A robotic fish with wide-ranging functions from search and rescue to providing entertainment at an aquarium sounds like an unattainable dream, but is the fruit of research by a young engineering team at the University of Hong Kong (HKU).
SNAPP, the robotic fish, currently holds the Guinness World Record for the fastest 50m swim by a robotic fish in 22.9s or at 2.2 m/s (meters per second), which is faster than most Olympic swimmers including Michael Phelps, who averages a speed of 2.1 m/s. The robotic fish was invented by a student-staff team led by the Department of Mechanical Engineering and sponsored by the Tam Wing Fan Innovation Wing under HKU’s Faculty of Engineering.
The founder of the robotics team BREED is Timothy Ng, a HKU mechanical engineering graduate, who is happy to see that the team’s joint effort had reached one milestone after another. The team started out trying to invent a fish that could beat top high-school swimmers. After initial success, they furthered their research with the goal of beating Olympic champions, and the result has been astounding. In January 2020, the team first set the Guinness World Record for the fastest 50m swim by a robotic fish with 26.79s. SNAPP is another breakthrough. “We have surpassed most Olympic swimmers except Cesar Cielo, who swam 50 meters in 20.91 seconds,” said Ng.
SNAPP is the fastest robotic fish to date, breaking the scientific boundaries known to mankind swimming, at a speed of 2.18 m/s. Other noteworthy fish robots such as Harvard’s Tunabot swims at 1m/s. Mr. Ng said: “By using flexible and soft methods in the tail design, we achieved our present record from the original 1.2m/s. This is the key to underwater propulsion.”
The team is encouraged by the fact that SNAPP is optimal for an array of functions. Professor Dennis Leung, Head of the Department of Mechanical Engineering and an environmental specialist, said: “I am very pleased with the research output of the robotic fish project. Apart from breaking the Guinness record, the robotic fish can also be applied in our everyday life. It is particularly useful in environmental protection such as monitoring water quality as well as surveillance of rubbish and oil spillage in seawater.”
Although SNAPP cannot yet match the swimming speeds of natural fishes, which have undergone millions of years of optimization in an evolutionary process, through the efforts of the team, it emulates the motions and profile of a real fish, hence it is able to integrate with the ocean environment seamlessly. Its fish-like gait produces low acoustic noise, keeping underwater sound pollution to a minimal.
With its unparalleled underwater mobility, and the ability to provide floating support and towing capability in the absence of lifeguards, the robotic fish is also ideal for rescue and search operations. When integrated with an artificial intelligence-based vision system and using an aerial-drone, it could form a robust system providing unparalleled search and rescue of victims from both air and water.
It brings many new opportunities when integrated with other robotic technologies like drones, according to the supervisor of the project, Dr. Fu Zhang, Assistant Professor of the Department of Mechanical Engineering, who is a robotics specialist especially in aerial drones. He commented: “The robotic fish project is truly interesting and significant in both research and practice. Its success would benefit applications such as underwater exploration and in saving lives etc. Most of the oceans are yet to be seen by humankind, and new technologies can help protect the shorelines and public beaches from sharks, while policing water boundaries and defining territorial maps.”
According to the World Health Organization, an estimated 320,000 deaths are caused by downing each year. “The deaths of the professional divers in the Thai cave rescue operation years ago could have been avoided if SNAPP were available to them.” said Mr. Ng.
With its thin profile, SNAPP is fit for both shallow and deep-sea operations, capable of moving through undersea rock formations and fitting through tight crevices. The current prototype allows it to accelerate to a maximum speed within 0.5s, make tight turns with its caudal fin, and swim continuously for hours in a mix swimming mode fish on a 48V, 850 mAh battery.
The robotics team is already working on using SNAPP to address ocean pollution and to scout for underwater garbage patches. The fish can relay their location back to a much larger collector, or be deployed to take water samples periodically in river basins, and to monitor the water quality, specifically for microplastics. “It can also be used as "pet" for divers, carrying crucial equipment and oxygen tanks for them,” Mr. Ng added. Snapp can also act as a lifeline for divers that are caught in an underwater current, pulling them away from it. While being in talks with commercial companies on utilizing the search, rescue, and patrol functions of SNAPP, Mr. Ng is eyeing other wider applications. “Perhaps in the future, we would not need to keep real fishes captive for entertainment; robots can replace them instead.”