I have an odd problem that just baffles me to no end.... I know this is not in the exact correct place, but I have a slight bit of pressure to get the quadcopter to tune-able conditions. I'm in a group working with autonomous vehicles as a project in college, and we changed frames from the older Jdrones frame to a hobbyking SK450, which is really bringing out some odd problems that the larger frames covered up. We have an arducopter APM 1.4, 850KV jdrones motors, 3S 2650 mha lipos, 3DR radio, magnometer, GPS, and a Turnigy 9x. First, we had some major vibration and balance problems, but with 9 years of rc airplane and heli experience, nothing too hard to take care of. Upon takeoff, the quadcopter would tip hard and fast back and too the right. After balancing, the flight characteristics were significantly better. However, we still had problems with back and to the right, but it was different. It was more of an exponential thing, and the quad would start stable, almost perfectly, then gradually move back and to the right, and requires full forward-left control after a while to keep level.

So, I went through the list. I tried leveling, calibrated the ESC's, re-balanced the props, checked the level of the motors, checked the motors for bent shafts, tested every esc and motor individually, checked all the joints, reloaded the firmware, changed version of the firmware, checked the parameters, checked them again, and nothing seems to make sense. Yesterday, I found something out that makes perfect sense and no sense at the same time. I leveled the quad in the mission planner, and flew, and the same behavior still existed, so I landed. I looked at the HUD, and on the same floor, same exact spot, the HUD read 15 degrees down and 15 degrees left. And, after a few seconds, the HUD returned to looking perfectly level. It happens, flying or not, I can manually tilt the quad, to the same effect. This problem seems to persist across all firmware from 2.6 - 2.8.1, so my question is, why does this happen, and how do I fix it? Any help appreciated, this one has me at a real loss.

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For clarification, after you level your quad the pitch and roll show level....and then they become offset by 15 degrees while left on its own or do you need to do something to get it to show out of level?  Does this happen gradually or instantly?  Does it ever go back to level or just stay wrong?

I set the quad down on the floor, run level from the mission planner, wait for it to finish, everything shows perfectly level, so I arm, then take off. I get about 4-5 seconds of perfectly stabilized flight, until it starts slowly pitching back and to the right. Correcting for this only adds to the problem, until I'm using almost full correction on the sticks. When I land, it shows the offset. It does re-level by itself once I set it down, more of a it gradual and slow return to level over 4-5 seconds. The HUD just kind of slowly returns to level, like with pre-programmed precision, no snapping, just a perfectly smooth return to level. I can also get this effect just by manually tilting the quad and holding it there for about 8-10 seconds, and again, the instant I set it back down, it's 15 degrees off forward and left, and starts to return back to level over 4-5 seconds again. 

Just a thought, do you have automatic trim enabled and assigned to channel 7?

The way I see it, if this were the case and channel 7 was always "high" this could lead to what you've described.

See here for auto trim:


Checked it, and just for good measure, set up channel 7 as auto-trim, and made sure it was off.... no joy, same problem exists.

I have a log file showing exactly what happens.... and it has serious repercussions on flight characteristics. Watch the HUD and you'll instantly see. I tilted in a few different directions, held it there, then returned to the exact level platform it started on.




Try loading the latest arduplane code into your APM and compare the difference in the HUD

Also check the box for tuning on the map window.

I find there is quite a bit of difference in how long it takes the HUD to return to level between the arducopter code and the arduplane code.

I will try that as soon as I get back form class, thanks! I have a plane I'm going to be putting another control board in anyway, and I should take a look at the firmware :) The problem is, though, the flight characteristics are exactly following what the hud shows..... I take of stable, the quadcopter adaptively changes its level, and starts flying specifically back and to the right, but upon setting it down and taking off again, it is perfectly level and stable for 4-5 seconds, then the process repeats all over again. I'll put up a log of the flight, and a log of the arduplane firmware when I get back from class.

Here are the logs for a testflight I just did with the quad, showing the disorientation in the HUD. The few seconds before I disarm, I've just landed, and the instant I disarm, it re-levels. The plane will be up in a minute.

Might help to upload the logs.....

The first file is the quadcopter flight, the second one is after loading arduplane on it....I find it interesting how the heading seems to be moving, even though it isn't, the quad is still, just tilted at an angle...


just wanted to bump and see if anyone's had a chance to take a look yet, thanks!

I looked at your file from the other thread and I see what you're talking about, but I'm afraid I don't have an answer.  The auto-tune sounds the most plausible to me, maybe try physically disconnecting channels 6 and 7 just to rule anything funny out?

It's odd how your pitch and roll are way off, and then slowly drift backup after you land, and appear to go back to the correct setting they were at before.

Also, in your parameters, your channel CH7_OPT is set to 5.  The default is 7, I don't know what having that set to 5 does, but it sounds more and more like auto trim.  

I would also advise with doing another erase on the APM, uploading fresh firmware, and do the very basic adjustments of rate p etc and then testing.

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