Researchers at Harvard have developed faster actuators that might speed up soft robots. Existing soft robots must move large amounts of liquid or gas, resulting in slow movements. The new approach takes advantage of snap-through instabilities: big changes that are instantly triggered by small changes.
Normally, snap-through instabilities are associated with mechanical failure, thought to be uncontrollable, and avoided. This new application embraces the instantaneous nature of such instabilities and makes them controllable.
“When inflating a balloon, the first few blows are the hardest but after reaching a critical pressure it becomes easier,” said Johannes Overvelde first author on a paper outlining the reseach. “Similar to the balloons, in our research we connect fluidic segments in such a way that an interplay between their non-linear response results in unexpected behavior. Certain combinations of these interconnected segments can result in fast moving instabilities with negligible change in volume.”
In one experiment, 1 ml. of water triggered a snap-through instability that resulted in an internal volume flow of 20 ml.
“The beauty of these individual segments is that they are easy and cheap to fabricate from off-the-shelve materials. Yet, when you connect segments you get soft actuators with very complex behavior,” Overvelde said. “By connecting multiple segments, you can embed a simple program in the actuator that is able to perform a complex sequence of local inflation and deflation.”
The next step is testing the devices in soft robots.