PX4
[Bug] GPS failure, notify user
Describe the bug
We had a customer experience some momentary GPS interference which kicked the vehicle out of position mode and into altitude mode. They reported the issue to us because it was not clear from the log what caused the failure. The log file contains some cryptic warnings.
After analyzing the log it appears that the speed accuracy exceeded the max threshold. Although I tried to reproduce this in sim and was unable to cause the failure by simply increasing the speed accuracy. It's hard to tell where exactly in ekf code the failure occurs without some kind of indicator.
To Reproduce
Experience GPS interference. Maybe a long term goal would be to add a failure injection test mode into sim for simulating GPS interference.
Expected behavior
There should be an event notification that informs the user at GCS that the vehicle has lost position hold (xy_valid goes false). Ideally it would be even more specific and indicate the exact reason for failure (eg speed accuracy exceeds max threshold). The log file should also contain this notification and we should suppress the other side effect warnings.
Screenshot / Media
Flight Log
https://logs.px4.io/plot_app?log=c25d5ee4-1531-4dc3-9906-637c52488da4
Software Version
v1.15.0
Flight controller
ARKV6X
Vehicle type
Multicopter
How are the different components wired up (including port information)
No response
Additional context
No response
The concern and tradeoff is detecting any potential GPS spoofing, but at first glance I don't think we should have invalidated the velocity estimate in the first place.
Here are another 2 logs with the same issue https://logs.px4.io/plot_app?log=f69359b9-e132-47f7-99cf-a5803bcf525a https://logs.px4.io/plot_app?log=6127c186-c2c1-46ff-b59a-c1b92f0423a0
This issue has been mentioned on Discussion Forum for PX4, Pixhawk, QGroundControl, MAVSDK, MAVLink. There might be relevant details there:
https://discuss.px4.io/t/px4-sync-q-a-feb-26-2025/43951/4
This issue has been mentioned on Discussion Forum for PX4, Pixhawk, QGroundControl, MAVSDK, MAVLink. There might be relevant details there:
https://discuss.px4.io/t/px4-sync-q-a-feb-26-2025/43951/1
to add it this, Freefly Systems is also having this problem in a few different forms
This log does the same thing when RTK stream on the ground station is stopped. https://logs.px4.io/plot_app?log=9c2fc42d-171b-40fe-ab77-32ac7895d92d
We have had similar problems where small spikes above PDOP threshold also cause this.
This issue has been mentioned on Discussion Forum for PX4, Pixhawk, QGroundControl, MAVSDK, MAVLink. There might be relevant details there:
https://discuss.px4.io/t/px4-sync-q-a-mar-26-2025/44527/1
This issue has been mentioned on Discussion Forum for PX4, Pixhawk, QGroundControl, MAVSDK, MAVLink. There might be relevant details there:
https://discuss.px4.io/t/frequent-local-position-loss-despite-good-gps/45362/4
This issue has been mentioned on Discussion Forum for PX4, Pixhawk, QGroundControl, MAVSDK, MAVLink. There might be relevant details there:
https://discuss.px4.io/t/wiki-errors-for-ek2-gps-check/45940/2