General Electric apparently has a thing for crawling, nature-inspired robots. It has already field-tested Sarcos Robotics’ snake-like Guardian S robot for maintenance applications. Now GE Research, the technology development arm of GE, is developing a worm-like robot that digs tunnels for military applications.

This is part of a 15-month, $2.5-million project through the Defense Advanced Research Projects Agency’s (DARPA) Underminer program. The goal is to demonstrate the ability of a robot to “rapidly and efficiently bore tactical tunnels in support of critical military operations.”

GE hasn’t released a name yet for this soft robot, but clearly it’ll be named “Grabboid” or “Mega-Worm.”

The robot is based on an earthworm’s hydrostatic skeleton, which is a muscular structure filled with fluid. When worms move, some sections of their structure radially expand to enlarge the tunnel while anchoring the worm, while others become longer to create movement and penetrate further into the soil.

The robot uses artificial muscles that move in a similar fashion to a worm. The robot is capable of adaptively changing its gait depending on soil conditions. And it can create tunnels without having to bring any material to the surface, giving it advantages of efficiency and stealth.

The GE Research team already has designed a prototype and performed some initial lab scale demonstrations of the robot tunneling through dirt. The goal of the project is to demonstrate a robot that can move at a speed of 10 cm/sec and dig a tunnel that is 500 meters in length and at least 10 cm in diameter. You can see the robot in action in the video below, which runs at 4X the actual speed.

“It turns out earthworms are probably the most prolific tunnel makers on the planet,” said project leader Deepak Trivedi. “We have designed a prototype that is several feet long, with hydraulic artificial muscles that mimics the agility of earthworms moving through soil and with the force of tree roots penetrating through soft rock.”

Underground autonomy a challenge

One of the main challenges of building the robot, Trivedi said, is enabling it to autonomously navigate its way around obstacles underground without the benefit of GPS.

“Because these tunneling systems are underground, we need to be able to build in autonomous and sensing capabilities that enable our robot to move and tunnel in the right places,” he said. “Fortunately, we’re able to pull in controls, AI and sensing experts from across the lab to help us integrate these new capabilities.”

“The soft robot design we’re creating will have many more degrees of freedom in movement than conventional robots with joints, Trivedi said. “One of the reasons, octopuses, for example, can squeeze through such small spaces is that they have no bones. The same thing applies for soft robots, which can be very advantageous when you want to reach small places like the inside of a jet engine or power turbine to inspect and make intricate repairs.”