Design and Experimental Validation of a Biomimetic Jellyfish Robot with Asymmetric-Stiffness Swimming Arms and Dual-Power Cooperative Drive

This study presents a biomimetic jellyfish robot integrating asymmetric-stiffness swimming arms with motor–spring cooperative actuation. Motor-driven spring charging and rapid spring release organize the recovery, power-stroke, and gliding phases. Hinged arm segments, return micro-springs, and a limiting structure are designed to permit recovery-stroke bending while resisting bending during the power stroke. Component CFD and MATLAB(R2024a) motion-cycle analysis provide preliminary hydrodynamic and structural configuration comparisons. An arithmetic check of the retained drag fits gives a velocity-dependent arm-drag reduction of approximately 52.87–54.41% over 0.10–0.30 m/s and a separate body-drag reduction of approximately 44.49%; these are fitted-model comparisons, not measured drag reductions or mesh-independent predictions. In the recorded water-tank experiments, the prototype traveled approximately 1.8 m over approximately 9 s, corresponding to an overall average straight-line speed of approximately 20 cm/s. The average speed during the combined power-stroke and gliding phases was approximately 27 cm/s, and the maximum turning angular velocity was approximately 4.2°/s. These observations support the engineering feasibility of the integrated prototype under the reported test conditions. Quantitative stiffness characterization, independent trial variability, and matched-timing model validation are not established from the retained records.