GPS glitch and failsafe while flying in fog (optical flow also enabled)

[Andre_Freitas (André Freitas)]

Hi everyone!

I have various copters that struggle to fly in loiter through fog. These drones have GPS and Optical flow enabled with:

• EK3_SRC_OPTIONS = 1 to FuseAllVelocities
• EK3_SRC1_POSXY = 3 (Primary horizontal position from GPS)
• EK3_SRC1_VELXY = 3 (Primary horizontal velocity from GPS)
• EK3_SRC2_VELXY = 5 (Secondary horizontal velocity from OpticalFlow)

After some seconds after entering fog the drone starts to drift in random directions and then I get gps glitch and EKF failsafe.

I believe this is caused by the rangefinder reporting a false low altitude which makes the EKF fuse wrong velocities from the optical flow.

Does anyone have a suggestion to solve this problem? I know I could use a lua script to manually change the EKF sources but I would like this to be done automatically.

Would a rangefinder with the ability to change to “last pulse reading” penetrate the fog and solve this problem?

Thanks

[vosair]

A log would be very helpful in this situation.

[Andre_Freitas (André Freitas)]

I will try to find a log. It has been a long time since I have flown in fog. I know I have this problem but have been delaying it