Building A Magnetic Levitating Quadcopter

hover Three days ago on October 21, 2014 it was announced to the world the Back to the Future hoverboard was real. It’s a Kickstarter, of course, and it’s trending towards a $5 Million dollar payday for the creator.  Surprisingly for a project with this much marketing genius, it’s a real, existing device and there’s even a patent. From the patent, we’re able to glean a few details of how this hoverboard/magnetic levitation device works, and in our post on the initial coverage, we said we’d be giving away some goodies to the first person who can clone this magnetic levitation device and put it up on hackaday.io.

[jellmeister] just won the prize. It’s somewhat cheating, as he’s had his prototype hoverboard working in July, and demoed a more advanced ‘upside-down quadcopter’ device at the Brighton Mini Maker Faire in September. Good on ‘ya [jelly]. You’re getting a gift card for the hackaday store.

hoverLike the Kickstarter hoverboard, [jelly] is using an array of magnets rotating in a frame above a non-ferrous metal. For the initial test, eight neodymium magnets were arranged in a frame, suspended over 3/4″ aluminum plate, and spun up with a drill. With just this simple test, [jelly] was able to achieve 2kg of lift at 1cm and 1kg of lift at 1 inch of separation. This test also provided some valuable insight on what the magnets do to the aluminum or copper; the 3kg aluminum plate was nearly spinning, meaning if this device were to be used on small plates, counter-rotating pairs of magnetic lifters would need to be used.

The test rig then advanced to two pairs of rotors with standard hobby brushless motors, but stability was a problem; the magnetic rotors provided enough lift, but it would quickly fall over. To solve this problem, [jellmeister] took a standard quadcopter configuration, replaced the props with magnetic rotors, and successfully hovered it above a sheet of aluminum at the Brighton Maker Faire.

Since [jellmeister] has actually built one of these magnetically levitating hoverboards, he has a lot more data about how they work than an embargoed press release. The magnetic rotor hoverboard will work on aluminum as well as copper, but [jell] suspects the Kickstarter hoverboard may be operating right at the edge of its performance, necessitating the more efficient copper half pipe. The thickness of the non-ferrous plate also makes a difference, with better performance found using thicker plates. No, you bojo, hoverboards don’t work on salt water, even if you have pow-ah.

So there ‘ya go. That’s how you build a freakin’ hoverboard. [jellmeister]‘s design is a little crude and using a Halbach array for the magnetic rotors should improve efficiency. Using a 3D printed rotor design is a stroke of genius, and we’ll expect a few more quad-magnetic-levitating-things to hit the tip line in short order.

Demos of [jellmeister]‘s work below.

Oh. These things need a name. I humbly submit the term ‘Bojo’ to refer to any device that levitates though rotating magnets and eddy currents.

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The Hoverboard You Can Build At Home

Press embargoes lifted today, heralding the announcement of the world’s first hoverboard. Yes, the hovering skateboard from Back to the Future. It’s called the Hendo hoverboard, it’s apparently real, and you can buy one for $10,000. If that’s too rich for your blood, you can spend $900 for a ‘technology demonstrator’ – a remote-controlled hovering box powered by the same technology.

Of course the world’s first hoverboard is announced to the world as a crowd funding campaign, so before we get to how this thing is supposed to work, we’ll have to do our due diligence. The company behind this campaign, Arx Pax Labs, Inc, exists, as does the founder. All the relevant business registration, biographical information, and experience of the founder and employees of Arx Pax check out to my satisfaction. In fact, at least one employee has work experience with the innards of electric motors. At first glance, the company itself is actually legit.

The campaign is for a BttF-style hoverboard, but this is really only a marketing strategy for Arx Pax; the hoverboards themselves are admittedly loss leaders even at $10,000 – the main goal of this Kickstarter is simply to get media attention to the magnetic levitation technology found in the hoverboard. All of this was carefully orchestrated, with a ‘huge event’ to be held exactly one year from today demonstrating a real, working hoverboard. What’s so special about demoing a hoverboard on October 21, 2015?

next year

I defy anyone to come up with a better marketing campaign than this.

The meat of the story comes from what has until now been a scientific curiosity. Everyone reading this has no doubt seen superconductors levitated off a bed of magnets, and demonstrations of eddy currents are really just something cool you can do with a rare earth magnet and a copper pipe. What [Greg Henderson] and Arx Pax have done is take these phenomena and turned them into a platform for magnetic levitation.

According to the patent, the magnetic levitation system found in the Hendo hoverboard works like this:

  • One or more electric motors spin a series of rotors consisting of an arrangement of strong permanent magnets.
  • The magnets are arranged in a Halbach array that enhances the magnetic field on one side of the array, and cancels it on the other.
  • By placing the rotors over a conductive, non-ferrous surface – a sheet of copper or aluminum, for example – eddy currents are induced in the conductive surface.
  • These eddy currents create a magnetic field that opposes the magnetic field that created it, causing the entire device to levitate.

hoverboard

That’s it. That’s how you create a real, working hoverboard. Arx Pax has also developed a method to control a vehicle equipped with a few of these hover disks; the $900 ‘Whitebox’ technology demonstrator includes a smart phone app as a remote control.

If you’re still sitting in a steaming pile of incredulity concerning this invention, you’re in good company. It’s a fine line between being blinded by brilliance and baffled by bullshit, so we’re leaving this one up to you: build one of these devices, put it up on hackaday.io, and we’ll make it worth your while. We’re giving away some gift cards to the Hackaday store for the first person to build one of these hoverboards, preferably with a cool body kit. The Star Wars landspeeder has already been done, but the snowspeeder hasn’t. Surprise us.

Levitating Speaker Plays Back Eerie Recordings

Let’s face it, levitating anything is pretty fascinating — especially when you think there should be wires. This project puts a new spin on magnetic levitation by using a PID controller to levitate a speaker while it plays music!

It uses the standard levitation setup — an electromagnet, a permanent magnet, and a hall effect sensor. A microcontroller implements the PID system, varying the current supplied to the electromagnet to keep the speaker floating at just the right height. Music is wirelessly transmitted to the speaker via Bluetooth, but unfortunately the speaker’s power is not. It features a small lithium ion battery which has a run-time of around 5 hours before it has to be recharged manually.

As you’ll notice in the following video, having a floating speaker has a pretty interesting effect — especially when it starts spinning.

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AVR Atmega based PID Magnetic Levitator

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[Davide] saw our recent post on magnetic levitation and quickly sent in his own project, which has a great explanation of how it works — he’s also included the code to try yourself!

His setup uses an Atmega8 micro-controller which controls a small 12V 50N coil using pulse-width-modulation (PWM). A hall effect sensor (Allegro A1302) mounted inside the coil detects the distance to the magnet and that data is used by a PID controller to automatically adjust the PWM of the coil to keep the magnet in place. The Atmega8 runs at 8Mhz and the hall effect sensor is polled every 1ms to provide an updated value for the PWM. He’s also thrown in an RGB LED that lights up when an object is being levitated!

So why is there a kid with a floating balloon? [Davide] actually built the setup for his friend [Paolo] to display at an art fair called InverART 2013!

After the break check out the circuit diagram and a short demonstration video of the device in action!

Oh yeah, those of you not impressed by magnetic levitation will probably appreciate acoustic levitation.

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Levitating Wireless LED Ring

magnetic levitation

Here’s an impressive example of a completely home built magnetic levitation setup… with wireless power transmission to boot!

[Samer] built this from scratch and it features two main sub-systems, a electromagnet with feedback electronics and a wireless power transfer setup.

The ring of LEDs has a stack of neodymium magnets which are levitated in place by a varying magnetic field. This levitation is achieved by using a Hall effect sensor and a PID controller using a KA7500 SMPS controller.

The wireless power transmission uses a Class E DC/AC inverter that operates at 800KHz. Two coils of wire pass the current between the stand and the LEDs.

It’s very similar to a build we featured last year, but it’s a great hack, so we had to share it! Check out the video after the break.

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Defying gravity for new user interfaces

[Jinha Lee] at the MIT Media Lab created a new interface allowing new ways to modify and play with 3D objects. It’s called ZeroN, and it’s nothing short of a futuristic device straight out of Star Trek.

ZeroN is simply a platform for levitating a small spherical permanent magnet in 3D space. It does this by mounting a hall effect sensor on an electromagnet. The hall sensor measure the strength of the magnetic field of the ball every few milliseconds and keeps the spherical magnet levitated. To move the object in 3D space, a few webcams track the ball over the platform and tell the electromagnet to move on a CNC-like x y table.

[Jinha] showed off a lot of cool stuff that is possible with the ZeroN; ping-pong is by far the coolest implementation, but it’s also possible to use the magnetic sphere to demonstrate n-body gravity or as a camera flying around a digital scene.

It’s a really amazing piece of work with an exceptional demo video. You can check that video out after the break. Thanks, [ferdinand] for sending this one in.

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