Inconsistent reporting of health data

[zulufoxtrot]

I’m trying to simulate a loss of GPS lock in SITL, using gpssim stop as suggested by the documentation. While QGC correctly reports the loss, the SDK’s Health query still returns is_local_position_ok: True, is_global_position_ok: True, is_home_position_ok: True.

Steps to reproduce

1. Launch an instance of PX4 in SITL and wait for EKF to get a position.

2. Launch your piece of code.

async for health in vehicle.telemetry.health():  
    print(str(health))

Make sure the parameters mentioned above return True.

3. run gpssim stop in the PX4 console.

pxh> gpssim stop
INFO  [gpssim] exiting
pxh> WARN  [ecl/EKF] EKF GPS data stopped
WARN  [ecl/EKF] EKF stopping navigation

Check EKF status with ekf2 status:

pxh> ekf2 status
INFO  [ekf2] local position: invalid
INFO  [ekf2] global position: invalid
INFO  [ekf2] time slip: 0 us

The parameters still return True. They should be returning False.

Observations

I have noticed 2 different behaviors depending on the order the steps are done:

• stop GPS, then start SDK: is_global_position_ok is correctly reported as False. Then start GPS again, and is_global_position_ok correctly (and immediately) switches to True.
• start SDK, then stop GPS: is_global_position incorrectly stays True indefinitely.

System info

PX4: 1.9.0

MAVSDK-Python: 0.1.0 (pypi)