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Hackaday Links: April 19, 2020

While the COVID-19 pandemic at least seems to be on a downward track, the dystopian aspects of the response to the disease appear to be on the rise. As if there weren’t enough busybodies and bluenoses shaming their neighbors for real or imagined quarantine violations on social media, now we have the rise of social-distancing enforcement drones. These have been in use in hot zones around the world, of course, but have only recently arrived in the US. From New Jersey to Florida, drones are buzzing about in search of people not cowering in fear in their homes and blaring messages about how they face fines and arrest for seeking a little fresh air and sunshine. We’re all in favor of minimizing contact with potentially infected people, but it seems like these methods might be taking things a bit too far.

If you somehow find yourself with some spare time and want to increase your knowledge, or at least expand your virtual library, Springer Publishing has some exciting news for you. The journal and textbook publisher has made over 400 ebook titles available for free download. We had a quick scan over the list, and while the books run the gamut from social sciences to astrophysics, there are plenty of titles that are right in the wheelhouse of most Hackaday readers. There are books on power electronics, semiconductor physics, and artificial intelligence, as well as tons more. They all seem to be recent titles, so the information isn’t likely to be too dated. Give the list a once-over and happy downloading.

Out of all the people on this planet, the three with the least chance of being infected with SARS-CoV-2 blasted off from Kazakhstan this week on Soyuz MS-16 to meet up with the ISS. The long-quarantined crew of Anatoly Ivanishin, Ivan Vagner, and Chris Cassidy swapped places with the Expedition 62 crew, who returned to Earth safely in the Soyuz MS-15 vehicle. It’s a strange new world they return to, and we wish them and their ISS colleagues all the best. What struck us most about this mission, though, was some apparently surreptitiously obtained footage of the launch from a remarkably dangerous position. We saw some analysis of the footage, and based on the sound delay the camera was perhaps as close as 150 meters to the launchpad. It’s hard to say if the astronauts or the camera operator was braver.

And finally, because neatness counts, we got this great tip on making your breadboard jumpers perfectly straight. There’s something satisfying about breadboard circuits where the jumpers are straight and exactly the length the need to be, and John Martin’s method is so simple you can’t help but use it. He just rolls the stripped jumpers between his bench and something flat; he uses a Post-it note pad but just about anything will do. The result is satisfyingly straight jumpers, ready to be bent and inserted. We bet this method could be modified to work with the stiffer wire normally used in circuit sculptures like those of Mohit Bhoite; he went into some depth about his methods during his Supercon talk last year, and it’s worth watching if you haven’t seen it yet.

Dropping A Glider From 18,000 Feet

[Tarik and Kemal] have an objective in mind: to drop a home-made autonomous glider from a high-altitude balloon and safely return it to home. To motivate them, [Tarik] has decided not to cut his hair until they reach 18,000 feet. Given the ambition of their project, it isn’t surprising that his hair is getting rather long now.

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The Drone That Flies In Any Orientation

Modern radio-controlled multi-rotor drone can be incredibly agile, but can only make orientation changes around the yaw axis while remaining in approximately the same position. Researchers at ETH Zurich have again built and tested multirotor with controllable motion six degrees of freedom, this time dramatically improving efficiency.

We covered a similar design from ETH Zurich previously which was hexacopter with arms with limited rotation. This new design is also a hexacopter, but with 2 coaxial motors on each rotating arm. Each arm has an increased range of rotation over the previous design, beyond 360 degrees. With the range of rotation and the very complex control system, the drone can efficiently fly in any orientation, while still being able to apply effective torque or linear force in any direction. This opens up a lot of possibilities for tasks that drones can perform, like close-up industrial inspection, using tools or pulling cables while keeping the rotors clear.

The arms do have a limited amount of rotation before winding the motor cable tight, but the control system keeps track of this and can unwind during or after movement. See the video after the break to see it in action. The complete scientific paper is not light reading, but definitely interesting. We’re looking forward to seeing if and when these type designs get used in real-world applications.

There are without a doubt a lot of drones in our future, and probably the most successful project to date is the Zipline fixed-wing drones in Rwanda and Ghana, which have made over 35000 deliveries of emergency medical supplies since 2016.

Thanks [Qes] for the tip!

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The Drone That Can Play Dodgeball

Drones (and by that we mean actual, self-flying quadcopters) have come a long way. Newer ones have cameras capable of detecting fast moving objects, but aren’t yet capable of getting out of the way of those objects.  However, researchers at the University of Zurich have come up with a drone that can not only detect objects coming at them, but can quickly determine that they’re a danger and get out of the way.

The drone has cameras and accompanying algorithms to detect the movement in the span of a couple of milliseconds, rather than the 20-40 milliseconds that regular quad-copters would take to detect the movement. While regular cameras send the entire screens worth of image data to the copter’s processor, the cameras on the University’s drone are event cameras, which use pixels that detect change in light intensity and only they send their data to the processor, while those that don’t stay silent.

Since these event cameras are a new technology, the quadcopter processor required new algorithms to deal with the way the data is sent. After testing and tweaking, the algorithms are fast enough that the ‘copter can determine that an object is coming toward it and move out of the way.

It’s great to see the development of new techniques that will make drones better and more stable for the jobs they will do. It’s also nice that one day, we can fly a drone around without worrying about the neighborhood kids lobbing basketballs at them. While you’re waiting for your quadcopter delivered goods, check out this article on a quadcopter testbed for algorithm development.

Drones Can Undertake Excavations Without Human Intervention

Researchers from Denmark’s Aarhus University have developed a method for autonomous drone scanning and measurement of terrains, allowing drones to independently navigate themselves over excavation grounds. The only human input is a starting location and the desired cliff face for scanning.

For researchers studying quarries, capturing data about gravel, walls, and other natural and man-made formations is important for understanding the properties of the terrain. Controlling the drones can be expensive though, since there’s considerable skill involved in manually flying the drone and keeping its camera steady and perpendicular to the wall it is capturing.

The process designed is a Gaussian model that predicts the wind encountered near the wall, estimating the strength based on the inputs it receives as it moves. It uses both nonlinear model predictive control (NMPC) and a PID controller in its feedback control system, which calculate the values to send to the drone’s motor controller. A long short-term memory (LSTM) model is used for calculating the predictions. It’s been successfully tested in a chalk quarry in Denmark and will continue to be tested as its algorithms are improved.

Getting a drone to hover and move between GPS waypoints is easy enough, but once they need to maneuver around obstacles it starts getting tricky. Research like this will be invaluable for developing systems that help drones navigate in areas where their human operators can’t reach.

[Thanks to Qes for the tip!]

Mars 2020 Rover: Curiosity’s Hi-Tech Twin Is Strapped For Science; Includes A Flying Drone

While Mars may be significantly behind its sunward neighbor in terms of the number of motor vehicles crawling over its surface, it seems like we’re doing our best to close that gap. Over the last 23 years, humans have sent four successful rovers to the surface of the Red Planet, from the tiny Sojourner to the Volkswagen-sized Curiosity. These vehicles have all carved their six-wheeled tracks into the Martian dust, probing the soil and the atmosphere and taking pictures galore, all of which contribute mightily to our understanding of our (sometimes) nearest planetary neighbor.

You’d think then that sending still more rovers to Mars would yield diminishing returns, but it turns out there’s still plenty of science to do, especially if the dream of sending humans there to explore and perhaps live is to come true. And so the fleet of Martian rovers will be joined by two new vehicles over the next year or so, lead by the Mars 2020 program’s yet-to-be-named rover. Here’s a look at the next Martian buggy, and how it’s built for the job it’s intended to do.

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Lego Drone Finally Takes Off

We were concerned when we saw [Brick Experiment Channel] test a drone propulsion pod made with Lego. After all, the thrust generated was less than the weight of the assembly. But a few tweaks got enough lift to overcome the assembly weight, as you can see in the video below.

The next step was to build three more pods and add some lightweight avionics and a battery. The first flight was a little dicey because the sensor orientation was off. Then there was some more software tuning before things really got airborne.

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