Motors not spinning at the same speed...

[o5b0rn3]

I've attached 2 videos to help explain my question...

When I use by DX6i Transmitter throttle, the motors don't increase uniformly, in fact motors 1 and 3 seem to be increasing but not motors 2 & 4. However when I use the master switch on cleanflight all the motors go up uniformly.

Is this normal or is these a problem that I need to address.

my configuration:

Lumenire RX 2206 2000kV
Lumenier BL Heli 30 amp
Tattu 1300 mAh 75c 4S
SPRacing F3 FC Board
Spectrum Dx6i
Lemon 8ch receiver w/PPM output​

 

[cranialrectosis]

Your videos require me to 'sign in to view'...

If you are on the bench, expect this. The copter is trying to fly and on the bench, the motors don't control the pitch so the FC overcompensates by slowing some motors down and speeding others up.

If all the motors start at the same time, put props on it and see if she flies. If the motors don't all start at the same time, synch your ESCs then go try the maiden.

 

[Craftydan]

Can't watch the video here, but from your description, this is normal.

From the motors tab you have direct control of each ESC, so what you set is what gets sent to the ESC. If you raise the master by 50%, they all get a command to increase by 50%. If they rise 50% in throttle in concert, they're all in sync.

From the TX, after arming, your command passes through the control loops, and they are trying to stabilize the airframe to match your inputs. If your airframe's attitude isn't yet under the control of the motors (it's still on the ground) those control loops will do seemingly stupid things to get the motors the change the attitude. It doesn't know the ground is enforcing that attitude, so it's over-reacting because nothing it does makes any difference.

As the skids get light and start to break free of the ground, a good controller will readjust. They'll start getting closer to the same speed, but will rev up/down each motor as necessary to maintain attitude. How well your controller is tuned determines if it does this without over/under reacting . . . but until the craft has left the ground, you can't know how far off from this you are.

Check your motor directions and assignments. Check your board orientation . . . then put on some props and get her running under her own power. Typically I'll get her light on the skids (always ready to cut the throttle), then slowly test each of the cardnal directions by slowly increasing the pitch/roll command until the correct side starts to lift . . . then back to center. Set it on a smooth-ish surface, throttle to light on the skids, then yaw to check direction. If anything doesn't look like it's moving in the right direction, stop and correct. After that, stand clear, throttle up to "light on the skids", take a deep breath and give it a brief burst of high throttle to "pop" it up into a hover.

 

[Ocean]

Nothing wrong with that. It's the PID Controller doing its thing.

 

[o5b0rn3]

Thank you all for your responses. Glad to know this is normal.

 

[FlyingMonkey]

Check this out too...