Closed Loop Control of a Cylindrical Tube Type Ionic Polymer Metal Composite (IPMC)
Creators: name: Mead, Benjamin 
Publisher: name: University of Nevada, Las Vegas
Year: 2013

description: The goal of this research is to provide a framework for the integration of tube type, cylindrical Ionic Polymer Metal-Composite (IPMC) into conventional devices. IPMCs are one of the most widely used types of electro-active polymer actuator, due to their low electric driving potential and large deformation range. For this research a tube type IPMC was investigated. This IPMC has a circular cross section with four separate electrodes on its surface and a hole through the middle. The four electrodes allow for biaxial bending and accurate control of the tip location. One of the main advantages of using this type of IPMC is the ability to embed a specific tool and accurately control the tool tip location using the large deflection range of the IPMC. This ability has widespread applications including in the biomedical field for use in active catheter procedures. 
First, this relatively new type of IPMC is investigated and characterized. The processes and materials used are described and the functional design is explored. Before the modeling process beings the basic functions of the IPMC are investigated. To this end force and displacement experiments are performed to describe the activation of the tube type IPMC. This data will be used later to verify and calibrate the mathematical simulations. 
Second, a three dimensional multi-physics finite element model is developed using COMSOL 4.3a. This model will automatically couple three physics packages and provide a description of the fluid interactions within the tube type IPMC. This model is then compared against the experimental displacement results to calibrate the simulation. Using this simulation design parameters are declared including, overall diameter, and tool hole size. The performance of the IPMC is then simulated while varying these parameters. 
Third, an electro-mechanical model of the IPMC is developed. This macroscopic model is used to relate the input voltage to an associated tip deflection. Several model types used for this purpose are tested and discussed. After determining a suitable type a mathematical electro-mechanical model is developed. Using this model several closed loop control systems are proposed. Once a final decision is reached the closed loop control system is implemented in the experimental setup. Several tests are designed to test the effectiveness of the closed loop system and mathematical models. 
Finally several improvements are made to enhance the users experience using IPMCs as well as incorporating them into conventional devices. To provide a better user interface the experimental control system is extended to allow the user to input controls via a standard computer mouse. This will allow a shorter operator training time and hopefully a wider array of real world uses for IPMCs. Attempts are also made to establish permanent connections to the IPMC. A tube type IPMC is meant to be used as part of a total system. To this end soldered connections to the IPMC are made. One of the main expected applications of tube type IPMCs are as active catheters. In this application the IPMC would be placed in-line with the plastic catheter line. As a proof of concept the IPMC is installed onto the tip of a conventional catheter line.