RTL on FailSafe Question...

I tested the TX failsafe by setting it to RTL and then once I started a mission I shut off the TX. Everything went as expected and it immediately aborted the mission and RTL. I then started a mission and unplugged the 3DR radio from DroidPlanner expecting it to RTL since the telemetry signal was lost, but it continued the mission... I verified I had the failsafe set up in Mission Planner for telemetry to RTL on signal loss. Is this because it did not detect a lost of telemetry because the IRIS+ has the telemetry built in? or did the Failsafe not work correctly? or is there some other reason?


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  • Okay, so in reality what I really want is to RTL whenever signal is lost unless in Auto mode (auto set by software or by TX switch). And if battery failsafe I want it to just land. Do I need to do anything in the receiver to get this functionality or is selecting the drop down sufficient on the failsafe page in mission planner? and do I check the GCS box or not?

  • There are multiple ways to setup FailSafe on Iris+. 

    Basically you can tell it to RTL whenever it looses radio signal no matter what it's doing. Or you can say RTL unless it's on a mission to not return home and continue the mission because you know it's on a mission where it will loose radio signal.

    For the Ground Station one, this only works when you tell it to go to Auto via the telemetry. Are you flipping the flight mode switch to auto to start you mission or doing it via Droidplanner or on Mission Planner? If you activate it via the software it will RTL when it looses telemetry signal.

    • I actually set the drop down to continue with the mission if in auto mode. The GCS is just a check box so I am not sure if that is saying to also set to return to land unless in auto mode or not? There is not much configuration options on the failsafe screen in mission planner.

  • Matt,

           It is a bit confusing, but, FS_GCS GCS in this case IS your TX radio, not your telemetry radio, There are also 2 failsafes built into your receiver, as well as low throttle failsafe, from Pixhawk, What you tested above was a no pulse failsafe, OR User defined failsafe, both set from the frsky receiver, If you were to set it to User defined, then you would set up your radio, in what ever mode you wanted it to lock into and whatever level you wanted the throttle to be etc, and if a radio loss happened, the receiver would lock into those settings, however, the question then becomes what component actually wins in a failsafe condition, Pixhawk, or the Receiver so, normally, we set the receiver no pulse failsafe, which is option 2 in the frsky directions and If I can find the link on how to set it up and test it, I'll post it here, but in this scenario, to test it, you would actually arm your copter and watch the failsafe screen, then kill your radio, this would result in going into land mode, or whatever you wanted it to do.


    • Paul, in the video why did it land when it lost radio signal? I did not see an option on the fail safe page for that. I see the RTL unless in auto mode so shouldn't it have done RTL instead of immediatly landing?

      Also, what was the purpose of pushing the failsafe button on the receiver? could you not have just set it in mission planner instead? I think I am confused on what that did...

  • 3D Robotics

    Hi Matt,

    Have you opened up a ticket with our Tech Support?  We can help you work through this.

  • Matt,

    I going to test it on mine tomorrow and let you know. I'm running 3.2. I have tested the loss of RC since I went to 3.2 but not the loss of GCS.


  • http://copter.ardupilot.com/wiki/configuration/failsafe-battery/

    Assuming I understood what you are saying correctly, the RTL feature doesn't trigger for a loss of telem. 

    • According to this, if the GCS telemetry goes down (I am assuming this means the 3DR Telemetry radio) then it should RTL if you have it set to always which is what I did. I unplugged the radio from my ground station and loss telemetry but it continued with the mission. There is an option to continue with the mission on the failsafe page, but I did not have it set...

    • Ahh, right you are. I suppose if im going to be too lazy to plug my copter in and check the settings in MP I should at least read the whole page and not skim through it. So if you check do you have the gcs fs under the advanced param list set to "1" or "2"? because it sounds like like it was behaving like the latter. I know you said you have it set to always, so maybe its not working properly. That definitely should have triggered the RTL if it was set to always do it regardless of flight mode

      • In Mission Planner’s Advanced Parameter List, set the FS_GCS_ENABLE parameter to:
        • 0 to disable the GCS failsafe
        • 1 to enable and always RTL in event of loss of contact
        • 2 to RTL unless in AUTO mode in which case we should continue with the mission
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