Water-pumping robot worms its way over rugged coastal terrain

Biomimicry involves borrowing ideas from nature to solve engineering problems. This is what one of the research teams at New York University's Tandon School of Engineering specializes in. We recently covered their fish-inspired robot, so exploring water bodies seems to be taken care of.

Exploring or inspecting a coastline, however, is a completely different story.

It involves dealing with very diverse terrain: going over rocks, climbing slopes, sliding into the water, and getting back out. This is a pretty complex task, at least for existing robots. So, what we need is pretty much a robotic snake – or a worm. That’s exactly what the NYU Tandon researchers came up with: WorMa. The name WorMa combines “worm” and “mass,” and the robot tackles its challenge with a pretty smart mechanism.

The device looks like a giant worm, with five connected segments and four joints. It measures 50 cm (19.7 in) long and weighs just over 1 kilogram (2.2 lb). The really interesting part is that almost one third of its weight sits in two latex water balloons – one in its head and one in its tail. A pump in the middle section moves those 300 grams (10.6 oz) of water between the head and the tail, shifting the robot’s center of mass depending on where it needs to go.

Here's how it works.

When WorMa needs to climb an inclined surface, water shifts towards its head. That extra weight puts more force on the front of the robot, giving it better grip and more contact with the surface. As a result, the robot can climb slopes of up to 19.5 degrees.

In water, the strategy flips. The water mass moves to the tail, shifting the robot’s weight backward and helping it swim about 26% faster than it could otherwise. And when it needs to get out of the water and back onto the shore, the water moves towards the head again, giving the front of the robot enough traction to pull itself onto a sloped surface.

But all that wasn’t even the hardest part. As is the case for most kinds of robots, stairs were the one of the biggest issue for WorMa. The researchers applied the same principle here, but the tricky part is that the weight needs to shift constantly as the robot climbs up.

First, the water goes forward to provide enough traction. Then the weight shifts backward, making it easier to lift the head and push it toward the step. Once the head and the “neck” joint are anchored on the edge of the step, the water shifts to the head again, so the robot can pull its tail forward, and the cycle repeats. With this technique, WorMa managed to climb steps up to 15 cm (5.9 in) high.

There is still a lot of room for improvement in WorMa, however.

The research team is already working on making the pump faster, but the bigger challenge is to make the robot more independent. For now, WorMa doesn’t have sensors to detect what kind of terrain it’s facing, so the weight shifting is controlled externally. In the future, if the worm-robot gets sensors and the ability to recognize its changing surroundings, it could distribute its weight on its own and eventually move around almost completely autonomously.

A paper on WorMa was recently published in the journal Advanced Robotics Research.

Source: New York University