[stepansonsky]

Hi, I've got Turnigy 6x radio with default receiver XR700 (without failsafe built in). I've tried to setup failsafe in GCS using this video



But when quad is armed, and I turn off transmitter, motors goes completelly off and CC3D does not fall into failsafe mode (connected variable stays true). Is it possible to somehow repair this behavior? I think it should be possible to detect transmitter disconnect, or am I wrong? Anyone solved this? Thanks for reply.

[TheOtherCliff]

It all depends on what you have set up for RC failsafe mode.

Does it truly have an RC failsafe?  I thought that even the 9X did not have failsafe.

What kind of signal comes out of the receiver?  One connector per channel (PWM)?  or PPM or SBus or ...

Hook up GCS and watch System Health.  If color of "Input" Health is green when transmitter is on, but orange when it is off, you don't have RC failsafe and you are getting FC failsafe each time you turn off transmitter.

FC failsafe is a flight mode switch position plus a set of stick positions.  The default is not to use a flight mode switch position, but to simply turn the motors off.  You go into GCS -> System -> Settings -> ManualControlSettings and set FailsafeFlightModeSwitchPosition (default -1) to whatever switch position you want MINUS 1, so for position 3 you put in 2.

While you are in the area you can set FailsafeChannels to some value.

For instance, if you have Attitude mode on position 1, and you want all sticks centered and throttle at 30% you set FailsafeFlightModeSwitchPosition to zero and FailsafeChannels to zero except for Throttle, which you set to 0.30 (the useful throttle positions are basically 0 to 1).

Click on ManualControlSettings to make it turn blue, and then click on the red up arrow at the top of the screen to save this stuff permanently.

BEWARE:  You have just made it so that (if armed) if you switch the transmitter off the motors will start up even if the throttle was all the way down!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Also beware:  If you use this to make it land more softly, the motors will run till you either regain control or the battery dies, or you somehow manage to disconnect the battery with the motors running.  That means, if it lands in tall grass, or upside down, etc.  It will burn some motor/ESCs/battery/wires up and maybe start a fire.

Also beware:  In this setup, the throttle setting you use should be to slowly come down with the best, hottest, lightest battery you use and on a full charge.  If you don't set it that low, it will climb with that battery pack and you have a fly-away.

Test it out to make sure it works before you rely on it.

The guy in the video doesn't have his ESCs calibrated/adjusted properly or his motors would stop when he switches his transmitter off (when he had default FC failsafe).

You can see that this needs to be thought out, and also that you are assuming a different set of risks when you change it.  Instead of falling out of the sky and maybe breaking, it may come down softer, but cut somebody up or catch on fire or otherwise damage different components.

Lecture over.    Be safe!

[stepansonsky]

Thanks for reply TheOtherCliff. Receiver is PWM and when I turn off transmitter, input health remains green, so it means receiver has failsafe built in? Ok

I've tried to setup failsafe throttle value little bit under the hover for smoother landing, but I've decided to stay with "motors off failsafe". You're right, it's better to fall down instantly and break the quad than fly away without control and injure somebody or break someone's Ferrari

[TheOtherCliff]

Well then since you have RC failsafe working, you set the flight mode channel failsafe to go to whatever mode you want and the sticks to whatever position you want.  Basically the same setup, but you do the setting in the RC, not the FC.

I have an old PCM radio that only has a 2 position switch, but I set up the switch to basically be full left and center of a 3 position switch setup.  I set the failsafe to put it in the third position that can't be reached with the transmitter on.  I now have a poor man's 3 position switch with the third position set to RTB.    Beware that some radios may cause issues with this by requiring the throttle to be low or the switches to be in a certain position when you switch on the Tx.

[Brunosanta]

Hi theOtherCliff,
this was really clarifying, the fact that i would have a possible fly away or a burned motor or damaged drained battery better motors off.

One question, is it possible to set it Like: in case of signal fail, hold position for X seconds? I use the Oplink as my TX PPM.
Thank you for the help.

[TheOtherCliff]

What do you want it to do after that though?

For those who know the risks and think the rewards are larger than the risks, have a failsafe (RC or FC) set it to Attitude mode with throttle below hover value or if you have a GPS, make it do RTB/Land or just Land.  The Land part has an automatic motor cut off at touch down.  I don't know about any other possible safety features that might shut the motors off if it gets unlevel by landing through a tree or tall grass.  I was very pleased to see that it shut my motors off the first time I tested it and saw the motor cutoff.

It would be nice to have a LandWithoutGPS mode that just used Attitude with fixed thrust (or with baro control if it has a baro) because it could do the motor cutoff on touchdown detect.