Failsafe RC-receiver VS Copter (Mission Planner-setting)?

Which one overrides the other?

Futaba RC-receiver is configurated to put the FlitgtMode-channel in RTL.
Mission planner is configurated to continue mission if RC-link is lost.

RC-transmitter gets lobat and dies. RC-Receiver recognizes this and puts the flightmode-chnnel into RTL-mode. But what do the firmware do? Does it sense that the receiver lost its contact to the transmitter and continue mission? Which one wins?

You should pick one method and not use two different ones. Your current configuration will conflict. Having your RC change modes to RTL is not going to tell ArduCopter there is a problem. It just sees a normal mode change to RTL and is unaware there is a problem. I suggest just letting ArduCopter handle it, which will give you the continue mission in auto thing too.

Configure your RC receiver to put the throttle channel low, less than the FS_THR_VALUE parameter. ArduCopter will take action based on your setting of the FS_THR_ENABLE parameter, which it sounds like you want set for 2 (enabled, continue in auto mission)

The throttle value won’t override the flight mode setting? If the throttle in setting is below FS_THR_VALUE will it not override whatever flight mode the receiver is sending? I’ve actually never tested this running an auto mission.

Am not saying this to be a smart ass. But I have my AR7700 set to go to RTL if connection is lost. But, I think my parameters are set that after FS_THR_FAILSAFE is present for 5 seconds the aircraft will do whatever action has been set in the parameters for the failsafe action. Whether it be continue on a mission or RTL. Again never tested this. I thought the throttle in setting tells Arducopter there is a problem.

The low throttle method is to tell the autopilot that the receiver is no longer receiving valid data. Based on this signal from the receiver the autopilot can declare a failsafe condition.

How you configure your Ardupilot failsafe parameters will decide what the autopilot does when the failsafe condition is in effect.

Now that I think about this… If in auto and connection is fading in and out. Receiver failsafe is set for RTL. Would receiver be toggling back and forth from auto to RTL until full disconnect. This might confuse things for a bit I suppose. Aircraft might think it should be in auto or RTL a lot until the full 5 seconds happened. I would need to check if the AR7700 needs a period of time with no connection before it itself goes to failsafe mode.

Using the throttle failsafe method also has the advantage of the RC failsafe message appearing in your log, so later you can see exactly what happened, when, and what the results and actions were.

If you set the receiver to output RTL mode, you’re going to get the RTL message in logs but you wont necessarily know why and it might be easy to miss.

If you configure your RC receiver to handle it’s own failsafe by setting the mode to RTL, the throttle failsafe will never happen in order to override it. This is not a wise way to handle it IMO. Guess what happens is you change the mode assignments on the flight mode channel without changing your receiver configuration? Now instead of putting it into RTL, it puts it into stabilize or acro or something silly. And if you do a mode change to RTL, you will never have the continue in auto functionality. And as it comes back into range, it will go back to whatever mode it was in before, which may or may not be horrible.

Use the failsafe the way it was designed to be used as I described above and don’t do any of this receiver based mode changing business.

So I guess basically the receiver should just be set to output its last known outputs in a failsafe event. Except throttle of course. IIRC The AR7700 has the option of setting throttle to low and other outputs hold position or you can preset all outputs to a specific PWM.

Yes, exactly. You should leave the flight mode channel PWM unchanged. Otherwise when it comes back on range, it could change modes on you.

O.K… I’ve only tested my set up by turning off the TX. About 200 hrs on the Ardupilot Pixhawk 1 F450. Autotune did a great job on it. Never did an Auto Mission in which it lost connection.

What happens if I am flying in Stabilize mode and RC-link is lost if I dont use the RC-receiever Failsafe and uses “continue mission” instead of RTL or Land?

I guess “Continue with mission” shouldnt be used. RTL is better (Pixhawk failsafe), since the flying never exceeds 500-600m anyway.

With that said, I should set the failsafe on the 8-channel Futaba-receiver (supports failsafe on all channels) to HOLD and the Throttle to what? Sometimes we fly up to an altitude in Stabilize mode and switches over to Auto, sometimes uses autotakeoff. Where should the throttle-stick be?

Copied from the docs-

  • “Enabled Continue with Mission in AUTO” to allow the vehicle to continue with missions even if it takes the vehicle outside of RC range (not recommended). In all other cases the vehicle will RTL.

Blockquote[quote=“MickeM, post:12, topic:32360”]
What happens if I am flying in Stabilize mode and RC-link is lost if I dont use the RC-receiever Failsafe and uses “continue mission” instead of RTL or Land?

The aircraft will crash.

Lol. The continue option only applies when flying a mission in auto mode. In any other mode, it will switch to RTL or Land.

To get things straight…

I fly with the same transmitter as I use for helicopters and planes (a Futaba-transmitter and receiver). With that said, the throttle-stick is not centered with a spring (like DJI-transmitters for their multicopters). When the throttle-stick is completely towards me its value is -100%, not 0.

Should I put the failsafe on the RC-receiver set to HOLD on all channels, except THROTTLE that should be set to -100%? Fully down (not away from me). If the transmitter suddenly dies by some reason, the Flightmode is still the same, the inputs for Tilt, Roll and Yaw are still the same. But… the throttle is suddenly fully down to -100%. Throttle channel is 1094 in Mission Planner. FS is set to 975 in Mission Planner as default.

“Motors will be immediately disarmed if the vehicle is landed OR in stabilize or acro mode and the pilot’s throttle is at zero”
That I do not want!

If the PPM-cable gets loose between the receiver and the Pixhawk, the pulse-signal is lost and that I can understand, the signal is lost.

How does the Pixhawk recognize when the transmitter fails if failsafe is not used on the receiver? HOLD on all channels? All channels still sends the correct signals. Failsafe on my Futaba is Failsafe or Hold. Failsafe equals a value. I cant change between “use failsafe” and “inactive”. Its Hold or Failsafe.

When reading the manual on Ardupilot:
Set the “FS Pwm” value to be:

  • at least 10 PWM higher than your Channel 3’s PWM value when the throttle stick is fully down and the transmitter is off
  • at least 10 lower than your channel 3’s PWM value when the throttle stick is fully down and the transmitter is on
  • above 910

What?.. on that.
When my transmitter is on, the value in Mission Planner Throttle-reading is 1094.
When my transmitter is off, the value is the same because I use -100% throttle as failsafe, 1094.
What value should I set the FS Value to? It is 975 as default.

I have max-min-programmed the ESCs. And then ESC-calibration using Mission Planner.

If I test now switching of the transmitter, nothing happens. Still Stabilize, but Mission Planner says No RC-Receiver.

I do not get it. I have used failsafe on multicopters before. RC Receiver-failsafe that puts the flightmode-channel to RTL and on simple

When you set up the throttle failsafe on the receiver try putting the throttle trim on the transmitter all the way down and make sure the stick is down of course. This will give you a lower PWM than1094 if you loose your connection.


Min-max -100 to +100 % as usual with no trims and when doing the ESC-calibration in Mission Planner.

And when doing the failsafe-setup, then I use the trim to for example -120% if that gets the pwm-value to between 910 and 965 if I have FS value as 975 in Mission Planner, wherever 975 comes from.

Is that correct? I havent tested yet, just ask. =)

Yes that sounds correct.

It Worked great! =)
If I read the howto above… some times… and then think a little bit more. Then I got it. =) English isnt my language.

  1. When transmitter is ON it sends PWM = 1100 when stick is at bottom (no trim used) (it was actually 1094)
  2. FS PWM in Mission Planner = 1050
  3. When transmitter is OFF it sends PWM = 1000 when stick is att bottom AND trim is used to get it down to PWM = 1000.
  4. Do not get that value under 910.

And it worked.

Also if the Receiver dies on the multicopter, the failsafe with RTL works.

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