If there is one thing the world doesn't need, more cockroaches would surely be it.
Not so, according to a collaborative group of boffins from China and the University of California at Berkeley, who have pooled their efforts to create a near-indestructible, super-fast, cockroach-sized robot.
While some of our readers may now be standing, raising their fists to the heavens and screaming “WHY? WHY?” at the prospect, insect-scale robots potentially have many extremely useful applications.
The China/Berkeley team listed “environmental exploration, structural inspection, information reconnaissance, and disaster relief” as possible uses, which all sounds helpful and above-board. With the possible exception of “information reconnaissance,” which sounds extremely creepy.
“Insect-scale soft robots are known to be easily damaged, exhibit poor control of locomotion, or are slow moving due to the nature of their small structures,” the team's paper in the journal Science Robotics points out.
"These robots are made of rigid or partially rigid parts, resulting in poor robustness and low adaptability to shape changes and/or external perturbations,” the paper adds.
So they are easily damaged and can't bend or twist to deal with terrain imperfections. Which is obviously no good if you're trying to build a robot which can do anything useful.
Researchers have also tried building tiny robots with soft, flexible bodies that are activated by heat, light, magnetism or even humidity. But these typically “have slow responses, whereas others require bulky setups to generate the external power sources such as magnetic fields”.
While such robots might have applications under certain conditions, light, heat or humidity are obviously not always going to be available, and it seems to miss the point of building an insect-scale robot at all if it has to be accompanied by a large and heavy set of external magnets.
So the China/UC Berkeley team tried a new approach and built a simple-looking robot out of a sheet of polyvinylidene difluoride (PVDF), a material with piezoelectric qualities that contracts and expands when an alternating current is passed through it.
When combined with additional “leg” structures mounted under the roach-bot, this confers its ability to move using a ripple-like motion (see video below).
As the paper explains:
Under an alternating current (AC) driving power near the resonant frequency (850 Hz) of the structure, a prototype 10-mm-long robot (0.024 g) attained a relative speed of 20 BL/s [body lengths per second] – the fastest among published reports of insect-scale soft ground robots.
So it can move and move quickly. So far, so roachy. But twitchy speed is not the only advantage PVDF gives. It's also tough and deformable, meaning that despite it weighing less than a tenth of a gram, the team were able to subject another 0.06g prototype to "an adult human's full body weight" of 59.5kg (131 lbs) – or around a million times its own mass – and it was still able to buzz in an uncanny valley fashion afterwards.
This allows the UC Berkeley robot cockroach to emulate one of the cockroach's most maddening qualities: they are incredibly difficult to get rid of.
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"Most of the robots at this particular small scale are very fragile," Liwei Lin, mechanical engineer and contributor to the project from the UC Berkeley, told the Berkeley News. "If you step on them, you pretty much destroy the robot. We found that if we put weight on our robot, it still more or less functions."
So what is the future for a tiny robot which behaves like a cockroach and even looks a bit like one? Well, the prototype currently relies on external power sources, so the team are hoping to build an improved version powered by an onboard battery.
Once that is sorted, the sky – or in this case, the ground – is the limit. As the video shows, the roach-bot can travel up and down slopes, through pipes and can carry six times its own weight. Its light weight and simplicity mean it would presumably be cheap enough to be disposable.
One application would be exploring disaster sites, checking for survivors, danger areas and gas leaks using an onboard gas sensor. While many roach-bots would become stuck while exploring a site such as the recent Surfside condominium collapse in Miami, if enough were released, some might find a route through the rubble to make useful contributions to the rescue effort.
Of course, once they are suitably developed they will also inevitably be used to spy on people, sabotage cables and play practical jokes on people who don't like cockroaches. Which is, at the last count, pretty much everyone.
So thanks for that, boffins. ®