wing levelers

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

Dan, did you ever get a chance to work with fuzzy logic?

It would require a stepper motor to control the control surface, but it
could easily maintain wing level or altitdude with grace and smoothness.
Have you ever seen the balancing trick with the mortorized car.

A weight on the end of a stick is hinged on top of a programmed electric
car. The car acclerates quickly to flip the weight vertical, and then
jostles back and forth to balance it there. All with not input except
an indicator of the angle of the stick holding the wieght. Impressive.

I have the information for the EZTrim altitude hold system. After I
have everything else on the plane working, I have a goal of reworking
the software to use a fuzzy algorithm.

"Ernest Christley" wrote in message
.. .

Ernest:

This reply is going to sound like a flame, and I really honestly don't mean
it to be, but I gotta step in and say something to ease my conscience in
case you go out and get yourself killed. If I were around and you were about
to go hop in your airplane to test something developed with this attitude,
I'd feel obligated to wrestle you to the ground, take away your keys, then
send you back to the lab to do a very thorough and formal system design
before allowing you to procede.

If I were ever to say the kinds of things you said in a design strategy
meeting, my coworkers would laugh their asses off, then beat the hell out of
me for suggesting such a thing. Then I'd probably end up in the tech pubs
department or fired or something like that.

Dan, did you ever get a chance to work with fuzzy logic?

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. There are other
methodologies much better suited for aircraft.

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.

It would require a stepper motor to control the control surface

Another big no-no. Steppers are fine for inkjet printers and stuff, but
initialization of position (need to be able to do a power-on reset in
flight), hazards of getting the windings out of sync (immagine you hit a
bump, and your underpowered servo gets knocked off a few ticks....now it's
running backwards.....yes, I've seen this happen), complexity of the power
electronics to drive it...... all these problems disappear with a decent
servo.

could easily maintain wing level or altitdude with grace and smoothness.

The way you say this, I can tell that you've never tackled a problem like
this before. There are tons of things to consider.

Have you ever seen the balancing trick with the mortorized car.

This is the undergraduate "intro to controls" lab experiment. It's meant to
illustrate the basic concepts of closed-loop control. Mastering this problem
only gives you a very small taste of what it takes to design even a simple
autopilot. If you've gotten that far, then next step is to either take a
flight controls class (grad level), or maybe start building some R/C models
if you don't want to go for more school (I'd suggest doing this anyway). The
school of hard knocks is fine with R/C, since the knocks aren't really all
that hard on you.

PLease, get yourself more experience with aircraft control before putting
yourself at risk. I'm guessing you already have a start in learning this
stuff, and don't think you should abandon your goals. However, take baby
steps.

Pete

Pete Schaefer wrote:

"Ernest Christley" wrote in message
.. .

Ernest:

This reply is going to sound like a flame, and I really honestly don't mean
it to be, but I gotta step in and say something to ease my conscience in
case you go out and get yourself killed. If I were around and you were about
to go hop in your airplane to test something developed with this attitude,
I'd feel obligated to wrestle you to the ground, take away your keys, then
send you back to the lab to do a very thorough and formal system design
before allowing you to procede.

If I were ever to say the kinds of things you said in a design strategy
meeting, my coworkers would laugh their asses off, then beat the hell out of
me for suggesting such a thing. Then I'd probably end up in the tech pubs
department or fired or something like that.


Dan, did you ever get a chance to work with fuzzy logic?


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. There are other
methodologies much better suited for aircraft.

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.


It would require a stepper motor to control the control surface


Another big no-no. Steppers are fine for inkjet printers and stuff, but
initialization of position (need to be able to do a power-on reset in
flight), hazards of getting the windings out of sync (immagine you hit a
bump, and your underpowered servo gets knocked off a few ticks....now it's
running backwards.....yes, I've seen this happen), complexity of the power
electronics to drive it...... all these problems disappear with a decent
servo.


could easily maintain wing level or altitdude with grace and smoothness.


The way you say this, I can tell that you've never tackled a problem like
this before. There are tons of things to consider.


Have you ever seen the balancing trick with the mortorized car.


This is the undergraduate "intro to controls" lab experiment. It's meant to
illustrate the basic concepts of closed-loop control. Mastering this problem
only gives you a very small taste of what it takes to design even a simple
autopilot. If you've gotten that far, then next step is to either take a
flight controls class (grad level), or maybe start building some R/C models
if you don't want to go for more school (I'd suggest doing this anyway). The
school of hard knocks is fine with R/C, since the knocks aren't really all
that hard on you.

PLease, get yourself more experience with aircraft control before putting
yourself at risk. I'm guessing you already have a start in learning this
stuff, and don't think you should abandon your goals. However, take baby
steps.

Pete


Agreed.

Dan, U.S. Air Force, retired

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

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

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


Why overcomplicate things. This is just too easy an application with a
BasicX board and an accerleometer.

http://www.basicx.com/
http://www.analog.com/en/prod/0%2C28...L203%2C00.html

Couple this with a cheap GPS, and big servos modelled after the ones used in
RC aircraft (the BasicX computer is designed to drive them directly), and a
complete autopilot is an easy design project.

I;ve been playing with this for a while, but I'll admit i've spent more time
thinking than soldering.

Anybody seriously interested in teaming up?



Ron Webb..

Ron Webb wrote:

"Predictor" wrote in message
oups.com...

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



Why overcomplicate things. This is just too easy an application with a
BasicX board and an accerleometer.

http://www.basicx.com/
http://www.analog.com/en/prod/0%2C28...L203%2C00.html

Couple this with a cheap GPS, and big servos modelled after the ones used in
RC aircraft (the BasicX computer is designed to drive them directly), and a
complete autopilot is an easy design project.

I;ve been playing with this for a while, but I'll admit i've spent more time
thinking than soldering.

Anybody seriously interested in teaming up?



Ron Webb..


Before anyone rushes into anything take if from someone who has worked
AFCS, stab aug and the like. I have been in rotor and fixed wing
aircraft when the systems have gone nuts during inflight ops checks.
Fortunately the systems could easily be overpowered manually and
disconnected either by a button on the stick grip.

In any event all the systems had a ton of engineering and flight testing
before being accepted for service.

On the other hand some of the nutso systems can be quite amusing in
hindsight. I had an H-3s aug system problem I couldn't duplicate on the
ground. I requested a flight. They sent me a pilot who had a habit of
placing his coffee cup on the floorboard near his foot. We hovered, he
engaged system which promptly went crazy. I'm standing in the back
looking over the FE's shoulder, holding on for dear life and collecting
dings and dents in my helmet. The pilot calmly reached down, picked up
his cup of coffee, took a swig, put it down and then disengaged. After
we disembarked I asked him why he had done that. He said something about
enjoying the ride. That was about 20 years ago. I still think it was a
bit funny

Dan, U.S. Air Force, retired

On Sun, 6 Mar 2005, Ron Webb wrote:


Why overcomplicate things. This is just too easy an application with a
BasicX board and an accerleometer.
snipped
Anybody seriously interested in teaming up?


I started one, but then found a Navaid too cheap to pass up.
I bought the BX24 development kit, and had a great time programming
it to read the autopilot signal from my Terra, and then the NEMA code
from my GPS, but I got the navaid before buying a gyro.

Many pilots are upgrading the Navaid to a Trio solid state unit.

I can tell you that an acceleation chip reads nothing in the air.

There is some freeware for an altitude hold.

George Graham
RX-7 Powered Graham-EZ, N4449E
Homepage http://bfn.org/~ca266