Meet SoFi, MIT’s New Robotic Fish
For decades, scientists have been trying to find a way to document the fascinating marine world. Despite having developed many underwater vehicles and cameras, because of the complexity of designing underwater robots, most machines have been bulky, disruptive, and unable to swim at varying depths.
Because of the complexity of designing underwater robots, most machines have been bulky, disruptive, and unable to swim at varying depths.
This past March, SoFi, a soft robotic fish, was born. MIT scientists have worked hard to create this remote-controlled, biomimetic robotic fish. Unlike previous robotic fish designs, SoFi swims untethered, moves in three-dimensional trajectories, and blends into the underwater environments. SoFi can swim independently in depths between one to 18 meters. Its main purpose is to “help divers remotely observe marine life and coral habitats without disturbing them, providing insights into underwater worlds,” according to Robert Katzschmann, the lead author of the paper on the robot fish and a doctorate student at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL).
Scientists faced many challenges in creating a fish-mimicking robot. “Natural systems often exceed the performance of rigid robotic systems because of their soft and compliant characteristics,” Katzschmann and his colleagues wrote in their paper for Science Robotics. Katzschmann explained to NU Sci that one of the biggest challenges was “to get it to swim faster, perform proper turning motion and swim at different depths, all while being waterproof, structurally sound, and controllable.”
Katzschmann and his team also found difficulties in creating a hydraulic propulsion system that could efficiently carry the weight of the robotic fish. Previous underwater vehicles used jet-based propellers which created turbulence, scaring away ocean life and preventing them from close-up observation. MIT’s SoFi tackles these obstacles by using a soft robotic fish tail as the propeller. The fish tail creates much less noise and turbulence than previous attempts at robotic fish. Additionally, creating an efficient and successful method of underwater communication with the robot also proved to be a challenge. Radio frequency communications dissolve quickly in saltwater. Optical communications similarly scatter in the ocean. Therefore, MIT researchers relied on acoustic communications. Using acoustic signals, a human diver can provide intricate navigational commands to SoFi from a distance.
Despite these challenges, SoFi has successfully navigated the coral reefs of the Pacific Ocean. The robotic fish has had multiple encounters with fish and other sea creatures during these tests. Even within one meter of proximity, the robot did not cause other fish to flee. MIT’s team is excited with the results of SoFi’s swim tests because they prove that the robot can camouflage in marine environments.
The use of robotic fish to study marine life is still in its beginning stages.
The use of robotic fish to study marine life is still in its beginning stages. Researchers still have endless goals for SoFi’s future. SoFi has only been tested in the Pacific Ocean, but the researchers envision more tests in different locations. Additionally, scientists want to test if SoFi can be used to influence the behaviors of marine life. “We also plan to build multiple ‘SoFis’ to see how additional robot fish will impact the behavior of schools of fish and increase the possibility of doing detailed oceanic observation,” Katzschmann said of his vision for the robot. SoFi is just the first step in having a robotic fish in the ocean. There are limitless possibilities for robotic fish and scientists are excited to further explore the underwater world with robotic fish like SoFi.
