Dropping a Rover from a HexaCopter

For those interested in using their multicopters to carry heavy objects you might be interested in the test that I performed today with Assistant Professor Nagatani-san of Tohoku university in Japan and Izu-san of EnRoute (a company that specialises mostly in Radio Controlled vehicles here in Japan and China).

The goal for later this year is to carry a rover to the top of Mt Asama (a volcano that errupts from time to time) and drop it in mostly as a proof of concept that it can be done.

Today was our first attempt at dropping one of the university's semi-autonomous rovers (2.5kg) from an ArduCopter equipped Zion Pro hexacopter (4.0kg not including the rover).

During the first try the copter was under manual control (stabilize mode) and the servo to drop the rover was activated by the tx/rx's channel 8 switch.  I was the pilot and although we were all fully expecting the copter to climb I was still surprised by the speed of the leap into the air and I couldn't keep the throttle low enough without cutting the engines completely.  You can see the disasterous result 44 seconds in.

After lunch and fixing the hexa the 2nd (1:02) and 3rd tests (1:11) went much better with lower weights (300g and 1kg) and this time using Alt-Hold.

The final test (1:24) was back again with the rover but this time using alt-hold and you can see how much better the new 2.9.1 Alt-Hold is than a human pilot (or at least this human pilot!) with the copter only climbing about 10cm or so.

So the moral of the story is sometimes it's best to trust the autopilot.

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  • Great test - proves a very good point - did I see a trickle of sweat running down the back of your neck on the second rover drop?:)

  • Developer

    @FlyingMonkey, yeah, quite a cute little rover isn't it?  as you guessed the wheels are all foam so it can survive a drop from a few meters at least.  They didn't seem happy with the idea of dropping it from 5m.  haha.

    @Eagle, the next test is in month so I'll tell y'all how it goes.

  • Love it!  Also like the blue (foam?) wheels on the rover :)

  • T3
    Very cool. It's said that most crashes are caused by pilot error. I can honestly say that all mine have been my fault. Thanks for sharing.
  • Developer


          Yes, a cable would be ideal.  then the release could be done manually (or it would become even easier for the autopilot).  Sadly my hair options have become extremely limited. :-).

  • Developer


         No hard plans yet to try and get the rover back although it's been discussed.  I'll point those guys at the open grab project.


         no sonar on that rig.  Just using the regular 2.9.1 alt-hold which is inertial nav + baro.

  • It needs to be lowered on cables & you need a mohawk.

  • You did it! 

    Congratulations for great Alt_Hold software, as usual.

    Want to see actual testing very soon.

    BTW, your testing took place indoor.

    Is it relies upon ultra sound sonar to detecting altitude (distance really)? 

  • Awesome Randy, thanks for sharing this. It's neat to see the difference in manual vs. stabilize with the drop!

  • 3D Robotics

    Awesome Randy! Sam and I have been meaning to do something similar for a while now but can never get to it. Keep it up!

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