Multimodal Bionic Magnetic Miniature Amphibious Soft Robots

Miniature amphibious soft robots (MASRs) show great potential for operation in unstructured and complex environments, owing to their ability to move flexibly through narrow spaces with complex obstacles. However, existing MASRs still lack diverse movement modes and struggle with inefficient performance in both aquatic and terrestrial locomotion, limiting their ability to meet the demands of motion in complex amphibious environments. Here, we propose a joint-based magnetic MASR with four locomotion modes: crawling, rolling, jumping, and swimming, inspired by the structural features of four organisms (i.e., inchworms, woodlice, click beetles, and jellyfish), which features a polyhedron deployable structure with a flexible joint. The flexible joint converts the global bending deformation into concentrated large deformation, which can store more energy to drive the robot, so that it can improve the energy efficiency, enhancing the robot's multimodal locomotion performance. After determining the dimensional parameters through multiobjective optimization, the robot achieves the following single-step displacements under a unit magnetic flux density: 0.038 BL (crawling), 0.153 BL (rolling), 0.22 BL (jumping), and 0.023 BL (swimming), respectively, demonstrating that it achieves more balanced and efficient locomotion performance than existing multimodal MASRs. Besides, with vision-based closed-loop control, the robot exhibits strong steering capability and can achieve precise tracking of complex trajectories. Furthermore, the proposed joint-based MASR is capable of multimodal locomotion on different surfaces and exhibits excellent mode-transition and obstacle-crossing capabilities in confined, complex amphibious environments as well as in an ex vivo porcine stomach, demonstrating its potential for operations in confined and unstructured environments.