A couple days ago we were talking about redundancy and reliability in the APM:Plane 2.74 thread. I have been thinking about how to add more redundancy without adding too much complexity and cost. I have been thinking about how to safely guide a plane after a total APM failure. This requires not giving the APM control of every servo, and hooking one of two elevator servos and the rudder servo directly to the receiver which is powered by a different source. This means that during autoflight, the APM will have to be tuned to make do with only half an elevator and no rudder. I believe that is totally doable, but not a very elegant solution. So then i was thinking how to backup the control of a servo so that it could still be utilized if the APM was dead.

Is it possible to simply Y-splice a servo signal line between the APM and the Rx so both had simutaneous control? So during auto flight the servo would be getting signals from the APM unless the pilot moved the sticks, then there would be two different signals being sent to the sevo at the same time. I wonder what a servo would do? Would it freak out and jitter, or would it simply react to the sum of the signals and behave sort of like the Stick_Mixing parameter?

I know this is a ridiculous idea, so feel free to ridicule it. Perhaps there is a more elegant way of sharing a servo for redundancy. Ideally the APM would have a true RX pass through that would function with no power. I don't know if such a device could be created as a stand alone unit, or if there could be a software solution.

Redundant system integration is the key to our success in the eyes of the FAA, so it is a conversation worth keeping active.

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HI Iskess,

I am building 2 pipeline surveillance planes with a backup parachute landing, and we should have the fail-safe or redundancy as priority. I am new in small UAV, so my ideas might be not working but I was thinking of them.

1- If we can put 2 x APM, in a way that if the first one goes off, the second one will continue its work.

2- If both go off, we can use the FailSafe Mux from https://store.3drobotics.com/products/failsafe-mux for the RX to take control

3- All items are connected to the main batteries, and one additional battery for backup power at least to do a parachute landing or continue helping the APM to do the RTL or give power to the RX to control it. 

4- If we can have parallel ESC as well, if applicable.

What else do we need to make a 101% redundant plane? Did I miss any point? and of course there are some small accessories to make the 4 above points functional.  What are they?

If you can help us, it will be great or if anyone can do. 

We have 2 planes, one of them has double engines. (For extra camera payload and safety).   


The Autopilot can be the Pixhawk and not necessarily the APM, if it works to have 2 autopilot for redundancy. 

We are looking to have a working solution. 

I saw that you have been recommended to use Batshare for battery backup.  https://www.smart-fly.com/Products/BatShare/batshare.htm 

I was reading somewhere, that we can put an additional Rx as backup , but how to do the connection between them?


Hello all together,

I just found this discussion.

This morning I also posted something in this direction. It might be interresting for you.

Please check: http://diydrones.com/profiles/blogs/soon-availible-redundancy-for-a...

Regards, Robert

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