Researchers at Harvard have created a new robot that’s the smallest, fastest, and most precise of its kind. It’s called the milliDelta, and can move so quickly — up to 75 motions a second — that on camera it’s just a blur. The bot could be put to a range of uses, says its creators, from working in assembly lines for making tiny circuitboards to assisting in delicate microsurgeries.
The milliDelta is an extreme example of what’s usually called a “delta robot.” This is a design of robot that was invented in the 1980s, and is usually found in factories doing “pick and place” work. This is exactly what it sounds like, and involves selecting items off a conveyor belt and slotting them into place. The first ever delta robot was actually built to work in a chocolate factory, and placed pralines into their packaging.
Delta robots are fast and precise thanks to a few clever engineering decisions. Unlike industrial robot arms, which have motors located in their joints, delta robots are controlled by motors in a central base station. This means their arms (which are arranged in a triangular formation, hence the name) can be extremely lightweight, so moving them about doesn’t require much force.
This leads to more speed and precision. Just think of the difference between waving a cardboard tube around in the air and waving a broom handle. You can see some standard delta robots in action in the video below, picking and placing salami:
The milliDelta takes this same basic configuration, but uses new components to shrink in size while retaining the characteristics that make delta bots useful. Instead of the usual electric motors, its motion is powered by piezoelectric actuators. Piezoelectric materials respond to electric voltage by shrinking or expanding, and the milliDelta’s arms are made from sandwiches of the stuff, one side positively charged, and the other, negative. Running a current through the milliDelta’s arms will make them bend back and forth.And because of its size and weight, it’s extremely quick.
“Delta robots are pretty fast, but ours basically blows those ones out of the water,” Harvard researcher Hayley McClintock, co-first author of a new paper describing the milliDelta, told Science Robotics. “Most currently available delta robots are around a couple of hertz, so a couple of picks per second, and our delta robot can move up to 75 hertz — so it’s 15 to 25 times higher frequency than anything that’s currently available.”
The milliDelta could be put to work doing the same sort of pick and place tasks that regular delta robots do, just at a much smaller scale. McClintock and her team also suggest a more intriguing use for the bot: assisting in delicate medical operations.
“One we were thinking of was eye surgery,” says McClintock. “You have problems with tremors when you’re operating in such a small area, so the milliDelta could be used as a tremor-counteracting end-effector for eye surgery.” In other words, it would be placed on the end of surgical tool, with its movements cancelling out the natural wobbles of the surgeon’s hands — like a small version of the self-stabilizing spoons used by Parkinson’s sufferers to compensate for tremors while eating.
That’s the milliDelta: mini, but mighty.