"...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..."
What has been the root-cause of each of the three failed ARM flights? A
robust controller solution would seem to be a primary factor for the
roll-control project, with either a single- or a multi- servo approach.
On Wed, Jul 8, 2009 at 1:41 PM, I <kirk...@pdx.edu> wrote:
> 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.
> psas-airframe mailing list
psas-airframe mailing list