One big problem with robots is that they crush things. Not just in the “crushing all human civilization” sense, though. They literally crush things that they pick up, because they’re not so good at knowing when to stop squeezing. MIT’s new 3-D-printed silicone hand fixes this using a combination of simple, soft fingers and some clever software that allows the robot to identify objects just by grabbing them.
For an example of how smart our hands are, imagine this precarious scenario: You need to take your cup of coffee and your refilled water bottle back to your desk, so you hang the heavy bottle from your pinkie using its cool carabiner. This take a lot of force to keep your little finger bent. Then you delicately lift the plastic cup, holding it lightly enough to avoid crushing it, and also gingerly, perhaps grasping only the cup’s rim, so you don’t burn your fingers.
Then you use the same hand, maybe bent so you can use your wrist, to shove open the heavy kitchen door. That’s three conflicting operations, all carried out without thinking. We’re also good at knowing how much force we need before we even touch an object: If you ever hefted what you thought was a heavy box, only to find it empty, you’ll know how this can also go wrong.
MIT’s grippy hand uses three soft silicone fingers. These are pretty good already, because the silicone will comply to the shape of the grasped object. But the addition of sensors in each finger lets the robot know how hard each one is pressing. This simple knowledge is fed into an algorithm that tells the robot what it is actually grabbing hold of. The robot is taught using a standard set of objects, which it can later identify correctly, just by picking them up.
“Our dream is to develop a robot that, like a human, can approach an unknown object, big or small, determine its approximate shape and size, and figure out how to interface with it in one seamless motion,” says MIT CSAIL Director Daniela Rus, lead author of the paper.
This learned data can then be applied to randomly selected household objects. The soft hand is way better at picking up unknown objects than a rigid hand, partly because its soft nature allows for some leeway, whereas a rigid hand needs to approach an object perfectly.
“Through experiments we show that our hand is more successful compared to a rigid hand,” says the report, “especially when manipulating delicate objects that are easily squashed and when grasping an object that requires contacting the static environment.”
That’s right. You should be able to shake this robot by the hand, without suffering the crushing grip of a middle manager desperate for promotion.
A robot equipped with these deceptively simple hands can pick up an impressive range of objects. It can lift a plush toy without dropping it, slip a CD off a table and then grab it, and even pick up an egg and place it in an egg cup.
Don’t worry, though. MIT’s magic hand still gets tripped up in the same places human hands do. “The gripper had trouble picking up a slippery chopstick and toothbrush, though it had no issues picking up a similarly sized pen or long Q-tip.”