Monday, November 28, 2011

Introducing the Inflight ACC Calibration


I programmed a feature that allows to find the perfect hovering zero point for the ACC sensor while inflight.

At the Shreddiquette community I took part in programming the same procedure after an idea of a fellow programmer and I ported the idea to Multiwii.


  • In reality there is no flat surface, so calibrating the ACC on ground will bring you close to a good value but you still have to find the perfect trim by trial and error.
  • Every copter is different so a perfectly flat surface does no recognice the inaccuracies in a copter, COG, bent arms, askew pylons etc.
Doing this inflight makes sure you are defining the zero point while in a perfect stable hover


  1. Arm the function with a stick combo (see below)
  2. take off and find the point of no drift (in acromode or in hovemode with TX-trimming)
  3. disarm via Aux1 and Aux2 (Aux disarming is a requirement) while flying, fon't worry there is a failsafe that prevents the engine from turning off while yu still have throttle > minthrottle. The offset is measured.
  4. Land and redo the combo to save the measured values. (be sure to undo the TX-trimming you did while flying in hovermode)
  5. Take off again and be happy ;-)
  6. You can do the combo again if you do not want to start the calibration anytime before taking off and do the measurement, to disarm the measurement. If you do not want to save the meausred value just do not do the combo. The values are lost after you cut power. You can always repeat the processover and over again  if you are unhapy with the result.

Stick Combo to arm/disarm the calibration.
You can find the code here:


Tuesday, November 8, 2011

The Mail man was there: A working FlyduGPS

Today, I received a new Shipment from my sponsor

Two friends of mine started building their quadrocopters and use Paul's complete quadrocopter frame with MWC board and black flydumini.

I got some new reenforced 10" props and new brand new GPS bob.

GPS Bob kit as delivered by flyduino with my FMP04

After 10 minutes of soldering I had everything onboard, including the FMP04 and the Bob was ready to go:

ready FlyduGPS

Just a little adjustment in the multiwii code and I got a tight satellite fix inside of my living room near the window:
FlyduGPS in comparison to a Get em... bob I am currently testing

Satellite fix after just a few seconds

working MultiWii GPS code

detailed comparisons and testing coming soon...

Oh by the way: You should really buy the new 10" props from Flyduino they have improved a lot and the mounting is perfect now, I can hardly tell the difference to Mikrokopter props

Wednesday, November 2, 2011


I would like to introduce and thank my sponsor!

Paul from is supplying me with all the stuff I need to get airborne.
He also delivers the newest protoypes for my testing purposes - like the GPS bob or the new Flyduino v2.1.

He developed the famous Flyduino controller which is powering many many multicopters right now. Also he developed several boards and bobs and offers a lot of RC products for reasonable prices.
The quality of his products is outstanding and the service is great. He delivers fast and reliable and is offering great support. I can recommend this shop and his products.

My nDROiiD quadrocopter is using the following Flyduino products:

  • Flyduino v2.1 flight controller
  • Flydusense v2 Sensor Board
  • Flydubution Power distribution board.
  • Green and orange 8" and 10" props
  • GPS Bob prototype
  • Numerous plugs, pins, bolts and a Bosch BMA020 Accelerometer bought at

Thank you Paul!!!

FPV Action, GPS and axes

some cool FPV Videos .... I am getting the hang of it.

I am optimizing the software right now. There were some very bad drift issues - so I think about replacing my BMA020 with another accelerometer.

I have a problem with the Mag, the motor currents distort the mag readings severely.


Today I got a GPS Bob made by aBUGSworstNightmare from Paul from for testing purposes.
After some time of reading and understanding the pins I now have a working GPS onboard.
I am looking forward to try position hold and coming home functions!!!

Working satellite fix on the Copter 
a GPS bob
Additionally I ordered a FMP04 GPS Chip from Kinderkram to fit it into Flyduino's upcoming GPS Bob.

FMP04 GPS Chip

Last week I made some custom motor axis out of spring steel - no more bent axes!

selmade spring steel axes