Researchers at the Ecole Polytechnique Federale de Lausanne (EPFL) have created the first functional robot powered entirely by vacuum. It is made of soft building blocks that move by having air sucked out of them. The robot can be reconfigured to perform different tasks, like climbing vertical walls and grabbing objects.

The architecture of the vacuum-powered soft pneumatic actuator (V-SPA) module. (Credit: Robertson and Paik, EPFL)

Inspired by muscle contraction, its individual soft components are activated (they collapse) when negative pressure (vacuum) is applied to them. The robot, which uses suction to grab objects or to stick to a smooth wall for climbing, can achieve a range of tasks because of the unique properties of vacuum. The robot can be reconfigured, making it modular and versatile, with a wide range of applications in both research and industry.

“What we have is a fully functional robot that is entirely powered by vacuum, which has never been done before,” said EPFL roboticist Matt Robertson, who worked on the project. “Previous work has shown individual components powered by vacuum, but never in a complete system.”

Vacuum-powered components are a recent addition to robotics, and more importantly, they’re safe. Today, most actuators on the market are activated by applying positive pressure, i.e. by injecting air into their components. But containing positive pressure requires stiff, high-pressure pneumatics, which also pose a safety threat — in extreme situations, they can explode. By comparison, vacuum-powered actuators are safe, soft, and simple to build.

The critical robotic actuator component, the V-SPA, uses vacuum power and a foam core. This actuator is simple in design and easy to fabricate without the need for either an internal or external mold. It is composed of a laser-cut, off-the-shelf foam core and thin, brushed-on layers of silicone rubber, and can be manufactured from scratch. The foam core acts as an internal scaffold over which uncured silicone rubber can be applied to form a thin sealing layer around the open-celled foam. This creates an enclosed, airtight structure that is only sparsely filled with soft, porous material.

A three-module robot configuration. (Credit: EPFL)

Upon activation, vacuum is applied internally through a supply channel, and the entire V-SPA structure collapses inward to produce tensile force that can be used for actuation. The low-density core is easily deformed and crushed when vacuum is applied, but immediately provides elastic return in conjunction with the elasticity of the outer silicone membrane after actuation to return the actuator to its original shape.

The actuator is one part of the V-SPA module building block, which also contains pneumatic and module connectors, solenoid valves, and electronics. “Our soft building blocks are designed to be plug-and-play, so ultimately we can assemble several types of robots from the same basic units,” said EPFL scientists and lead researcher Jamie Paik. “They can be reconfigured to perform different tasks like crawling, gripping canisters, and climbing a vertical wall.”

A five-module robot can move like a tentacle; a four-module robot with a suction gripper can grab an object and drop it on a target; a three-module robot can crawl on the ground; and a two-module robot can be equipped with suction-cup feet to climb a smooth, vertical surface such as glass. The versatility of the new robots can be exploited for studying locomotion, and for future applications at an industrial level.

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