Unstable Drone - PID settings? - ArduCopter User Group

David Pulvermacher February 10, 2016 at 6:44am

Hi Daniel

As others have said there's loads of info in the wiki....

This could be useful:

http://diydrones.com/group/arducopterusergroup/forum/topic/show?id=...

Best DP.

Paul Atherton February 9, 2016 at 3:42pm

Its hard to provide more specific response without more information about your setup. Photos maybe, plus an indication of which FC hardware you are using? Also logs would help - these can be copied off the SD card and attached to a reply here allowing the community to have a look.

I did experience similar lack of control exactly as you describe above when I built a quad recently - I'm not suggesting that the underlying cause is the same on your quad, but in my case I had applied too much dampening on the flight controller mounting - basically the foam I used between the FC and the frame was far too soft and the quad's movement would fling the FC on its mounts screwing up the accelerometer readings causing the FC to over compensate. I was basically inducing vibration into the FC instead of dampening the vibes from the frame. I now have 10mm thick 3m style foam squares fixing the FC to the frame, and this provides the right level of vibration resistance plus it still holds the FC firmly in place. 9/10 of stability issues on new builds come from vibration. A properly isolated FC helps attenuate the vibes produced by the frame, but its always best to deal with the source issue. This could be a frame which allows too much flex/twist, motor bell play, unbalanced props, or even something coming into contact with the FC which passes vibes directly through. I would suggest checking the AccX, AccY and AccZ values in your logs after a flight test. The 3.3 firmware provides even better vibration analysis. There is a lot in the wiki about vibes. See here: http://copter.ardupilot.com/wiki/common-vibration-damping/ Plus, you are using a very old version of arducopter. Would suggest using the newest possible version compatible with your FC.

Best of luck

Clifton Hipsher February 9, 2016 at 2:55pm

I have two aircraft. One is a quad with an APM, and the other is a hex with a Pixhawk. Both aircraft fly just fine on the default PIDs. The only "tuning" I have done is Auto Trim.

If you have built the aircraft properly, and if the aircraft is balanced in roll and pitch, the only thing you really need is more stick time.

The big mistake that most beginners make is assuming the aircraft will stay in one place with no stick input, or assistance from a GPS. The fact of the matter is, unless you are using a GPS assisted flight mode (and in some cases even if you are using GPS) the aircraft will drift in one direction or another.

The bottom line is, unless the aircraft is in a GPS assisted flight mode, you have to fly it.

John O'Brien February 9, 2016 at 2:36pm

Daniel, when I was getting my drone going I found it best to go back to the beginning with Mission Planner(MP) also the Wiki. If you go through the wizard and the guided steps to set one up it makes a huge difference to the outcome - so latest firmware, claibrate the ESc's calibrate the accelerometer and compass as well as the radio. I think there are 16 steps. Read about all the tools in there that will let you know if the engines all spin at the same rate. I know its a bit of work but it pay you back many times.

After you have done the calibration make sure you set up the machine for an autotune flight and it will adjust the PIDs from their initial state. We found this made a huge difference. Basically in a giant field the machine is in ALt Hold mode and it will attempt a whole bunch of pitches and roll and adjust the PIDs...there are some great videos on youtube - just use the AUTOTUNE.

Also make yourself a preflight card like Adam Savage has done - just starting of safely thats all.

I cant stress the back to basics startup comment. Check everything. Good luck

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