wing levelers

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.

Actually, its not that simple. Trust me, I worked on a similar problem
for 2 years. How can you tell whether you are straight and level? If
you're in a balanced turn, your accelerometer (which actually measures
net force) will believe you are straight and level.

And a GPS won't help much at all, mostly because its response rate is
too slow.

Frank

How can you tell whether you are straight and level? If
you're in a balanced turn, your accelerometer (which actually measures net
force) will believe you are straight and level.

And a GPS won't help much at all, mostly because its response rate is too
slow.

Frank

As I see it, accelerometers and GPS together are all that's needed. If the
vectors from all 3 accelerometers are in the right direction, and the
average GPS heading is not moving much- you're straight and level.

My GPS updates about once per second. That's plenty fast enough.Once every
10 seconds would work.When flying, do you react to every bounce, or just
ride with the flow and provide general guidance? I don't know about you, but
I try to stay relaxed.

The GPS does too make the differance between a really sticky problem and a
slam dunk.
I'm betting your practical experience was before $50 GPS and $3
accelerometers? (say, 5 years ago). Am I right?




Ron Webb

I'll take a few of those $3 accelerometers! Where may one find them,
please?

Thanks.


Ron Webb wrote:
How can you tell whether you are straight and level? If
you're in a balanced turn, your accelerometer (which actually measures net
force) will believe you are straight and level.

And a GPS won't help much at all, mostly because its response rate is too
slow.

Frank


As I see it, accelerometers and GPS together are all that's needed. If the
vectors from all 3 accelerometers are in the right direction, and the
average GPS heading is not moving much- you're straight and level.

My GPS updates about once per second. That's plenty fast enough.Once every
10 seconds would work.When flying, do you react to every bounce, or just
ride with the flow and provide general guidance? I don't know about you, but
I try to stay relaxed.

The GPS does too make the differance between a really sticky problem and a
slam dunk.
I'm betting your practical experience was before $50 GPS and $3
accelerometers? (say, 5 years ago). Am I right?




Ron Webb

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


More than 'just a wing leveler'
http://www.trioavionics.com/


If I were me I'd go with something like that rather than homebrew. My
main objection is its panel gulping size. It would be nice to have a
gyro/accelerometer package elsewhere and a small panel you can pace as
you please.

Dan, U.S. Air Force, retired

But what if you weren't you ? 8*)

Frank van der Hulst wrote:
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.


Actually, its not that simple. Trust me, I worked on a similar problem
for 2 years. How can you tell whether you are straight and level? If
you're in a balanced turn, your accelerometer (which actually measures
net force) will believe you are straight and level.

And a GPS won't help much at all, mostly because its response rate is
too slow.

Frank

And the cruise control on your motorhome doesn't allow you to go to the
back and get a cup of coffee while tooling down the highway.

Why does it have to be all or nothing, people? Why can't it be an
electonic 'assistant' that can take the edge off of a bumpy ride and
keep the course drift to a minimum, without being asked to save the
pilot from an IFR death spiral? How can it tell your straight and
level? It WON'T, and no one need ask it to. Just pretty much maintain
the status quo, thereby making flight more enjoyable.

Fuzzy logic isn't inherently risky, per se, but how it's utilized is a
different matter. Novices often get enamored with gain computation
methodologies, thinking that they've got the grail for adaptive and
self-tuning control. But all the optimal, adaptive, learning, self-tuning,
yadda yadda yadda, stuff has the same difficulties. It's really a matter of
properly constraining the algorithms so that they can only produce
valid/safe solutions. All too often, people try to use the fuzzy stuff as a
generic cure-all that gets them around the difficulty of understanding the
physics of the control problem, which could back you into an unsafe
solution. The thing is, to appropriately constrain the tuning algorithm,
you've already done a ton of analysis and already have to come up with
appropriate handling qualities criteria, performance and stability
boundaries, taking your system performance into account, yadda yadda. Given
that, you've already done the design that you're trying to design an
algorithm to achieve. So, what's the point? At the end of the day, a gain is
a gain. Your success in coming up with a viable design will depend very
little on the methodology you use to compute the gain.


"Predictor" wrote in message
oups.com...
Why is fuzzy logic "risky"?

"Ernest Christley" wrote in message
. com...
But it is obvious that you have spent years in the industry designing
flight systems for large aircraft.

Actually, I've only worked on one large aircraft MD-11 Propulsion Controlled
Aircraft. The rest of my time has been on the F-15 HIDEC Propulsion
Controlled Aircraft, the F-15 ACTIVE (mostly the research processor and
engagement and reversion logic), X-35 directional control law (STOVL), and a
bunch of other "stuff". So, I tend to be very conservative in my design
approaches, since an error in controlling a highly unstable air vehicle can
quickly result in a lost aircraft.

At the end of the day, if you can't overpower the
the electronic gizmo with moderate effort then leave it on the ground.

A system can also get you into oscillations that you're not going to be able
to stop in a heartbeat if it's not tuned right or you operate it beyond it's
performance limitations. So, being able to statically overpower it isn't
nearly enough.

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.

Early nudges mean lots of lead in the system, which translates into lots of
noise and spiky output.

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.

Putting springs also puts lag into your system. More tendency for
oscillatory behavior.

Do not even bring up the subject of 'fly-by-wire'. I'm a software

Well, the thing is, any level of automatic stability augmentation has to
deal with the same types of issues, whether it be a rate damper or a
full-authority FBW system.

"AINut" wrote in message
...
I'll take a few of those $3 accelerometers! Where may one find them,
please?


Actually, you probably already own several, you just don't know it. The ADLX
series is used for air bag sensors...

A source for these is he
http://www.digikey.com/scripts/DkSea...213180&Site=US

The data sheet is he
http://www.analog.com/en/prod/0%2C28...L202%2C00.html


But I apologize - they aren't $3 - they are $6.19...


Ron Webb

Pete Schaefer wrote...

Actually, I've only worked on...

I wonder if we've crossed professional paths sometime over the years.
Dryden? PSFCC ring a bell?

Nauga is sitting this one out, Pete's doing a fine job :-)

Dave 'means to an end' Hyde

Ernest Christley wrote:

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

Blueskies wrote:


More than 'just a wing leveler'
http://www.trioavionics.com/


If I were me I'd go with something like that rather than homebrew. My
main objection is its panel gulping size. It would be nice to have a
gyro/accelerometer package elsewhere and a small panel you can pace as
you please.

Dan, U.S. Air Force, retired


But what if you weren't you ? 8*)

Then I would be someone else and I would be worried

Dan, U.S. Air Force, retired