"...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. Thanks- Doug 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@lists.psas.pdx.edu > http://lists.psas.pdx.edu/mailman/listinfo/psas-airframe >
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