Pusher Throttle Pulsing With VT_FWD_THRUST_EN

PX4 version 1.13, using a Holybro Pixhawk 6X. Everything else on our vtol is beginning to work quite well, but using the pusher for forward thrust has been misbehaving since I started testing it. When the pusher should be activated, it is instead pulsing from the desired throttle and back to in bursts of about 1/10 second. In fixed wing mode the pusher works fine. It also works when set to RC passthrough.

The issue occurs at all throttle scale values.

Here is a telemetry report from a quick test hop; notice that the actuator control for the VTOL pusher activates, but it pulses rather than holding its value.


Running out of ideas for a root cause. I haven’t COMPLETELY ruled out pitch overdamping, but even if I set the min pitch angle to greater than 0, it still pulses, and there’s no evidence of overdamping when I’m not using the pusher. So it definitely doesn’t look likely at all; with VT_FWD_THRUST_EN off, it flies quite well.

Sounds to a lot like an issue that was fixed in July: Fixed pusher assist for standard vtol by RomanBapst · Pull Request #19865 · PX4/PX4-Autopilot · GitHub
Could you test if making this small change fixes your problem?
PR to include in 1.13: standard: fixed pusher assist in hover by sfuhrer · Pull Request #20220 · PX4/PX4-Autopilot · GitHub

Yes, but that cherry pick doesn’t include 6C support, so I went with a nightly build and as of Monday everything is working. Apologies for not posting, we pulled an all nighter getting the demo together for the client. Thanks for the help.

I do think clearer communication of board support level issues needs to happen after the fiasco with holybro’s communication and finding information about the state of 6C overall, but that this went well.