I have my copter flying very well in stabilize mode. But in alt hold and position hold i’m getting lots of variation in altitude sometimes having massive climbs that only seem to stop but flipping back to stabilize. I have my motors and props balanced. My pixhawk is mounted on kyosho gel. You can see in the logs that the spikes in acc z correspond directly with the spikes in altitude. Any idea what could be the likely cause of this? is it likely that some how my motor/prop balance is to blame? ( balanced my motors with the laser technique and my props with my dubro balancer).
I’d really appreciate any advice as I’m kinda at the end of my rope. Thanks!
looking at my log between the spikes in z vibrations the vibrations are actually very low. What would be the likely cause of such big spikes in vibration when overall vibrations are pretty small?
Any “event” can create a spike if the board doesn’t have the capacity to filter them out.
A change in flight mode, gust of wind or strong control input.
You might find running your log through the http://www.rcgroups.com/forums/showthread.php?t=2151318 helpful. It provides an insightful summary. Of course one of the log reading gurus here can help as well, if you are logging enough parameters.
Someone reading the log manually might have different advice. Although your flight report sounds classically vibration related, to me.
Based on my experience adding a VB board made my IMU mismatch and vibrations a non-issue. It has improved all modes of flight.
I was getting a similar bottom line summary even through I had fairly decent flights in all modes. With the VB board with 32db ear plugs I get “excellent vibration levels” and it seems to fly like it’s on rails.
[quote=“FullScalePilot2”]Someone reading the log manually might have different advice. Although your flight report sounds classically vibration related, to me.
Based on my experience adding a VB board made my IMU mismatch and vibrations a non-issue. It has improved all modes of flight.
I was getting a similar bottom line summary even through I had fairly decent flights in all modes. With the VB board with 32db ear plugs I get “excellent vibration levels” and it seems to fly like it’s on rails.
What were you using before the VB board? I’m using 4 squares of very expensive Kyosho gel. Which is whats recommended in the APM manual.
I was using 3M tape. In the beginning the vibrations were good. Then they began to degrade and the IMU mismatch was quite high. Dennis Baldwin’s YTV’s (available in the link above) provided some good objective testing and I went with that. I believe he tested the Kyosho gel was well. I may have stated I bought Moongel, but then found out it melts in >90 degree weather. So I went with the 3db ear plugs.
[quote=“Flyhigh”][quote=“FullScalePilot2”]Someone reading the log manually might have different advice. Although your flight report sounds classically vibration related, to me.
Based on my experience adding a VB board made my IMU mismatch and vibrations a non-issue. It has improved all modes of flight.
I was getting a similar bottom line summary even through I had fairly decent flights in all modes. With the VB board with 32db ear plugs I get “excellent vibration levels” and it seems to fly like it’s on rails.
What were you using before the VB board? I’m using 4 squares of very expensive Kyosho gel. Which is whats recommended in the APM manual.[/quote]
If the PH is mounted in the open it could be, “all of the above.” I came across some thread supporting the concept of a firm FC mount, with finely tuned motors and props. Ultimately that logic still leaves the craft open to the issues you experienced.
I haven’t pursued a dome cover yet, due to the added weight.
I’ve conceded the VB board provides another level of protection against the sources of vibration you describe. So far… very good.
[quote=“iseries”]I am experimenting with this effect right now. I build a quad copter and Velcroed the Pixhawk right to the base plat. This should produce bad vibs.
During normal flight it looks good. Only when I fly against the wind do I get heavy vibrations and fly aways.
So is it the wind blowing against the Pixhawk, The face plat vibration, Induced motor vibration, or all of the above.
In any case the logs are showing the same issue I have except I did mine on purpose.
