hey guys , I have just set a 500 heli up with a pix mini and im struggling with vibes. I have set it up and flown it with a spectrum flybarless system with no problem but on the move to arducopter it seems to have been a problem. I have attached a px4 mini to a flying heli on the spectrum system and powered it to record a log and the vibes are still very high , Does anyone know a way to mitigate this or am i missing something very simple
here is the log from the flight. https://drive.google.com/file/d/1ikcFVAp-gPS0CK5bSdH2ChLY3IJq4sUQ/view?usp=sharing
Hi Tom,
Is this an electric powered heli? I looked at your log but the data sampling rates were too low to determine the cause of the vibrations. You’ll need to set IMU FAST bit on the LOG_BITMASK parameter. Where and how is the system mounted to the helicopter? There are several places on this forum where this topic is discussed as well as a section of the wiki that discusses this. Most of the time I will mount it to the side of the frame where it is the stiffest and close to the center of the body. I use double sided foam or rubber tape that is no more than a few millimeters thick. In your set up where it is flying along with the spectrum system, do you have it calibrated and the orientation set correctly?
I’m not sure how the spectrum system determines attitude or even if it does. It has to be able to measure angular rates but depending on the features of the system, it may not need attitude or accelerations. Ardupilot requires attitudes for autopilot control and uses the accelerations for it’s inertial navigation system. It has a more complex way of determining attitude and managing drift in accelerometers and it is very sensitive to vibrations. These vibrations cannot be removed through software; they must be handled through physical means like mounting location and vibrations absorbers as well as ensuring proper rotor balancing and tracking.
Hi Bill,
yeh its and electric heli. I will set the IMU FAST and have another flight. The flight controller is mounted to one of the existing flight controller mounts on the top of the helicopter on a 3m pad. I realised I haven’t changed the orientation of the px but will do that before the next flight so that we can get logs
I would also suggest that you have the GPS mounted as well. The GPS provide crucial data to the controller to help the EKF in estimating position.
Just and update on this, i have been busy and only just got round to finishing this project off. I mounted the gps as you recommended and increased the sampling rate and worked out that the vibration was inline with the head speed. On closer inspection the align DFC head has been mis manufactured as was allowing a small amount to movement on the shaft which was casing the tracking to go out of alignment. Talking to the spectrum guys they have a high tolerance for vibes and the gains are pretty low on the gyro , which explains why it would fly on that and not on the pix mini. Thanks alot for your help @bnsgeyer much appreciated.
2 Likes