Employees at Ward Aquafarms in Cape Cod frequently undergo the monumental task of overturning thousands of floating mesh bags of oysters. Farmworkers kayak out to the bags, which can weigh up to 70 lb, and flip each one by hand.
The farmworkers have to fight against rough waters and bad weather. When the bags are flipped, any algae or barnacles growing on the side of the bag below the waterline are exposed to air. Once exposed to the air, the biofouling organisms dry and chip off, ensuring that water flow to the oysters is never cut off.
Manually flipping the oyster bags can cost Dan Ward, owner of Ward Aquafarms and a marine biologist, about $3,500 every year. The job is dull and potentially dangerous, which means at times it can be difficult for Ward to find workers who are up to the task.
This was the problem students in MIT’s Sea Grant program were presented with. The group, with the help of Michael Triantafyllou, an MIT professor of ocean science and engineering, decided to create an autonomous robot that could take over the bag-flipping.
The team worked closely with Ward, who has experience reviewing new technologies for aquaculture.
“It was always ‘I already have this remotely operated vehicle; would it be useful to you as an oyster farmer if I strapped on some kind of sensor?’” Ward said. “They try to fit robotics into aquaculture without any industry collaboration, which leads to a robotic product that doesn’t solve any of the issues we experience out on the farm. Having the opportunity to work with MIT Sea Grant to really start from the ground up has been exciting. Their approach has been, ‘What’s the problem, and what’s the best way to solve the problem?’ We do have a real need for robotics in aquaculture, but you have to come at it from the customer-first, not the technology-first, perspective.”
In the spring of 2020, students came up with what they called Oystamaran, a catamaran with a flipping mechanism between its two hulls. The work is similar to tasks a robot might perform in other industries, but this one came with unique challenges for the students.
“You have a floating device, which must be self-propelled, and which must find these objects in an environment that is not neat,” Triantafyllou said. “It’s a combination of vision and navigation in an environment that changes, with currents, wind, and waves. Very quickly, it becomes a complicated task.”
Michelle Kornberg was a student in last year’s class who graduated in May 2020. After graduation, she constructed the central flipping mechanism and basic structure of the planned robot as a staff member at MIT Sea Grant.
In the spring of 2021, Kornberg acted as a lab instructor for a new class of students taking on the same problem. These students created Oystamaran 2.0. The new version of the robot was tested at Ward Aquafarms, and managed to flip over several rows of bags while being controlled remotely.
Challenges arose when trying to get Oystamaran to navigate between tightly packed rows of oyster bags to get to the ones in the middle.
The students’ next step is to make the robot more autonomous, so it doesn’t have to be remotely controlled as it flips bags. The next class to take on the project will be in the spring of 2022.
Editor’s Note: MIT’s full story can be found here.