Robots are good at exploring land, sea, sky, and space, but a more difficult environment for them to navigate is through the ground. Now, engineers at UC Santa Barbara (UCSB) and Georgia Tech have developed a snake-like robot that uses a range of methods to dig deep through sand or soft soil.
Snakes have long been an inspiration for robots, thanks to their relative simplicity but flexibility in movements. As a result, they have been used to explore environments such as sand dunes, seabeds, pipelines, defunct nuclear power plants, and even the human body.
Now they are going underground. Of course, the biggest hurdle here is that there is more resistance, even in granular materials like sand and soil, than in water or air. But the UCSB and Georgia Tech team have developed a robot that can solve that problem in a number of ways.
The new design begins with an existing soft robot that moves by “growing” from its tip, like a vine. This has helped it during underground adventures – because the tip is the only moving part, the friction is much lower than when the whole body is in motion. To make it even easier to navigate, a device was attached to the growing robot’s head to blow air in front of it, pushing the sand aside to clear the way.
But there is another challenge: while moving horizontally through the sand, the robot tends to rise until it rises to the surface. That’s basic physics – there’s less pressure from a small amount of sand above the robot, compared to the pressure of compressed sand below it.
To combat that, the team built the robot to also shoot air downwards, to reduce that friction. Adding a wedge in the front, inspired by a tunneling sandfish lizard, also helps cut a path.
The end result is a small robot that can move with relative ease through dry, granular materials. It can avoid obstacles by twisting and spinning like a snake, or dive into the sand and emerge on the other side.
The team says the design could be useful for things like taking soil samples and installing underground pipes and cables.
The study was published in the journal Robotics Science. The snake robot can be seen in action in the video below.
Robotic trenching with tip extensions and granular vulcanization