May 31 2019
When it comes to infrastructure maintenance, precision agriculture, environmental monitoring, and specific security applications, slow and energy efficient can be better than fast and always requiring a recharge. That is where “SlothBot” comes in.
Graduate Research Assistant Gennaro Notomista shows the components of SlothBot on a cable in a Georgia Tech lab. The robot is designed to be slow and energy efficient for applications such as environmental monitoring. (Image credit: Allison Carter, Georgia Tech)
SlothBot is driven by two photovoltaic panels and can remain in the forest canopy incessantly for months together. It moves only when it has to determine environmental changes, like chemical and weather factors in the environment that can be seen only with a prolonged presence. Presented on May 21st, 2019 at the International Conference on Robotics and Automation (ICRA) in Montreal, the proof-of-concept hyper-efficient robot may soon be lingering among treetop cables in the Atlanta Botanical Garden.
In robotics, it seems we are always pushing for faster, more agile and more extreme robots. 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”
Magnus Egerstedt, Principal Investigator and the Steve W. Chaddick School Chair, School of Electrical and Computer Engineering, Georgia Institute of Technology
On the basis of what Egerstedt referred to as the “theory of slowness,” Gennaro Notomista, a Graduate Research Assistant, and his colleague Yousef Emam, developed the unique SlothBot with the help of 3D-printed parts for the wire-switching and gearing mechanisms required to crawl via a network of wires in the trees. According to Notomista, changing from one cable to another without falling was the biggest challenge for a wire-crawling robot.
The challenge is smoothly holding onto one wire while grabbing another. It’s a tricky maneuver and you have to do it right to provide a fail-safe transition. Making sure the switches work well over long periods of time is really the biggest challenge.
Gennaro Notomista, Graduate Research Assistant¸ Georgia Institute of Technology
Mechanically, the robot contains a pair of bodies joined by an actuated hinge. In each body, a driving motor is accommodated that is linked to a rim on which a tire is placed. According to the researchers, the use of wheels for locomotion purpose is safer, simple, and energy efficient when compared to other kinds of wire-based locomotion.
To date, SlothBot has functioned in a cable network on the Georgia Tech campus. Then, a unique 3D-printed shell—that makes the robot look a lot like a sloth—will guard the cameras, computer, actuators, gears, motors¸ and other components from the wind and rain. That will lay the groundwork for longer-term analyses in the tree canopy at the Atlanta Botanical Garden, where Egerstedt believes that visitors will soon observe a SlothBot monitoring conditions this fall.
The term SlothBot is not an accident. As a matter of fact, real-life sloths are tiny mammals that dwell in jungle canopies of Central and South America. These animals make their living by eating the leaves of trees, and are capable of surviving on the daily caloric equivalent of a tiny potato. Sloths have slow metabolism and rest almost the entire day, that is, 22 hours, and they rarely climb down from trees where they tend to spend their whole lives.
The life of a sloth is pretty slow-moving and there’s not a lot of excitement on a day-to-day level. 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.
Jonathan Pauli, Associate Professor, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison
Pauli has consulted with the Georgia Tech researchers on the new project.
That is precisely what the team anticipates from SlothBot, whose design and development was funded by the U.S. Office of Naval Research.
“There is a lot we don’t know about what actually happens under dense tree-covered areas,” stated Egerstedt. “Most of the time SlothBot will be just hanging out there, and every now and then it will move into a sunny spot to recharge the battery.”
In addition, the team is planning to test SlothBot in a cacao plantation located in Costa Rica, where real sloths can be found abundantly. “The cables used to move cacao have become a sloth superhighway because the animals find them useful to move around,” stated Egerstedt. “If all goes well, we will deploy SlothBots along the cables to monitor the sloths.”
Egerstedt is an expert in algorithms that power groups of flying or tiny wheeled robots; however, during a visit to Costa Rica, he became keen on sloths and started to develop what he refers to as “a theory of slowness” along with Professor Ron Arkin in Georgia Tech’s School of Interactive Computing. The concept exploits the advantages of energy efficiency.
“If you are doing things like environmental monitoring, you want to be out in the forest for months,” added Egerstedt. “That changes the way you think about control systems at a high level.”
Although flying robots are already being utilized for environmental monitoring, they require high amounts of energy, which means they cannot stay for a long time. On the other hand, wheeled robots are more suitable since they require less amounts of energy, but one major drawback is that they can be hampered by tree roots or get stuck in mud, and will not be able to obtain a big picture view from the ground.
The thing that costs energy more than anything else is movement. 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.
Magnus Egerstedt, Principal Investigator and the Steve W. Chaddick School Chair, School of Electrical and Computer Engineering, Georgia Institute of Technology
Pauli explores a range of wildlife, and working with Egerstedt to aid SlothBot come to life has been truly rewarding.
“It is great to see a robot inspired by the biology of sloths,” he stated. “It has been fun to share how sloths and other organisms that live in these ecosystems for long periods of time live their lives. It will be interesting to see robots mirroring what we see in natural ecological communities.”
The study was sponsored by the U.S. Office of Naval Research through Grant N00014-15-2115.