Efficient thrust generation in robotic fish caudal fins using policy search
Yixi Shan,Yagiz E. Bayiz,Bo Cheng +2 more
- Vol. 1, Iss: 1, pp 38-44
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TLDR
In this paper, the kinematics of caudal fin motion of a robotic fish are optimized experimentally to maximize the thrust-generation efficiency of the caudals of the robotic fish.Abstract:
Thrust generation is a crucial aspect of fish locomotion that depends on a variety of morphological and kinematic parameters. In this work, the kinematics of caudal fin motion of a robotic fish are optimised experimentally. The robotic fish actuates its caudal fin with flapping and rotation motion, and also measures the fin hydrodynamic force and torque. Total nine designs of the caudal fins are investigated, with three different shapes (or inclination angles) and three stiffness. The optimisation is based on a policy search (PS) algorithm, which is used to maximise the thrust-generation efficiency of the caudal fins. The authors first parametrise fin spanwise-rotation as a sinusoidal function using rotation amplitude and phase delay and test whether it is beneficial to thrust-generation efficiency. The result shows that the rotation does not contribute to the efficiency, as the efficiency is maximised at zero amplitude. Next, the authors optimise flapping amplitude and trajectory profile without fin rotation. Results show that smaller flapping amplitude results in higher efficiency and linear flapping trajectories are preferred over sinusoidal ones. Fins that have the highest flexibility are more efficient in thrust generation although they generate less thrust, while an inclination angle of 30° yields the most efficient fin shape.read more
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References
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Energy-minimizing kinematics in hovering insect flight
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TL;DR: In this article, the authors investigate aspects of hovering insect flight by finding the optimal wing kinematics which minimize power consumption while still providing enough lift to maintain a time-averaged constant altitude over one flapping period.
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Wake mechanics for thrust generation in oscillating foils
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