When i throttle even a little (even without the motors) the quad starts shaking/vibrating like hell

V

vidyut

Member
I have made a custom quad with a 250mm wheelbase frame and 2300kv motors and 5.1 inch props and am trying to fly with an apm2.8 flight controller, my battery is 40c 2200mah ,

i tried tuning it and all but nothing seems to be working, when i callibrate the 4 in 1 esc and then simply throttle up it works perfectly but when i connect the apm and then try to fly it normally even without reaching the air it started wobbling and vibrating and shaking soooooooo badly, could anyone help me with whats happening.
 
LoneRCRanger

LoneRCRanger

Well-Known Member
Sounds like a motor imbalance caused by electrical fluctuations driven by the ESC. Try scoping for OHM and Voltage spiking. Not sure about what will cure it.
 
V

vidyut

Member
When i throttle up even a little then if the quad is in a horizontal position it stats wobbling like crazy

how do i upload video in this forumn? its not supporting mp4 files
 
V

vidyut

Member
when i callibrate the ESCs and then when i throttle up it doesnt wobble at all, but then when i disconnect the battery and get out of callibration mode and then actually try to fly it it starts wobbling really badly
 
LoneRCRanger

LoneRCRanger

Well-Known Member
1) Post video to YouTube. 2) Include link to YouTube video in the response box where you normally enter the text.
 
wafflejock

wafflejock

Well-Known Member
Does it do a similar thing with props on and standing far away from it outside? You might need to do a "softer" soft mount if using up to date betaflight. Found I was getting a similar yaw twitch with JBF7 on the latest.

Make sure the FC can move a little bit down and springs back up into place, if screws/nuts are too tight then vibrations from the screws starts knocking the IMU around and it responds poorly.
 
V

vidyut

Member
wafflejock said:
Does it do a similar thing with props on and standing far away from it outside? You might need to do a "softer" soft mount if using up to date betaflight. Found I was getting a similar yaw twitch with JBF7 on the latest.

Make sure the FC can move a little bit down and springs back up into place, if screws/nuts are too tight then vibrations from the screws starts knocking the IMU around and it responds poorly.
Click to expand...
yes it does do the same thing with props on
 
wafflejock

wafflejock

Well-Known Member
Yah it is really hard to guess would suggest check all your solder connections to ESC from motors a loose or bad one could cause motor to be kicking on and off and introducing the oscillation and making it worse (I also had that problem a few times but once I tried with props on in a tennis court the problem became obvious, race wire lights helped determine which motor wasn't getting consistent power after that I ran into the soft mount issue with the FC that also caused some yaw jerks and ultimately oscillating out of the air, honestly didn't bench test with motors running and quad in my hand though)
 
wafflejock

wafflejock

Well-Known Member
Take a picture close up of how the FC is mounted in the stack (make sure it has rubber grommets in the holes between screws and FC or are using nylon standoffs but prefer the former). If you can get blackbox logs from attempting to take off to disarm so can try to see if control input is all good and gyro data looks reasonable or if it is getting blips in the gyro data it's then reacting to with throttle to the motors that starts off the oscillations
 
holtneil

holtneil

Well-Known Member
Moderator
Hi i know this is going to be a pain but disable one motor at a time to see if vibration stops it may be a bad motor
So you need to pop off 2 wires off the motor tape the bare ends so it cant short out then run quad and ses vibration stops you may have to test all 4 but one at a time
Also check the gains on the flight board if one has gone max this will make it shake
 
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