Modeling of a Robotic Transcatheter Delivery System

Intracardiac transcatheter systems guided by advanced imaging modalities are gaining popularity in treating mitral regurgitation in non-surgical candidates. Robotically steerable transcatheter systems must use model-based control strategies to ensure safer and more effective transcatheter procedures with less trauma while using smaller control gains. In this paper, a 4-DoF robotically steerable tendon-driven robot was fabricated, and the relationship between the tendon displacement and the joint angle was derived. This relation was derived in two parts to make this approach applicable to any other catheter system. A model was derived to determine the tendon tensions needed to achieve desired joint angles. Then, the tendon characteristics were studied, and a tendon elongation (TE) model was derived as a function of tendon length. Executing the modeling process in two steps makes it easy to introduce additional parameters like length, friction, and pose, to characterize complex systems like catheters. The TE model was used to actuate the joints of the robot and RMSE was computed to characterize its performance. Also, PID control was used along with the TE model to improve the system's performance, and the contribution of the model and the controller in the system was recorded.