Recently I have noticed a strange diagonal wobble on motors 3 and 4 which is really noticeable if I turn down the Pitch/Roll D Gain. From the included logs I notice that All motors do not have the same PWM value in the hover.
Is this normal, do I have a bad esc calibration or is there a hardware issue
David Ardis
I was thrown off initially by your motor outputs. It just looks like a side to side imbalance to me. Right side motors working harder than left. Just curious, why are you using EK3?
Am I not reading my logs correctly RCOU 5(in my case this is motor 1 and RCOU 2 are working the hardest are these not front right and back left. What do you mean by using why are you using EK3 is this wrong
David Ardis
You are right, the odd motor order thru me off. I assumed they had just shifted down from 1-4 to 2-5.
I don’t mean anything by it just curious as it’s not common to enable EKF3 unless there is a reason to do so. Special sensors, etc. And in any case it’s not enabled for flight control you have AHRS_EKF_TYPE at 2.
Definitely a mechanical issue. If weight is balanced, the motor imbalance is so great that maybe you are using reversed props flipped upside down? Can you provide a detailed pic of the craft? I think a tune is not possible with such an imbalance and this is causing the wobble.
Enclosed is a link to a number of detailed pictures of the aircraft
Please note motor 1 is plugged into 5 because of an issue with an early version of pixhawk 2.1
David Ardis
are the bell housings rubbing under load?
Keith
Nothing is rubbing have checked this and there are no scrarch marks on the motors.
I have been flying this machine for quite a few years and this issue has only started recently.
David Ardis
then im lost… only thing i can think of is incorrectly configured/calibrated escs
i would have to say the motors are balanced because FC is commanding the 2 sets of motors evenly, so I have to think the FC is countering a yaw… can test this by setting MOT_YAW_HEADROOM to 100 and see if it wants to spin as soon as you get off the ground
if it wants to spin, check binding in motor 3 or 4 (bearings or rubbing)… if it doesn’t want to spin, check your escs
Keith
Figured out the problem. After recalibrating the esc’s checking the motors and doing 4 test flights discovered the rears props where not sitting completely level.
Did a quick adjustment and test flight the difference in the is now much less. will all need properly levelled over the next few days
Thanks for trying to help and sorry for wasting you time
David Ardis
ahh i forgot to add motor level as something to check if it wants to spin… you would have spun if set MOT_YAW_HEADROOM to 100