Geofence autoenable when there is no fence

timtuxworth · March 31, 2022, 5:43pm

I created a new plane for some SITL testing and loaded a previously saved param file that contained FENCE_AUTOENABLE = true. I set up a mission, but no fence.
When the plane successfully completed takeoff I got the “Geofence enabled, autoenabled” message - but there was no fence. So as a pilot I might be under the mistaken impression that there is a geofence in place - when in fact there is not. I could imagine that this might be disastrous if this was a real plane.
Perhaps fence autoenable ought to check that there is a fence?

This is with a local build from master (last pulled 2022-March-30)

amilcarlucas · March 31, 2022, 6:34pm

Which version? Did you use master branch? if yes, can you open a github issue?

timtuxworth · March 31, 2022, 6:52pm

Yes it was, sure I can do that.

timtuxworth · March 31, 2022, 9:50pm

I’ve created a PR with my proposed fix. Sorry @amilcarlucas I’ve messed up the PR with a bunch of unrelated changes. I’ll delete it and try again.

amilcarlucas · March 31, 2022, 10:18pm

Excellent. PRs are a lot better than open issues. Thanks for helping out!!

timtuxworth · March 31, 2022, 11:34pm

I think I got it - one PR, one commit, one file changed. Please review:

github.com/ArduPilot/ardupilot

AC_Fence: add check for enabling non existant fence

ArduPilot:master ← timtuxworth:no-fence

opened 11:32PM - 31 Mar 22 UTC

timtuxworth

+15 -5

It's currently possible to Arm a vehicle with FENCE_AUTOENABLE = 1 but with no f…ence set up. Once armed and flying - if an auto enable of a Geo Fence is triggered, the plane will send the message to the GCS that the fence is enabled, even if there is no fence to enable. So either way, a pilot might think they have a geofence and it is enabled whereas there might be no fence. This PR does two things. adds a pre-arm check to prevent arming if FENCE_AUTOENABLE = 1 but there is no fence if pre-arm checks are disabled, if a vehicle attempts to auto enable the geofence after takeoff, a warning message is sent to the GCS and the AC_Fence::enable() function is not called.

timtuxworth · April 1, 2022, 5:06am

I’ve noticed that there is a similar problem with RC fence enable - you can “enable” the fence using the switch, even if there is no fence. A related problem is that RC tells the GCS that the switch has gone high or low, but doesn’t notify it that the fence is enabled/disabled.
and also the fact that a MavLink command to enable the fence will also apparently work, even if there is no fence on the plane.
I’ve done an improved version of this PR that fixes these two issues two.

timtuxworth · April 18, 2022, 4:51pm

Hi @amilcarlucas , I’ve tested this PR now and submitted it for review. I updated the PR to include pre-arm checks and also GCS warnings if fence is enabled using FENCE_ENABLE, Auto-enable, RC channel switch or mavlink message when there is no fence.

I think it makes it much safer. Please take another look at my PR. Thank you!

timtuxworth · April 29, 2022, 2:56pm

I’ve updated the PR to fix the autotest. Now the autotest expects a fail to arm if there is no fence and I also added arm/disarm checks after adding each different type of fence.