Performance evaluation of the static thrust and efficiency of an actuated biomimetic jellyfish model

Abstract This study offers an in-depth analysis of a jellyfish-inspired robotic model designed to simulate the expansion and contraction mechanisms found in natural jellyfish. By employing variable Duty Cycles to replicate the cyclic motions of the jellyfish, the thrust generation of the model is measured through static thrust assessments using a load cell, while its efficiency is evaluated using the Thrust-to-Power Ratio, TPR . The findings indicate that increasing the amplitude of the motion leads to more complex wave patterns, which in turn reduce the peak-to-peak force generated. Specifically, a 25% increase in the A/D ratio results in a significant 30% decrease in static thrust. It was observed that higher actuation frequencies do not notably influence thrust generation when the A/D ratio remains constant. Importantly, the TPR was found to be highest at an A/D ratio of 0.10, with an increase of up to 6% observed at higher Duty Cycles, suggesting that smaller actuation amplitudes are more efficient in enhancing thrust performance. These results highlight the critical role of amplitude in the efficiency of static thrust generation within a given Duty Cycle, emphasizing that lower amplitudes generally lead to higher efficiency. The study underscores the importance of optimizing both geometric and kinematic parameters for improved propulsion performance. It suggests that future research should focus on fine-tuning A/D ratios and Duty Cycles, as well as exploring alternative geometric configurations and materials to further enhance the hydrodynamic performance of jellyfish-inspired robots. The insights gained from this study provide a valuable foundation for developing more efficient and effective bio-inspired underwater vehicles.