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-   -   Point me in the right direction diagnosing a quad problem? (https://www.wattflyer.com/forums/showthread.php?t=73366)

tehlump 03-18-2014 12:55 AM

Point me in the right direction diagnosing a quad problem?
Hello everyone,

I am new to quadcopters, dove in headfirst and bought a kit from rctimer, the 450 sized spider quadcopter. Here's what I have:


RCtimer spider quad frame
arduflyer 2.5.2 updated to 3.0.1 arducopter (I think that's the version, it's the latest version I have uploaded)

I got it built and took it up for its first flight yesterday. It flew and was controllable but had a very severe wobble or oscillation. I searched around and figured it was a PID problem. By default the values were:


I watched a couple of youtube videos explaining what the PID look was and figured I was now a PID expert! I changed the P value to .1200, attempted another flight and it promptly flipped upside down on its back. :) Obviously I have no idea what I'm doing so I was hoping for a nudge in the right direction.

After reading and watching some more videos for similar problems I began to suspect that my problem was more vibration related. It turns out one of my prop adapter shafts wasn't true, this caused a nasty vibration so I figured if I sorted that out it would improve things. My neighbor is a machinist so he got that sorted out. Running the motors without props now is very smooth.

So I attempted another flight today with my neighbor filming so I could get the expert's opinion on what I need to address first.


As you can see, the problem is bad. I have reset the default PID values I stated above, those values were in effect for that flight. At first I thought the wobble was purely roll related but having watched it for a bit it seems to be rotating around like a quarter spinning on a table.

The vibration log shows that X and Y are staying below +-3 and probably closer to +-2, the Z is centered on -10 and stays within -8/9 and -11 or so

Thanks in advance!

tehlump 03-19-2014 12:55 AM

For anyone who has a similar problem...

I spoke with a couple of more experienced users who both said that the wobble in the video seemed to almost definitely be a symptom of a too high P value.

Over a number of trials I ended up settling on a P value of .0500 and the shaking is gone. It's flying smooth as glass now!

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