Just over six years ago, when researchers at Harvard declared that they had made tiny flying robots, they instantly began talking about the possibility of their tiny creations working autonomously in complex environments. That seemed recklessly optimistic, given that the robots flew by trailing a set of copper wires that brought power and control instructions; the robots were controlled by a computer that observed their positions using a camera.
Since then, however, the team has continued working on improving the tiny machines, giving them enhanced landing skills, for instance. And today, the team is advertising the first demonstration of self-powered flight. The flight is very short and isn’t self-controlled, but the tiny craft handles to carry both the power supply circuitry and its own power source.
There are two ways to miniaturization, which you can think of as top-down and bottom-up. From the top-down side, companies are shortening components and cutting weight to allow ever smaller versions of quadcopter drones to fly, with some now available that weigh as little as 10 grams. But this type of hardware faces some hard physical limits that are going to limit how much it could shrink. Batteries, for example, end up with more of their mass going to packaging and support hardware rather than charge storage. And friction begins to play a dominant role in the performance of the standard rotating motors.
The alternative is bottom-up. Start with something similar to the flying insect-like robots and figure out how to expand their abilities. Not surprisingly, since they built the insect-like robot, the Harvard team has chosen a bottom-up approach.
Their original design had piezoelectric motors that could rapidly flap two wings, giving the robot with powered flight. Power with the high voltage and rapid oscillations was supplied externally. The same was true with flight control information: a camera system tracked the robot while in flight, and a computer figured out what adjustments were needed and sent similar adjustments directly to the wings.
The goal of this work is to get rid of some of that external hardware, shrinking it down so it can be placed on board the robot itself. For this new task, the researchers focused on the power source that keeps the robot airborne.