UAV Flight Controller Saves Weight

When building autonomous airborne vehicles like drones or UAVs, saving a little bit of weight goes a long way, literally. Every gram saved means less energy needed to keep the aircraft aloft and ultimately more time in the air, but unmanned vehicles often need to compromise some on weight in order to carry increased computing abilities. Thankfully this one carries a dizzying quantity of computer power for an absolute minimum of weight, and has some clever design considerations to improve its performance as well.

The advantage of this board compared to other similar offerings is that it is built to host a Raspberry Pi Compute Module 4, while the rest of the flight controllers are separated out onto a single circuit board. This means that the Pi is completely sandboxed from the flight control code, freeing up computing power on the Pi and allowing it to run a UAV-specific OS like OpenHD or RubyFPV. These have a number of valuable tools available for unmanned flight, such as setting up a long range telemetry and camera links. The system itself supports dual HD camera input as well as additional support for other USB devices, and also includes an electronic speed controller mezzanine which has support for quadcopters and fixed wing crafts.

Separating non-critical tasks like cameras and telemetry from the more important flight controls has a number of benefits as well, including improved reliability and simpler software and program design. And with a weight of only 30 grams, it won’t take too much cargo space on most UAVs. While the flight computer is fairly capable of controlling various autonomous aircraft, whether it’s a multi-rotor like a quadcopter or a fixed wing device, you might need a little more computing power if you want to build something more complicated.

Wireless Charging For Border Patrol Drones

It makes sense to use drones to patrol borders or perimeters. But there’s a problem. Drones have to carry batteries or fuel and mostly have a short operating time. A new paper from the University of Houston proposes a solution by recharging drones in flight using a novel wireless charging mechanism. What’s the cost? Another paper explores the economics of the approach.

The system relies on electric lines running along a border wall feeding wireless power transfer devices that allow the drone to recharge in flight. This is akin, we think, to an electric train that takes power from the third rail except, in this case, the power rail is wireless. Also, the drone would still have batteries to enable it to go off the rail as needed.

The paper mentions that the source power could be from wind or solar, but that’s not necessarily important and it also requires a storage battery in the system that you could omit if using conventional power. In addition, you’d think batteries and solar panels might be targets for theft in remote areas.

The paper mentions that another alternative is to simply have charging towers along the wall where drones land to recharge. This is easier, we think, but it does put the drone out of full operation status while charging. On the other hand, cheap drones could work in shifts to cover an area, so it seems like that might be a better solution than charging while flying.

What do you think? How would you make a long-duration drone? Fuel cells? In-flight battery swapping from a refueling drone? Laser power? Maybe a magnetic battery swap system where the drone swoops over a charger to drop off and pick up a fresh battery? Let us know what you would try or — even better — what you have done.

We’ve seen a drone pit stop robot already. Refueling drones have been done, too. But it does seem like something better is possible.

Single-Rotor Drone: A Thrust-Vectoring Monocopter

We’re not entirely sure what to call this one. It’s got the usual trappings of a drone, but with only a single rotor it clearly can’t be called by any of the standard multicopter names. Helicopter? Close, but not quite, since the rotor blades are fixed-pitch. We’ll just go with “monocopter” for now and sort out the details later for this ducted-fan, thrust-vectored UAV.

Whatever we choose to call it — builder [tesla500] dubbed it the simultaneously optimistic and fatalistic “Ikarus” — it’s really unique. The monocopter is built around a 90-mm electric ducted fan mounted vertically on a 3D-printed shroud. The shroud serves as a mounting point for the landing legs and for four servos that swivel vanes within the rotor wash. The vanes deflect the airstream and provide the thrust vectoring that gives this little machine its control.

Coming to the correct control method was not easy, though. Thanks mainly to the strong gyroscopic force exerted by the rotor, [tesla500] had a hard time getting the flight controller to cooperate. He built a gimballed test stand to work the problem through, and eventually rewrote LibrePilot to deal with the unique forces on the craft and tuned the PID loops accordingly. Check out the results in the video below.

Some attempts to reduce the number of rotors work better than others, of course, but this worked out great, and we’re looking forward to the promised improvements to come.

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Drone Registration Is Just FAA Making You Read Their “EULA”

Over the last few weeks we’ve waded through the debate of Drone restrictions as the FAA announced, solicited comments, and finally put in place a registration system for Unmanned Aerial Systems (UAS). Having now had a week to look at the regulation, and longer to consider the philosophy behind it, I don’t think this is a bad thing. I think the FAA’s move is an early effort to get people to pay attention to what they’re doing.

The broad picture looks to me like a company trying to get users to actually read an End User Licensing Agreement. I’m going to put the blame for this firmly on Apple. They are the poster children for the unreadable EULA. Every time there is an update, you’re asked to read the document on your smartphone. You scroll down a bit and think it’s not that long, until you discover that it’s actually 47 pages. Nobody reads this, and years of indoctrination have made the click-through of accepting an EULA into a pop-culture reference. In fact, this entire paragraph has been moot. I’d bet 99 out of 103 readers knew the reference before I started the explanation.

So, we have a population of tech adopters who have been cultivated to forego reading any kind of rules that go with a product. Then we have technological advancement and business interests that have brought UAS to the feet of the general public both with low costs, wide availability, and pop-culture appeal. What could possibly go wrong? Let’s jump into that, then cover some of the other issues people are concerned about, like the public availability of personal info on the drone registry.

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OpenVulture, Software For Unmanned Vehicles


The first talk of ShmooCon was [Ethan O’Toole] and [Matt Davis] presenting their OpenVulture software for unmanned vehicles. In the initial stages, they had just planned on building software for Unmanned Aerial Vehicles, but realized that with the proper planning it could be used with any vehicle: airplanes, cars, boats, and subs (or more specifically, their Barbie PowerWheels). The software is in two parts. First is a library that lets you communicate with each of the vehicle’s modules. The second half is the actual navigation software.

They’ve spent a lot of time sourcing hardware modules. They are looking for items that work well, aren’t too expensive, and have a fairly plug and play implementation. For their main processor, they wanted something that wasn’t a microcontroller and could run a full Linux system. The ARM based NSLU2 NAS seems to be the current frontrunner. You can find the opensource software and descriptions of the supported modules on their site.

They’re building the first test UAVs now. One has a 12 foot wingspan for greater lift and stability. We’ve covered the Arduino based Ardupilot and other UAVs in the past.