Simulation research on the dynamics of shape memory alloy actuated catheter robots

This study focused on the dynamic behavior of a flexible catheter robot which is composed of a bias spring and a shape memory alloy (SMA) coil spring. Based on the mechanical model of the catheter and SMA's constitutive equation and heat transfer equation, a complete set of modeling methods for SMA actuated catheter robots were brought forward. In consideration of the fact that it is difficult to obtain a precise position control by the conventional proportional-integral-differential (PID) controller due to the presence of the nonlinearity of SMA such as hysteresis and saturation, a self tuning fuzzy PID controller was designed for such situation. The simulation results validated the accuracy of the model and the controller's effectiveness. These modeling and control methods are useful for the practical application of catheter robots actuated by a single SMA spring and provide the foundation for the control study for multi-SMA actuated catheter robots.