CRII: RI: Embedded and Continuous Shape Morphing using Twisted-and-Coiled Artificial Muscle

Colorado State University, Fort Collins CO

Investigators

Abstract

Many animals have the ability to locomote in different environments, such as on land, in the water, and in the air. Developing biologically inspired robots with similar abilities would open up many new types of applications for robotics. Towards this goal, this research investigates a novel shape morphing scheme that can autonomously modify the shape of a structure, such as by changing legs to flippers. With shape morphing capabilities, robots can leverage varying shapes from the same structure for locomotion in different environments, which can drastically reduce the robot's costs while dramatically improving their performance. The approach can enable a structure to precisely morph into a three-dimensional shape without using bulky external sensors and actuators, making it suitable for various applications such as morphing wings, multimodal robots, programmable matter, foldable robots, etc. The project will also broadly impact STEM students of all ages through outreach to K-12 students, enhancement of existing curriculum with research-inspired projects, and promotion of undergraduate research. The new shape morphing scheme is accomplished by embedding a novel twisted-and-coiled actuator (TCA) into soft materials, together with a thermoplastic material with temperature-dependent stiffness. With the proposed scheme, this project aims to accomplish embedded and continuous shape morphing through closed-loop shape control enabled by the TCA's dual actuation and sensing capabilities. To do this, physics-based models will be first established to relate a desired shape of a structure to the embedded TCA's electrical resistance. Then, closed-loop shape control can be accomplished by controlling the TCA's resistance to a desired value. Finally, the proposed shape morphing scheme is applied to a miniature amphibious robot that can swim in water with straight legs and travel on ground by morphing the legs into a curved shape. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.