Quoting rq1...@q7.com:

If i were doing it i'd use 4 mechanically independent servos. I estimate
the reliability of doing this is about 1/2 of the single servo system
being proposed. (Can we put the cool linkage drawing on the wiki page?)

Despite the reduced reliability, i still think the 4 independent scheme
is a winner.

  * Reliability is still very high

  * Mechanically ready for full flight control

  * Mechanically simpler

  * Same system that must be developed down the road anyway

Add higher cost to the list.

The reason I was pushing for a linked system is because there were reservations on the team about what could go wrong if the micro messes up and the servos go out of sync. Keep in mind we have NEVER successfully flown an ARM micro in 3 airborne tests. I will be happy to machine both the linked single servo system and the four servo system, so multiplying the work required is not a big problem. I really want to take baby steps on this, and I think the additional insurance is worth the work. We'll do the independent version, but I don't think we should do that one first.

In the 4 independent scheme, the servos must be individually trimmed. To
do this i would consider an absolute magnetic shaft encoder:

Why add a shaft encoder when the existing servo positioning system gives minute of angle precision? I think the additional sensor violates the KISS principle. Modern digital servos are strong, fast, and accurate. I plan to align the fins the same way RC helicopter blades are aligned; using an inclinometer style pitch gauge.

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