Backlash characterization and position control of a robotic catheter manipulator using experimentally-based kinematic model

This paper deals with the problem of position control of a robot-assisted catheter manipulator for intracardiac interventions. Kinematic controllers based on the Jacobian inverse are not suitable for the catheter because of multiple singularities in the workspace and significant backlash of the system. To tackle these issues, first, the backlash of the system in axial translation and twist motion due to the interaction of the catheter with the veins through which it passes, are characterized. The effects of variations in clinical settings on the backlash parameters are identified through extensive experiments simulating the clinical procedure. Next, to properly compensate for the backlash behavior of the catheter distal shaft, an inverse kinematic model is proposed based on experimental data. A position controller is developed and implemented using the experimentally-based inverse kinematics and the identified inverse backlash model for the twist and axial motion. The results of experiments performed using a robotic catheter manipulation system show that with a proper choice of controller gains, the proposed scheme is able to guide the catheter tip to the goal with the desired behavior. The tracking performance of the controller has also been evaluated under the dynamic external force simulating the blood drag force. The empirical results demonstrate the improved performance of the proposed approach against the existing kinematic-based and uncompensated control schemes.