Wow! What an adrenaline rush! After some more tuning, I felt comfortable to get my heli some real flying, Since I just had a sonar installed and the sonar numbers looked fine from the console test, I took her out for some Attitude Hold (AH) test. I've read so much that the AH could have quite a bit of error so I took her up above my roof and hover there.
My backyard is real small and surrounded by trees. Above my roof is the only viable place.
After hover a bit, I enabled the AH. It seemed to be doing well, and all of a sudden, it dropped like a stone and I immediately throttle up and fight against the AH for a bit. Then tried to let it hold again. And it still drop like that a few times. Quite scary. lol.
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Oops. First crash.
Was trying to hover using the sonar again, but this time on a flat ground to make sure it is not EM spikes. The APM insist on climbing up. Before it hit the branches on a very tall tree up there, I tried to lower the throttle to get it down, but it was still using pitch to climb. So I hit the throttle hold and try to auto it down, but the APM was doing some other control and got the heli spinning. Not to mention I forgot it was already using the pitch to tried to climb. I had no more pitch control to slow it's decent. Lesson learn. Should have shut off the Attitude hold instead...
Robert pointed me at your post and you have a bit of an offset between your desired roll (or pitch) and the actual roll (or pitch).
You can see it in the graph below of your desired pitch (red) and the actual pitch (green). The gap between them is unusual. I notice you have your stabilize roll and pitch I terms as zero. Could you try increasing that a bit. Keep your IMAX low though (like 1 or 2).
I think Robert has already told you about the issue with your sonar but just to prove it. Have a look at this graph of your sonar (green) and the altitude hold's output. You can see a lot of spikes downwards from the sonar and at the same time a spike up from the navigation controller. There are instructions for ensuring your sonar is free of EMI and power line noise on the wiki.
Good luck.
-Randy
This is how I mounted my Sonar. I modified a 500 landing skid for my 450 so that I can mount battery at the bottom and camera go to the front where battery usually go to for FPV. The 500 landing skid has a wider stand, and much stronger as well.
I had a look at the rest of your log and... it seems strange.
First of all, were you more or less pointed almost due north most of the time? The log indicates that, but I'm not sure it's right. It looks like you took off facing east, and then yawed to the north and held that? If you were standing in the backyard, flying over the roof, maybe it makes sense.
Your pitch and roll don't look great either. The pitch is not tracking the pitch in very well at all. Ditto roll. Like a permanent offset.
I looked at your logs. There baro and sonar do not have good agreement. It could be noise, but it sort of doesn't look like it. If I had to guess, I'd say your sonar was picking up things on the ground and responding to it.
I would suggest you disable the sonar for now, and tune your Alt Hold using just the baro. You have an APM2, and might not need the sonar at all, the baro is very good. For certain at this point, your baro is more reliable than the sonar. The sonar can be tricky.
Don't fly in an area like that. At least while you're tuning it in. It's a recipie for disaster. You're best trying to work on the sonar in an area where the ground is flat with no obstacles to pick up. Then you can be sure if you have noise on the sonar or not.
How did you mount the sonar?