REFLECTOR:Navaid Autopilot

[Chuck Jensen]

Is there some reason the oscillation would be barely perceptible, if present
at all, at low altitudes but fairly aggressive at higher alt (+8,000)?  Does
the higher altitude induce behavior that mimics, or aggravates, having slop
in the servo/control surface or incorrect sensitivity?

Brian's comments about PIDs and their associated alogorithms being
interesting creatures is certainly true.  We control heating in an
industrial process with a heater that's driven by a controller that uses
Fuzzy Logic.  I assume this is the same type of alogorithm application.  The
closer the heater gets to the desired target, the slower it goes, until it
stops right on the target without overshoot.  Then it stays there so
consistently you'd think the indicator was stuck.

As a side note, I understand my parents practiced the alogorithm method but
there was too much slack in the controls and that's why I'm here now.  But
that's another story for another day.

Chuck
N27GV


-----Original Message-----
From: reflector-admin@tvbf.org [mailto:reflector-admin@tvbf.org]On
Behalf Of Jim Agnew
Sent: Friday, July 11, 2003 9:18 AM
To: reflector@tvbf.org
Subject: Re: REFLECTOR:Navaid Autopilot


The oscillation almost always occurs when there is slop in
the control system between the servo and control surface. 
Have someone hold the aileron flush with the wing and move
the servo arm back and forth and look for slop.  It doesn't
take a lot.  If you don't have slop then the sensitivity of
the unit (the dead zone) may have to be turned down.

Jim

--- Chuck Jensen <cjensen@dts9000.com> wrote:
> I found the comments about the S-TEC and its oscillation
> phenomena
> particularly interesting.  I'm running a Naviad AP and
> Wing Leveler and see
> the same type of behavior, especially above approx.
> 8,000'.  When the WL is
> turned on, it rapidly oscillates L/R.  
> 
> I really didn't have a clue what was wrong and hadn't had
> it looked at yet,
> but now I wonder if this is, in fact, the same thing that
> occurs in the
> S-TEC.
> 
> Has anyone had a similar behavior with the Navaid?  
> Solution?   Is this
> problem likely similar/same as with the S-TEC?
> 
> Chuck
> N27GV
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=====
James F. Agnew
Jim_Agnew_2@Yahoo.Com
Tampa, FL
Velocity 173 Elite Aircraft Completed
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