Like maintaining a zen garden, or pruning a bonsai tree, some people stack and balance rocks as a way to relax. But robots don’t really experience emotional stress, so why bother teaching a bot to balance rocks? One day, this robot’s skills could prove invaluable when it comes to building structures on distant worlds we’re trying to colonize.


Robots at excel at building structures using simple materials, like the repetitive task of assembling a brick wall. But when uniform bricks are replaced with randomly-sized rocks, the task becomes far too complex for most automatons, with too many random variables for them to handle.

That might not be the case for much longer. At the 2017 International Conference on Robotics and Automation (ICRA) last week, researchers from ETH Zurich presented a paper detailing a robotic system they’ve developed that’s capable of intelligently stacking and balancing irregularly-shaped objects, with the ultimate goal of building larger structures. Such bots could be used to build giant stone walls that help shield man-made structures from inclement weather, or assist in the building of levees or breakwaters. On construction sites where an existing building has already been demolished, these robots could even re-use giant chunks of concrete for foundations, minimizing the amount of clean-up work needed.

Using a camera that’s capable of scanning objects in 3D, a robot arm with a three-fingered gripper was able to create detailed models of multiple sandstone rocks, and use those models to intelligently stack and balance rocks on top of each other, making a simple tower.


As the video of the robot in action demonstrates, even when able to simulate how the rocks will stack ahead of time using 3D models, the bot’s towers still occasionally toppled as small instabilities added up. But according to the researchers, this robot has been able to stack as many as six rocks, outperforming untrained humans.

Aside from building decorative rock towers in your mom’s flower garden, the ETH Zurich roboticists see their research being practical for more industrial applications. In a factory or warehouse setting, for example, a robot arm that knows the size, shape, and weight distribution of a delicate object could pack it in a box or crate in a way that ensures it won’t move or shift in transport, reducing the risk of damage.

As roboticist and project collaborator Hironori Yoshida told Gizmodo in an email, he sees this research being especially valuable when it comes to automating construction, and taking advantage of materials that already exist on a jobsite:

“The core value of our work in architecture is minimum material processing, whereas most of other digital fabrication methods are dependent on complex feeding mechanism, such as in 3D printing or brick laying. In our methods, ideally, we can use objects found onsite without use of mortar or cement, which makes maintenance much easier.”




Taking that idea further, as humanity inches closer to visiting other planets, on what would at least initially be one-way trips, we’ll need to find ways to build shelters and structures with the natural materials waiting for us on arrival. Astronauts visiting Mars, strewn with rocks and boulders, could deploy a robot to build the overall structure of a habitat using whatever it can scavenge. This could then be reinforced with materials from Earth, making it hospitable for humans.

[Hironori Yoshida - Autonomous Vertical Dry Stacking via IEEE Spectrum]