Pile-driving autonomous robot builds walls in the ground

Driven vertically into the ground, interlocking metal plates known as sheet piles can keep soil from eroding after rainfall, they can serve as retaining walls on slopes, or perform other functions. Installing them is a laborious process, though, which is why scientists have created a robot to do the job.

Developed by a team at Harvard University's Wyss Institute for Biologically Inspired Engineering, the wheeled robot is called Romu, and it's presently capable of carrying several sheet piles at a time.

In order to build structures such as erosion-minimizing check dams, it starts off with its chassis raised, gripping one of the piles and inserting its bottom end into the ground. The robot then lowers its body, on which the gripper is located, within its frame. This allows it to use its own weight to push the pile down. At the same time, an electric hammer mechanism within the body causes it to vibrate, helping to wiggle the pile into the soil.

Once the body has gone as far down as it can go, it releases the pile and raises itself back up. It then regrips the pile at a higher point, and starts pushing it down again. This process is repeated until Romu determines that the pile has been inserted to the desired depth.

The robot then moves forward, and inserts another pile that interlocks with the first one along its edge. Continuing in this manner, the device can build a dam (or other structure) made of multiple linked piles. And when the robot runs out of piles, it's capable of autonomously returning to a base station to get more.

As an added bonus, the system that allows it to raise and lower its body also lets all four of its wheels independently move up or down – this in turn makes it possible for Romu to remain level on sloped terrain, driving the piles straight down instead of at the angle of the slope.

So far, the technology has been demonstrated both in the lab and on a beach. The scientists hope that once it's developed further, wirelessly-linked swarms of the robots could work on large projects together. Utilizing onboard sensors, they could make sense of their environment, collaboratively figuring out where and in what manner the structures should be built.

"This sheet pile driving robot with its demonstrated ability to perform in a natural setting signals a path on which the Wyss Institute's robotics and swarm robotics capabilities can be brought to bear on both natural and man-made environments where conventional machinery, manpower limitations, or cost is inadequate to prevent often disastrous consequences," says Wyss Institute Founding Director, Donald Ingber. "This robot also could address disaster situations where walling off dangerous chemical spills or released radioactive fluids makes it difficult or impossible for humans to intervene."

Romu is demonstrated in the following video.

Source: Harvard University