Analytical Modeling and Inverse Design of Centimeter-Scale Hard-Magnetic Soft Robots

Hard-magnetic soft robots can form diverse soft-body deformation modes and safely interact with their surrounding environment, offering great promise in performing complex functions. Although there have been significant theoretical developments of small-scale soft robots, the design of centimeter-scale soft robots with larger workspace and output forces remains elusive. In this paper, we develop an analytical model to automatically design centimeter-scale hard-magnetic soft robots that exhibit desired configurations, enabled by programming the magnetization profile. The model considers the varying magnetization profile, gravity effect and large deformation, and directly relates the material, geometric and loading parameters to the final configurations. We develop an inverse design method for configuration matching based on the theoretical model. We demonstrate soft robots designed by the theoretical model with the capability to pass through narrow channels and crawl over obstacles. We further demonstrate optimized soft grippers showing conformal grasping of complex objects. The proposed methodology paves the way to design centimeter-scale soft robots and broaden their applications <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —The motivation of this work is to analyze, predict, and control the centimeter-scale hard-magnetic soft robot under external magnetic fields. While smaller magnetic-driven soft robots have been extensively studied, the centimeter-scale soft robots offer larger workspace and output forces, making them more versatile for certain applications. This paper develops an analytical model for centimeter-scale hard-magnetic soft robots that takes into account the varying magnetization profile, gravity effect and large deformation. It allows magnetically driven soft robots to pass through narrow channels and crawl over obstacles. In addition, an optimization method is proposed by virtue of the analytical model, enabling the inverse design of soft robots with prescribed grasping postures. The analytical model and optimization method can be implemented for the dexterous locomotion and manipulation of magnetic soft robots with large workspace and output forces in medical and industrial settings.