Wonderful Engineering

Robobee Flies Tether-Free For The First Time

How many of you are aware of the small Robobee from Harvard? The Robobee first appeared during the demonstration of its controlled flight leading to learning how to perch and swim and even coming out of water in style. Up till now, it was being powered using a tether, but the research team has managed to fly the Robobee without any wire tether by installing tiny solar panels on the robot.

The first solo flight of Robobee took place in August 2018. However, it has been described only recently in a paper that was published in the journal Nature. Graduate student Elizabeth Farrell Helbling, PhD and postdoctoral fellow Noah T. Jafferis have been developing the Robobee for six years. Certain modifications had to be made for this particular demonstration.

According to Jafferis, ‘The change from two to four wings, along with less-visible changes to the actuator and transmission ratio, made the vehicle more efficient, gave it more lift, and allowed us to put everything we need on board without using more power.’

When it comes to solar panels, the smallest yet commercially available ones weigh in at 10mg and are unable to collect enough energy from the sunlight to power a tether-free flight. This led the researchers to make use of halogen lights to provide solar power equivalent of three Suns. The PV cells are placed 3cm above the wings and have been connected to an electronics panel that is allowed to hand below Robobee.

The robot insect requires 120 mW of power to stay afloat in the air, and the task of this hanging panel is to carry out the conversion of low-voltage form the solar array into power that would suffice to control the actuators. The modified robot insect weighs 259 mg and is the lightest robot to fly yet.

The first flight was brief; the robot insect flew straight for the lights, and the researchers had to kill the lights, thus allowing the robot insect to be captured using the Kevlar safety harness. The next phase of the project will be to incorporate onboard steering and control systems.