I’ve been bench testing my 650mm quad (Cube Orange FC) and keep getting vibrations that I identify at 70Hz through the FFT. If I do a motor test (so no feedback) I don’t see this. I’ve tried various levels of damping, changing the ESC (F35 T-motor) protocol from PWM, DShot 150-600, and setting the initial parameters according to the documentation. This vibration won’t go away, and I think it is getting amplified in the control loop. I’ve checked the frame for cracks and loose screws.
I’m terrified to take it for a flight test with this vibration. Any ideas what is causing this, and what I could do about it? Maybe a filter, or a setting in the BL Heli configurator? Or just bite the bullet and fly it.
Yes, a filter. Configuring the Dynamic Notch Filter(s) is a step in basic tuning. Post a link to a .bin flight log, let’s see this 70Hz mode. You should be running the BDshot version of firmware, set Dshot to 600,and If you are already looking at FFT then you must have INS_LOG_BAT_MASK set to 1 already. Make a short hover flight in AltHold and post that.
I installed BDShot firmware, and set all the parameters in the Bidirectional part of the documentation. I checked that the motors responded still. They did. When I updated the ESCs to Bidirectional 3d in BLHeliSuite, afterwards, the motors ‘stutter’ pretty badly. Should I leave the settings “normal” in BLHeliSuite?
Bdshot and Bidirectional 3D are not even related. Put them back to forward/reverse as required for proper direction.
After confirming motor order and direction with Motor Test forget about bench testing, it’s a waste of time and will tell you very little.
OK. I fixed some mechanical issues after an initial flight (added some vibration damping and a stiffer GPS mast) and did a test flight today. Still seeing x-axis vibration but the flight was pretty stable and smooth with some drift. Are the levels of vibration I’m seeing something necessary to filter?