The mechanism is adapted to actuate a prototype of the modified COaxially Aligned STeerable (COAST) guidewire robot to perform follow-the-leader (FTL) motion. The design of this mechanism consists of a spool, with actuation components nested inside to vary the bending length, actuate the tendon, and deflect the tip of the guidewire. The spool is mounted onto a lead screw that dispenses the guidewire with a tolerance of ±2mm. A modified bending joint kinematics and statics model is developed to characterize and validate the relationship between the tendon stroke and the desired curvature. The model is further used in a control system to navigate the distal tip through an ex vivo porcine aorta.