Flexible robots are often more practical than regular hard robots because they can negotiate rough terrain without getting stuck. They can squeeze themselves through tiny gaps in rescue operations, and they are more resilient, bouncing instead of breaking. And nothing is more flexible than an octopus. Therefore, the robot octopus is the most practical robot of all, and that’s before you get to its overdose of arms.
The robot octopus comes from a team at Italy’s Bio Robotics Institute at the Scuola Superiore Sant’Anna in Pisa, led by Cecilia Laschi. The OCTOPUS (as it is named) mimics its living counterpart in some surprising ways. First, it has eight jointless arms, which means that they can bend anywhere along their length and wrap around objects to grab them. The robot can also move in multiple ways. It can use its arms to “walk,” dragging itself along the seabed, or it can propel itself by inflating its body to pull in water, then squeezing the water out to make a jet.
Soft robotics its a fascinating field, and research has explore many directions. For instance, one model fills the robot’s limbs with a granular material like sand, which remains bendy until a vacuum is applied, sucking out the air and stiffening the limb, like a brick of vacuum-packed coffee. Other approaches include limbs with liquid-filled chambers that can expand and contract to twist and bend the arm, and electro-active polymers, soft materials that change shape when electricity is applied.
Laschi’s team used shape-memory alloys (SMA), metals which change shape when heated. They put SMA springs into the tentacles, and when an electric current is applied, the springs contract. The material that forms the actual tentacle looks a little like a section of hosepipe, but it too is built so that it lengthens when the springs pull tight. This lets it mimic a real muscles, which elongates as it contracts.
Soft robot design isn’t as precise as that of stiff-limbed robots, and it doesn’t have to be. Robot on a car production line, for example, needs to repeat the exact same movement, over and over. A soft robot can afford some slack. It can bump its way to a final destination, for example, without damage. Mimicking nature has other advantages, too. In the real world, animals’ bodies “are designed to respond to their environment in certain automatic and useful ways,” writes Laschi in Spectrum IEEE. Her team used this principle when designing the OCTOPUS’s walking method.
Instead of trying to control multiple motors to coordinate eight different legs into an organized movement, the team created a computer model with an “evolutionary algorithm.” They fed the computer information on not only the legs, but the kinds of environment they’d be working in.
This algorithm started by creating many hypothetical octopus body shapes, each with its own set of characteristics. Then it tested those octopuses’ arms to see which performed best in the models, and used the “fittest” limbs’ attributes to inspire a new batch of possibilities. In this way, we identified an arrangement that would generate the correct amount of propulsive force and produce the desired crawling movement.
In the future, this kind of soft robot could be used to do things like maintenance in difficult environments—manipulating tools to make repairs underwater, for example. And tiny versions could be set to work inside our bodies. And soft robots are better-suited to working with humans than are their inflexible, hard-limbed cousins, which makes them ideal for rescue work in close quarters with disaster victims.
Soft robotics is fascinating, both for the possibilities for their future use, and for the engineering that goes into them. If only they didn’t have to be as creepy as this crawling, be-tentacled undersea horror.
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