Failsafe not RTL on other modes

Hi all, I have been testing and setting up failsafe and it seems to work as expecting on either battery fail safe or RC loss while in Poshold but in Althold or Loiter the motors disarm which isn’t ideal.

The way I am testing this is outside I wait for a 3d lock, arm, throttle up and pick the craft up and move it around in my backyard with rough inputs from the controller and then stop with it approx 1.5m from the ground and turn the transmitter off.

In Poshold the motors start working to bring it back to launch and I walk it back over to the take off point and place it down where it disarms.

In the other two modes, after it gets RC loss detection it disarms with no attempt to RTL.

Any ideas on why it behaves differently in those modes ?

I think it’s because you never gained any altitude, so craft thinks it already landed and disables the motor.

hi all.

We had similar problem too. While cruising,the copter went behind a small hill and radio failsafe got triggered.After radio failsafe,RTL mode engaged.Despite being in RTL mode copter flew away and drifted about 20-30 meters and then crashed.Crash detection did not work either,motors kept on running for a while when the copter was upside down.I assumed that when the copter would enter RTL mode and fly to a higher altitute then come to back to home position where it was last armed.

i share the log.

thanks in advance. best regards.

It is possible the Here GPS and barometer isn’t sensitive enough to notice the difference of 1.5 I guess.

I’ve repeated the process a number of times and it still works in Poshold but not the others. I am going to only use Poshold for any situation where there could be a loss of signal or low battery issue for now as I am not sure how else I can safely test it without putting the craft at risk… maybe a second person at a different height as a catcher may work. I fly in very remote areas and I would like to confirm it works before relying on it, previously I have set the throttle slightly under hover for a slow decent with no RTL for easy recovery which I may go back to if I cannot work this out.

Your testing methodology is all wrong and therefore your “results” will also be “wrong.”

Regardless of what you are doing with the transmitter, moving the aircraft by hand is not flying, and if the aircraft is not flying, the flight controller may as well not be installed.

Second, I am going to assume you are doing this with props OFF. Here again, this is totally wrong. When you arm the motors the PID controllers are active. When the PID controllers are active and you play with throttle, the FC “expects” the aircraft is flying, and because it isn’t, the FC gets confused and the PID controller go spastic.

Thirdly, RTL requires the aircraft to be a specific distance from the launch point (which is set when you arm the motors), and if the aircraft is not far enough from the launch point the FC goes to LAND. If you are holding the aircraft (and right now the FC is totally confused and perhaps digitally catationic) when the FC goes to LAND, the FC measures ZERO vertical velocity. The motors will be disarmed.

You need to do actual flight testing. So put some props on the motors and have at it. I think you will be surprised, especially when the aircraft climbs to 15 meters (the default) and then heads towards the initial launch point.

That makes sense, it would be nice to have some safer way of testing it. I do this for fun and I don’t have the money to just try it for real on the hope it will work without some test work before hand. The one time it has triggered on low battery it did work pretty well but I still quickly took control and manually landed it as it was in a good area to land anyway.

There is a safe way to test the fail safe and RTL: You save it for last.

I don’t test the fail safes until EVERY THING ELSE has been tested and calibrated, and this includes compass, AltHold, Loiter, and RTL flight modes, and the battery monitor for voltage AND current. If your battery monitor is “off,” the low battery fail safe may trigger too early or not at all…

Once I know that every thing is right THEN I test the fail safes. The first one I test is the radio fail safe, after that I get a fresh battery, put the aircraft into a hover and switch to Loiter and wait. This last one can be a little nerve raking, but if you did the battery monitor current calibration properly you’ll be fine.