Inverted Pendulum Balanced On A Drone

November 25, 2021 by Dave Rowntree 9 Comments

[Nicholas Rehm] works during the day at the Applied Physics Laboratory at Johns Hopkins, Maryland, so has considerable experience with a variety of UAV applications. The question arose about how the perseverance mars rover landing worked, which prompted [Nicholas] to hang a rock under his drone, attached via a winch. This proved to be interesting. But what is more interesting for us, is what happens when you try to attach an inverted pendulum to the top of a drone in flight? (video embedded, below)

This is a classic control theory problem, where you need to measure the angle of the pendulum with respect to the base, and close the loop by calculating the necessary acceleration from the pendulum angle. Typically this is demonstrated in one dimension only, but it is only a little more complicated to balance a pendulum with two degrees of freedom.

[Nicholas] first tried to derive the pendulum angle by simply removing the centering springs from an analog joystick, and using it to attach the pendulum rod to the drone body. As is quite obvious, this has a big drawback. The pendulum angle from vertical is now the sum of the joystick angle and the drone angle, which with the associated measurement errors, proved to be an unusable setup. Not to be discouraged, [Nicholas] simply added another IMU board to the bottom of the pendulum, and kept the joystick mechanism as a pivot only. And, as you can see from the video after the break, this indeed worked.

The flight controller is [Nicholas’] own project, dRehmFlight (GitHub), which is an Arduino library intended for the Teensy 4.0, using the ubiquitous MPU6050 6-DOF IMU. [Nicholas] also made an intro video for the controller, which may prove instructive for those wishing to go down this road to build their own VTOL aircraft. The code for pendulum experiment is not available at the time of writing, perhaps it will hit the GitHub in the future?

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Omnirotor flies over obstacles with its gimballed, caged, coaxial rotors.

Gimballed Omnirotor Goes Over Great Obstacles

November 13, 2021 by Ryan Flowers 6 Comments

What can drive on the ground, hop in the air, and continuously move its coaxial rotor assembly without ever having to reset its position? The answer is [New Dexterity]’s Omnirotor All-Terrain Platform.

Although still very much a prototype, the video below the break shows that the dexterity claimed by Omnirotor isn’t just a lot of hype. Weaving through, around, and over obstacles is accomplished with relative ease by way of a coaxial rotor configuration that’s sure to turn some heads.

While not novel in every aspect, the Omnirotor’s strength comes from a combination of features that are fairly unique. The coaxial rotors are fully gimballed, and as such can be moved to and from any direction from any other direction. In other words, it can rotate in any axis infinitely without needing to return to a home position. Part of this magic comes from a very clever use of resources: The battery, speed controllers, and motors are all gimballed as one. This clever hack avoids the need for large, heavy slip rings that would otherwise be needed to transmit power.

Adding to the Omnirotor’s agility is a set of wheels that allow the craft to push itself along a surface, presumably to decrease power consumption. What if an obstacle is too difficult to drive around or past? The Omnirotor takes to the air and flies over it. The coaxial rotors are caged, protecting them from the typical rotor-snagging dangers you’d expect in close quarters.

[New Dexterity] has Open Sourced the entire project, with the Omirotor design, Firmware, and even the benchmarking platform available on Github so that others can share in the fun and iterate the design forward even further.

You might also enjoy this tetrahedron based omnirotor, or another omnirotor that knows how to play fetch. Really.

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[Nick Rehm] explains the workings of a gps-less self guided drone

Autonomous Drone Dodges Obstacles Without GPS

November 3, 2021 by Ryan Flowers 5 Comments

If you’re [Nick Rehm], you want a drone that can plan its own routes even at low altitudes with unplanned obstacles blocking its way. (Video, embedded below.) And or course, you build it from scratch.

Why? Getting a drone that can fly a path and even return home when the battery is low, signal is lost, or on command, is simple enough. Just go to your favorite retailer, search “gps drone” and you can get away for a shockingly low dollar amount. This is possible because GPS receivers have become cheap, small, light, and power efficient. While all of these inexpensive drones can fly a predetermined path, they usually do so by flying over any obstacles rather than around.

[Nick Rehm] has envisioned a quadcopter that can do all of the things a GPS-enabled drone can do, without the use of a GPS receiver. [Nick] makes this possible by using algorithms similar to those used by Google Maps, with data coming from a typical IMU, a camera for Computer Vision, LIDAR for altitude, and an Intel RealSense camera for detection of position and movement. A Raspberry Pi 4 running Robot Operating System runs the autonomous show, and a Teensy takes care of flight control duties.

What we really enjoy about [Nick]’s video is his clear presentation of complex technologies, and a great sense of humor about a project that has consumed untold amounts of time, patience, and duct tape.

We can’t help but wonder if DARPA will allow [Nick] to fly his drone in the Subterranean Challenge such as the one hosted in an unfinished nuclear power plant in 2020.

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IBM Attempts An Uncrewed Atlantic Crossing (Again)

October 11, 2021 by Al Williams 23 Comments

IBM and a non-profit company, ProMare, failed to send their 49-foot Mayflower autonomous ship across the Atlantic back in June. Now they are almost ready to try again. The Mayflower will recreate the path of its more famous namesake.

The total voyage is set to take a month, but the last attempt developed mechanical problems after three days. Now they are running more sea trials closer to shore before attempting another crossing in 2022. Continue reading “IBM Attempts An Uncrewed Atlantic Crossing (Again)” →

Tiny Winged Circuits Fall With Style

October 11, 2021 by Danie Conradie 10 Comments

Researchers at Northwestern University is moving the goalposts on how small you can make a tiny flying object down to 0.5 mm, effectively creating flying microchips. Although “falling with style” is probably a more accurate description.

A larger "IoT Macroflyer" with more conventional cicruitry — A larger “IoT Macroflyer” with more conventional circuitry

Like similar projects we featured before from the Singapore University of Technology and Design, these tiny gliders are inspired by the “helicopter seeds” produced by various tree species. They consist of a single shape memory polymer substrate, with circuitry consisting of silicon nanomembrane transistors and chromium/gold interconnects transferred onto it.

Looking at the research paper, it appears that the focus at this stage was mainly on the aerodynamics and manufacturing process, rather than creating functional circuitry. A larger “IoT Macroflyer” did include normal ICs, which charges a super capacitor from a set of photodiodes operating in the UV-A spectrum, which acts as a cumulative dosimeter. The results of which can be read via NFC after recovery.

As with other similar projects, the proposed use-cases include environmental monitoring and surveillance. Air-dropping a large quantity of these devices over the landscape would constitute a rather serious act of pollution, for which case the researchers have also created a biodegradable version. Although we regard these “airdropped sensor swarms” with a healthy amount of skepticism and trepidation, we suspect that they will probably be used at some point in the future. We just hope that those responsible would have considered all the possible consequences.

When Benchies Fly

October 9, 2021 by Al Williams 5 Comments

Most of us have printed a few benchies to test our 3D printers. The intrepid little boat has a variety of features that tax different parts of the printing process. However, the guys at [FliteTest] had a different idea. They set out in a competition to build a giant flying benchie. They aren’t quite done, but they did make some interesting progress, as you can see in the video below.

In all fairness, the benchies are not, themselves, 3D printed. Foamboard, however, is a bit more practical. Inevitably, you can’t help but think of a flying boat when you see the results.

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LEONARDO, a hybrid drone and bipedal robot

LEONARDO: The Hopping, Flying Bipedal Robot

October 7, 2021 by Dan Maloney 22 Comments

We appear to have a new entry atop the “Robots That Creep Us Out” leader board: meet LEONARDO, the combination quadcopter/bipedal robot.

LEONARDO, a somewhat tortured name derived from “LEgs ONboARD drOne,” is actually just what it appears to be: a quadcopter with a set of legs. It comes to us from Caltech’s Center for Autonomous Systems and Technologies, and the video below makes it easy to see what kind of advantages a kinematic mash-up like this would offer. LEO combines walking and flying to achieve a kind of locomotion that looks completely alien, kind of a bouncy, tip-toeing step that really looks like someone just learning how to walk in high heels. The upper drone aspect of LEO provides a lot of the stabilization needed for walking; the thrust from the rotors is where that bouncy compliance comes from. But the rotors can also instantly ramp up the thrust so LEO can fly over obstacles, like stairs. It’s also pretty good at slacklining and skateboarding, too.

It’s easy to see how LEO’s multimodal locomotion system solves — or more accurately, avoids — a number of the problems real-world bipedal robots are going to experience. For now, LEO is pretty small — only about 30″ (76 cm) tall. And it’s rather lightly constructed, as one would expect for something that needs to fly occasionally. But it’s easy to see how something like this could be scaled up, at least to a point. And LEO’s stabilization system might be just what its drunk-walking cousin needs.

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