Control Of Ionic Polymer-metal Composites For Active Catheter Systems Via Linear Parameter-varying Approach

摘要

The ionic polymer metal composite (IPMC) is one type of electro-active material with the characteristics of low electric driving potential, large deformation, and aquatic manipulation. It is highly attractive to biomedical applications as an actuator or a sensor. The main purpose of this study is to explore closed-loop control schemes to an IPMC actuator for active catheter systems. In this article, by measuring frequency responses of a 20 mm × 5 mm × 200 μm IPMC, an empirical model is developed and used for closed-loop control. From previous work, two resonant peaks ranged at 3-4 Hz and 18-20 Hz are found in the Bode diagram for the frequency responses of IPMC. Based on this fact, a 4th order transfer function was modeled to describe the system. A parameter-dependent transfer function was then created to describe the bending dynamics of IPMC in response to different driving voltages. As IPMC actuators are nonlinear and slow time-varying systems, the controller was designed using linear parameter varying (LPV) approach. Compared with the conventional closed-loop PID control, the maximum overshoot and steady-state error was decreased to 2% and 1.32%, respectively. The rise time was about 0.186 s, which is within the limit for many biomedical applications.