GCS Failsafe preventing emergency copter landing

ArduCopter
1

Multi rotor UAV is nearly 1km away from take-off/RTL location and has a critical battery failure and is unable to return to RTL location. There is about 60 seconds to land somewhere and the area has water hazards, trees, and open patches of vegetation. When switched into Land mode the craft descends to land but just before touch down looses GCS telemetry and climbs again for GCS failsafe RTL. When Land mode is engaged again the same process is repeated and the UAV is unable to land until battery runs out and crash lands.

One solution is to select Land mode on the GCS and then quickly disable all GCS failsafes.
Is this the only solution?

2

If RC is the primary control then I’d probably leave GCS failsafe disabled.
But it brings up a good point: if there’s already a failsafe in action and another occurs, should the first action be canceled or changed, or allowed to continue?

3

Providing both GCS logs and vehicle logs are the best way to assess the issue, and if necessary provide a correction on the behaviour you describe.

4

I’ve noticed that obvious case about two years ago https://github.com/ArduPilot/ardupilot/issues/6390

Thought there was a long discussion and several attempts to fix such an simple case - it still not somewhere.

Personally I’ve compiled a customized FW with the described feature: if LAND mode is selected - all failsafes are ignored then. Just for the subject scenario.

5

thanks. that’s the exact same issue.
the only solution appears to be to disable failsafes and initiate LAND mode
before loosing the telemetry connection on the remote landing.

6

Solution is here: https://github.com/ArduPilot/ardupilot/pull/7432 but it needs a rebase and review

7

Is it maybe time for a concerted effort to go through and process/clean out PRs? Important fixes/improvements like this shouldn’t sit around for months/years with people having to apply their own hacks

8

thanks. we are going to simply create a switch on the ground station that enables/disables failsafes.

1 Like
9

I would offer a big red button on the Actions tab (MP) with the writing “emergency landing” that will override everything and initiate immediate landing. (multi-rotor)

10

Has it been solved yet?

11

This is an aging discussion so some of the options have changed or been fixed where there was a bug.
Check these parameters, and also test in your situations

This is probably the most relevant one first:

Failsafe options bitmask

“Continue if landing on any failsafe”
https://ardupilot.org/copter/docs/parameters.html#fs-options-failsafe-options-bitmask

Ground Station Failsafe Enable

https://ardupilot.org/copter/docs/parameters.html#fs-gcs-enable-ground-station-failsafe-enable

GCS failsafe timeout

https://ardupilot.org/copter/docs/parameters.html#fs-gcs-timeout-gcs-failsafe-timeout

1 Like
12

I was thinking the same thing. Thank you for confirmation.
What would be an appropriate way to test this?
I am thinking of setting a higher value of voltage for Battery failsafe to trigger Land mode and then turn off the RC to analyze the behavior of the copter.