The soft, atraumatic construction of passive flexible catheters help reduce injury
to delicate cardiac structures while providing a means of tool placement and
control. To provide kinematic and control relationships, various models of continuous catheters have been developed. However, these approaches cannot explain the nonlinear behavior of the catheter when the effect of internal friction is considered. A nonlinear model was developed based on a lumped-parameter modeling approach which directly accounts for the effects of internal device friction. The model with friction was extensively validated against experimental data obtained with a prototype experimental robotic catheter. Specifically, the nonlinear model correctly predicted the variation in curvature along the length of the catheter under various catheter motions.
In addition, the nonlinear model correctly predicted the instantaneous motion of the catheter end-point position, demonstrating the path dependent behavior of the catheter.
Comparison of catheter curvature: articulation and retraction