Snail-inspired robot climbs walls

Researchers based at the Bristol Robotics Laboratory have developed a robot that mimics the motion of a snail, an advance that could be applied to autonomous inspection of difficult-to-access surfaces.


The robot’s sliding suction mechanism enables it to slide on water, mimicking a snail’s mucus that also acts as an adhesive. 

The study, published in Nature Communications, shows a novel way for robots to scale walls easily, potentially changing how surfaces such as blades of wind turbines, hulls of ships, aircrafts and glass windows of skyscrapers are inspected. According to the team, these features also endow sliding suction with great potential for future applications in robotic fields, including industrial gripping, climbing, outdoor and transportation. 

Snails can stably slide across a surface with a single high-payload sucker, offering an efficient adhesive locomotion mechanism for next-generation climbing robots. The critical factor for snails’ sliding suction behaviour is mucus secretion, which reduces friction and enhances suction. 

In a statement, lead author Tianqi Yue, a research associate at Bristol University’s School of Engineering Mathematics and Technology, said: “People know that snails have a stable adhesive sliding behaviour, even though they are carrying a heavy payload, in this case a shell.

“Inspired by this, we presented a ‘sliding suction’ mechanism and developed a sliding suction robot, which achieved comparable sliding ability as snails.” 

As mucus plays an important role in the sliding suction mechanism, the team used water as a cheap, easy-to-access and clean artificial mucus to help the robot slide while the suction remained.

They optimised the materials of the suction cup, designed the mechatronic system of the robot, and were able to demonstrate practical applications of the robot, such as carrying a 200g mass and avoiding obstacles.

The robot also demonstrated high loaded sliding ability carrying 1kg mass, which is ten times heavier than itself. 

The sliding suction allows a lightweight robot to slide vertically and upside down, achieving high speeds and does not require energy during static adhesion.  

Tianqi said: “Through the performance of sliding suction robot, we demonstrated that sliding suction offers low energy consumption, high adhesion efficiency and safety, high loading capacity and low complexity, while only leaving a quick-to-evaporate water trail. 

“The most exciting finding of our research it that the proposed sliding suction mechanism is a novel clean climbing strategy and will significantly advance the development of the next-generation climbing robots.”