wing levelers

The good news is thats the part that has gotten more doale in recen
years. Electronics that used to take a dozen guys to tweak, one kid
with a PC and PIC can do. He may not understand the application, but
the implementation technology has gotten quite powerful and cheap.

Fuzzy Logic, from what I can tell, if you do a really good job, you can
get to where a properly tuned PID controller would be, but without that
pesky math.

Now neural networks, that would be something to see. Watch the network
learn how to fly from a few simple rules 1) Stall is bad 2) crashing is
really bad 3) Its good to keep the oily side down. I think I'd have
it learn that sucker learn the basics flying an model (R/C or
computer).

Stepper motors- Why go to all the trouble when you have cheap off the
shelf full up servos?

Dan, U.S. Air Force, retired wrote:
wrote:

You can get really nice R/C servos for way under $100. Ball
bearingsand the works. The quarter scale size servos would
probably be
about right to fly a control surface.

Piezo gyros are also under $100 for R/C applications.

Regards


The hard part is the electronics package between the two. I know the
systems I worked on, but I would be reluctant to attempt builing a
system. Not my bowl of rice, but I'd like see what others come up
with.

Dan, U.S. Air Force, retired

wrote in message oups.com...
The good news is thats the part that has gotten more doale in recen
years. Electronics that used to take a dozen guys to tweak, one kid
with a PC and PIC can do. He may not understand the application, but
the implementation technology has gotten quite powerful and cheap.


http://www.radioshack.com/product.as...5Fid=276%2D625

http://hometown.aol.com/ccady/eztrim.htm



"Blueskies" wrote in message
. ..

wrote in message
oups.com...
The good news is thats the part that has gotten more doale in recen
years. Electronics that used to take a dozen guys to tweak, one kid
with a PC and PIC can do. He may not understand the application, but
the implementation technology has gotten quite powerful and cheap.



http://www.radioshack.com/product.as...5Fid=276%2D625

Ernest Christley wrote:
"Dan, did you ever get a chance to work with fuzzy logic?"

Pete Schaefer responded:
"I have. It's been a while. I'd never, ever use it on an airplane.
Maybe a washing machine controller or something like that. I'm not
saying that it can't be done, but just that it's a risky design
approach."


Why is fuzzy logic "risky"?



Pete Schaefer continues:
"There are other methodologies much better suited for aircraft."


Why are other methodologies "much better suited for aircraft"?



-Will Dwinnell
http://will.dwinnell.com

In article .com,
Predictor wrote:
Ernest Christley wrote:
"Dan, did you ever get a chance to work with fuzzy logic?"

Pete Schaefer responded:
"I have. It's been a while. I'd never, ever use it on an airplane.
Maybe a washing machine controller or something like that. I'm not
saying that it can't be done, but just that it's a risky design
approach."


Why is fuzzy logic "risky"?

BECAUSE it _is_ fuzzy. grin

Seriously, the nature of fuzzy logic is that it it _not_ deterministic.
Given a specific set of inputs, you cannot predict exactly what the
fuzzy logic will do for every occurrence of those inputs.

Identifying and analyzing "boundary" conditions in fuzzy logic is
"difficult, at best". _at_ a boundary condition, there is no telling
how far back one must trace to find the 'bias' that changes the output,
when all 'intermediate' inputs are identical. Even worse, the decision
may be based on 'noise' in the system.

This like this can lead to "unexpected" behavior in "unusual" circumstances.



Pete Schaefer continues:
"There are other methodologies much better suited for aircraft."


Why are other methodologies "much better suited for aircraft"?


Because they're more "predictable". see above.

You *really* want to be able to predict what the control system will
do, under every possible combination of inputs.

While 'strange things' may happen, at least you can rely on the fact
that "given the same circumstances again", the *same* "strange thing"
will happen.

..

Robert Bonomi wrote:

In article .com,
Predictor wrote:

Ernest Christley wrote:
"Dan, did you ever get a chance to work with fuzzy logic?"

Pete Schaefer responded:
"I have. It's been a while. I'd never, ever use it on an airplane.
Maybe a washing machine controller or something like that. I'm not
saying that it can't be done, but just that it's a risky design
approach."


Why is fuzzy logic "risky"?


BECAUSE it _is_ fuzzy. grin

Seriously, the nature of fuzzy logic is that it it _not_ deterministic.
Given a specific set of inputs, you cannot predict exactly what the
fuzzy logic will do for every occurrence of those inputs.

Fuzzy logic is deterministic. The rules are well defined, there is no
random number generator in any fuzzy logic implementation that I've seen.


Identifying and analyzing "boundary" conditions in fuzzy logic is
"difficult, at best". _at_ a boundary condition, there is no telling
how far back one must trace to find the 'bias' that changes the output,
when all 'intermediate' inputs are identical. Even worse, the decision
may be based on 'noise' in the system.

Noise will make any system behave randomly, but that is because you are
providing random inputs. Fuzzy logic is no different than PID or any
other control algorithm in this regard. However, the identical inputs
will produce the same outputs if the software is designed correctly.


This like this can lead to "unexpected" behavior in "unusual" circumstances.

Baloney.

Matt

Pete Schaefer wrote:

Rule #1 of Flight Controls Design: KNOW YOUR PHYSICS! At the end of the day,
F still equals ma, and you ain't getting past that doing any fuzzy stuff.


Pete, thank you for your concern, and I don't mind the flaming. Really 8*)

But it is obvious that you have spent years in the industry designing
flight systems for large aircraft. I applaud that and hope to learn a
thing or two. But let me throw a rule out:

Rule #1 of Homebuilt Flight Controls Design: DON'T EVER GIVE ANYTHING
ELECTRONIC CONTROL! At the end of the day, if you can't overpower the
the electronic gizmo with moderate effort then leave it on the ground.

I've had this discussion before. I'm building and airplane for
ENJOYMENT. Getting beat to death in the soup is not my idea of a good
time, so I would not bother with a system that has enough power to
control things in choppy weather. I'm currently designing a cooling
system for my rotary auto conversion, and I'm not designing it for
sustained operations at 100F, because sitting under a plexiglass
slowcooker of a canopy is also not my idea of a good time.

Smooth flight in a light plane is predicated on a lot of small inputs
made early. The earlier it's made, the smaller it has to be. A long
series of continuous nudges. Stepper motor would be fine. You tie it
into the system through a couple of springs, and if you're asking for
more force than what they deliver then you've already gone off the wrong
side of the page. If it goes belly up, then it is an irritation, but no
more so than the CFI who won't get his $&*$ feet off the rudder pedals.
You can't tell it to move it's feet, but you can shut it down and then
nullify it's input with trim. (That's right. Trusty mechanical trim
stays right where it's at. Maybe beefed up just a tad, since it may be
given new duties.) In any case, there is no point where the pilot is
free to let go of the yoke.

Do not even bring up the subject of 'fly-by-wire'. I'm a software
engineer, and there is no way I'd trust a computer with my butt unless
it was built and maintained by a properly trained team (which I am not)
and had multiple backups (which I couldn't fit in my little plane). I
don't even think that most GA aircraft should fly IFR, especially those
depending on electronics. Very few people have the budget to buy the
type of equipment that is really necessary for blind operations (the
sort of equipment that I suspect you helped design), fewer can afford a
plane big enough to carry it all, and even fewer can afford to maintain
it properly.

Ernest Christley wrote:
"Dan, did you ever get a chance to work with fuzzy logic?"


Pete Schaefer responded:
"I have. It's been a while. I'd never, ever use it on an airplane.
Maybe a washing machine controller or something like that. I'm not
saying that it can't be done, but just that it's a risky design
approach."


Predictor asked:
"Why is fuzzy logic "risky"?"


Robert Bonomi answered:
"BECAUSE it _is_ fuzzy. grin

Seriously, the nature of fuzzy logic is that it it _not_ deterministic.
Given a specific set of inputs, you cannot predict exactly what the
fuzzy logic will do for every occurrence of those inputs."


Fuzzy logic is completely deterministic. Given the same inputs, fuzzy
systems will produce exactly the same outputs.

Here are links to some reasonably good introductory material on fuzzy
logic:

http://www.austinlinks.com/Fuzzy/overview.html
http://www.ncst.ernet.in/education/a...nt/fuzzy/fuzzy...
http://www.fpk.tu-berlin.de/~anderl/...uzzyintro4.pdf
http://www.phys.ufl.edu/docs/matlab/...y/fuzzy_tb.pdf
http://www.faqs.org/faqs/fuzzy-logic/part1/
http://www.fuzzy-logic.com/ch3.htm


-Will Dwinnell
http://will.dwinnell.com

Ernest Christley wrote:
"Dan, did you ever get a chance to work with fuzzy logic?"


Pete Schaefer responded:
"I have. It's been a while. I'd never, ever use it on an airplane.
Maybe a washing machine controller or something like that. I'm not
saying that it can't be done, but just that it's a risky design
approach."


Predictor asked:
"Why is fuzzy logic "risky"?"


Robert Bonomi answered:
"BECAUSE it _is_ fuzzy. grin

Seriously, the nature of fuzzy logic is that it it _not_ deterministic.
Given a specific set of inputs, you cannot predict exactly what the
fuzzy logic will do for every occurrence of those inputs."


Fuzzy logic is completely deterministic. Given the same inputs, fuzzy
systems will produce exactly the same outputs.

Here are links to some reasonably good introductory material on fuzzy
logic:


http://www.austinlinks.com/Fuzzy/overview.html
http://www.ncst.ernet.in/education/a...uzzy/fuzzy.pdf
http://www.fpk.tu-berlin.de/~anderl/...uzzyintro4.pdf
http://www.phys.ufl.edu/docs/matlab/...y/fuzzy_tb.pdf
http://www.faqs.org/faqs/fuzzy-logic/part1/
http://www.fuzzy-logic.com/ch3.htm


-Will Dwinnell
http://will.dwinnell.com

"Predictor" wrote in message
oups.com...
Ernest Christley wrote:
"Dan, did you ever get a chance to work with fuzzy logic?"


Pete Schaefer responded:
"I have. It's been a while. I'd never, ever use it on an airplane.
Maybe a washing machine controller or something like that. I'm not
saying that it can't be done, but just that it's a risky design
approach."


Predictor asked:
"Why is fuzzy logic "risky"?"


Robert Bonomi answered:
"BECAUSE it _is_ fuzzy. grin

Seriously, the nature of fuzzy logic is that it it _not_ deterministic.
Given a specific set of inputs, you cannot predict exactly what the
fuzzy logic will do for every occurrence of those inputs."


Fuzzy logic is completely deterministic. Given the same inputs, fuzzy
systems will produce exactly the same outputs.

Here are links to some reasonably good introductory material on fuzzy
logic:


http://www.austinlinks.com/Fuzzy/overview.html
http://www.ncst.ernet.in/education/a...uzzy/fuzzy.pdf
http://www.fpk.tu-berlin.de/~anderl/...uzzyintro4.pdf
http://www.phys.ufl.edu/docs/matlab/...y/fuzzy_tb.pdf
http://www.faqs.org/faqs/fuzzy-logic/part1/
http://www.fuzzy-logic.com/ch3.htm


-Will Dwinnell
http://will.dwinnell.com

And you might also want to google for:
Pease "fuzzy logic"

Bob Pease is a staff scientist at National Semiconductor. His conclusions:
There is a tremendous amount of hype and outright falsehood, with very
little supporting data for the miracle applications.
It can help simplify some non-linear problems.

Tim Ward