Developer

Indoor fun with a tiny ArduCopter quadcopter



Do you have an Ardupilot Mega and shield and want some fun for little money? check this tiny quad... my last drone in family...



Some specs:
- Size : 26.5cm (10.4 inches) from motor to motor
- Motors : 18-11 200kv 10 gram motors
- Props : 4x2.5 (standard CCW props)
- ESCs : Turnigy 6A
- Battery : 3S610 (or 3S800)
- Sonar : Maxbotics LV-EZ0 [optional]


The nice part about this frame is that it use standard kite parts, so it´s very easy to construct and it´s perfect for some radical tests.
Itried to find a bit different design that also make the quad less simmetrical (it´s very easy to loss the orientation with a quad) and I wanted to do as small as posible to flight indoors...
At this size and weight it´s very safe and robust also. The props use prop savers and this help a lot in crashes...
I am not very good writing... so I took a lot of photos during the build phase and I created a build log:
https://docs.google.com/document/d/1fIZL-Ca2fx2RPhBQLzoOdqdCuikXRKePwKbxDlJWiss/edit?hl=es

This code supports a sonar for altitude hold and also has a battery alarm (2 alarms).
Thisquad works with ArduCopter code, but because how main board is mounted, actual code doesn´t work. This is the code that I used with this quad :
http://code.google.com/p/arducopter/source/browse/#svn/branches/Arducopter_indoor
(as zip format:
Arducopter_indoor.zip )
note that this will be integrated on main Arducopter code. Now is temporarily in a branch.
ThePID gains are different than in standard ArduCopter, so you need to Initialize EEPROM on Configurator or put this ones manually:
-Stable mode: P : 4.8 ; I : 0.12 ; P_rate (D in configurator) : 0.4 ; Yaw : (4.5 ,0.15 ,2.8 )
-Acrobatic mode : P : 0.75 ; I : 0.1 ; D : 0 ; Yaw : (2.4 ,0.2 ,0 )

OK, but was all so perfect like in the video? I don´t believe that...
Yes, you are right, but fortunately this design is very crash resistance... and this part is also fun...


After all this battles I only needed a few drops of ciano in the crash with the lamppost :-)

What´s the real size?


On center, standard arducopter frame, on left, old ArduIMU quadcopter part III, on right-top this project.

And what about the automatic aerobatics on video?
I am starting to test a new function to do automatic aerobatics (Automatic Aerobatic Procedure). The idea is that you enable this function with a switch in the Tx to make an automatic predefined aerobatic and then automatically recover to a stable mode.
Thisis actually a proof of concept but works very nice. One limit here is the maximun rate of the gyros, in our case 500deg/s. If we exceed this, the IMU get confused...
An interesting point to note is that the IMU doesn´t loose the orientation in this hard movements...
Thestory is that I have never feel too much confidence doing flips manually with quads. Then I start thinking that with an automatic code we can get a precise timing and controled movement so maybe this could help to do better aerobatics. I started testing this function outdoor, on an open field but I was improving the code and got more tightly maneuvers, so tight, that I ended up doing flips with a quad inside my room!!!


Here is the code I was testing : (AAP function:
AAP.txt )
I implemented this functionality as a state machine where there are three kind of states:
- fixed commands for a limited period of time. (example : Apply a throttle command)
- fixed commands until we reach some IMU state (example : roll until we reach a certain angle)
- And a mix between this categories and a control (example : Throttle command + stable mode on roll, pitch, yaw)
There are many things to test and improve here but the basic concept works very nice...

If I can get a bit of help from a friend, I will probably made a carbon fuselage for this prototype...

Enjoy this “Science & Fun” mix...

Jose Julio.
Arducopter Team
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Comments

  • There are multicopters like this http://gallery.mikrokopter.de/main.php/v/Nachbau/IMAGE_571.jpg.html...
  • Now ive got a question about the Quadracopter design more or less the props..do they all have to face up like typical design..or could some props face for more direct thrust??
  • Thank you for all the responses: Up to now I understand that right now only Jose's code is working with exactly this design.

    Also, I assume that counter rotating pairs of props do compensate for yaw by design (However, if you want the quad to turn left or right, having all props rotating in the same direction should be faster). Are there any left- and right-turning props in this size?

     

    Another question is if Jose's code and/or ArducopterNG is actually supporting an ultra-sonic sensor for low-altitude control?

     

    I appreciate any comments.

    Ralph

  • my question is if is it necesary to make another modification in the original design of this tiny quad (props, motors or even code..) in adittion to the IMU orientation in order to use the NG code. I understand that with the new code two motors will rotate oposite to the others, so tilt would´nt be necesary.. ¿is it right?
  • Developer

    arashi, yes old release of Arducopter software works that way eg. if you align motors perfectly it can be used with motors that spins same direction. But that is not most efficient way to fly them. On smaller quads it is not so important but more bigger your quad is more important you are wasting a lot of resources while your motors are "fighting" on each other.

     

    That's why we are using counter rotating groups to compensate yaw. Also when using counter rotating motor/prop groups we do not need to be so careful with alignment of motors.

     

     

     

     

     

  • FYI, I made a similar mini quad with all of the motors spinning in the same direction (angled for torque)  and it flies just fine with stock code.  The IMU is aligned with an arm though.

     

    In fact, it is the stock Arducopter code and I can swith the IMU from my large to mini frame with no problems or changes.

     

     

  • Developer
    It flies both + and x and IMU is aligned along F/R arms. Jose uses special Arducopter code on this his tiny quad. And we are looking to make those too in close future so people would have nice acrobat kit quads... You cannot use this software on bigger quads due this tiny quad all motors are spinning same direction, so control algorithms are different than in bigger ArduCopter.
  • Same question as Ralph. what software does work better in this tiny quad?

    @Jeni, with the new NG software I understand that the orientation of the IMU must to be along the front/rear arm axis, so does it mean that the quad will fly in "+" mode? is it posible to fly in "x" mode?

  • Developer
    While using official ArducopterNG, IMU needs to be mounted along direction of front/rear arms
  • @Jani

    Thank you - do you by any chance know if that code also works considering the orientation of the IMU on Jose's copter?

     

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