Just When the researchers at Harvard announced more than six years ago that they had made tiny flying robots, they immediately talked about the prospect of autonomously working their tiny creations in complicated environments. This was highly optimistic as the robots tracked a couple of copper wires that provided power and control instructions. The robots were guided by a computer that monitored their position with a camera.
Since then, however, the team has been working to refine the tiny machines and, for example, give them improved landing skills. And today the team announces the first demonstration of a self-propelled flight. The flight is very short and not self-directed, but the small vehicle manages to carry both the power supply circuit and its own power source.
A Question of Miniaturization
There are two approaches to miniaturization that you can think of as top-down and bottom-up. From top to bottom, companies are shrinking their components and reducing their weight to fly ever smaller versions of quadcopter drones. Some of them are already available from 1
The alternative is bottom-up. Start with something similar to the flying insect-like robots and find out how to expand their abilities. Not surprisingly, the Harvard team has chosen a bottom-up approach since building the insect-like robot.
The original design featured piezoelectric motors that quickly beat two wings and powered the robot. Power with the high voltage and fast oscillations was supplied from the outside. The same was true for flight control information: a camera system tracked the robot during the flight, and a computer made the necessary adjustments and sent the appropriate adjustments directly to the wings.
The goal of this work is to eliminate these from some of these external hardware, downsize it so it can be placed aboard the robot itself. In this new work, the researchers focused on the energy source that holds the robot in the air.
Shrinking the Energy
As mentioned above, batteries have problems shrinking to the weights required for it, as things like the case, wiring and materials used to collect charges always add weight, no matter how small the weight Energy storage is. The best battery the researchers could find weighed four times as much as the robot's prototype. Instead, the team turned to photovoltaic hardware, where a 10-mg device can generate more than 7 watts of power in full sunlight.
However, flying the original hardware would require about seven times the performance. Therefore, the researchers improved the efficiency of the robotic flight by increasing the wing area and at the same time slowing down the flapping of the wings. And the easiest way was to double the number of wings, with each actuator now beating with two wings. Together with some improvements to the actuators, these have increased the lift of the wings by almost 40%.
The next problem was the connection of the piezo actuators to the solar power source. The piezo actuators require a high voltage (200 volts) and a fast switching (200 hertz oscillations). These parts were assembled from a mix of handmade and handmade components.
The ultimate design is to place the solar panels on a stalk, a bit like an umbrella. This is done to prevent the panels from interfering with the airflow driven by the blades. The electronics, on the other hand, stick to the bottom of the robot and provide a little balance. The entire pack weighs only 90 milligrams and has a weight ratio of 4: 1. The somewhat cumbersome result, the authors refer to as RoboBee X-Wing.
Flight in short bursts
How does it work? Well, the attached video shows that it flies, but only extremely short; Typical flights last less than half a second and require the incoming light of three suns. The authors refer to this as "sustainable," which appears to expand the definition of the word. The robot usually manages the control simply by not flying long enough to deal with it.