Because I Like the Name

It's natural that the news in the tech world tends to focus on the glamorous aspects: self driving cars, 5G wireless networks, autonomous AI, sexbots and so on.  In reality, a lot of applications are pretty mundane.  Autonomous monitors that could survey a section of forest or some amount of land and work on its own for days or weeks at a time would solve a few problems.

With that in mind, let's introduce SlothBot - an autonomous robot under development at Georgia Tech and inspired by a sloth:

“In robotics, it seems we are always pushing for faster, more agile and more extreme robots,” said Magnus Egerstedt, the Steve W. Chaddick School Chair of the School of Electrical and Computer Engineering at the Georgia Institute of Technology and principal investigator for Slothbot. “But there are many applications where there is no need to be fast. You just have to be out there persistently over long periods of time, observing what’s going on.”

Based on what Egerstedt called the “theory of slowness,” Graduate Research Assistant Gennaro Notomista designed SlothBot together with his colleague, Yousef Emam, using 3D-printed parts for the gearing and wire-switching mechanisms needed to crawl through a network of wires in the trees. The greatest challenge for a wire-crawling robot is switching from one cable to another without falling, Notomista said.

SlothBot consists of two plastic bodies connected by an actuated hinge with one body holding a couple of small solar panels.  SlothBot doesn't swing between branches like its namesake; instead, wires or ropes are pre-strung in areas the robots will operate.  Each body houses a driving motor connected to a rim on which a tire is mounted. The use of wheels for locomotion is simple, energy efficient and safer than other types of wire-based locomotion, the researchers say.

So far, SlothBot has operated in a network of cables on the Georgia Tech campus. Next, a new 3D-printed shell – that makes the robot look more like a sloth – will protect the motors, gears, actuators, cameras, computer and other components from the rain and wind. That will set the stage for longer-term studies in the tree canopy at the Atlanta Botanical Garden, where Egerstedt hopes visitors will see a SlothBot monitoring conditions as early as this fall.

Real-life sloths are small mammals that live in jungle canopies of South and Central America. Making their living by eating tree leaves, the animals can survive on the daily caloric equivalent of a small potato. With their slow metabolism, sloths rest as much 22 hours a day and seldom descend from the trees where they can spend their entire lives.

“The life of a sloth is pretty slow-moving and there’s not a lot of excitement on a day-to-day level,” said Jonathan Pauli, an associate professor in the Department of Forest & Wildlife Ecology at the University of Wisconsin-Madison, who has consulted with the Georgia Tech team on the project. “The nice thing about a very slow life history is that you don’t really need a lot of energy input. You can have a long duration and persistence in a limited area with very little energy inputs over a long period of time.”

(Two-toed sloth using cables on Georgia Tech campus as a Sloth Monorail)

The operational plan for the SlothBot is exactly that last sentence: hang around for a long time in a small area, observe and record, then move to an area of bright sun to recharge.

The researchers also hope to test SlothBot in a cacao plantation in Costa Rica that is already home to real sloths. “The cables used to move cacao have become a sloth superhighway because the animals find them useful to move around,” Egerstedt said. “If all goes well, we will deploy SlothBots along the cables to monitor the sloths.”

About 12 years ago, I consulted to local school on the radio system for a monitor like this that would be left in the field and then report back from time to time.  Energy usage becomes a major concern - budgeting how big the battery is, how much power individual systems are allowed and a lot of tough, systems engineering questions.  Egerstedt is no stranger to these decisions.

Egerstedt is known for algorithms that drive swarms of small wheeled or flying robots. But during a visit to Costa Rica, he became interested in sloths and began developing what he calls “a theory of slowness” together with Professor Ron Arkin in Georgia Tech’s School of Interactive Computing. The theory leverages the benefits of energy efficiency.

“If you are doing things like environmental monitoring, you want to be out in the forest for months,” Egerstedt said. “That changes the way you think about control systems at a high level.”

Flying robots are already used for environmental monitoring, but their high energy needs mean they cannot linger for long. Wheeled robots can get by with less energy, but they can get stuck in mud or be hampered by tree roots, and cannot get a big picture view from the ground.

“The thing that costs energy more than anything else is movement,” Egerstedt said. “Moving is much more expensive than sensing or thinking. For environmental robots, you should only move when you absolutely have to. We had to think about what that would be like.”

Closeup of SlothBot showing the 3D printed gears. 

There's a video of SlothBot in motion.