Anybody flying PX4?

I'm trying to set up 2 machines using a PX4 FMU and IO Board, and using Arducopter 3.1 rc7, and I'm having a lot of problems with glitching that seems to be coming from the Rx input.  It shows up in the logs as blips in the roll/pitch/yaw inputs.  The copter flies, but it not safe because of this.  When in Stabilize mode, the roll/pitch blips are almost imperceptible, but you can see the yaw position jump. In Loiter mode the copter can suddenly jump about 1 meter.

Has anybody else experienced this?  Or are you successfully flying a PX4?  Any insight appreciated.

I've tried updating the FrSky Rx firmware to the special 27us PPM firmware, and it doesn't seem to help.  But I have no real way of knowing if the update even worked as the FrSky program doesn't indicate any success or failure, and I have no other way of checking if it's actually running at 18 or 27us frame length.

Update: The problem does not seem to be restricted to FrSky equipment, so I'm opening up the question to find out who is actually successfully on PX4 V1 equipment? Can you share any details of your setup?

Thanks,

Rob

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Replies

  • By the way I removed my on board power module long ago.  Never seemed like a good idea from the get go.  

    3692891642?profile=original

  • Been using the PX4 for some time now.  Been working great for me.  Haven't had time to mess with it much over the last couple of months.  Can you share more info on your setup? picts of how you have configured the hardware.  I could throw suggestions out at you, but be good to know more info.  

    https://www.youtube.com/watch?v=GnosZSoNvPs

    https://www.youtube.com/watch?v=iP3vpjboDTY

  • I had strange glitches on the flight mode channel on my PX4 in a plane. Sometimes, the PPM value of channel 8 would show 0 in the flight modes configuration page in MP. Just for a few milliseconds. And the flight mode would change to what I had set for zero pulse length.

    There probably are some gremlins somewhere in that system...

    Regards

    Soren

  • Rob, as far as I can see in one of my recent RC7 logfiles (attached), I don't see glitches (do you?), all motors sound well.

    I'm using a Futaba R-118F 40Mhz receiver. This one is not providing PPM out-of-the-box, however it's available inside the receiver. Had to add a level converter to make it a decent signal to feed the PX4IO. Next hurdle was to make the px4 recognise the signal because the PPM´s 'pulse' is too long. Also there is no fail-safe built in this receiver. I ended up changing the drv_hrt.c to accept the pulse, provide the failsafe and also made it accept only valid 8 channel input. Normally it accepts everything >= 4 channels, so if the signal is not perfect, it can lead to errors I think.

    I use an external compass.

    Coincidently I ordered a FrSky conversion kit a few weeks ago and expect it to arrive soon. I will update to 27us, check this using a oscilloscope and see how it performs. I'm very curious if I will also see the glitches, I´ll let you know.

    Frank

    4.bin

    drv_hrt-v1.c

  • I am flying PX4 with Flamewheel F330, but there are problems.

    I have glitching as Robert has described and clearly visible in my logs in roll and pitch in.

    On my little Flamewheel, these short glitches result in nothing more than a very quick arm dip and do not even effectively cause it to change position.

    But now it turns out there is almost certainly another problem as well. Namely the PX4IOs built in power supply has a ferromagnetic transformer on it which is way too close to the magetometer on the PX4FMU.

    It produces an over 100 degree offset and this can be verified by hooking up an external magnetometer and putting it the same distance away from the power supply transformer as the internal one on the PX4FMU is.

    With it at that distance you will see an over 100 degree offset and with it further away none at all.

    The Pixhawk has an external power supply like the APM, this was undoubtedly a very good decision.

  • Is it possible to reproduce this issue while connected over USB?

    Because i have similar setup but didn't flown my hexa yet

    I have PX4+IO and FRSky D8R Plus/XP (two receivers) both flashed with 27us firmware

This reply was deleted.

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