A simulated soft robot controlled to reach the same target (red dot) while acting either soft (left) or stiff (right). (Credit: MIT researchers)

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

The researchers have proposed that an algorithm could operate soft robots. Using a simulation to help control a cable-driven soft robot, they 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. A similar sequence happens in our bodies each time we reach for something: A target position for our hand is translated into contractions of the muscles in our arm.

They are able to simultaneously control the position and stiffness of a cable-driven soft robot. 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. The team emphasizes that the advance isn’t a revolution in mechanical engineering, but rather a new twist on controlling cable-driven soft robots.