Servos wont work in Pixhwak

Hello im currenlty trying to make some servos work with the ixhawk autopiot.It seems tht everythig is connected correctly and the servos are getting powered as well. 

i have the ESC connected ot the servo raila nd two servos connected to the main outputs.

The ESC callibration doesnt seem to work but i thought that i would even see some movement even if the ESC unit is not callibrated. 

Any idea in what could cause me problems...

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  • I thought reading somewhere that it is not allowed to connect servo's to the pixhawk due to power restrictions.

    Can't you power the servo's separately and use only Signal and GND that go to the Pixhawk, this way it would be safe.

    • You can connect the servos as you long you as you provide power through the ESC unit.At least that's how i do it for the two servos that will control the elevons of my plane.What i am trying to do now is to add two extra servos that will control the camera and parachute .

      PX4 flight stack though seems that doesn't support mavlink commands for controlling specific servo outputs so i might have problems with that section..

  • Hello guys,
    Thank you for the quick replies. I did resolve this issue. I had a hil airframe loaded that's why the servos weren't working.
    But now i have a different problem. My aircraft is a flying wing with elevons. Even though i see that the RC controller has the correct mixing, the servos are connected to the ailerion and elevator ports and the qgroundcontrol seems to send the correct signals the servos are not moving as they should. They should move in oposite directions when i move the stick left or right but instead the move to the same direction.
    Do you think that there is somewhere else in the process that i need to also do some mixing of the signals?
    • Hey,
      It is also my first attempt so im as well pretty new to this kind of issues. Any advice that i can get is valuable :).

      I think if i change at this point to apm and mission planner i will have to do the tuning of the pid from the beginning.

      The weird thing is that while im in HIL simulation the model in the xplane behaves correctly in both manual or auto mode. So i thought that it should not have any problems in real time. By just plugging the servos to the correct ports the behavior should be the same.

      I ll try a bit more to see if I can solve this problem with any other way and if not succeed i will also try the apm3.1

      Thanks for the help.i ll keep you posted if your suggestion also worked for me.
      • i manged to fix the problem by working out some mixing signal options.Of course a new problem came up now...I connect the dc motor with the esc unit and when i try to throttle up i get this weird bbeping form the dc motor.It doesnt move or anything , it just beeps every few seconds.

        I ve read that there might some issue with the esc unti that generates this beeping through the motor.Have you also encountered any same problem?

        MOTOR.IT
        • I have encountered this with some brands of ESC - it will beep slowly and make the motor "twitch" slightly until the arming button is pushed. I have had issues with initial ESC calibration through the Pixhawk as well to set the throttle ranges - the best way to handle that is by directly connecting the ESC to the receiver and doing it outside of the PX4 loop.

          As far as your control surface issues, take a look here: http://plane.ardupilot.com/wiki/arduplane-setup/first-time-apm-setu...

          You can use the old way with ELEVON_MIXING in tandem with transmitter mixing, or the new ELEVON_OUTPUT option that uses the Pixhawk to do all the mixing and not have to mess around trying to set it up on your transmitter.
          loop.as is parked
        • Admin

          @Efstratios,

          Have you calibrated the ESC to the R/C transmitter throttle?

          Regards,

          TCIII AVD

          • Hello ,

            Yeh apparently it had to do with ESC unit.I managed to calibrate it but it only worked with manual claibration.

            There was also some weird problem with the ESC going to a kind of failsafe due to vrop of voltage.I was using an external voltage sourse and not battery for testing the whole connection.

            Thanks for the help guys ;) 

            Another thing i wanted to ask is that im planning to have two extra servos , one is gonna be used for deploying the parachute and the other for deploying the camera.I m working with qgroundcontrol so i was wondering if there is widget that can assign value to servo through the mavllink protocol.

            i ve seen that exist the MAV_CMD_DO_SET_SERVO.Is there any other way to achieve this?I want to be able to deploy the parachute through the qgroudcontrol and not with any extra external hardware.

        • That can be a problem with your ESC signal input not going low enough. Normal ESCs will only activate if the pwm signal gets under a certain level.

    • Moderator

      Efstratios,

      I am very, very new to most of this, so please take my advice with a grain of salt. Hopefully someone more knowledgeable will come along and help. 

      I'm only trying to offer a little limited advice because I experienced (again) some of the same problems as you when setting up my first flight controller recently.

      What version are you using? I had the same problem as you, and I was using qgroundcontrol also. I was reversing the correct RC output parameter and would instantly see the result when in manual mode, but all auto modes were unaffected. I believe this is a known bug.

      I eventually corrected the problem by wiping the flight controller and using mission planner to flash the firmware to APM3.1.  I'm hesitant to try to explain what I did because I'm almost positive that my understanding of the firmware terms is incorrect, but the way I understand it is that I converted from PX4 to APM flight stack.

      Again, be cautious when reading my inexperienced advice, but I fixed the same problem you're having (with the same GCS) a few weeks ago by wiping my firmware and using missionplanner to install apm3.1

      Good luck

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