FW Cruise Mode - Altitude Hold Behaviour

[kolabuzlu]

Current Behavior

When in Cruise mode, if a turn command is executed via deflecting the aileron stick fully left or right, plane starts turning at proper bank angle and rate. But in altitude control, there is a strange behaviour. Vario graph and m/s indicator shows climb (starts rising gradually), but the plane starts losing altitude at the same time. Altitude starts decreasing. Opposite of each other. This happened to me in real flight. I thought that a gps altitude or baro glitch. Switched planes, did it again. Tried in HITL, did it again. Not everytime but 5 out of 10 turns, it happens.

If I deflect the stick full left or right softer, more gradually (maybe in 3 seconds time) it does not happen.

Also, if I change roll inclination limit from 45 degrees to 30 degrees in Tuning/Rates tab, it does the same issue but less aggresively.

Steps to Reproduce

1. Engage Cruise mode when in the air.
2. Start turning left or right using full aileron stick deflection.
3. Observe the variometer and actual altitude indicator.

Expected behavior

Plane should turn using the rate set by stick deflection and keep the current altitude. Vario should not indicate climb other than small fluctuations.

Suggested solution(s)

It may be some altitude interpretation issue when in Cruise mode, gyro related I think.

Additional context

https://pastebin.com/kcCzbR3a

Video of the issue :

https://youtu.be/yHHjUyPDDVk?si=5jzHkMlA-GVWb6gz

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• FC Board name and vendor: Matek H743 V3
• INAV version string: 9.0.0

[breadoven]

I checked this with HITL and couldn't replicate it. Would be useful if you could post a log for the HITL test please.

[kolabuzlu]

Hi again. I've finally figured out why this happens checking and comparing every single parameter in CLI.

Despite not modifying them before in iNav 8 (flying with default values), three parameters translates into iNav 9 in a different way (different from iNav 9 defaults) if Diff All is used to upgrade.

These are :

inav_w_z_baro_v
inav_w_z_gps_p
inav_w_z_gps_v

iNav 9 default values for these parameters are not the same with default params in iNav 8.

After changing them to iNav 9 defaults, problem has gone.

For your information.

Best regards.

[Jetrell]

@kolabuzlu That was mentioned in the release notes.