A ROBOT that automatically categorises waste from construction and demolition projects could enable valuable raw materials to be recycled instead of ending up in landfill.

Industrial robots normally excel at precise tasks in controlled environments, such as assembling cars. More chaotic and hazardous tasks have fallen to humans – for example, sorting through piles of waste in search of precious raw materials that could be recycled. But perhaps not for much longer.

Led by Tuomas J. Lukka, a team of researchers at ZenRobotics in Helsinki, Finland, are hoping robots can take over waste recycling.

The company’s Recycler robot uses data from a combination of visual sensors, metal detectors, weight measurements and tactile feedback from a robotic arm to pick out likely pieces of refuse and categorise them.


Through trial and error its machine learning software has been taught to recognise around a dozen types of material, including different plastics. And it can pluck out concrete, metal and wood from a stream of waste as it moves along a conveyor belt.

“I’ve never heard of anyone actually trying to do this in such an unstructured environment,” says Edwin Olson, a computer scientist at the University of Michigan in Ann Arbor.

For more ambiguous types of waste, such as a piece of plywood with nails driven through it, the robot uses a spectrometer to recognise objects based on the unique patterns of light they reflect. This means the robot can distinguish the type of waste based on its colour and drop it into the appropriate bin.

Since the launch of the test phase in February, the robot has learned to correctly identify half of the construction debris it is fed.

That’s far from perfect. But in the US, construction waste accounts for 50 per cent of all landfill material, according to the Construction Materials Recycling Association. Recycling just a fraction of that would mean big savings in resources, as well as landfill fees.

Though engineered for construction waste, the robot could one day sort household waste as well, says Lukka.