Engineers design boat robots in Pottruck pool

For one group of mechanical engineering students a late night at the gym doesn’t mean a few extra reps on the weight machine.

Engineering professor Mark Yim and his team of undergraduates, doctoral students and staff— all in the Department of Mechanical Engineering and Applied Mechanics—rent out the Sheerr Pool at Pottruck to test a design for robotic boats several nights per week, typically working from 11 p.m until 5 a.m.

Yim and his team receive funding from the Defense Advanced Research Projects Agency’s Tactically Expandable Maritime Platform. TEMP aims to design a system of moving shipping containers that can link together to form islands, bridges and landing strips. At Penn, Yim and his team are building a scale model of the system.

According to DARPA, the project is intended for use in disaster response and a variety of other military purposes.

The team has built more than 100 scaled-down shipping container boats out of laser-cut black plastic that cost about $100 each.

These boats are certainly not like a typical RadioShack remote-controlled vehicle. They are slightly larger and longer than a shoebox and each is named after a chemical element.

Additionally, Yim and his students spent hours writing and manipulating code so that the boats can complete tasks on their own. When directed by the engineers to form an island, the boats move into place and hook together without further instructions.

“We want to press go and for them to figure it out themselves,” explained Jimmy Paulos, one of the doctoral students working on the project.

The boats are also equipped with tiny Gumstix computers, which keep track of the boats’ location and tell them where they need to go.

“It’s about as good as a state of the art computer would have been in 1999 or 2000 and it’s the size of your thumb,” said Jon Greco, another doctoral student from the project. “It sends [the boat] a trajectory.”

According to Jay Davey, a member of mechanical engineering staff, the Gumstix computer communicates with the boats’ four motors. Davey, who designed much of the boats’ mechanics, says the boats are unique in their movements.

“Our boats are not like regular boats in that they do not need to go forward to turn,” he says.

Since there is one motor on each side of the boats, they easily scoot through the water in any direction, making a mechanical grinding noise.

Last Wednesday, the objective was to get the boats to form a bridge across a corner of the pool and drive a car across the bridge. The week before, the boats successfully configured themselves into an island for one of Engineering professor Vijay Kumar’s quadrotor drones to land on.

Davey got in the water to attach the first boat to a ramp, installed on the edge of the pool deck.

“How’s the water?” asked Greco.

“Better than outside!” Davey said, referencing the dismal rainy weather that night.

The boats were put into the water. Greco and other doctoral students began to tinker with the code.

The coding was slow going and it seemed the mechanics of the boat still needed to be perfected. At one point in the night, Engineering senior Gabby Merritt realized that one boat, “Carbon,” was filled with water and its batteries were ruined. Other boats had issues with their docking system and could not connect with each other.

Around 2:30 a.m., three boxes of pizza arrived and some of the students took a break to eat and talk. Merritt took the time to show professor Yim a bit of a Korean variety show called “Running Man.”

After the break, when most of the undergraduates had left, the exhausted doctoral students remained, moving around the boats and rewriting lines of code.

“I’m pretty sleep deprived at this point. Can you look over my shoulder while I code this?” Greco asked another doctoral student, Tarik Tosun.

Finally, at 3:30 a.m. the boats started to form the desired pattern. It was too late to go forward with making the bridge. However, since the boats now knew how to make the pattern, this next step did not seem far off.

But the team could not stay long, as it was near time to pack up the boats and leave. They needed to be out of the pool by 6:00 a.m. when the swim team would arrive for practice.

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