Abstract
Jellyfish uses jet propulsion to achieve a diversity of propulsion modes in the water. In this article, a miniature jellyfish-inspired swimming robot is designed and built, which is capable of executing horizontal and vertical propulsion and maneuvers. In order to imitate the jellyfish in terms of morphology and kinematics, the robotic jellyfish is designed to be comprised of a streamlined head, a cavity shell, four separate drive units with bevel gears, and a soft outer skin encasing the drive units. A combination of four six-bar linkage mechanisms that are centrally symmetric is adopted as the driver to regulate the phases of contraction and relaxation of the bell-shaped body. Furthermore, a triangle wave generator is incorporated to generate rhythmic drive signals, which is implemented on the microcontroller. Through independent and coordinated control of the four drive units, the robotic jellyfish is able to replicate various propulsion modes similar to real jellyfish. Aquatic tests on the actual robot verify the effectiveness of the formed design scheme along with the proposed control methods.
Highlights
Recent years have witnessed the rapid development of bioinspired robots that use creatures as a source of inspiration.[1]
Researchers have created bioinspired robotic jellyfish with flexible bells, which may lead to better underwater vehicles.[8,9,10]
Tests conducted indicated that the design scheme mainly involving a six-bar linkage-centered drive mechanism and fine-tuned motion control is well suited to mimicry of jellyfish-like swimming
Summary
Recent years have witnessed the rapid development of bioinspired robots that use creatures as a source of inspiration.[1]. Where i 1⁄4 1,2,3,4, yi is the torsional angle of the i-th servo, ki is the slope of the second line segment of signal of the i-th servo, i is the ratio of slower phase speed and faster phase speed of the i-th servo, fi is the oscillation frequency of the i-th servo, ai is the oscillation amplitude of the i-th servo, t is the time, t1i is the time of trough of wave of the i-th servo, and t2i is the time of crest of wave of the i-th servo Among these parameters, ai, fi, i, and ki are the key ones set in the control algorithm. The outer skin of the robotic jellyfish will wrinkle, causing that real volume change rate is less than the theoretical value, the thrust generated by squeezing water with such speed is sufficient to make the robotic jellyfish swim forward. Please refer to the research by Li and Yu21 for similar simulation analysis
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