A pig to fly - in flight oscillation

[hibbo]

Hello all.

The weather backed off enough today for me to finally get out, shovel some snow and fly my quad; HJ450 (dji clone) with a crius se (which I now also believe to be cloned pr something totally different as the pictures on google don';t add up lol) any way.  I have balanced and trimmed everything using WinGui and the help of people here on the forum 

I can fly my quad and had it up around the roofs, put 2 batteries through it and brought her home. 

The thing is tho it constantly oscillates and bounces around but to no set rhythm if you get me?  My question is have I bought cheap rubbish  http://www.ebay.co.uk/itm/F450-Quadcopter-Frame-ESC-Motor-Propeller-New-MWC-2-1-Fully-Assembled-/280994237070?pt=UK_ToysGames_RadioControlled_JN&hash=item416c8fca8e and I need to get a better set up or are there some of the PIDs I can change for a more stable hover?

Mucho help very much needed and thanks in advance

Hibbo

[hibbo]

Well, what can I say, out flying today in my back garden having tired to alleviate some vibration issues, then all of a sudden BOOM into the roof, total loss of control.  Luckily getting her down was easy and there appeared to be no visible damage, not even a broken prop.

On further inspection I noticed the bottom bearing on one of the motors had come out and the shaft was no longer attached to the base of the motor.

Then it hit me, while I was tinkering around inside yesterday I found a tiny little cir-clip on the floor and thought "hmm that';s odd, oh well"  Now when I look at the other motors it was definitely from there.

Lesson learned I guess, and here';s hoping some new, better quality motors will keep me level and true  ::)

P.S.

If anyone has any recommendations for replacement motors that';s be great.  My 450 weighs 900g with a 3s 2200 battery and currently have 9x4.7';s

[guest325]

Mine has got Rcrimer 2212 1000 kv motors runs very nicely on 3S 2200';s (about 8 mins)

[teslahed]

A screenshot of your PID settings may shed some light on the oscillations you are getting in flight.

[hibbo]

Thanks, things are getting better since I reset to default.  Feel free to suggest other settings.

[teslahed]

If your quadcopter is more or less PID tuned but still flies a bit jittery it';s worth looking at the low pass filter settings in the multiwii code;

MPU 6050 Low pass filter Quadcopter test

Basically it allows you to tune out vibrations from motors and props - you want to try a few different settings but you';ll probably find either 98 or 42hz works the best. In an ideal world you';d have perfectly balanced motors and props and you wouldn';t need to use a low pass filter - in reality most of my quads either run with 98 or 42hz filters and fly better as a result. If you go too low (below 42hz) you may start filtering out the actual signal from the gyros / accelerometers and this can make your quadcopter fly badly. 

I can';t work out exactly what flight controller you are flying with or what sensors it uses. Do you know what the gyros / accelerometers are? You need to know if it';s the MPU6050 or ITG3200 in order to select the right low pass filter option in the multiwii code.

Some more details in this thread;

http://www.multi-rotor.co.uk/index.php?topic=426.msg3224#msg3224

[hibbo]

Ha, had a mare, but ok so far.  Will let you know how I get on

[hibbo]

Well, like a noob I accidentally loaded a blank version of 2.1 onto my quad  , but pretty much only really need to state it';s an QUADX and what board it is (which I';m unsure of to be honest, but will take a pic when tonight and see if anyone knows what it is), will play around more tonight, not tried anything in config.h before and it looks pretty good to be honest.  So was thinking once I get the basics set up in config.h and I do the rest of the tuning in the GUI?

Thanks for all your help

[teslahed]

There are lots of different multiwii boards with different sensors on them.

You set the basic options up on the config.h file to specify which sensors the board should expect and alter motor start and stop values to work as best as possible with whatever ESCs you are using and similar - then you use the GUI to PID tune the board to get it flying properly - then you go back to the config.h file to fine tune some of the more advanced options like the low pass filters i described above.

Altering stuff like the low pass filters is a bit tricky to start with, partly because you have to get everything else working mostly right first or it';s just more variables to confuse yourself with, but you aren';t ';writing'; code so much as just altering code written by other people that is well commented - the video i posted up shows the kind of stuff you will see, you just alter values and comment in and out sections that are already written to turn stuff on and of and alter values for specific features.

You will need to know exactly what multiwii board you have in order to alter the code correctly for the right sensors though. If you take a close up picture of your flight controller in good quality i should be able to work it out from that for you.

[hibbo]

Thanks for the clarification, maybe you could clear up what type of board I actually have lol

[teslahed]

I can';t really tell from the picture. You may have to message the guy you bought it from and ask unless anyone else recognises it.

[hibbo]

No worries, I was told I was getting a Crius SE, but don';t think it is, Have set it as a Crius SE in config.h and I';ll see how I get on.

Thanks again