CAREER: Artificial Muscle Based on Dielectric Elastomers for Dexterous and Compliant Prostheses

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This Faculty Early Career Development (CAREER) project has the main goal of realizing artificial muscle with mechanical and dynamic properties similar to natural muscle. In particular, this project considers the use of a class of materials called dielectric elastomers (DEs) that have compliance, resilience, and force per area comparable to biological muscles. Like biological muscles, these materials can be self-sensing, allowing precise control of contraction or extension without needing visual feedback or other auxiliary sensing schemes. The ultimate goal of the project is to achieve dexterous, lightweight, and energy-efficient prostheses using DE-based artificial muscles, in contrast to the heavy and inefficient electric motors of the current generation of robotic arms. The project incorporates aspects of bio-inspired design, device fabrication, and dynamic modeling, sensing, and control. The success of this project will help provide affordable, reliable, and comfortable prostheses to the estimated two million military veterans and civilians who have lost hands, arms, or legs to accidents, natural disasters, wars, diseases, or aging. This project will also train the next-generation workforce with skills in the dynamic modeling, control, and fabrication of devices based on smart materials and structures. Activities to attract students to this area of research will improve enrollment in science, technology, engineering, and mathematics (STEM) disciplines.The long-term goal of this research is to develop lightweight, compliant, and self-sensing DEs to emulate the actuation and sensing of biological muscles for robotic assistive applications. A first step towards this goal is to obtain bio-inspired design, modeling, self-sensing, and control strategies for DE actuators in a prosthetic hand application. This project will emphasize the following core goals: 1) create a novel artificial muscle structure consisting of a tubular DE artificial muscle attached to carbon fiber artificial tendons; 2) derive a low-order physics-based model capturing the nonlinear elasticity and strain-dependent electrical impedance of the DE actuator; (3) implement a sensitive and robust nonlinear state observer using actuator self-sensing of the strain-dependent electrical impedance; (4) derive a state-boundary avoidance control strategy to protect the DE actuator from damage; and (5) build a DE-enabled prosthetic hand to demonstrate dexterous manipulation with efficient, and compliant actuation.