Weird Pixhawk/PPM/Taranis/Dragonlink problem.

Hello, 

So i'm having a weird problem with Taranis, dragonlink, ppm, or pixhawk I'm not sure really what it is.

I'm using a Taranis controller, dragonlinlink TX/RX PPM to pixhawk. My quad flies great, tested in all modes. all channels operate correctly in the RC calibrate screen. 

I'm using 6 channels, but gimbal tilt is mapped to channel 7, with channel 6 doing nothing.

My problem is, when I move the gimbal slider all the way in one direction, to make the gimbal look up... my pitch and roll stick become reversed. IE when i push the pitch stick forward, instead my quad rolls to the right. and when I pitch back, instead my quad rolls to the left.

Now if i move the gimbal slider back down so the gimbal looks down, the controlls return to normal, and pitch controls pitch, roll controls roll.

I tried to recreat the issue while the quad was disarmed. While lookling at my RC calibrate screen, i moved the throttle to mid stick to simulate hover, and moved the gimbal slider all the way up to make the gimbal look up. When i move my pitch stick forward, pitch moves as it should, not effecting roll at all on the RC Calibrate screen. But sure enough, when i try to actually fly again.... When I make the gimbal look up, my pitch stick starts making the quad roll instead. 

I'm guessing this has to do with PPM framing or something with my PPM signal, but that's really just a guess and i'm not sure. My taranis PPM setting is set to CH 1-10, 26.5ms 300u +. I've tried changing it to CH 1-7, and also increasing my pulse legnth, but still the same problem.

Any ideas? I'm lost.

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Replies

              • If you have access to an oscilloscope, it would be simple to look at the pulse stream your taranis is outputting to the DL transmitter and see what happens when you move that gimbal to it's limit.  That would remove some variables.

                 

                An alternative test would be to use another Frsky receiver like an X8R in S.Bus mode or a D4R-II in PPM mode and see if the problem persists.  If so, it's probably an electrical problem on the aircraft.

                If you want to post your EEPE for the model I can take a look at it.

                • I assume you mean the file for my quad model on the taranis? Here you go. Thanks for the help.

                  the_scout.bin

                  • I looked at your settings and don't see anything odd.

                    I'll try it with a Taranis and Dragonlink tonight when I get home to see if I can reproduce your issue.

                     

                    In the meantime, here's a config for arducopter I did almost two years back which supports 6 flight modes and announces them.

                    http://rcsettings.com/index.php/viewdownload/6-multirotors/33-arduc...

                     

                    That one is set up for the internal module but you could just turn on the external PPM and turn off the internal to make it work with your Dragonlink.  You'd also need to turn off the A2 voltage warning settings.

                    After seeing how simple your Taranis setup is, I'm leaning towards this being a problem with your gimbal pulling too much current when you tilt it up.

                     

                    You're not trying to power a servo from the Pixhawk current sensor are you?  It doesn't provide enough current for that and you will have brown-outs for sure.

                     

                    The PPM port on the Pixhawk is powered from the current sensor.  If you use that to power your RX then connect a servo directly to the RX you will have major glitchyness when you move the servo.

  • Make sure you re-bind your Dragonlink RX every time you change anything about your transmitter's PPM stream.

    • Thanks I will try re-binding my TX/RX but i find it very strange everything shows up correctly on my RC Calibrate screen, but acts differently when I fly. 

      This problem only happening when the gimbal is in the UP position.... very strange 

      • It's possible your gimbal is hitting the stops and drawing too much power causing some sort of brown-out.

This reply was deleted.

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