[Tzfat]

I believe you ... but what is the purpose for summing the inputs from the two sets of controls?

It has to do with why there are two pilots. There are times when takeover is needed - when using the override is not timely - for only momentary transitory use. In the landing flare is an example. It is highly discouraged, but technically possible and something we train for.

[r9etb]

OK.... so the summed inputs are pretty much predicated on the assumption that only one pilot is in control at a time. It would be the same as dual inputs to a purely mechanical system, and the difficulty of creating software to achieve a foolproof automatic “I’ve got it” switchover would be prohibitive.