Noob build: Twitchy control with Quadcopter using Pixhawk...what am I missing?

Posted by Glenn Hollowell on May 12, 2016 at 11:03pm

I've got a genuine Pixhawk that I bought from 3DR that I am trying to get configured properly. I am running Mission Planner 1.3.36 and have run through the basic configuration process (compass, level, radio, ESCs), but after this when I put the propellers on and power up, the controls are really twitchy. I built a small quadcopter using 2204 motors and 6" props and was never comfortable getting the craft more that 12" off the ground. Very twitchy and difficult to control with some of the motors seeming to run at erratic speeds. Thinking this might be ESC/motor related, I've assembled a second quadcopter using 3506 motors and 12" props. While this one is not twitchy, control still is not what it should be. Clearly I am missing a step. Please advise. Attached is a picture of the second craft. TIA

12InchQcopter_zpslpaipyf6.jpg

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Tags: pixhawk, tuning
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Replies

  • Eddi Maevski February 7, 2017 at 12:10am

    hmm strange, the chance that both compasses are bad is small to none.

    Assuming the connection is correct and you used those compasses with that pixhawk, 

    Maybe try following this page - http://ardupilot.org/copter/docs/common-compass-setup-advanced.html

    (try to disable the internal compass which should be compass #2)

    Also when you press live calibration - do you see both globes rotating when you rotate the craft ?

    Advanced Compass Setup — Copter documentation
  • Glenn Hollowell February 6, 2017 at 9:48am

    I've tried a uBlox GPS/compass as well as the 3DR GPS/compass that came with the kit. Both have two sets of wires that come out. These connect to the 12c and GPS ports on the Pixhawk. Thanks again.3702349264?profile=original

    Eddi Maevski said:

    Light effects - are those blinking after each firmware flash....

    What is your setup - external compass or only internal ?

  • Andy Piper February 6, 2017 at 1:58am

    It's easy to figure out if you compass health is really bad - there is a dataflag log message that I added which records compass health. Something like MAG->Hlt and MAG2->Hlt maybe. Check these. If either is not a solid "1" line then you have a faulty compass.

    andy

    Glenn Hollowell said:

    Thanks Eddi...the mass email was unintentional. My apologies. Could you elaborate on "...and all the light effects". I just installed ArduPlane on the quad, then reinstalled Arducopter-quad but am still getting "Bad Compass Health messages. Thanks again.

    Eddi Maevski said:

    Glenn  

    To answer your question sent by message function (BTW this is very bad way to ask as there is no way to answer it properly, why not post in the group or on the forum)

    Anyway... I have pixhawk clone and each version increment it goes this way:

    1. I'm using quad so I burn latest firmware of plane (yes plane)

    2. Restart reboot and all the light effects.

    3. Burn the quad version I need.

    Without going thru "plane" I've always got those bad compass health messages.

    Hope that helps.

  • Eddi Maevski February 5, 2017 at 11:14pm

    Light effects - are those blinking after each firmware flash....

    What is your setup - external compass or only internal ?

  • Glenn Hollowell February 5, 2017 at 10:02pm

    Thanks Eddi...the mass email was unintentional. My apologies. Could you elaborate on "...and all the light effects". I just installed ArduPlane on the quad, then reinstalled Arducopter-quad but am still getting "Bad Compass Health messages. Thanks again.

    Eddi Maevski said:

    Glenn  

    To answer your question sent by message function (BTW this is very bad way to ask as there is no way to answer it properly, why not post in the group or on the forum)

    Anyway... I have pixhawk clone and each version increment it goes this way:

    1. I'm using quad so I burn latest firmware of plane (yes plane)

    2. Restart reboot and all the light effects.

    3. Burn the quad version I need.

    Without going thru "plane" I've always got those bad compass health messages.

    Hope that helps.

  • Eddi Maevski February 5, 2017 at 9:41pm

    Glenn  

    To answer your question sent by message function (BTW this is very bad way to ask as there is no way to answer it properly, why not post in the group or on the forum)

    Anyway... I have pixhawk clone and each version increment it goes this way:

    1. I'm using quad so I burn latest firmware of plane (yes plane)

    2. Restart reboot and all the light effects.

    3. Burn the quad version I need.

    Without going thru "plane" I've always got those bad compass health messages.

    Hope that helps.

  • looninho May 13, 2016 at 1:51am

    Hi Gleen,

    it seems that your first quad hadn't ESCs calibrated properly.

    And the second hadn't good PID or your frame is too soft or over powered. Check your vibration curves (http://ardupilot.org/copter/docs/common-measuring-vibration.html)

    I've experienced with my F450-pixhawk some issues concerning throttle, compass and tuning PID and hereafter what i did to solve them:

    1) save your PID if it was already tuned.

    2) reset all parameters to default.

    3) calibrate accelerometer, compass. For my compass, i desactive the internal compass because it has values higher than 400, so i use only my external GPS-compass .

    4) radio and ESCs calibration : For ESCs calibration i've performed radio calibration with USB (NOT TELEMETRY, i don't know why but it works better than by telemetry) then i did ESCs calibration with telemetry (NOT USB) with 'all at once' method (http://ardupilot.org/copter/docs/esc-calibration.html)

    5) recopy your PID or do autotune (one axis at a time prefered).

    What is the weight of your quad? And your PID?

    good luck

    Measuring Vibration — Copter documentation
    • Glenn Hollowell > looninho May 13, 2016 at 1:51pm

      I really think the problem lies in the PID tuning which I know nothing about. I did program the ESCs on Quadcopter #1 with some improvement, but it still seemed massively twitchy and erratic. I would highly appreciate suggestions regarding how to do PID tuning.

      Thanks.

    • looninho > Glenn Hollowell May 13, 2016 at 3:46pm

      Fisrt of all if your ESCs aren't calibrated properly you can't flight safe.

      Before autotune your PID your quad has to be able flight in alt hold mode (stabilize mode work also for autotune). No vibration, no trim in Tx, for autotune, follow this:

      http://ardupilot.org/copter/docs/autotune.html

      good luck

      AutoTune — Copter documentation
    • Glenn Hollowell > looninho May 19, 2016 at 10:49pm

      Ooooh, got it. Nice 20 minute flight, mostly hovering, nothing fancy. Problem was PID settting. Now I need to get auto tune figured out, or how to tune by hand. Aircraft overcompensates like mad and rocks back and forth and side to side in response to joystick in-flight adjustments. Suggestions appreciated.

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