Wireless Power Transfer for Quadrotors

quadcopter

Quadrotors are great, but what kind of range can you get on them, really? What if you could charge them up just by flying over high voltage power lines, by or temporarily hovering by a charging station? That’s just what [Dr. Carrick Detweiler] wrote a paper about! (Caution: PDF)

The paper discusses the method of wireless power transfer via magnetic resonance, which, depending on the scale, can transfer power at medium distances (~1 meter). This outperforms inductive coupling which requires a much closer proximity (~1-2 centimeters) for power to transfer. It does still require a certain amount of accuracy, but as we all know, quadrotors have no problem with even the most complex aerodynamic feats!

There is an excellent demonstration video of a small scale wireless quadrotor prototype after the break.

Curious about wireless power transfer? We also covered a great article about the theory behind evanescent wave coupling a few years ago!

[Via Hizook]

Comments

  1. eldorel says:

    James, please have another cup of coffee and rewatch that video. (Or actually read the paper)

    This research is about using a UAV as an autonomous charging unit to recharge remote sensor stations.

    It has nothing to do with trying to charge a UAV from power lines.

    Stealing power from a power line would use inductive resonance, and would work at a range of several meters.

    The downside is the amount of power obtained is pretty low, so it would be faster to program a UAV to just steal from outdoor outlets instead. (Since you are stealing anyway)

    • RooTer says:

      isn’t powered harvested from powerlines wasted anyway? so it is different than ‘stealing’ from power outlets. Probably useless unless copter would land on the line itself (w/ a hook perhaps?).

      • ChalkBored says:

        Remember the experiment where you drop a magnet down a copper pipe, and the magnet slows down? The same principles are at work.
        Since you’re causing a load, the power plant has to work harder to push electricity through it.

        The only real difference between stealing from outlets and stealing from power lines is who you’re taking it from.

      • Greenaum says:

        No. It’s like a transformer. The primary draws little power, until something draws power from the secondary. Or a generator is easy to spin, until you connect a load to it, then it gets much harder. It’s not like light or radio, where the energy just flies through space waiting to be collected, both coils interact.

        The exact details of which, I’m not sure of.

    • shawn says:

      This would be extremely useless if it were to charge the quad. I don’t know what a modern quad draws but my collective pitch can draw over 10 amps at 11 v continuously while hovering which is 20x what this thing can do. Now charging sensors that is cool and actually useful.

    • Greenaum says:

      I wondered, cos in the diagram why is the load coil on the bottom, and the drive coil on the copter? Seemed kinda massively wrong.

      Still, tiny airborne petrol tanker of the future here we go!

  2. rasz says:

    dont know about low, there have been cases of people powering whole houses by using induction with neighbor power line :)

    • eldorel says:

      Those cases usually involve a 6 foot or longer secondary conductor (like a chain link fence) and a high voltage line as the primary.

      • Greenaum says:

        Has any case actually being documented? We’ve all heard of clever farmers keeping a big spool of wire near to power lines and powering his house, but I think it’s an urban legend.

        • eldon says:

          you could get some power running 1000 feet of fencing under a power line and insulating it.. you’re picking up capacitive coupling at 60hz. but you really do need 1000+ feet of fencing to get any significant power from it

  3. ChalkBored says:

    Seems like an absurdly inefficient way to transfer power to remote devices.

    • Greenaum says:

      Not really. If the devices are in the middle of nowhere, somewhere hard to get to, it’s infinitely easier than sending a person up. Even if the magnetic transfer was inefficient (and I don’t think it is), as a means of getting small amounts of power to awkward locations, can you think of a better solution?

  4. None says:

    @James Hobson
    Please provide links to resources explaining the difference between “magnetic resonance” and “inductive coupling”! Thanks

    • ChalkBored says:

      Inductive coupling is like a DC generator, the electromagnetic field is trying to drag the electrons down the wire.

      Magnetic resonance is like an AC alternator or a transformer, the changes in magnetic flux causes a wave of electrons to move through the line.

    • Pinky's Brain says:

      With the former they mean inductive power transfer between two resonant tank circuits with the latter they mean straight transformer action.

  5. CRJEEA says:

    It would be interesting to see some wireless sensor nodes monitoring the environment for example. Built to monitor and record on very low power and then when the receiver is in range draw enough power to transmit the data back. Effectively like an RFID tag that can program the code it transmits. I can see this having applications at sea and in the air with weather warnings or in space for monitoring with a flyby or perhaps even rovers deploying sensor nets on other planets.
    I would love to see some more information about this. Details on the coupling between the load coil and the RX resonant coil as well as operating frequencies, dimensions, components, extra would be much appreciated. Perhaps an instructible :D

  6. Bobby says:

    Nikolai Tesla was actually already working on that….

  7. These are even worse articles than before. Not only does spelling get messed up here and there, but the titles are editorialized and the content isn’t accurate to the topic!

    This feels like Gizmodo!

  8. your name here says:

    Why does hackaday always warn us away from reading pdfs?
    What is the problem with pdf? Will it break my computer or something?
    Please can we have similar warnings for videos and pictures and complicated words.
    Why?

    • eldorel says:

      PDF is actually a variation of postscript, which is a complete programming language. A lot of viruses have been written to turn a PDF into a nasty delivery system, and many people do not want to open them if they don’t know who wrote it.

      • snow says:

        there is also a more practical reason like not wanting to waste bandwidth on you smartphone/mobile device if your not gonna be able or wanting to read those pdf while on the move.. (have you seriously ever tried to read a pdf on a smartphone i can tell you its a real pain in the A**)

  9. kpharck says:

    The paper contains an error “Just as the pendulums’ resonant frequency can be de-
    termined by their mass and pivoting distance,”

    It is the gravity, not mass.

  10. stefan says:

    How about simply building a UAV that simply uses very little power to begin with? UAVs based on copter or aircraft designs are going to inherently need alot of energy because must use energy to produce lift to just stay aloft. If you built a uav based on a dirigible or lighter than air aircraft, you’d only need energy for propulsion and could stay aloft much longer before needing a charge. Perhaps such a uav could even all it energy needs from solar energy and stay aloft continuously.

    • colecoman1982 says:

      Problems with blimps/dirigibles:

      * Hydrogen is hard to store reliably due to it’s small molecule size making it easy for it to leak out of even steel containers.
      * Manufacturing Hydrogen on-site is a significant safety risk.
      * Helium is a very limited natural resource that is irreplaceable in many important situations such as research and medicine. We are already fast on our way towards depleting the world’s supply of helium and we have no, even remotely, cost effective way to manufacture more.
      * Blimps and dirigibles are extremely slow compared to almost all ‘copter-based UAVs.
      * Even extremely large/massive blimps/dirigibles are well known for being very unstable and uncontrollable in even moderate windy conditions.

      As with anything, this is a case of using the right tool for the right job. Blimps/dirigibles are very promising for situations such as indoor UAVs and extremely high altitude situations (70,000+ feet) where turbulence isn’t much of an issue and high speed isn’t usually needed. The use-case being discussed here isn’t, necessarily, the best fit for them.

  11. pedro says:

    remote mobile stations with built in batteries could be built and it could be activated by NFC since it’s so low power.

  12. paul says:

    Very neat,

    A note of worry though:

    Most modern automatically piloted UAV’s rely on precision magnetometer’s in combination with GPS to maintain position, unless you have image-analysis to back up your position (not as robust) you can end up messing up your Gyro with one of these and crashing :c

    Power lines, magnetic resonance would probably be bad things to fly beside if you have one of these types of UAV’s

  13. dijit says:

    Does this mean we are any closer to wireless power transmission inside my house?? :)
    I am okay with accepting the (undocumented?) risks of living inside a powerful electromagnetic field if it means that all of my devices, appliances, etc., “just work” and I don’t have to mess around with power cords or perhaps even batteries. I am jaded, as I read Popular Mechanics and watched sci fi shows growing up……I still don’t have a flying car or robotic personal assistant either, but I will take wireless power for all of my devices….if we are close to that.

    • Greenaum says:

      Main problem with that, I think, is that power cords just aren’t that bad. Doesn’t bother me plugging things in. Batteries, OTOH, still have some marginal pain. You don’t have to buy as many anymore, now everything’s rechargeable, but auto-charging batteries would be nice. Like Qi, but without having to even bother taking stuff out of your pocket. Your TV remote could charge, or have no batteries at all, as it sat on your couch.

      I’d give that up for a robot chum though.

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