| Endocardial ablation is commonly used to treat atrial fibrillation, a cardiac arrhythmia that affects nearly 3 million Americans. These ablation procedures often use manuallyactuated catheters with limited degrees of freedom, and are therefore tedious, timeconsuming, and result in significant X-ray exposure to the patient and clinical staff. Teleoperated (i.e. robotic) catheters have the potential to enhance catheter maneuverability in the heart, reduce procedure times, and improve patient outcomes. Previous work has focused on the design and fabrication of shape memory alloy (SMA) actuated robotic catheters for this application. Widespread clinical adoption of robotic catheter technology, however, requires precise and robust catheter control through an intuitive user interface. Real&;First, the development of an indirect intelligent sliding mode controller (IISMC) for a reduced-order system (a flexible beam actuated by single or dual offset SMA tendons) is presented. This system exhibits many of the control challenges of the robotic catheter (actuator hysteresis, model uncertainties, etc.), but is more tractable. The IISMC algorithm manipulates applied voltage, enabling temperature control in the SMA tendons, to produce bending in the flexible beam. Hysteresis compensation is achieved using a hysteretic recurrent neural network (HRNN), which maps the nonlinear, hysteretic relationships between SMA temperatures and bending angle. Incorporating this HRNN into a variable structure control architecture (sliding mode control) provides robustness to model uncertainties and parameter variations. Experimental results demonstrate precise tracking of a variety of reference trajectories, with superior performance compared to an optimized PI controller. Robustness to parameter variations and disturbances is shown.;The robotic catheter is a direct extension of the flexible beam system: it consists of two bending segments, each actuated by four offset pull wires (which are attached externally to SMA tendons), allowing four degree-of-freedom motion. This four&;A real-time path optimization and control strategy is developed to take advantage of the two segment catheter&... |
