Gazebo-SITL Strange copter behavior when pitch forward

When I pitch forward more than 25 degrees, the copter always turns right after a few seconds. I don’t do any roll or yaw movement at this time. This happens regardless of whether the wind is enabled or not and its direction. In my case, the problem is reproducible in 90% of the cases, so I’m wondering if it’s a bug or some misconfiguration on my side. Attaching the video that demonstrates the problem. If necessary, I can provide any additional logs or configuration details.

@rhys
would be great to hear your opinion

@David_S - I can’t reproduce your results using the default iris model and world for Gazebo Harmonic. Which version of Gazebo / ArduPilot are you using, and what commands are you using to achieve a pitch of > 25 deg. When I try to pitch forward full using:

rc 2 1100

I don’t exceed about 16 deg.

@rhys
Thanks for having a look at this.
Gazebo version is 11.14.0
Ardupilot version is 4.4 (but the same behavior on 4.5)

Could you please try to update the param ANGLE_MAX to value about 3000 to achieve bigger lean angle

@rhys did you have a chance to look at it?

Hi @David_S, yes had another look. The default value of ANGLE_MAX is 3000, so no change required there. I can’t replicate - attached is a recording of my test.

gz_iris_pitch_fwd

I’m running Gazebo Garden and using the plugin here: GitHub - ArduPilot/ardupilot_gazebo: Plugins and models for vehicle simulation in Gazebo Sim with ArduPilot SITL controllers; which is the supported version (Using SITL with Gazebo — Dev documentation). There may be some difference between the plugin and SITL interface I’m using and that for the previous version used with Gazebo Classic, although nothing jumps to mind that would result in the behaviour that you are seeing.

If you’re able to provide a detailed step by step means to replicate using the newer environment I’d be happy to help, but as it stands I can’t reproduce the issue.