Bee-sized micro-drones could one day be used for a variety of inspection tasks, or to even replace the bee population to artificially pollinate crops.
These micro-drones must consume low power but be powerful enough to take quality images. Researchers at MIT have shrunk a tiny computer chip, which it introduced last year, in both size and power consumption to cater to these bee-sized drones.
The new chip, named Navion, is just 20 square millimeters, roughly the size of a LEGO, and consumes just 24 milliwatts of power — about 1/1000 the energy needed to power a lightbulb. Navion is powerful enough to process real-time camera images at up to 171 fps, as well as inertial measurements.
Navion can be integrated into drones as small as a fingernail to help vehicles navigate, particularly in remote or inaccessible places where GPS data is unavailable. MIT said the chip design can also be run on a small robot or a device that needs to navigate over long stretches of time on a limited power supply.
“I can imagine applying this chip to low-energy robotics, like flapping-wing vehicles the size of your fingernail, or lighter-than-air vehicles like weather balloons, that have to go for months on one battery,” says Sertac Karaman, a member of the Laboratory for Information and Decision Systems and the Institute for Data, Systems and Society at MIT. “Or imagine medical devices like a little pill you swallow, that can navigate in an intelligent way on very little battery so it doesn’t overheat in your body. The chips we are building can help with all of these.”
Palm-sized drones can only carry so much battery power, most of which is used to run the motor, leaving little energy for other operations such as navigation. To shrink the chip in both size and power consumption, the team decided to build a chip from the ground up rather than reconfigure existing designs.
To reduce the power, the group decided on a design with a minimal amount of data stored on the chip at any given time. The design also optimizes the way this data flows across the chip.
“Any of the images we would’ve temporarily stored on the chip, we actually compressed so it required less memory,” said Vivienne Sze, associate professor in MIT's Department of Electrical Engineering and Computer Science (EECS).
The team was able to reduce the chip’s memory from 2 MB in earlier versions to about 0.8 MB. MIT then tested the chip on micro-drones flying through multiple environments like offices or warehouses.
“While we customized the chip for low-power and high-speed processing, we also made it sufficiently flexible so that it can adapt to these different environments for additional energy savings,” Sze said. “The key is finding the balance between flexibility and efficiency.”
The full research was presented as part of the 2018 Symposium on VLSI Circuits Digest of Technical Papers.