Hi All,

I'm not sure if this is the forum to place this, but it just might be interesting to some of us..

A while ago I was waiting for having my car-tires balanced when I thought that must be possible with my motor-prop combination as well.
So what I did...
Got an old 9DOF razor board from Sparkfun, a motormount, a laserpointer, old transistor uses as light sensitive element, ESC and some programming skills and assembled this into a "Dynamic outrunner and propellor balancing Unit".
The razor board is equiped with an 8 MHz Atmega 328 chip that drives the ESC and reads the light sensitive transistor. Communication to a PC application is done by serial I/O
How it basically works:

- connect the razor serial port to your PC running the visual basic application.
- place the outrunner with propellor mounted on the stand. This stand is flexible mounted on the wooden base plate.
- mark one blade of the propeller with a marker. With each succesive balancing-run this marked blade should be on the same starting position.
- on the pc-application click the "RUN" button.
- now the motor runs from 1000 to 3000 RPM while the accelerometers on the razor board are constantly read. The measurements are sent to the PC-app.
- this pc-app shows the place where a counterweight should be put. It also kind of indicates the mass of it.

Done this several times to test the system and till now it works very well :-) I noticed that not only propellors need balancing, but also the outrunner itself. Could just be poor chinese quality as well :-(
All video's I shoot with my quad are without any halo-vibration-effect since and the quad is vibration free.

What else did I do:
- motors are mounted with shock absorbing supports.
- I removed the circlip from the outrunner-axle. This not only makes the balancing action very easy (just pull off the propellor unit) but also saves the bottom ball-bearing from excessive wear. I know some people may say
this is dangerous, but I never experienced a lost propellor. Every 50 flying hours I replace all bearings with quality european bearings.

Config:
motors: 4 X KDA 20-22L from Hobby King
Prop: APC SF 4,7 * 10
APM 1.4 Hotel & Oilpan with selfmade MS5611 baro-modification
ESC: Turnigy 25A basic 3.1 met simonk firmware, all calibrated manual
3DR radios 900 Mhz, HF decoupled by ferrite ring
sparkfun compass removed from frame by Starship Enterprise construction, shielded cable
Ublox LEA-6 GPS
RX/TX 40Mhz Robbe/Futaba F14 8 channel, ch5:6-way diy-mode-switch, ch6:potty, ch7 extra switch
No sonar
Lipo 4000 1p3s
2 X ubec DE-SW050 Fixed 5V switching regulator(http://www.dimensionengineering.com/products/de-sw050) both with 220uF, 10uF tantal and 100nF parallel. One system for apm + RX, the other for, leds, 3DR radio
4 Ledstrips, discrete driver 2n2222 (yes, leftovers from the stone age)
quad made of: carbon en forex (= foamed PCV). The carbon arms are two crossed rods of 1 meter each.
motors on flexi mounts
apm, dampening with 2 millimeter neoprene + aluminum.
Powerboard: diy 2 * Y, wires to motors not yet twisted, but no effect on compass
No bullet connectors to ESC and motors, all soldered
Camera Canon A3300 with CHDK hack for interval shots and RAW images, even movies are good (love it)
Camera gimball: some chinese carbon thing, works well. 2 X Hitec HS-322HD servo

Total weight: 1.8 Kg w/ camera & gimball, Flighttime 10 min, without camera 12 minutes.
Size M2M diagonal 75 cm

See attached files for pictures and pc app screen dump

Off course, I'll be happy to share code and more insight information if anyone is interested.

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Update, I've now tested the schematic I drew in Fritzing and it works great! The only change I made was adding a resistor on the lead to the IR diode.

Hello!

I saw you shared the code. Why not use Github or similar. That way people can help with bug reports and even coding a little bit.

Let me know if you do this.

Cheers!

Hi Frank! I have a question about sketch for arduino (.ino file). Am I supposed to code it by myself or it exist? If so maybe you share it? thank you! 

HI!

I also constructed circuit.

Change the original plan: a fixed 5V infrared LED and resistor 200 ohm

two problems:

1:   sometimes turns off program:

" Windows Explorer has encountered a problem and needs to close. We are sorry for the inconvenience. "

2:  

propeller and engine will not change.

Measurement results are always other  / pictures /

So circuit useless  ?

Please help me. Any ideas?

Istvan from Hungary

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HI Frank!

I also constructed circuit.

Change the original plan: a fixed 5V infrared LED and resistor 200 ohm

two problems:

1:   sometimes turns off program:

" Windows Explorer has encountered a problem and needs to close. We are sorry for the inconvenience. "

2:  

propeller and engine will not change.

Measurement results are always other  / pictures /

So circuit useless  ?

Please help me. Any ideas?

Istvan from Hungary

Attachments:

I had similar issues at first.  Watch this video and start with the settings they used, then tweak as needed.  The windows application still crashes on occasion but much less often if I use fewer sample runs.

http://youtu.be/eWWOqcSu8IY

This project is awesome.

Will there be a set to buy from you?

Problem solved.
Adxl345 modul works, but fals data transfer to pc.

Use spare modul.
Everything works!

Is still experimental.

I tested many many

After talking

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Thanks!

Problem solved.

Adxl345 modul works, but fals data transfer to pc.

Use spare modul.
Everything works!

Hi All,

I have build this balancer, and I am getting good readings on the PC app, but I struggle with them being consistent, and in the right direction, as compared to the way I have my accelerometer mounted.  Under the configuration section on the GUI program, what is the "magic box" option?  I was wondering is anyone knows?  Also, has there been an update to the software?  Have been looking for a long time to be able to dynamically balance props, and this project is awesome.  Thank you Frank for your effort, and your genius coding skills in putting this together...

A set up Video would be nice, confused?

I just sit down for when have enough time to build one

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