Cockroach Robot Flips Itself With Insect-Inspired Wings

Using cockroach-like shells and wings keeps this robot bug upright and mobile

3 min read
Researchers develop cockroach robot that flips itself with insect-inspired wings
Photo: Terradynamics Lab/JHU

For the last several years, we’ve been following closely (and somewhat uncomfortably) the development of robot cockroaches. Depending on your perspective, it’s either good news or bad news that they seem to be spreading. As roboticists graduate from the original home of the robot cockroach at UC Berkeley, they’re taking roachbot research everywhere.

Chen Li was a researcher at Berkeley’s Poly-PEDAL Lab and Biomimetic Millisystems Lab, where he gave little legged robots cockroach-inspired shells to help them push through obstacles. Li now has his own lab at Johns Hopkins University: the Terradynamics Lab studies “movement science at the interface of biology, robotics, and physics.” At IROS 2016, he presented a paper demonstrating a new trick for legged robots with shells: Ground-based dynamic self-righting, or flipping over using wing covers like a real insect does.

Li’s earlier research on small legged robots with rounded shells showed that the shells helped the robots get through obstacle courses, but because of the shape of the shells, if the robots flipped upside-down, they got stuck that way. Real cockroaches don’t have this problem, because they’re able to use their wings to right themselves. By cutting the shell in half and adding some actuators, Li gave his robots the same capability:

In order for this to work, the robot has to be fairly aggressive about it, quickly opening its wings as wide as it can. Interestingly, experiments also showed that if your robot is tired (i.e. low on battery), you still have a reasonable chance of a successful flip even at low opening magnitudes as long as you open the wings asymmetrically. 

For more details, we spoke with Professor Li via email:

IEEE Spectrum: Why is this method of self-righting better than other methods of self-righting for small robots?

Chen Li: One major uniqueness of our study is that the wings are designed directly by modifying the earlier shell that helps traverse obstacles, and with future integration in mind so we can “morph” the body by opening and closing wings. This would allow it to realize multiple locomotor functions and capabilities, including obstacle traversal via terradynamic streamlining and self-righting. My lab at JHU is working on this integration for multi-functional capabilities.

In addition, the winged self-righting is dynamic, e.g. using large kinetic energy to overcome potential barriers. This can offer higher performance (higher probability of success and faster) than most existing righting mechanisms that use quasi-static shape change, center of mass shifting, passive rotation (being unstable when upside down), or self-reassembly. 

Our systematic experiments also discovered how winged righting performance depends on wing opening magnitude, speed, asymmetry, and wing shape, so we can use these quantitative relationships as principles to control wing actuation and design appropriate wing shapes to guarantee righting and achieve the desired performance, as compared to the majority of righting mechanisms that do not yet have such principles.

Robot cockroach developed at Johns Hopkins University Photo: Terradynamics Lab/JHU

When do you think we will be able to build a robot with similar capabilities to a cockroach (being able to run, fly, climb, and self-right)?

I think this will take quite a while. The mobile robotics research community is just beginning to work towards robots that are truly multi-functional in environments that are dynamic complex. For terrestrial locomotion, this is particularly challenging, as we are in lack of advanced locomotor-terrain interaction models analogous to aerodynamics and hydrodynamics. This is a new research area that my lab is focusing on and hoping to contribute to. 

Other than these scientific principles that we still need to discover, there are also many engineering issues that remain to be solved, such as power limitations and materials and mechanisms that are as robust and resilient as those of animals.

What are you working on next?

Along the lines of this research, my lab is currently working on integrating wings and shells to enable multi-functional locomotion (e.g., first hold wings closed as shells for obstacle traversal, then, when flipped over, open them for dynamic self-righting). We are also developing a more robust winged self-righting robot as a physical model to further study the physics of dynamic self-righting.

More generally, my lab is developing new experimental tools and theoretical models to better understand the mechanics of locomotor-terrain interaction of both animals and robots in the real-world, and use such understanding to guide the design and control of terrestrial robots. We call this the new field of “terradynamics,” analogous to aero and hydrodynamics that help advance the design of aerial and aquatic robots.

“Cockroach-Inspired Winged Robot Reveals Principles of Ground-Based Dynamic Self-Righting,” by Chen Li, Chad C. Kessens, Austin Young, Ronald S. Fearing, and Robert J. Full from Johns Hopkins University, ARL, and UC Berkeley, was presented last month at IROS 2016 in South Korea.

[ JHU Terradynamics Lab ]

The Conversation (0)

How the U.S. Army Is Turning Robots Into Team Players

Engineers battle the limits of deep learning for battlefield bots

11 min read
Robot with threads near a fallen branch

RoMan, the Army Research Laboratory's robotic manipulator, considers the best way to grasp and move a tree branch at the Adelphi Laboratory Center, in Maryland.

Evan Ackerman
LightGreen

“I should probably not be standing this close," I think to myself, as the robot slowly approaches a large tree branch on the floor in front of me. It's not the size of the branch that makes me nervous—it's that the robot is operating autonomously, and that while I know what it's supposed to do, I'm not entirely sure what it will do. If everything works the way the roboticists at the U.S. Army Research Laboratory (ARL) in Adelphi, Md., expect, the robot will identify the branch, grasp it, and drag it out of the way. These folks know what they're doing, but I've spent enough time around robots that I take a small step backwards anyway.

This article is part of our special report on AI, “The Great AI Reckoning.”

The robot, named RoMan, for Robotic Manipulator, is about the size of a large lawn mower, with a tracked base that helps it handle most kinds of terrain. At the front, it has a squat torso equipped with cameras and depth sensors, as well as a pair of arms that were harvested from a prototype disaster-response robot originally developed at NASA's Jet Propulsion Laboratory for a DARPA robotics competition. RoMan's job today is roadway clearing, a multistep task that ARL wants the robot to complete as autonomously as possible. Instead of instructing the robot to grasp specific objects in specific ways and move them to specific places, the operators tell RoMan to "go clear a path." It's then up to the robot to make all the decisions necessary to achieve that objective.

Keep Reading ↓ Show less