Abstract: Pulsed jet propulsion, a highly efficient locomotion strategy commonly observed in marine organisms, offers significant potential for bioinspired underwater robotics. Drawing inspiration from the jet propulsion mechanism of squids, this study presents the design and implementation of a soft biomimetic robotic fish powered by liquid metal-based electromagnetic actuators. The robot employs a novel actuation strategy in which Lorentz forces are generated via the interaction between embedded permanent magnets and energized liquid metal coils, inducing periodic contraction and relaxation of a flexible body cavity to achieve efficient pulsed jet propulsion. Through comprehensive analysis of actuator dynamics and systematic optimization of structural and control parameters, the robotic fish attains a maximum linear swimming speed of 1.71 BL/s (Body Lengths per second), equivalent to 8.9 cm/s. To enhance maneuverability, a dual-cavity independently controlled architecture is employed alongside an inclined nozzle design, enabling precise directional control with a maximum turning rate of 47.4 deg/s and a minimum turning radius of 0.4 BL. Furthermore, the successful integration of miniaturized power and control systems within the body enables fully untethered autonomous swimming, greatly enhancing the system’s practicality. Experimental results demonstrate that the proposed robotic fish combines a compact structure with rapid response, versatile control, and excellent locomotion performance, highlighting its strong potential for applications in marine exploration, underwater surveillance, and environmental monitoring.

Key words: squid-inspired robotic fish')">squid-inspired robotic fish, pulsed jet propulsion, liquid metal, electromagnetic actuators, high-speedpropulsion