Studying marine life without altering its natural behavior is a significant challenge, as human divers or bulky underwater vehicles can disturb aquatic ecosystems. To address this, researchers at MIT’s Computer Science and Artificial Intelligence Laboratory (CSAIL) developed SoFi, the Soft Robotic Fish. This robot is designed to swim untethered among real fish, acting as an underwater observer that gathers information without causing a disturbance.
The Technology Behind SoFi
SoFi’s design prioritizes a life-like appearance and movement to avoid startling real fish. Its body is constructed from flexible silicone rubber and 3D-printed components, making it both durable and nimble. This soft-bodied approach enables safer and closer interactions with marine organisms. The robot’s internal components are protected within a waterproof compartment in its head.
The robot’s swimming motion mimics that of a real fish through a hydraulic system. A small motor pumps water into two balloon-like chambers in its tail. As these chambers sequentially fill and empty, they create a side-to-side undulation that propels SoFi forward with a realistic, fish-like motion. This method is exceptionally quiet, helping the robot go unnoticed by nearby wildlife.
The robot is powered by a lithium polymer battery, the same type found in smartphones. All of SoFi’s operations are managed by an onboard Raspberry Pi, a small computer that processes commands and controls its movements. To manage its position in the water column, SoFi uses a buoyancy control unit that alters the robot’s density by compressing or decompressing air, allowing it to dive or surface.
Navigating the Ocean Depths
Controlling a robot underwater is complicated because radio waves do not travel well through water. The CSAIL team engineered an acoustic communication system to overcome this. A diver operating SoFi uses a specialized console that sends high-frequency ultrasonic signals through the water to the robot, transmitting commands for speed and direction.
Using this acoustic link, a diver can direct the robot to swim straight, turn, and adjust its depth to follow specific fish or explore features of a coral reef. During test dives in Fiji, SoFi demonstrated its ability to navigate complex underwater environments for up to 40 minutes at a time.
The control system for SoFi incorporates a waterproofed Super Nintendo controller. This familiar interface makes piloting the robot accessible and straightforward. This allows the operator to focus on the scientific objectives of the mission rather than complex controls.
Studying Marine Life Up Close
The primary application of SoFi is to serve as an unobtrusive tool for marine biology research. Its quiet motor and natural swimming motion allow it to approach marine life without causing alarm. Fish and other sea creatures do not perceive SoFi as a threat, permitting it to swim alongside them and observe their undisturbed, natural behaviors.
To document its observations, SoFi is equipped with a high-resolution camera with a fisheye lens in its nose. This camera captures detailed photos and videos of the surrounding environment and its inhabitants. The visual data helps scientists study social interactions, feeding habits, and other behaviors in sensitive ecosystems like coral reefs.
By getting closer to marine life than human divers or traditional underwater vehicles can, SoFi acts as a mobile underwater observatory. This technology allows researchers to gather information from delicate habitats with minimal impact, advancing the study of marine ecosystems.