Moderator Comment by Chris Anderson on March 27, 2009 at 4:50pm

Can you explain a bit more what that does? How does it work?

Comment by Reto on March 27, 2009 at 5:09pm

Are those two circuits just simple failsafe units? If yes, the first on ArduPilot CTRL line is probably programmed just to be sure autopilot is on when out of radio range. As to the second unit between Rx and FMA Co-Pilot, I imagine it is plugged to the Co-Pilot control channel to be sure stabilizing is on when out of range. I cannot imagine any other logic implementation for such failsafe units. But maybe I miss something, though.

Comment by Michal on March 27, 2009 at 5:15pm

Sure :) When I switch of my RC transmitter simulating RC signal loss one tiny failsafe force ArduPilot to switch to autonomous mode. At the same time second failsafe switch CPD4 to 80% stablisation. So when I will fly out of RC range the airplane will have CPD4 stabilisation and ArduPilot will drive it home.

The small devices like one on the first picture has similar functionality to this one.

Comment by Michal on March 27, 2009 at 5:20pm

Reto - yes this works exactly as you described.

Comment by Gagarien on March 27, 2009 at 10:25pm

Question -- By changing the Attiny code to work in reverse iaw. toggle switch up autopilot off then in case of TX loss autopilot alway's on. Or does not all RX behave the same way? Also setup will have to be flown with Co-Pilot connected after Ardupilot so that stabilization is on Ardu controlled channels.

Moderator Comment by Chris Anderson on March 27, 2009 at 11:23pm

I'm still confused by how the failsafe works. On all of our RC systems, the Rx traps the signal loss and generates its own pre-programmed failsafe command (usually cuts throttle). What does yours do?

Comment by Reto on March 28, 2009 at 1:44am

In my case, my 9 channel Futaba Rx will just do exactly what both failsafe units of Michal are doing (autopilot and Co-Pilot on). But since he seems to have trouble with his Rx failsafe, he uses separate units. If I were Michal, I would probably change the Rx for one with working failsafe.

Comment by Michal B on March 28, 2009 at 3:47am

When Spektrum RC loses signal, it keeps last values for all channels except throttle, which is cut down. Also autopilot toggle channel keeps last value (probably manual mode). This would result in plane crash.

Assuming Ardupilot can read all RC channels, possible detection of signal loss would be checking is throttle is down, and other channels not moving for certain time (e.g. 2 seconds).

Comment by Reto on March 28, 2009 at 8:43am

Ok, so this is a Spektrum specific issue, and not a problematic Corona Rx. Then the two failsafe units are just the right thing for Michal.

Comment by Michal on March 28, 2009 at 2:43pm

The reason I modified my platform is that Corona (+lenghtened antenna to 3.04m) is really great Rx due to its glitch free behaviour. Thats why I want to stick with this receiver . My previous RC receiver HFD-06MN didnt even passed antenna down range tests. Another thing is that Hitec Rx didnt cooperate with ArduPilot in case of signal loss as well.
Corona have its built-in failsafe but it is limited somehow (sometimes it falis to turn on the MUX).

I dont know why but till now the only bullet proof device that could properly switch MUX and CPD4 on is the small failsafe from the first photo. It could be preprogrammed to hold desired state after RC signal is lost. I connected them between Rx and CPD4 / Rx and ArduPilot.

It can be confusing indeed. But I wanted to post the solution to problems with some of the RC receivers since it could be vital for FPV pilots.

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