Level automatically adjusting in flight...

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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  • Ok, I have an update for everyone: The board is still exhibiting the same problems, and now even a KK 2.0 board isn't helping stabilize the copter. All of the hardware I have comes from the remains of a project that was started a year before I got to it, so I will be most likely replacing the whole system. Meanwhile, I found a great way to repurpose the 1.4 board! It works perfectly as a HIL simulation unit, and I now have a dedicated simulation rig! Thanks for all your help!

  • Hello,

    I've the same problem with my hexa. and I try differents solution, but nothing 's good yet.At this time I think it's the cold temperature which create this phenomene.

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  • Thank you very much everyone for your help! It looks as if the school has put enough money into the project that they are willing to pay for the APM 2.5 instead of grounding the project. With any luck, after I come back from break, there will be a new board waiting for me to pick up, and I'll keep you posted! I will most likely be back on here soon, we have a plane that we're going to help coding for a competition using the paparazzi autopilot system. With any luck, we hope to have the quadcopter and plane to communicate with each other to direct each other towards targets they identify by post-processing video to accomplish missions. That should be about a year away, though. ;) Thanks again for the help!

            -Austin

  • Unfortunately, while we do have another IMU board, it is currently down, and most likely dead, due to a USB issue. The current hardware seems to be working, just with some incredibly odd behaviors. What would you recommend as a course of action from here? Just a full replacement/upgrade to 2.5, or any other tricks for me to try? I have swapped props, triple-checked them, replaced a motor already because of a bent shaft, etc. It flies well in acro, so it isn't a hardware with my power/radio system. Do you think it could be a problem with the sensors being dirty or having residue built up on them from soldering within the general vicinity? We have done a significant amount of soldering in the last month or so, from redoing the Jdrones V1.0 kit to upgrading frames. What is the professionally accepted way to clean a board like this so I can rule that out? At this point, I don't quite know exactly what's causing this problem, and it's quite baffling. I had a few engineers in the UAV field look at it yesterday, and they came to relatively the same conclusion that it was tentatively a hardware problem. I don't even have the GPS or the compass enabled, or mounted for that matter, at the moment, figured that taking out any possible source of extra complexity would make it easier to debug. 

  • I tried eliminating all vibrations, including mounting the board to a rather large kitchen sponge, to no avail. Any thoughts? This log is with the board mounted on the sponge, and not quite in the air, just on the ground on the edge of taking off. 

    2012-12-09 15-23-16.tlog

  • mmm... switch your props, check if the problem switches too. 

    If so, get harder props, APC or CF.

  •  

    I am not an expert but when  iloaded your tlog files i dont see your satelite fixed? do you have satelite fixed? and you see 3D fixed on your Mission planner? have you tried to test it when the sat is fixed?

  • 100KM
    Have you tried setting your I terms to zero? This kinda sounds to me like an I-term winding up and back down again after you set the copter down. In the pid settings, try setting all I to 0. If that helps, then significantly (50%) lower the I-max values en try again with the I-terms set to previous values.
  • Sounds like vibration to me.
    Just for laughs try a kitchen sponge under the FC.
    If that works put some sorbuthane under it permanently.
  • Hi,

    Well if you need to save time, better try find somebody experienced in Arduino stuff to help you..

    Actually is it easier to connect to the APM from Mission Planner, then go to Terminal and you should get (to) a prompt:

    ArduCopter Vx.x.x]

    Type "test" and ENTER

    at the ensuing test] prompt, type "ins" and ENTER.

    After "g" there are 3 numbers; this is gyro rates. All should react to rotations around different axes.

    After "a" there are 3 numbers; this is accelerations. All should react to holding the copter/plane in different attitudes.

    Regards

    Soren

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