South Korean team develops morphing wheel

South Korean researchers are reinventing the wheel - literally - with a shape-shifting "morphing" wheel that could allow wheelchairs to climb stairs and navigate rocky paths.

Engineers at the Korea Institute of Machinery and Materials (KIMM) have developed what they claim to be the “world’s first” wheel that changes its stiffness in real time depending on the situation to allow wheelchairs and other mobility devices to overcome obstacles with ease.

Traditional wheels, while ideal for flat surfaces, struggle with stairs and uneven terrain due to their rigid, unchanging shape. The morphing wheel, however, shifts between rigid and soft states, offering stability on flat ground and transforming into a flexible form when encountering obstacles, without needing complex machinery or sensors.

This technology allows the wheels to overcome obstacles up to 1.3 times their radius and reach speeds of 30 km/h.

Using a smart chain block on its outer edge, the wheel can tighten or loosen in response to the terrain, much like how increased surface tension stabilizes a liquid droplet’s shape.

When wire spokes pull the smart chain blocks inward, the wheel becomes rigid for stability; when loosened, it softens, allowing it to mold to uneven surfaces.

The research team sees vast potential for this wheel in a range of applications, from personal mobility devices to industrial robots.

"This modularised wheel can be attached to any mobile platform simply by replacing existing wheels. Once installed, the wheel provides variable stiffness, adapting to each application," Song said. "We are continuously conducting research to optimize the wheel’s performance for various applications."

The wheel’s adaptability is inspired by the surface tension of liquid droplets, the researcher said.

This morphing wheel was featured on the cover of research journal Science Robotics in August 2024.