Scientists have successfully pushed past their own records to design a record-breaking comfortable robotic swimmer, inspired by the majestic manta ray’s mastery of fluid dynamics.
“Recalling our milestone achievement two years ago, we showcased an innovative aquatic robot that effortlessly reached cruising speeds of 3.74 body lengths per second,” Jie Yin, co-author of the research paper and Associate Professor of Mechanical and Aerospace Engineering at North Carolina State University, notes. “We’ve successfully built upon our initial concept, refining its efficacy.” Our newly designed robot excels in creating an ultra-vitality friendly environment while effortlessly reaching speeds of up to 6.8 physical lengths per second. As well as, the early mannequin was capable of swimming only on the floor of the water. The revolutionary new robot effortlessly navigates its way up and down the entire water column.
The comfortable robot features fins shaped like those of a manta ray, crafted from a durable material that remains steadfast when its expansive fins are unfolded. The fins are attached to a flexible, silicone-based body comprising a compartment that can be inflated with air via a pump mechanism. As the air chamber is inflated, the fins flex and conform, mimicking the motion of a manta ray’s downward fin stroke during its characteristic flapping motion. As the air pressure within the chamber subsides, the fins naturally spring back to their initial position.
“With this innovative approach, we’re able to inject vital energy into the system,” notes Haitao Qing, the pioneering researcher who authored the study, holding a Ph.D. pupil at NC State. The fish wish to revert to their natural state, and by slowly releasing more air, they’re able to tap into their innate energy reserves within the fins. We require a single actuator for the robot to enable faster and more efficient actuation.
The investigation into the fluid dynamics of manta rays played a crucial role in determining the optimal control mechanisms for the vertical motion of the advanced robotic system, thereby enhancing its overall comfort and functionality.
“Mimicking the majestic swimming movements of manta rays, our team has successfully replicated their habits to control whether the robot descends to the seafloor, plunges downward or remains stationary in the water column,” says Jiacheng Guo, co-author of the paper and a Ph.D. A student at the University of Virginia. As manta rays propel themselves through the water, they create two powerful streams that effectively push them forward. Manta rays adjust their flight path by modifying their fluid propulsion technique. We implemented a consistent methodology to regulate the up-and-down movement of our swimming robot. “We are actively exploring strategies to achieve effective control over lateral movements.”
According to Yuanhang Zhu, co-author and assistant professor of mechanical engineering at the University of California, Riverside, “Simulations and experiments substantiated that our robotic’s downward jet outperforms its upward counterpart in terms of effectiveness.” The robot’s fins flutter briefly to lift it higher. As we reduce the actuation frequency, the robot can slowly descend between fin flaps, allowing for both diving and maintaining a consistent depth.
Compressed air serves as the primary source of power for this robotic system, according to Qing. “When the robotic’s fins are at rest, the air chamber is devoid of air, thereby reducing the robot’s buoyancy.” When a robot flaps its fins at a leisurely pace, they tend to relax naturally. As the robotic wings flap more rapidly, the air chamber fills to maximum capacity, resulting in a prolonged period of increased buoyancy.
Researchers have conclusively showcased the comforting robotic’s capabilities through two additional demonstrations. The initial prototype of the robot successfully navigated a challenging obstacle course situated both on the floor and the surface of a water tank. The study successfully showcased an autonomous robot capable of transporting a load across the ocean floor, accompanied by self-sustaining life support systems for air and power.
“This cutting-edge design belies its simplicity,” Yin notes. “And with just one seamless activation, our robot effortlessly navigates complex vertical environments.” As we strive to advance lateral motion, we’re actively investigating various forms of actuation that have the potential to significantly enhance this technology’s versatility. Can we achieve our purpose with a design that seamlessly blends elegance and simplicity?
A groundbreaking paper titled “Spontaneous Snapping-Induced Jet Flows for Quick, Maneuverable Floor and Underwater Gentle Flapping Swimmers” has been made openly accessible in the journal. The research paper was jointly authored by Yinding Chi and Yaoye Hong, both of whom are former doctoral students. College students from North Carolina State University, led by researchers Daniel Quinn and Haibo Dong of the University of Virginia.
The work was accomplished with assistance from the National Science Foundation under grants 2126072 and 2329674, as well as from the Office of Naval Research under grant N00014-22-1-2616.
