Self-reconfigurable robotic fish swarms: Collective achievement of diverse locomotion and challenging aquatic tasks.

Conventional aquatic robots are typically constrained by fixed morphology and single-mode locomotion, limiting adaptability to unstructured environments. Inspired by the diverse fin-driven locomotion strategies of natural fish, we present a self-reconfigurable robotic fish swarm system capable of operating across a wide range of aquatic conditions and tasks. Each robotic fish unit features autonomous physical assembly and disassembly capabilities by electropermanent magnets, enabling both connection and intermodule communication, allowing the swarm to dynamically reconfigure its morphology. Systematic evaluation reveals that swarm configurations substantially outperform individual units in various locomotion performance, including stability, maneuverability, swimming speed, energy efficiency, and multimodal locomotion ability. The swarm also demonstrates collaborative capabilities in navigating through complex environments, manipulating obstacles, and transporting objects, both in laboratory and outdoor aquatic settings. This work provides a framework for aquatic robots to adapt to unstructured environments and complex tasks, contributing to the advancement of multifunctional, reconfigurable robotic systems.