Multi-Scale Distributed Port-Hamiltonian Representation of Ionic Polymer-Metal Composite

This paper shows that one of soft actuators, Ionic Polymer-Metal Composite (IPMC) can be modeled in terms of distributed port-Hamiltonian systems with multi-scale. The physical structure of IPMC consists of three parts. The first part is an electric double layer at the interface between the polymer and the metal electrodes. The frequency response of the polymer-metal interface shows a fractal degree of gain slope. Then we adopt a black-box circuit model to this part and give considerations for distributed impedance parameters. The second part is an electrostress diffusion coupling model with bending and relaxation dynamics. This part is represented by an electro-osmosis, which is a water transport by an electric field, and a streaming potential, which is an electric field created by a water transport. We discuss the relationship of stress and bending moment induced by swelling. The third part is a mechanical system modeled as a flexible beam with large deformations. The representation has the capability extracting the control structure based on passivity from distributed parameter systems possessing a complex behavior.