‘SlothBot’ hangs out at Botanical Garden

Georgia Tech’s slow robot can measure and record information about plants.

Look, up in the sky, it’s a bird, it’s a plane, it’s a …

Sloth robot?

Yes, 45 feet above the forest floor in a wooded section of the Atlanta Botanical Garden, there is a slow-moving robot called SlothBot, hanging from a wire.

Created by robotics engineers at Georgia Tech, SlothBot has origins in the world of agricultural robots but has been adapted for work in plant research and conservation.

It is also as cute as a button. Its 3D-printed outer shell, which protects its sensors, motors, gears and batteries from the weather, was fashioned to resemble its inspiration, the two-toed sloths of South America.

Sloths taught Tech robotics professor Magnus Egerstedt a useful lesson, as he observed them during a vacation trip to a vineyard in Costa Rica. They demonstrated the value of slowing down.

“I could not understand sloths,” said Egerstedt in a recent interview, his accent revealing a lilting trace of his native Sweden. “They are sitting there, waiting to be eaten by a jaguar. How come these things exist?”

It turns out that slowness can be an advantage. Predators, in particular birds, operate on what Egerstedt calls “optical flow,” which he said is “fancy speak” for detecting movement. “So if

you’re slow enough, you become invisible to predator birds.” Also if you’re living in a tree, and you eat leaves, which are a terrible food source for energy production, you will have to move slowly anyway, as a means of shepherding the small energy resources you have.

Translate that tactic to a solar-powered agricultural robot, with limited energy resources and no great hurry. If we want to have a robot out in the field for six months or more, observing the entire growing cycle of a plant, then it makes sense, said Egerstedt, to have it move at the speed of a plant.

“Why not embrace slowness as a design principle?” The idea has been used before, notably in the plodding but reliable Mars Rover robots, and Egerstedt had many conversations with his friends at the NASA Jet Propulsion Lab about slow robot design.

After conversations with Emily Coffey, the Botanical Garden’s vice president of conservation and research, Egerstedt saw even more possibilities for SlothBot.

“I struck gold when I met with Emily Coffey,” said Egerstedt, who is chair of Georgia Tech’s School of Electrical and Computer Engineering. “She saw potential uses for SlothBot I had hoped were there but hadn’t fully articulated.”

Coffey’s research into plant conservation takes her to the mountains of North Georgia and the rain forests of South America, as she fulfills the garden’s commitment to protect endangered plants and find ways to ameliorate the effects of climate change.

She is interested in the presence of certain pollinators, which are strong indicators of the health of a particular ecosystem.

Up until now, she said, to learn which pollinator interacted with which plant, in, say, a South American rainforest, you’d have to put a human up in that tree for a long time. “We don’t have the resources to put humans in trees,” she said. Enter SlothBot.

“In Ecuador, we’d like to look at the high elevation canopy,” she said, in a telephone conversation from the Linville Gorge area in North Carolina, where she is collecting seeds from rare orchids while kayaking along the river. “We’re also thinking of looking at the North Georgia bogs,” to monitor damage from storms and feral hogs.

The robot can measure and record information about relative light, humidity, rainfall, and temperature, and transmit that data by Wi-Fi or Bluetooth. “In addition, we’re working on a camera system, that can take images of the canopy and images of plants,” said Coffey.

One of the problems facing robots that must navigate uneven forest terrain is locomotion. They can’t roll and can’t afford the energy to walk, crawl or fly.

Creeping along a wire was an excellent solution. But why does it need to move at all? The reason: SlothBot will spend most of its time under the shade of the canopy, but must emerge every now and then to sunbathe and recharge its solar panels. Eventually, it will be able to navigate a network of wires.

Plans to bring SlothBot to Ecuador were postponed during the first months of the pandemic. In the meantime, the robot is practicing its high wire act at the Botanical Garden. It’s not just demonstrating proof of concept; it is also engaging a new generation of scientists, as young visitors observe the charming machine and learn about its purpose.

The SlothBot didn’t get cute until one of Egerstedt’s students looked at its Lego-like body, its tubular middle and its LED “power on” and “low power” lights and thought, “Hey, that looks like an animal.” Then a Tech undergraduate with artistic abilities began to design a kind of face for the creature.

Egerstedt hopes that SlothBot’s sweet smile will engage young visitors to the Atlanta Botanical Garden, who will then go on to learn about this unique tool of conservation technology.

“I believe anything that can get kids excited about science and engineering and the biological sciences is good,” he said.

COURTESY OF ATLANTA BOTANICAL GARDEN The SlothBot, a slow-moving robot that monitors plant growth, sunshine, rainfall, and other variables, travels along a wire at the Atlanta Botanical Garden. It was created by Georgia Tech robotics students.

OF ATLANTA BOTANICAL GARDEN COURTESY The SlothBot is tended by a group of students from Georgia Tech, led by professor Magnus Egerstedt (third from the right). Egerstedt, chair of Tech’s School of Electrical and Computer Engineering, developed SlothBot from his interest in agricultural robots.