Quadcopter With Tensegrity Shell Takes A Beating And Gets Back Up

November 5, 2020 by Roger Cheng 11 Comments

Many of us have become familiar with the distinctive sound of multirotor toys, a sound frequently punctuated by sharp sounds of crashes. We’d then have to pick it up and repair any damage before flying fun can resume. This is fine for a toy, but autonomous fliers will need to shake it off and get back to work without human intervention. [Zha et al.] of UC Berkeley’s HiPeRLab have invented a resilient design to do so.

We’ve seen increased durability from flexible frames, but that left the propellers largely exposed. Protective bumpers and cages are not new, either, but this icosahedron (twenty sided) tensegrity structure is far more durable than the norm. Tests verified it can survive impact with a concrete wall at speed of 6.5 meters per second. Tensegrity is a lot of fun to play with, letting us build intuition-defying structures and here tensegrity elements dissipate impact energy, preventing damage to fragile components like propellers and electronics.

But surviving an impact and falling to the ground in one piece is not enough. For independent operation, it needs to be able to get itself back in the air. Fortunately the brains of this quadcopter has been taught the geometry of an icosahedron. Starting from the face it landed on, it can autonomously devise a plan to flip itself upright by applying bursts of power to select propeller motors. Rotating itself face by face, working its way to an upright orientation for takeoff, at which point it is back in business.

We have a long way to go before autonomous drone robots can operate safely and reliably. Right now the easy answer is to fly slowly, but that also drastically cuts into efficiency and effectiveness. Having flying robots that are resilient against flying mistakes at speed, and can also recover from those mistakes, will be very useful in exploration of aerial autonomy.

[IROS 2020 Presentation video (duration 14:16) requires free registration, available until at least Nov. 25th 2020. One-minute summary embedded below]

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Flies Like A Quadcopter, But This Drone Design Has Only One Propeller

November 2, 2020 by Danie Conradie 35 Comments

When mentioning drones, most people automatically think of fixed-wing designs like the military Reaper UAV or of small quadcopters. However, thanks in large part to modern electronics, motors, and open-source control systems, it is possible to build them in a variety of shapes and sizes. [Benjamin Prescher] is working on the second version of his single rotor Ball-Drone, which uses four servo-actuated fins for control.

The first version of the ball drone flew but was barely controllable and had a tendency to tip over. After a bit of research, he found that he had fallen victim to the drone pendulum fallacy by mounting the heavy components below the propeller and control fins. Initially, he also used conventional fin control that caused the servos to jitter due to high torque loading. By changing to grid fins, the actuation torque was reduced, eliminating the servo jitter.

Mk2 corrected the pendulum problem by moving most of the components to the top of the drone. The 3D printed frame (available on Thingiverse) was also dramatically changed and simplified to reduce weight. Although [Benjamin] designed a custom flight controller with custom control software, the latest parts list contains an off-the-shelf flight controller. He mentions that he had started working with Betaflight. The most complex part of a drone is not the mechanics or even the electronics, but the control software. Thanks to open source projects like Betaflight and Ardupilot, you don’t need to write control software from scratch to get something in the air.

The ball drone seems well suited to an indoor environment, but we’re not sure if it has any real advantages over a quadcopter with ducted propellers. Servos are cheaper than motors and ESCs, so there might be a small cost saving. Drop your thoughts on the advantages/disadvantages in the comments below. Continue reading “Flies Like A Quadcopter, But This Drone Design Has Only One Propeller” →

Fuel Cell Drone Aims For Extended Flight Times

October 31, 2020 by Lewin Day 15 Comments

The RC world was changed forever by the development of the lithium-polymer battery. No longer did models have to rely on expensive, complicated combustion engines for good performance. However, batteries still lack the energy density of other fuels, and so flying times can be limited. Aiming to build a drone with impressively long endurance, [Игорь Негода] instead turned to hydrogen power.

The team fitted a power meter to the plane, aiming a camera at it to measure power draw during flight.

With a wingspan of five meters, and similar length, the build is necessarily large in order to carry the hydrogen tank and fuel cell that will eventually propel the plane, which uses a conventional brushless motor for propulsion. Weighing in at 6 kilograms, plenty of wing is needed to carry the heavy components aloft. Capable of putting out a maximum of 200W for many hours at a time, the team plans to use a booster battery to supply extra power for short bursts, such as during takeoff. Thus far, the plane has flown successfully on battery power, with work ongoing to solve handling issues and determine whether the platform can successfully fly on such low power.

We’re eager to see how the project develops, particularly in regards to loiter time. We can imagine having a few pilots on hand may be necessary with such a long flight time planned — other drones of similar design have already surpassed the 60-minute mark. Video after the break.

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Dynamic Soaring: 545 MPH RC Planes Have No Motor

September 24, 2020 by Elliot Williams 59 Comments

The fastest remote-controlled airplane flight ever recorded took place in 2018, with a top speed of 545 miles/hour. That’s 877 km/h, or Mach 0.77!

What was the limiting factor, preventing the pilot-and-designer Spencer Lisenby’s plane from going any faster? The airstream over parts of the wing hitting the sound barrier, and the resulting mini sonic booms wreaking havoc on the aerodynamics. What kind of supercharged jet motor can propel a model plane faster than its wings can carry it? Absolutely none; the fastest RC planes are, surprisingly, gliders.

Dynamic soaring (DS) was first harnessed to propel model planes sometime in the mid 1990s. Since then, an informal international competition among pilots has pushed the state of the art further and further, and in just 20 years the top measured speed has more than tripled. But dynamic soaring is anything but new. Indeed, it’s been possible ever since there has been wind and slopes on the earth. Albatrosses, the long-distance champs of the animal kingdom, have been “DSing” forever, and we’ve known about it for a century.

DS is the highest-tech frontier in model flight, and is full of interesting physical phenomena and engineering challenges. Until now, the planes have all been piloted remotely by people, but reaching new high speeds might require the fast reaction times of onboard silicon, in addition to a new generation of aircraft designs. The “free” speed boost that gliders can get from dynamic soaring could extend the range of unmanned aerial vehicles, when the conditions are right. In short, DS is at a turning point, and things are just about to get very interesting. It’s time you got to know dynamic soaring.

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You Don’t Need A Weatherman To Know Which Way The Drone Blows

September 7, 2020 by Al Williams 11 Comments

“How’s the weather?” is a common enough question down here on the ground, but it’s even more important to pilots. Even if they might not physically be in the cockpit of the craft they are flying. [Justin Parsons] explains how weather affects drone flights and how having API access to micro weather data can help ensure safe operations.

As drone capability and flight time increase, the missions they will fly are getting more and more complex. [Justin] uses a service called ClimaCell which has real-time, forecast, and historical weather data available across the globe. The service isn’t totally free, but if you make fewer than 1,000 calls a day you might be able to use a developer account which doesn’t cost anything.

According to [Justin], weather data can help with pre-flight planning, in-flight operations, and post-flight analysis. The value of accurate forecasting is indisputable. However, a drone or its ground controller could certainly understand real-time weather in a variety of ways and record it for later use, so the other two use cases maybe a little less valuable.

While on the subject, it seems to us that accurate forecasting could be important for other kinds of projects. Will you have enough sun to catch a charge on your robot lawnmower tomorrow? If your beach kiosk is expecting rain, it could deploy an umbrella or close some doors and shutdown for a bit.

If you insist on using a free service, the ClimaCell blog actually lists their top 8 APIs. Naturally, their service is number one, but they do have an assessment of others that seems fair enough. Nearly all of these will have some cost if you use it enough, but many of them are pretty reasonable unless you’re making a huge number of calls.

How would you use accurate micro weather data? Let us know in the comments. Then again, sometimes you want to know the weather right from your couch. Or maybe you’d like your umbrella to tell you how long the storm is going to last.

Approaching The Drop Location: Seeds Away!

September 4, 2020 by Brian McEvoy 8 Comments

Arbor Day is a holiday many countries dedicate to planting trees, but with the steady encroachment of climate change, we need to maximize our time. Dronecoria doesn’t just plant a tree; it sows “hectares in minutes.” A hectare is 10,000 square meters or 2.471 acres. These aren’t the drones you’re looking for if you intend a weekend of gardening, this is in the scope of repopulating a forest with trees or reinvigorating a park with wildflowers. The seed balls in the hopper are 10kg of native seeds coupled with beneficial microorganisms to help the chances of each drop.

The drone’s body is laser cut from what looks like baltic birch plywood. The vector files are available in Illustrator (.ai) and CAD (.dxf) formats released under Creative Commons BY-SA, so give credit if you redistribute or remix it. In the 3D realm, you’ll need a SeedShutter and SeedDisperser, and both models are available in STL format.

We have other non-traditional seed spreading methods like canons, but it is a big job, and if you’ve build something to pitch in, drop us a tip!

An Up-Close Look At The First Martian Helicopter

September 2, 2020 by Dan Maloney 49 Comments

The news was recently abuzz with stories of how the Mars 2020 mission, which launched from Cape Canaveral at the end of July, had done something that no other spacecraft had done before: it had successfully charged the batteries aboard a tiny helicopter that is hitching a ride in the belly of the Mars 2020 rover, Perseverance.

Although the helicopter, aptly named Ingenuity, is only a technology demonstrator, and flight operations will occupy but a small fraction of the time Mars 2020 is devoting to its science missions, it has still understandably captured the popular imagination. This will be humanity’s first attempt at controlled, powered flight on another planet, after all, and that alone is enough to spur intense interest in what amounts to a side-project for NASA. So here’s a closer look at Ingenuity, and what it takes to build a helicopter that will explore another world.

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