Swarming nanorobots

How robots modeled after insects can work harder and smarter

The phrase “get back to nature” may not evoke images of high-tech innovations. But some Midwestern researchers are creating better robots by using principles found in nature: They’re modeling the bio-inspired technologies after animals like insects to improve performance and unlock unique functions. 

Michigan Technological University engineers wanted to expand robots’ movements from solely traveling on land, underwater, or in the air. They targeted the air-water interface and organisms — insects and bacteria — that can stand on the boundary by leveraging surface tension. 

The engineers focused on the few animals that are able to manipulate surface tension to propel themselves across liquids at a high speed and while still maneuvering well. They knew that certain insects release substances that change surface tension on the liquid immediately surrounding them, similar to adding a drop of dish soap to water. This creates a thrust that pulls the bugs forward. 

The MTU team’s remote-controlled robot uses this thrust principle for propulsion and changing directions. It releases isopropyl alcohol in a controlled manner, allowing the robot to “surf” on the liquid’s surface. The researchers developed custom flow control and steering mechanisms to work with the power and fuel sources, remote transmitter, and receiver. The unique technologies are said to make the robot nearly silent by eliminating engines and propellers that could disrupt underwater environments and organisms.

These devices could be used to access hard-to-reach locations and for applications like monitoring water pollution. The researchers are working to improve the surfing robot’s fuel efficiency and speed. 

Making robots fully autonomous can also help them work in a swarm, which is what a University of Notre Dame engineer is trying to do with bio-inspired robots that mimic ant and honeybee group behaviors. She developed four-legged robots that can maneuver through difficult environments and complete difficult tasks by working together.

Yasemin Ozkan-Aydin

Individual robots can perform simple tasks like carrying a light object, but physically connecting to other robots could help a single unit carry out more difficult tasks, explains Yasemin Ozkan-Aydin, assistant professor of electrical engineering, in a news release.

“When ants collect or transport objects, if one comes upon an obstacle, the group works collectively to overcome that obstacle. If there’s a gap in the path, for example, they will form a bridge so the other ants can travel across — and that is the inspiration for this study,” she said. 

“Through robotics we’re able to gain a better understanding of the dynamics and collective behaviors of these biological systems and explore how we might be able to use this kind of technology in the future.”

Each of the 3D-printed robots contained a lithium polymer battery, a microcontroller, and three sensors so the robots could connect with each other. Ozkan-Aydin tested them on challenging terrains including shag carpeting and stairs. When a single unit got stuck, it sent a signal to other robots and they linked together to collectively get past the obstacles.

Eventually, these robots are expected to be useful for a variety of real-world tasks such as environmental monitoring, space exploration, and search-and-rescue operations. A key area for improvement is the swarm robots’ power and sensing capabilities; researchers need to figure out how much power is needed for real-world functions and incorporate an appropriately powerful and sized battery. 

“For functional swarm systems, the battery technology needs to be improved,” Ozkan-Aydin said. “We need small batteries that can provide more power, ideally lasting more than 10 hours. Otherwise, using this type of system in the real world isn’t sustainable.”