Autonomous flapping-wing micro-aerial vehicles (FWMAV) have a host of potential applications such as environmental monitoring, artificial pollination, and search and rescue operations. One of the challenges for achieving these applications is the implementation of an onboard sensor suite due to the small size and limited payload capacity of FWMAVs. The current solution for accurate state estimation is the use of offboard motion capture cameras, thus restricting vehicle operation to a special flight arena. In addition, the small payload capacity and highly non-linear oscillating dynamics of FWMAVs makes state estimation using onboard sensors challenging due to limited compute power and sensor noise. In this paper, we develop a novel hardware-in-the-loop (HWIL) testing pipeline that recreates flight trajectories of the Harvard RoboBee, a 100mg FWMAV. We apply this testing pipeline to evaluate a potential suite of sensors for robust altitude and attitude estimation by implementing and characterizing a Complimentary Extended Kalman Filter. The HWIL system includes a mechanical noise generator, such that both trajectories and oscillatinos can be emulated and evaluated. Our onboard sensing package works towards the future goal of enabling fully autonomous control for micro-aerial vehicles.

What these tiny robots can do will amaze you! There is a robotic revolution underway and unfortunately, we are somewhat distracted to witness it. From microbot swarms that could shapeshift, walk, fly, swim, climb, crawl and organize themselves to do various tasks, deliver drugs in our bodies, identify cancers, destroy tumours, these are the kind of stuff that dreams are made of. And all these have been a possibility thanks to the latest advances in nanotechnology, computing, electronics, and mechanics. Here are those most advanced, creative, and enigmatic microbots that you never knew existed and would make life so much easier for us.

The sight of a RoboBee careening towards a wall or crashing into a glass box may have once triggered panic in the researchers in the Harvard Microrobotics Laboratory at the Harvard John A. Paulson School of Engineering and Applied Science (SEAS), but no more. Researchers at SEAS and Harvard's Wyss Institute for Biologically Inspired Engineering have developed a resilient RoboBee powered by soft artificial muscles that can crash into walls, fall onto the floor, and collide with other RoboBees without being damaged. It is the first microrobot powered by soft actuators to achieve controlled flight. "There has been a big push in the field of microrobotics to make mobile robots out of soft actuators because they are so resilient," said Yufeng Chen, Ph.D., a former graduate student and postdoctoral fellow at SEAS and first author of the paper. "However, many people in the field have been skeptical that they could be used for flying robots because the power density of those actuators simply hasn't been high enough and they are notoriously difficult to control. Our actuator has high enough power density and controllability to achieve hovering flight."

A group of scientists have created a resilient RoboBee, that can survive crashing into walls and other robots without being damaged. The invention marks the first microrobot powered by soft artificial muscles that has achieved a controlled flight. Researchers in the Harvard Microrobotics Laboratory at the Harvard John A. Paulson School of Engineering and Applied Science (SEAS) developed a resilient artificial bee powered by soft actuators. Often these soft components have been dismissed as too difficult to control as their flexibility can lead to the system buckling at weak points if pushed to activate movements at speed. Yufeng Chen, a former graduate student and postdoctoral fellow at SEAS and first author of the paper, said: 'There has been a big push in the field of microrobotics to make mobile robots out of soft actuators because they are so resilient.'

In the Harvard Microrobotics Lab, on a late afternoon in August, decades of research culminated in a moment of stress as the tiny, groundbreaking Robobee made its first solo flight. Graduate student Elizabeth Farrell Helbling, Ph.D.'19, and postdoctoral fellow Noah T. Jafferis, Ph.D. from Harvard's Wyss Institute for Biologically Inspired Engineering, the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), and the Graduate School of Arts and Sciences caught the moment on camera. Helbling, who has worked on the project for six years, counted down: "Three, two, one, go." The bright halogens switched on and the solar-powered Robobee launched into the air. For a terrifying second, the tiny robot, still without on-board steering and control, careened towards the lights.

To achieve untethered flight, this latest iteration of the Robobee underwent several important changes, including the addition of a second pair of wings. 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, the team said. The extra lift, with no additional power requirements, allowed the researchers to cut the power cord -- which has kept the Robobee tethered for nearly a decade -- and attach solar cells and an electronics panel to the vehicle. The solar cells, the smallest commercially available, weigh 10 milligrams each and get 0.76 milliwatts per milligram of power when the sun is at full intensity. The Robobee X-Wing needs the power of about three Earth suns to fly, making outdoor flight out of reach for now.

In 2013, some folks from Rob Wood's lab at Harvard, including then-postdoc Sawyer Buckminster Fuller, published a paper in Science introducing a (mostly) controllable version RoboBee, an insect-size flying robot that could lift itself, hover, and move around a bit using two flapping wings. Since then, there have been several more generations of RoboBee, including this nutty explosive diving one. The problem with robots at this scale, and especially flying robots at this scale, is energy storage. It takes a lot of oomph to lift off of the ground and stay there, which means that high power is necessary, which means a relatively big battery to provide that power for a significant amount of time, which means a heavier robot over, which means more power is required to lift off, and you can see what the problem is. Fuller has since moved on to a professorship at the University of Washington, where he's been working on ways of solving this problem of power autonomy.

While engineers have had success building tiny, insect-like robots, programming them to behave autonomously like real insects continues to present technical challenges. A group of Cornell engineers has been experimenting with a new type of programming that mimics the way an insect's brain works, which could soon have people wondering if that fly on the wall is actually a fly. The amount of computer processing power needed for a robot to sense a gust of wind, using tiny hair-like metal probes imbedded on its wings, adjust its flight accordingly, and plan its path as it attempts to land on a swaying flower would require it to carry a desktop-size computer on its back. Silvia Ferrari, professor of mechanical and aerospace engineering and director of the Laboratory for Intelligent Systems and Controls, sees the emergence of neuromorphic computer chips as a way to shrink a robot's payload. Unlike traditional chips that process combinations of 0s and 1s as binary code, neuromorphic chips process spikes of electrical current that fire in complex combinations, similar to how neurons fire inside a brain.

When Harvard University first introduced RoboBee back in 2013, it could do little more than fly and cling to walls. Come 2018, the same research team has put out a new and improved RoboBee -- one that can successfully dive into and burst out of water. The latest in a series of minuscule, flight-capable robots, this RoboBee is a mere two cm tall and has a weight about one-fiftieth that of a penny. In order to achieve this, the team utilized a combination of experimental data and theoretical modeling to find the ideal flapping frequency for the wings in the air and in the water. Too low a frequency would make it difficult for RoboBee to fly after submerging in fluids, and too high a frequency would result in the wings snapping off. They found that 220 to 300 hertz was suitable for aerial flight, and nine to 13 hertz was best for water.

RoboFly is only slightly bigger than a real fly. A new type of flying robot is so tiny and lightweight -- it weighs about as much as a toothpick -- it can perch on your finger. The little flitter is also capable of untethered flight and is powered by lasers. This is a big leap forward in the design of diminutive airborne bots, which are usually too small to support a power source and must trail a lifeline to a distant battery in order to fly, engineers who built the new robot announced in a statement. Their insect-inspired creation is dubbed RoboFly, and like its animal namesake, it sports a pair of delicate, transparent wings that carry it into the air. But unlike its robot precursors, RoboFly ain't got no strings to hold it down.