Good morning DIY DRONES,
You guys are my only hope as I have tried everything I can to fix this problems but it seems like an never ending journey.
So, let's me start by saying that I have followed and researched about every possible way to build a TBS Discovery with Pixhawk but my knowledge is still very limited, as I keep on reading, I feel like I have made so many stupid mistake.
So my TBS build list:
TBS Discovery w/ core.
900kv TBS motors and bulletproof escs
9x5 propellers
Pixhawk w/ GPS
4500mah 4s battery.
I have been facing so many problems since thay day I switch from 750kv to 900kv, as everybody said the samething, 900kv is way much better, better bearing, i choose 900kv for long flight etc...
After I install the 900kv on my tbs, everything started to fall apart, Mag_field is really high, over 680 :( Vibration is absolutely ridiculous (eventhough my X+Y axis is still under range but my Z is way beyond measure). My quad could not hold position or altitude, when I fly in stabilize mode it seems to be okie but when i switched from stabilize to either Loiter or Altitude hold, the quad started shooting up and down just like when you change throttle from lowest position to highest in a matter of second. I have to switch to stabilize mode immediately other it will keeps going up.
Could you guys please help me to make this right, i'm truly desperate, i have tried everything but non of them seems to work.
Please find my attachment for the log file, i have tried to fly it as long as i can to review the problems. Please DIYDrones, you are my only hope. 2014-09-12%2023-29-04.log
P/s: I have calibrated all escs, compass, etc.. I followed the introduction closely but non seems to work
Replies
Hey Long,
May I ask what firmware you're flying? Another Disco owner and myself had throttle issues that were fixed by moving down from 3.1.5 to 3.1.4:
http://ardupilot.com/forum/viewtopic.php?f=21&t=9545
I read about your post and it seems to me that we are having the same problem, i will try it first thing tomorrow buy downgrade the firmware from 3.1.5 to 3.1.4 and see if it helps.
If it does because of the firmware upgrade, I will report bug so that everyone know what they are dealing with. By the way, how heavy is your quad? I'm having trouble building my TBS discovery with gimbal. Can you show me some pictures?
Thanks again JoeBob
Just want to say that these Carbon Props can be the cause for the vibration.
I had them on my F450 as well with 1000kv motors but until i changed to Graupner E-Props i had problems with this machine. I balanced them but these are crap propellers if you ask me.
Is it by RcTimer as well? I will purchase some 9x5 Graupner if it helps, but I balanced the problem quite well so I don't think it is the problem here. I have completely no ideal what to do now :(
i couldn't believe it either. but trust me and try the E Props. my problems were definitely introduced by these props. yes they came from rctimer. since then i have put a whole bunch of these 9x5 carbon props and 8x5 ones into the trash bin. they are stiff, cheap and strong but else they only brought troubles.
Followed your advise, I have just purchased the e Props 9x5 for my TBS. It will take sometime to arrive, I will give it a shot :D
Any suggestion on the mounting pixhawk? I saw a post on building the TBS Discovery with Pixhawk by kf6bbl here at FPVLAP (http://fpvlab.com/forums/showthread.php?25533-Discovery-with-Pixhaw...). It looked quite amazing, but would it make any different if we move the Pixhawk to the top?
Yep, I'm in that thread actually. I have a Discovery Pro and I used to mount my Pixhawk on the bottom plate, but I just moved it to the top plate because I wanted better vibration isolation. I purchased one of these guys here:
http://www.readymade3d.com/anti-vibration-mounts/omnimac-pixhawk-mo...
If you have access to a 3d printer, you can print it yourself from the files here:
http://www.thingiverse.com/thing:163472
and buy the dampeners from HK here:
http://www.hobbyking.com/hobbyking/store/__37447__General_Purpose_A...
It's just too big on the Disco Pro to fit on the bottom plate, but it seems to work quite well on the top plate. There might be a little more space on the regular Disco to put it on the bottom though. It doesn't really make any difference if you move it to the top, other than that it doesn't look as clean and neat, but now you have much easier access to the Pixhawk, which is definitely a plus.
I have just purchase that as I don't own any 3d printer...lol.. this is a out of space question but do you have any recommendation on a budget 3D printer? or best DIY?
You should also check the vibration levels coming from the new motors. Do one at a time. You can get an app for your smartphone which will check vibration levels. Tape it firmly to the arm of the motor you are testing. You might have an out of balance motor.
What was mentioned about the loom. Definitely keep any stiffness of the wires away from the pixhawk. I tied mine down to the bottom plate away from the pixhawk with just enough play to not affect the vibrations. If you get one stiff wire resting or pulling on the pixhawk you will get vibrations. Especially with the gel pad. I am using the same Kyosho gel and x,y are below 3 and z is below 5.
Thanks for your comment, I have already balanced the Props and the motors one by one using 3 axis vibration app. I would not say that it is perfectly balance but it is a lot better than stock. Further more, I will definitely follow your advise on wiring, i have twisted it but it seems that I let it loose too much and that might cause the problem. This is sound really
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