Designing and manufacturing an efficient aircraft is a challenge no matter the scale. Strong but lightweight components are required in order to support power and propulsion structures, electronics, etc. Last month, Harvard Microrobotics Lab researchers introduced RoboBee X-Wing, a solar-powered micro-aerial vehicle that fits in the palm of your hand.

Photo: Harvard Microrobotics Lab

The original, two-wing RoboBee mimics the body structure and behavior of real bees and is the lightest-ever vehicle to achieve sustained flight without being tethered to a power source. Its new and improved solar-powered four-wing cousin RoboBee X-Wing appears on the cover of the June 27 issue of Nature magazine.

Synced invited Shai Revzen, an assistant professor at the University of Michigan and principal investigator with the Biologically Inspired Robotics and Dynamical Systems (BIRDS) lab, to share his thoughts on RoboBee X-Wing.

How would you describe RoboBee X-Wing?

The RoboBee X-Wing is a free-flying platform with mass and power requirements comparable to those of insects. At this time, it is capable of flight and little more, but has excess payload capacity suggesting that it, or a similar platforms, could be used in future applications.

Why does this research matter?

The RoboBee X-Wing is a huge milestone in terms of scale (more than 10x lighter than previous micro-flyers) and in terms of the technologies that it uses. The RoboBees fly using piezoelectric actuators driving a flapping wing. This is a fundamentally different mode of flight from nearly all other man-made flying platforms in existence. As we know from insects in general, and dragonflies (Odonata sp.) in particular, small fliers with four wings can be extremely maneuverable and capable. The RoboBee X Wing could lead to an entirely new space for technological development of micro-fliers.

What impact might this work bring to the field?

Most directly, the RoboBee robots developed by Harvard Microrobotics Lab lead by Robert Wood, required the development of new manufacturing methods, new design methods, new lightweight power electronics, and more. These technologies will have impact on the kinds of robots we build, in particular in the smaller size scales, for many years to come. Specifically the RoboBee X-Wing opens the door to small, mass-produced flying robots in the 100mg weight class which could be used for a variety of sensing and communications applications.

Can you identify any bottlenecks in the research?

The most obvious bottleneck is power. The RoboBee X-Wing requires illumination at triple that of direct sunlight to obtain enough power to fly. Without another tenfold improvement in power consumption, this class of flying platforms cannot get off the ground even in full daylight. Alternatively, some other means of beaming power to these robots would need to be found. A second, non-trivial bottleneck is control — the RoboBee X-Wing flies, but has no sensing or processing capabilities that would enable any kind of autonomous operation. To be more than a novelty flying toy, this class of robots must be able to sense their environment and either make control decisions autonomously or communicate with a remote controller.

Can you predict any potential future developments related to this research?

Micro-flying Air Vehicles (MAV-s) hold great promise as platforms for sensing and communications. This promise is being realized today in the toy industry, for photography and surveillance, and is even creating new classes of consumer products such as a flying selfie cameras. The ability to miniaturize flying surveillance devices to less than 100mg will likely be the first domain in which RoboBee devices will be used (semi-)commercially. However, the miniaturization technologies behind the RoboBee devices will, in the longer term, have even greater impact — as they offer a recipe for building millimeter scale mechanical devices in general, and not just flying devices.

Anything else we should know about the tech?

RoboBee X-Wing, the RoboBees before it, and the revolutionary technologies behind them did not appear overnight. Like many fundamental technological innovations, they started with basic science. Nearly 20 years ago, Michael Dickinson and his students set out to understand how insects manage to fly, despite the fact that the aerodynamic theory used for fixed wing aircraft and rotor-craft predicts they cannot. The existence of biological examples — flying insects — gave certainty that flying platforms at the centimeter length scale are possible, and in 2001 RoboFly (JM Birch, MH Dickinson, Spanwise flow and the attachment of the leading-edge vortex on insect wings, Nature Aug 2001) first demonstrated the principles that gave us RoboBee X-Wing in 2019. The natural world gives us an enormous library of possibilities, with each species carrying precious knowledge evolved into its form and function. The fundamental science that reveals this knowledge to us is what feeds into and enables the brilliant and innovative engineering of groups like the Harvard Microrobotics Lab.

More details about Solar-Powered RoboBee X-Wing Flies Untethered is on Nature