A team of researchers at the Reconfigurable Robotics Lab (RRL) at France’s École Polytechnique Fédérale de Lausanne (EPFL) is developing soft, flexible, and reconfigurable robots that behave like human muscles. The intended application for the robots is as exoskeletons for use in physical rehabilitation of patients, to help them move.

“There’s very little risk of getting hurt if you’re wearing an exoskeleton made up of soft materials,” says RRL director Jamie Paik.

A soft-robot belt will hold stroke victims upright and guide their movements during rehabilitation exercises.The so-called "soft robots" are made of elastomers—silicon and rubber, for example—and are controlled using air pressure. The cucumber-shaped actuators can stretch as much as six times their normal length and bend in two directions. Computer-based modeling has been a critical focus of the R & D team, and it has conducted simulations and developed a computer model that precisely predicts how the actuators deform based on their shape, thickness, and base material. Those design tools are available online for roboticists and students.

As proof of concept, RRL researchers developed a soft-robot belt, built of several of the inflatable actuators, to hold stroke victims upright and guide their movements during rehabilitation exercises. The actuators are made of rubber and fishing line; fishing-line placement is what controls actuator deformation when air is injected using external pumps. The next generation of the belt will feature a miniaturized pumping system placed directly on the belt.