Mechanics of Bioinspired Soft Slender Actuators for Programmable Multimodal Deformation

Soft slender actuators are active structures that have one dimension much larger than the other dimensions, and are ubiquitous in nature. In general, these structures have an infinite number of degrees of freedom, making them challenging to manipulate with high precision. There is an urgent need for efficient theoretical and computational tools to guide actuator design for high precision actuation. Inspired by elephant-trunk motion, this project fundamentallly investigates the mechanics of soft slender actuators under programmable multimodal actuation. Dimensional reduction makes the proposed model computationally efficient, inexpensive, and robust, especially with a view towards large deformations and inverse analyses. Proposed activties can provide opportunities to transform soft robotic research from a trial-and-error approach to a science-based design strategy. The work can serve as a platform to promote STEM education. After validation, the model will be implemented in an open-source simulator that can be used by students, educators, and researchers in the soft robotics community. The model will inform new design strategies for soft robots in various high-precision applications including wearable devices, flexible electronics, and surgical robotics. This project integrates theoretical modeling, computational mechanics, material multiphysics, experimental mechanics, and machine learning to address the research problem. Mechanics models and experimental validation will be combined to establish an open-source simulation platform to optimize the design of such actuators. The underlying construct is the active filament theory that harnesses the concept of dimensional reduction—from a fully three-dimensional structure to an active Kirchhoff rod—by describing deformation exclusively through extension, curvature, and torsion. It will create an open-source simulator that will be shared with the broader, soft robotics, community . The research will first establish a new mechanics theory to predict the trajectory of the end effector of a soft slender actuator. It can then serve as the foundation to optimize the trajectory of the end effector. The new theory will be validated via experiments through the actuation of liquid crystal elastomer fibers. This project will involve the simultaneous development of theory and experiments and will iteratively revise both activities to ultimately establish an experimentally validated theory and an optimal design model with high predicting accuracy. 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.