While robots armored with hard exoskeletons are common, they’re not always ideal. Soft-bodied robots, inspired by fish or other soft creatures, might better adapt to changing environments and work more safely with people. Roboticists generally have to decide whether to design a hard- or soft-bodied robot for a particular task. But that tradeoff may no longer be necessary.

Working with computer simulations, researchers developed a concept for a soft-bodied robot that can turn rigid on demand. The approach could enable a new generation of robots that combines the strength and precision of rigid robots with the fluidity and safety of soft ones.

Until recently, most soft robots were controlled manually but in 2017, the researchers — using a simulation to help control a cable-driven soft robot — picked a target position for the robot and had a computer figure out how much to pull on each of the cables in order to get there. Now, similar techniques are being used to determine that if the cables are pulled in just the right way, the robot will act stiff. While contracting the biceps alone can bend your elbow to a certain degree, contracting the biceps and triceps simultaneously can lock your arm rigidly in that position. The same principle was applied to robots.

The method takes advantage of the robots’ multiple cables — using some to twist and turn the body, while using others to counterbalance each other to tweak the robot’s rigidity.

On the computer, the roadmap was used to simulate movement and rigidity adjustment in robots of various shapes. The team tested how well the robots, when stiffened, could resist displacement when pushed. Generally, the robots remained rigid as intended, though they were not equally resistant from all angles.

Potential applications include healthcare, where soft robots could one day travel through the blood stream, then stiffen to perform microsurgery at a particular site in the body. Or they could be used in caring for human patients, where a robot’s softness could enhance safety, while its ability to become rigid could allow for lifting when necessary.

For more information, contact Abby Abazorius at This email address is being protected from spambots. You need JavaScript enabled to view it.; 617-253-2709.