In the article, “The RoboBee Flies Solo,” Harvard John A. Paulson School of Engineering and Applied Sciences (2019) has stated that after decades worth of research, they have successfully developed the lightest ever vehicle to maintain sustained untethered flight on solar power.
They stated they have developed an extremely lightweight circuit and integrated high-efficiency solar cells to tackle the trade-off between mass and power. The addition of an extra pair of wings and a more efficient transmission gave the vehicle the extra lift it needed to forego the power cord and instead, integrates the smallest commercially available solar cells. These weigh in at 10 milligrams each and can harvest 0.76 milliwatts of power per gram, weighing the vehicle at 259 milligrams with a power consumption of 120 milliwatts. It stated their next aim was to add a control board to fly it outdoors.
What the team behind the RoboBee project has accomplished is remarkable. They were able to develop a drone that can sustain untethered flight, in a package that is no heavier than 259 milligrams. However, the RoboBee is still in its infancy stage and is unable to operate outside of controlled lab conditions but regardless, its implementation of untethered flight may be closer to reality than its predecessors.
The most compelling factor as to why the RoboBee is not ready to explore the outdoors is how the solar panels are being utilised. According to Jafferis et al. (2019), it requires the intensity of 3 suns to power the circuitry. They were able to replicate this in the lab by using large Halogen lamps pointing directly at the solar panels. However, stated in the article, the team later reassured that they are planning to work on a model that is 25 per cent times bigger than its current iteration. This would reduce the number of suns to 1.5, much closer to reality.
The second most compelling factor as to why it is not ready for the outdoors is that
it has no battery power reserve. This means that the solar panels that are affixed atop the RoboBee only power the actuators and circuitry. Without a power reserve, any change in pitch or yaw that causes the solar panels to divert away from the light source will cut off the power supply that is powering the actuators. According to Jafferis et al. (2019), the RoboBee only flew for about 0.5seconds before it flew outside the illuminated area. This reinforced the idea that flying out of the illuminated area, will cause the RoboBee to crash land.
However, it needs to be said that, RoboBee is not the first of its kind to have been developed. Researchers in the University Of Washington unveiled the RoboFly at the IEEE International Conference on Robotics and Automation in Brisbane, Australia in 2018. RoboBee and RoboFly have similar ideas of attaining untethered flight. However, the RoboFly is powered by a laser which is pointed at its photovoltaic cell, which can harvest 250 milliwatts to power the drone. Much like RoboBee, when the light source misses its target, the drone will stop flying. According to James et al. (2018), they stated that they will develop a laser that will track the drone’s photovoltaic cell.
When these two concepts of untethered flight are compared, it seems that RoboBee has a greater potential of flying outdoors than its counterpart. Although there is the issue of requiring three suns to power the RoboBee, it is a more practical solution as there is no need for a laser to track the drone’s movement. The implementation of lasers outdoors to power a drone does not seem practical, especially in huge numbers.
Reference
Jafferis, N. T., Helbling, E. F., Karpelson, M., & Wood, R. J. (2019, June 26). Untethered flight of an insect-sized flapping-wing microscale aerial vehicle. Retrieved from https://www.nature.com/articles/s41586-019-1322-0
James, J., Iyer, V., Chukewad, Y., Gollakota, S., & Fuller, S. B. (2018). Liftoff of a 190 mg Laser-Powered Aerial Vehicle: The Lightest Wireless Robot to Fly. 2018 IEEE International Conference on Robotics and Automation (ICRA). DOI: 10.1109/icra.2018.8460582
The RoboBee flies solo. (2019, June 27). Retrieved from https://wyss.harvard.edu/news/the-robobee-flies-solo/
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