Micro Brushless Gimbal

I’ve built a micro brushless gimbal, i.e. a brushless direct-drive gimbal for cameras of the 808 key chain size, which I will describe here.

The worlds first 3-axis micro brushless gimbal has arrived!

micro brushless gimbal olliw
(picture of my first well working 2-axis micro brushless gimbal)

Camera
The camera is a key cam 808 #16 V2 with lense D. For all details see ChuckLohr’s great web page here. It’s not too expensive, and for its price it provides, IMHO, great video quality. Unlike its precessor (#3 etc.) it’s also quite well developped, i.e. a precise manual is available and a setup program making things really simple.

Gimbal
The gimbal itself is made from standard stuff found in any hobby shop. Building the motor holders had been the most difficult mechanical step. It’s not really difficult, but you need appropriate tools, which I don’t have. I only could succeed because a comrade had access to a lathe which he allowed me to use. The camera holder is magnetic, which adds quite a bit of weight to the gimbal, but is really cool since mounting/dismounting the camera is quite simple.

The weight of the whole construction seen in the above photo, i.e. gimbal + camera + contoller + cables + vibration damping + frame, is 90.5 grams.

Motors
The motors are IMHO key to the whole project, and searching for appropriate ones had been a major thing. If money is no issue then you will find excellent motors from Maxon (the maxon EC flat series looks very promising). I instead did test, with support from some nice fellows, see here, a couple of micro brushless motors, but they all showed IMHO way too much cogging. I went when with disc motors, since they usually come with a sintered magnet ring instead of individual hard magnets, which minimizes cogging torques. Among the several disc motors I tested, I liked this one most:

PS2 Slim disc drive replacement motor

  • 9n12p, diameter 24 mm, height of bell 5.5 mm, spindle 2 mm
  • original wind: 80 turns, ca. 0.17 mm wire, ca. 4 Ohm
  • new wind: wye configuration, 150 turns, 0.10 mm wire, 24.1 Ohm (perfekt for 2S and 3S)
  • bushing needs to be replaced by bearings, hence an approiate holder needs to be build
  • weight is ca. 10-13 g

Controller
I have designed the mini Brushless Gimbal Controller (all details here). The mBGC consists of an Arduino Pro Mini with an extension board, which carries TC4427 or TC4424 motor drivers. It also provides a voltage divider to measure the battery voltage, which allows to implement a lipo saver function as well as to make the PID controller adaptive to voltage changes.

Firmware
The firmware oBGC I’ve written myself. It has been developped from scratch, and is written in C using AvrStudio. I like the Arduino hardware, but I don’t like the Arduino language since it is very bad on resources… good performance is IMHO usually linked to optimized code. The firmware is in some parts quite highly developped, but in other parts, such as RC control etc., behind alternatives.

Background Theory
In the course of the project I stumbled across some things which I didn’t understand at first, and some which surprised me. So, I did also some basic theory considerations to understand better what’s going on. Some of them I’ve presented here.

Flying Vehicle
The gimbal is currently designed to be mounted on a Lama V4 coaxial helicopter, which has been modded substantially. I did a BLBL conversion using a GA250 gyromixer and Turnigy 1811-2900 motors. It runs from 3S, which provides plenty of power to lift the gimbal. I installed all tuning hardware I had available, but the single most important thing to minimize vibrations from the heli was to carefully balance the motors. The most serious thing with the coax is however its flying characteristic, it handles wind breezes badly. I gave it enough pop to fight it in the sense that it is able to move against it, but it then wobbles strongly.

Results
Some results I have already presented in a couple of places:

Articles:
Brushless Gimbal Direct Drive: Theory and Experiment
Mini Brushless Gimbal Controller

Threads:
Micro Brushless Gimbal – HILFE (@ FPV-Community)

Youtube Videos:
Micro Brushless Gimbal: 2nd step towards it

Micro Brushless Gimbal: Understanding better the dynamics of brushless direct drive

Micro Brushless Gimbal: 2-Axis Gimbal with KeyCam #16 V2

Micro Brushless Gimbal with oBGC Firmware: It’s flying ­čÖé

Micro Brushless Gimbal on a Coax Heli

(there are some more videos on the topic on my youtube channel OlliW42)


7 Kommentare

  1. Lucamax sagt:

    Thank you for your great job and for sharing.

    I’m working on a little quadcopter , the frame is 3D printed in Abs.
    With a 450mah 3S battery and a Mobius camera the AUW is 240 grams while Mobius only is 45 grams.

    I would like to add at least a one axis brushless gimball but weight is very relevant as you might imagine.

    What is the maximum weight that PS2 motors you had use can handle ?

    Regards and thnks again !

  2. ingo sagt:

    hallo Olliw,
    ich wurde mir gern so ein mini controler board bastelen, nur kan ich dieses driver board nicht finden im web.?
    (das board das unter dem arduino nano komt) hast du da vieleicht ein par info f├╝r mich?

    gr.ingo

  3. skystalker sagt:

    Hi, OlliW.
    NICE Job! The follow mode works perfectly! !
    I have read the info u posted, and was not able to find any sensor can provide frame angle, like encoder,potentiometer or current sensor on the scheme. That is interesting, how did u make it? Did I miss something?

    skystalker

  4. R K sagt:

    Hallo OlliW,

    Dein Gimbal gef├Ąllt mir sehr gut. Ich bin auf der Suche nach einem g├╝nstigen Gimbal f├╝r eine Mobius Actioncam. Verkaufst Du Dein Gimbal?

    W├╝rde mich ├╝ber eine Nachricht freuen ­čÖé

    • OlliW sagt:

      Hallo RK
      also, ich betreibe keinen Shop oder derart, wenn du das meinst…
      das hier gezeigte Gimbal gibt es auch schon nicht mehr, es ist ein 3_Achs-Gimbal geworden…
      ich bin gerade (langsam) dabei eine neue Version zu bauen, und ich k├Ânnte mir vorstellen dann die „alte“ Gimbalmechanik, wieder auf 2-Achs zur├╝ckger├╝stet, zu verkaufen, allerdings m├╝sste dann klar sein dass das nichts Plug&Play-Fertiges ist, und ich gehe ehrlich gesagt davon aus dass das nicht das ist was du mit „Verkaufst“ gemeint hast… oder?
      Cheers, Olli

  5. e_lm_70 sagt:

    Excellent job.

    I recently build up my own DIY mini gimbal, that did came down to 150g (all parts included), but I’m using a Mobius Full HD camera, and ready available 2206 gimbal motor

    My results are here: http://youtu.be/PWHX9epXWvg

    Is your firmware available ?
    Is anybody producing the Arduino Pro Mini board with the MOS FET ?

    It would be nice to compare your firmware with AlexMos or BruGi

    Your Helicopter as video platform is not idea, too much vibrations … still your gimbal make a good job on keep the camera level … but nothing can be done for compensate the vibration from your copter

    Tchuss
    e_lm_70

Hinterlasse einen Kommentar