DAEJEON, South Korea — Imagine a wheelchair equipped with wheels flexible enough to navigate all manner of obstacles from curbs to humps and even staircases.  


Or perhaps an unmanned delivery vehicle using the same wheels that takes the stairs to deliver food and groceries right to your door. 


This is what researchers from the Korea Institute of Machinery and Materials (KIMM) envision for their "morphing" wheel, which can roll over obstacles up to 1.3 times the height of its radius.  


Inspired by the surface tension of water droplets, it goes from solid to fluid when it encounters impediments. 


Other possible applications include robots that spy on the enemy in the battlefield. 




The KIMM team also hopes that morphing wheels will eventually be used with two- and four-legged robots - currently limited in movement efficiency and susceptible to vibration - that can carry payloads that need stable movement in industrial settings. 


"The goal is to make this viable for speed up to 100 kph, or the speed of an average car," said Song Sung-hyuk, principal researcher at KIMM. 


Wheels developed for a similar purpose such as nonpneumatic or airless tires have flexibility but are limited in their ability to overcome obstacles, said Song, who is a member of KIMM's AI robotics research team.  


The morphing wheel consists of an outer hoop of a chain and a series of spoke wires running through the hub. The stiffness of the spokes - and hence the wheel - is automatically regulated by a sensor as it reacts to the terrain. 


Song's team demonstrated to Reuters a prototype wheelchair mounted on morphing wheels as it climbed stairs with 18-cm steps with a life-size dummy sitting in it. The team has also tested a device mounted with the wheel at speeds of up to 30 kph. 


The morphing wheel was featured on the cover of the journal Science Robotics in August.