mavlink heartbeat stream: Fix system status always reporting FLIGHT_TERMINATION in HITL

[KonradRudin]

Solved Problem

When performing a HITL simulation, the PX4 heartbeat always sends the system_status FLIGHT_TERMINATION, although the simulation works just fine and the simulated vehicle reacts to the commands. This is due to the fact, that in HITL the actuators are always locked. This flag is mapped to the system status flight termination.

Solution

• In the mavlink Heartbeat stream only consider the armed.lockdown flag, if the system is not configured as HITL.

Changelog Entry

For release notes:

Bugfix Mavlink heartbeat stream: Fix system status always reporting FLIGHT_TERMINATION in HITL

Alternatives

We could also ...

Test coverage

• SIH simulation, check mavlink inspector in AMC.

[dagar]

This seems kind of wrong, maybe we should to untangle this mess of flags instead of making it more convoluted?

#21129

[julianoes]

I agree that we should fix this mess but it is very much correct that lockdown is true (on purpose) in HITL.

So this PR is good to be merged and we shouldn't block it trying to fix it more broadly.

[KonradRudin]

@dagar How should we proceed? I like the PR you are mentioning but this does not solve the issue i try to fix here. As long as we use armed.lockdown to stop the motors in HITL we should not map this into the heartbeat system status in HITL. So i guess it is either redefining on how to stop the motors from turning in HITL, rethink which flags should be mapped to the system_status or use this small fix.

[MaEtUgR]

I agree, let's go in steps. First fix this interface problem where HITL behaves completely different than a real vehicle and then the internal arm, kill, lockdown mess 👍