Ionic Polymer-Metal Composites (IPMCs), informally known as artificial muscles, are an innovative class of smart materials that generate large bending motions under low actuation voltages. As a first step towards the realization of the full potential of IPMCs, the proposed research aims to develop a control-oriented model for IPMC actuators that captures essential dynamics and nonlinearities. It addresses a problem of practical interest that is largely unexplored in existing IPMC modeling work, which typically deals with either complex continuum models (infeasible for real-time control) or simplified linear models (valid only within limited actuation ranges). This project will explore a novel model structure that accounts for major actuation mechanisms and incorporates two nonlinear modules, stress-strain hysteresis and nonlinear dependence of the electrical behavior on the IPMC bending curvature. Given the explicit physical interpretations of individual modules, model identification will be performed by exploiting the separation of energy domains and time scales. Integrating the core nonlinearities, the proposed model is expected to provide a basis for fast, precision, and energy-efficient control of IPMC actuators.
As artificial muscles, IPMCs have a wide spectrum of potential applications in biomedical devices, biomimetic robotics, and micro- and nanomanipulation systems. One crucial barrier to these applications is the complicated, nonlinear, electromechanical behaviors of IPMCs. By capturing the key characteristics in a succinct yet adequate way, the proposed research will facilitate the design of effective controllers ("brains") for robots, devices, and systems enabled by these artificial muscles. This can lead to agile prosthetic devices, active bioinstrumentation tools (for example, steerable catheters), and dexterous micro- and nanomanipulators, with potential impacts on health care and micro/nano-manufacturing. In this project the PI will also hold appealing "artificial muscles in action" demos and lectures for K-12 students, and inspire the interest of young students, especially female students, in science and engineering.
