When it comes to radio communications on the VHF bands and above, there’s no substitute for elevation. The higher you get your antenna, the farther your signal will get out. That’s why mountaintops are crowded with everything from public service radios to amateur repeaters, and it’s the reason behind the “big stick” antennas for TV and radio stations.
But getting space on a hilltop site is often difficult, and putting up a tower is always expensive. Those are the problems that the Sky Anchor, an antenna-carrying drone, aims to address. The project by [Josh Starnes] goes beyond what a typical drone can do. Rather than relying on GPS for station keeping, [Josh] plans a down-looking camera so that machine vision can keep the drone locked over its launch site. To achieve unlimited flight time, he’s planning to supply power over a tether. He predicts a 100′ to 200′ (30 m to 60 m) working range with a heavy-lift octocopter. A fiberoptic line will join the bundle and allow a MIMO access point to be taken aloft, to provide wide-area Internet access. Radio payloads could be anything from SDR-based transceivers to amateur repeaters; if the station-keeping is good enough, microwave links could even be feasible.
Sky Anchor sounds like a great idea that could have applications in disaster relief and humanitarian aid situations. We’re looking forward to seeing how [Josh] develops it. In the meantime, what’s your world-changing idea? If you’ve got one, we’d love to see it entered in the 2020 Hackaday Prize.
Bees. The punchline to the title is bees carrying sensors like little baby bee backpacks. We would run out of fingers counting the robots which emulate naturally evolved creatures, but we believe there is a lot of merit to pirating natural designs, but researchers at the University of Washington cut out the middle-man and put their sensors right on living creatures. They measured how much a bee could lift, approximately 105 milligrams, then built a sensor array lighter than that. Naturally, batteries are holding back the design, and the rechargeable lithium-ion is more than half of the weight.
When you swap out brushless motors for organics, you gain and lose some things. You lose the real-time control, but you increase the runtime. You lose the noise, but you also lose the speed. You increase the range, but you probably wind up visiting the same field over and over. If your goal is to monitor the conditions of flowering crops, you may be ready to buy and install, but for the rest of us, dogs are great for carrying electronics. Oh yes. Cats are not so keen. Oh no.
Who doesn’t love magnets? They’re functional, mysterious, and at the heart of nearly every electric motor. They can make objects appear to defy gravity or move on their own. If you’re like us, when you first started grappling with the refrigerator magnets, you tried to make one hover motionlessly over another. We tried to position one magnet over another by pitting their repellent forces against each other but [K&J Magnetics] explains why this will never work and how levitation can be done with electromagnets. (YouTube, embedded below.)
In the video, there is a quick demonstration of their levitation rig and a brief explanation with some handy oscilloscope readings to show what’s happening on the control side. The most valuable part, is the explanation in the article where it walks us through the process, starting with the reason permanent magnets can’t be used which leads into why electromagnets can be successful.
[K&J Magnetics]’s posts about magnets are informative and well-written. They have a rich mix of high-level subjects without diluting them by glossing over the important parts. Of course, as a retailer, they want to sell their magnets but the knowledge they share can be used anywhere, possibly even the magnets you have in your home.
Simpler levitators can be built with a single electromagnet to get you on the fast-track to building your own levitation rig. Remember in the first paragraph when we said ‘nearly’ every electric motor used magnets, piezoelectric motors spin without magnets.
Continue reading “Hovering Questions About Magnetic Levitation”
This installation by artist [Nils Goudagnin] is a recreation of the hoverboard from Back to the Future II. We would like to see inside that plinth. We’ve seen levitating magnets before, but this is particularly stable. He says he is using lasers and a control system of some kind to stabilize it. Just to guess, we’d say that the lasers determine the distance of the board and an array of electromagnets below is adjusted to keep it level. Then again, we might be over thinking this. Even though it can’t be ridden, we’d love to have one around the office just to look at.