GPS Failsafe

[muhammedoney]

Hello,

I have an FPV setup which includes a GPS on it. I was using it with GPS supported modes, and suddenly it fell down to the ground. I couldn't define the problem with neither logs or OSD, because it says disarmed by switch.

I think that it suddenly not able to take GPS sensor readings. Because before taking off, inav doesn't allow any GPS guided modes. And if you try to arm it doesn't allow even if you have GPS lock. I wonder if the GPS wasn't able to operate after the takeoff, will it trigger failsafe or disarms the motors and simply falls down?

And after fell off, i try to use my stack : even i switch of the GPS sensor from inav configurator, there was a ARMING_DISABLED_NAVIGATION_UNSAFE error. It seems like stack was stuck.

[mmosca]

Disarmed by switch means that whatever channel you had used for the arm signal had changed value.

What radio system are you using and how does it behave when your radio connection fails? If you configured your radio to set a fixed value for the arm channel it could easily cause you aircraft to disarm and drop from the sky.

You also have to remove any navigation modes for the modes tab, before removing the gps sensor.

Do you have dvr / blackbox logs of the flight?

[muhammedoney]

Hello @mmosca

I was using TBS Crossfire TX modul with my Jumper T15. And here is my log file, please check legend 14. On time 02:20 arm mode changes

LOG66_LEGEND14_14.TXT

[mmosca]

Blackbox log has many flights, no idea which one you are reporting.

The last one I checked, disarmed at end of flight, with good rx status.

[stronnag]

• There is no compass
• At no point does the vehicle attain a heading that corresponds to GPS track
• The GPS is working perfectly the whole fiight
• RSSI is consistent through out the flight
• The vehicle log reports "Disamed by switch" at a relative altitude of 28m

xxx.mp4

[sensei-hacker]

before taking off, inav doesn't allow any GPS guided modes.

That's right and normal. Arming the aircraft shouldn't make it immediately start going along the ground at cruise speed, with zero altitude, if you're in cruise mode. Or whichever mode - the pilot needs to explicitly take off on purpose. That doesn't mean there is a problem with your GPS.

It just means you need to take off, then have it navigate after it's airborne - not try to navigate across the ground.

even i switch of the GPS sensor from inav configurator

Yeah if you don't have GPS enabled, but you have failsafe set to return-to-home and you've ordered position hold mode, that's a problem. It won't arm in a configuration where it clearly can't do what you've set it up to do.

[muhammedoney]

@mmosca yes i was mentioning about the last flight. Legend 14.
@sensei-hacker fully agree with you, but the main reason why i write here is asking your help to determine the leading issue for falling off. What would be the issue, is it bacause of failsafe, RC transmitter settings, GPS and so on?

[sensei-hacker]

why i write here is asking your help to determine the leading issue for falling off. What would be the issue, is it bacause of failsafe, RC transmitter settings, GPS and so on?

There are a lot of possibilities. Can you post your diff?

Based on the log, the most likely cause seems to be that you accidentally bumped the arm switch. One can put arm on a potentiometer (knob) that has to be turned, rather than a switch, to make it nearly impossible to operate it accidentally. It's much harder to accidentally turn a knob than to accidentally touch a switch.

There are many possibilities, though - I had an aircraft fall out of the sky when I flew too close to a radar. When the radar dish pointed at the aircraft, it completely overwhelmed the electronics and the plane dropped.

[muhammedoney]

diff_fpv0.txt
Please see