wing levelers

[Dick]

Sitting around the hanger and discussing the possibility of somehow using
off-the-shelf electronic/computer components or gadgits for semi-automatic
wing leveling on lightly loaded, short wingspans.

Not being computer guys, the current thought is that something should be out
there that is available cheaply and modifiable to use a simple wing
leveler.

Having heard someplace that automotive computers, as an example, sense data
millions of times leads us to believe that sensing the wing tip initial
movement and counteracting very very quickly would be a good thing.

As an example: One fellow pictured a rolling ball bearing inside a tube
somehow activating a magnetic switch which in turn pulses a dc linear motor
to operate the aileron minutely.

We are not sure how to detect the very earliest initial wing tip movement or
drive the small trim type motor and would appreciate some thoughts or site
recommendations to investigate.

Thanks, Dick

[Morgans]

"Dick" > wrote

> Sitting around the hanger and discussing the possibility of somehow using
> off-the-shelf electronic/computer components or gadgits for semi-automatic
> wing leveling on lightly loaded, short wingspans.
>
>
> As an example: One fellow pictured a rolling ball bearing inside a tube
> somehow activating a magnetic switch which in turn pulses a dc linear
motor
> to operate the aileron minutely.
>
> We are not sure how to detect the very earliest initial wing tip movement
or
> drive the small trim type motor and would appreciate some thoughts or
site
> recommendations to investigate.


Hmmmm. No free (or even cheap) lunch, here.

The idea of a ball bearing in a tube is not even close. Ever hear of the
graveyard spiral? It is what killed Kennedy. (not the president) In such
a spiral, you experience several 360 degree turns, diving steeply enough
that vertical descent rates of 10,000 feet per minute (if the plane holds
together) are possible. Still, the ball in the tube would stay right in the
middle. One G all the way.

You need a gyroscope, or an electronic equivalent. Some have played using
very sensitive GPS antennae in the wingtips.

Best advice? Trim the plane, stay awake and fly it, or BUY an autopilot, or
wing leveler. Or google wing leveler.
--
Jim in NC

[Montblack]

("Morgans" wrote)
<snips>
>> We are not sure how to detect the very earliest initial wing tip movement
>> or drive the small trim type motor and would appreciate some thoughts or
>> site recommendations to investigate.

> The idea of a ball bearing in a tube is not even close. Ever hear of the
> graveyard spiral? It is what killed Kennedy. (not the president) In
> such
> a spiral, you experience several 360 degree turns, diving steeply enough
> that vertical descent rates of 10,000 feet per minute (if the plane holds
> together) are possible. Still, the ball in the tube would stay right in
> the
> middle. One G all the way.
>
> You need a gyroscope, or an electronic equivalent. Some have played using
> very sensitive GPS antennae in the wingtips.
>
> Best advice? Trim the plane, stay awake and fly it, or BUY an autopilot,
> or
> wing leveler. Or google wing leveler.


Automotive world is using electronic stability-control (ESC) systems with
documented success. The article says the system used a decade ago wasn't
very good, but they've come a long way since then.

http://www.detnews.com/2005/autosconsumer/0502/19/F01-91164.htm

http://www.caranddriver.com/idealbb/view.asp?topicID=60884

I'm guessing some variant of this is what you'll eventually cobble together
in your garage.


Montblack

[Morgans]

"Montblack" wrote

> Automotive world is using electronic stability-control (ESC) systems with
> documented success.

> I'm guessing some variant of this is what you'll eventually cobble
together
> in your garage.

More than likely, they are using piezzo electric rate sensors for the
direction information. They are relatively cheap, and do well at sensing
rapid changes. They have been used for a while in the RC airplane world, as
a stability aid, with good success, also. Any really stable electronic gyro
system in the commercial auto-pilots world, are much more expensive, and as
far as I know, not available to the public.

Problem is, piezzo sensors have a fairly fast "drift." which makes the
leveling ability good only for a few seconds. If you handed over control to
one of these units, within 30 seconds, you would be upside down, and the
unit would think everything is still OK.

In the RC world, if the plane makes a sudden move to go upside down, it
senses the sudden move and if the sticks have not commanded the sudden move,
it will move the control surfaces to stay right side up. It counts on you
keeping it somewhat upright, and recalibrates itself often - based on your
MarkII eyeballs telling the plane to fly level.

Same thing with the car unit in the links. It knows that you are going
straight, or following curves. (still reasonably slow changes compared to
sudden loss of control) It continually reminds itself that it is going
straight, and re-sets itself. Only when a real sudden move is made, does it
correctly sense that it is not going straight and the steering wheel wants
the car to go straight. The computer then makes corrections to keep the car
straight.

If a plane wing leveler were based only on these units, and the plane
started banking very slowly, the sensor would not realize it. That is the
drift. It would re-set as level, then the plane banks another slow degree,
and the unit re-sets, and the plane banks...you get the picture.

I believe the concoction that had some success, was a GPS wingtip
differential altitude sensor. It used these rate sensors in unison to help
backup the control movements and make the controls smooth. The units
re-set using the GPS info as the reality of what was level. You have to use
something (MarkII eyeballs or GPS) doing this.

Good luck to the OP, figuring out a homemade wing leveler. It is a tough
problem.
--
Jim in NC

[Dick]

Thanks for everyones input.

Our group was discussing flying in VFR only (no IMC or IFR) and wing leveler
only with respect to roll sensitivity of lightly wing loaded, short wing
spanned experimentals.

Trying to make summer flying in chop somewhat easier. We didn't plan on
turning over controls to the device and would still keep a light grip on the
stick; just wouldn't have to constantly play the stick.

Although we had the impression that a heavier plane would be more stable in
chop and require less than continual input by stick, that wasn't much of an
option <G>.

Although not discussed among us, I wonder if
an increased dihedral result is possible without actually increasing it
physically..

Still would appreciate a little discussion that I can pass on for the next
non-flying day.

Thanks, Dick


"Morgans" > wrote in message
...
>
> "Montblack" wrote
>
>> Automotive world is using electronic stability-control (ESC) systems with
>> documented success.
>
>> I'm guessing some variant of this is what you'll eventually cobble
> together
>> in your garage.
>
> More than likely, they are using piezzo electric rate sensors for the
> direction information. They are relatively cheap, and do well at sensing
> rapid changes. They have been used for a while in the RC airplane world,
> as
> a stability aid, with good success, also. Any really stable electronic
> gyro
> system in the commercial auto-pilots world, are much more expensive, and
> as
> far as I know, not available to the public.
>
> Problem is, piezzo sensors have a fairly fast "drift." which makes the
> leveling ability good only for a few seconds. If you handed over control
> to
> one of these units, within 30 seconds, you would be upside down, and the
> unit would think everything is still OK.
>
> In the RC world, if the plane makes a sudden move to go upside down, it
> senses the sudden move and if the sticks have not commanded the sudden
> move,
> it will move the control surfaces to stay right side up. It counts on you
> keeping it somewhat upright, and recalibrates itself often - based on your
> MarkII eyeballs telling the plane to fly level.
>
> Same thing with the car unit in the links. It knows that you are going
> straight, or following curves. (still reasonably slow changes compared to
> sudden loss of control) It continually reminds itself that it is going
> straight, and re-sets itself. Only when a real sudden move is made, does
> it
> correctly sense that it is not going straight and the steering wheel wants
> the car to go straight. The computer then makes corrections to keep the
> car
> straight.
>
> If a plane wing leveler were based only on these units, and the plane
> started banking very slowly, the sensor would not realize it. That is the
> drift. It would re-set as level, then the plane banks another slow
> degree,
> and the unit re-sets, and the plane banks...you get the picture.
>
> I believe the concoction that had some success, was a GPS wingtip
> differential altitude sensor. It used these rate sensors in unison to
> help
> backup the control movements and make the controls smooth. The units
> re-set using the GPS info as the reality of what was level. You have to
> use
> something (MarkII eyeballs or GPS) doing this.
>
> Good luck to the OP, figuring out a homemade wing leveler. It is a tough
> problem.
> --
> Jim in NC
>
>

[Jan Carlsson]

Dick,

I think that winglets would improve roll stability, and L/D, climb
performance and high alt. performance.

Jan Carlsson

www.jcpropellerdesign.com


"Dick" > skrev i meddelandet
m...
> Thanks for everyones input.
>
> Our group was discussing flying in VFR only (no IMC or IFR) and wing
leveler
> only with respect to roll sensitivity of lightly wing loaded, short wing
> spanned experimentals.
>
> Trying to make summer flying in chop somewhat easier. We didn't plan on
> turning over controls to the device and would still keep a light grip on
the
> stick; just wouldn't have to constantly play the stick.
>
> Although we had the impression that a heavier plane would be more stable
in
> chop and require less than continual input by stick, that wasn't much of
an
> option <G>.
>
> Although not discussed among us, I wonder if
> an increased dihedral result is possible without actually increasing it
> physically..
>
> Still would appreciate a little discussion that I can pass on for the next
> non-flying day.
>
> Thanks, Dick
>
>
> "Morgans" > wrote in message
> ...
> >
> > "Montblack" wrote
> >
> >> Automotive world is using electronic stability-control (ESC) systems
with
> >> documented success.
> >
> >> I'm guessing some variant of this is what you'll eventually cobble
> > together
> >> in your garage.
> >
> > More than likely, they are using piezzo electric rate sensors for the
> > direction information. They are relatively cheap, and do well at
sensing
> > rapid changes. They have been used for a while in the RC airplane
world,
> > as
> > a stability aid, with good success, also. Any really stable electronic
> > gyro
> > system in the commercial auto-pilots world, are much more expensive, and
> > as
> > far as I know, not available to the public.
> >
> > Problem is, piezzo sensors have a fairly fast "drift." which makes the
> > leveling ability good only for a few seconds. If you handed over
control
> > to
> > one of these units, within 30 seconds, you would be upside down, and the
> > unit would think everything is still OK.
> >
> > In the RC world, if the plane makes a sudden move to go upside down, it
> > senses the sudden move and if the sticks have not commanded the sudden
> > move,
> > it will move the control surfaces to stay right side up. It counts on
you
> > keeping it somewhat upright, and recalibrates itself often - based on
your
> > MarkII eyeballs telling the plane to fly level.
> >
> > Same thing with the car unit in the links. It knows that you are going
> > straight, or following curves. (still reasonably slow changes compared
to
> > sudden loss of control) It continually reminds itself that it is going
> > straight, and re-sets itself. Only when a real sudden move is made,
does
> > it
> > correctly sense that it is not going straight and the steering wheel
wants
> > the car to go straight. The computer then makes corrections to keep the
> > car
> > straight.
> >
> > If a plane wing leveler were based only on these units, and the plane
> > started banking very slowly, the sensor would not realize it. That is
the
> > drift. It would re-set as level, then the plane banks another slow
> > degree,
> > and the unit re-sets, and the plane banks...you get the picture.
> >
> > I believe the concoction that had some success, was a GPS wingtip
> > differential altitude sensor. It used these rate sensors in unison to
> > help
> > backup the control movements and make the controls smooth. The units
> > re-set using the GPS info as the reality of what was level. You have to
> > use
> > something (MarkII eyeballs or GPS) doing this.
> >
> > Good luck to the OP, figuring out a homemade wing leveler. It is a
tough
> > problem.
> > --
> > Jim in NC
> >
> >
>
>

[COLIN LAMB]

Very difficult to thermal with wing levelers.

Wing leveler suggestion:

Take neighbor kid along. Show him how to move stick to keep wings level.
Give him stick and tell him you will give him a quarter (whoops, $5 in
today's market) to keep wings level. Show him how to keed airspeed with
fore and aft movement of stick and tell him to wake you when ground is near.
Then take a nap.

Take Walkman along so you will not be bothered with the rushing of the wind
noise.

Good god, why would you want to put a wing leveler in the last bastion of
flight where the pilot is still a requirement?

Colin

[Peter Dohm]

In an effort not to go too far beyond my own knowledge, I'll avoid detail.

My best recollection, being about twenty years from being current as either
a pilot or a technician, is that "wing leveler" is a very missleading term
applied
to a single axis auto-pilot. Typically, the single axis would be yaw
(heading)
and would have been accomplished be slaving to either a rate gyro (such as
a turn coordinator or turn and slip) and a potentiometer, or a system of an
air jet and heated resistors, to provide a correction signal with
considerable
integration (a/k/a damping or low pass filtering). Although it would seem
intuitive to have the wing leveler steer the plane with the rudder and have
the dihedral roll the wings, the only systems that I have seen used the
ailerons and depended on the vertical stabilizer to keep the resulting yaw
within reason.

If you are still interested in learning more about how autopilots work, I
would
suggest trying to obtain some of the factory trianing manuals for the
technicians who will work on them. Try Bendix/King, S-Tech, and others.
Some books may also be available at college bookstores on booksellers
like Borders or Barnes & Noble.




"Dick" > wrote in message
om...
> Sitting around the hanger and discussing the possibility of somehow using
> off-the-shelf electronic/computer components or gadgits for semi-automatic
> wing leveling on lightly loaded, short wingspans.
>
> Not being computer guys, the current thought is that something should be
out
> there that is available cheaply and modifiable to use a simple wing
> leveler.
>
> Having heard someplace that automotive computers, as an example, sense
data
> millions of times leads us to believe that sensing the wing tip initial
> movement and counteracting very very quickly would be a good thing.
>
> As an example: One fellow pictured a rolling ball bearing inside a tube
> somehow activating a magnetic switch which in turn pulses a dc linear
motor
> to operate the aileron minutely.
>
> We are not sure how to detect the very earliest initial wing tip movement
or
> drive the small trim type motor and would appreciate some thoughts or
site
> recommendations to investigate.
>
> Thanks, Dick
>
>

[Morgans]

"Jan Carlsson" > wrote in message
...
> Dick,
>
> I think that winglets would improve roll stability, and L/D, climb
> performance and high alt. performance.
>
> Jan Carlsson

At the speeds we fly, winglets do little to nothing. They only become
useful at higher speeds.
--
Jim in NC

[Wayne Paul]

Jim,

I disagree. Winglet are most effective at high angles of attack. They
significantly improve roll rate and control at low speeds. Their use on
several models of sailplanes solved the problem of the wing dropping during
the initial takeoff roll. They also decrease the speed at which the wing
stalls.

Here is a good article that may, for some, be worth reading.
http://www.soaridaho.com/Schreder/Technical/Winglets/Masak.htm

Wayne
http://www.soaridaho.com/Schreder


"Morgans" > wrote in message
...
>
> At the speeds we fly, winglets do little to nothing. They only become
> useful at higher speeds.
> --
> Jim in NC
>
>

[Ed Sullivan]

On Fri, 25 Feb 2005 13:27:00 GMT, "Dick" > wrote:

>Thanks for everyones input.
>
>Our group was discussing flying in VFR only (no IMC or IFR) and wing leveler
>only with respect to roll sensitivity of lightly wing loaded, short wing
>spanned experimentals.
>
>Trying to make summer flying in chop somewhat easier. We didn't plan on
>turning over controls to the device and would still keep a light grip on the
>stick; just wouldn't have to constantly play the stick.
>
>Although we had the impression that a heavier plane would be more stable in
>chop and require less than continual input by stick, that wasn't much of an
>option <G>.
>
>Although not discussed among us, I wonder if
>an increased dihedral result is possible without actually increasing it
>physically..
>
>Still would appreciate a little discussion that I can pass on for the next
>non-flying day.
>
>Thanks, Dick

My Jungster II has zero dihedral, but 15° of sweepback. The wing
loading is about 13 lb per sq. ft. It is quite stable in moderate
turbulence. While it can be upset it returns to level flight with very
little input. That probably won't solve your problem, but it is
another factor.

Ed Sullivan

[Dan, U.S. Air Force, retired]

Morgans wrote:

> "Jan Carlsson" > wrote in message
> ...
>
>>Dick,
>>
>>I think that winglets would improve roll stability, and L/D, climb
>>performance and high alt. performance.
>>
>>Jan Carlsson
>
>
> At the speeds we fly, winglets do little to nothing. They only become
> useful at higher speeds.

But they will look pretty.

Dan, U.S. Air Force, retired

[Jan Carlsson]

When I said "I think" I was very humble...

Regarding winglets I am an "expert" (definition of an expert is someone that
have read what other have don :-)
Peter Masak did a great pioneer work on effective winglets. result was
winglets that didn't decrease performance at high speed as the large earlier
winglets.

Winglets make the wing act like it was of greater span, the improvement is
larger then if the wing was lengthened the amount of the winglets height.
And the increase in bending moment is smaller then the longer wing will
produce.

Winglets and longer wings reduce the induced drag (that come from the work
of producing lift) that work is harder at low indicated speed, =slow speed
at low altitude, low indicated speed at high altitude and getting there.

So even an "high speed" jetliner will be helped by using winglets, it spend
a long time at high weight climbing to economical cruising altitude, there
it cruise at low indicated speed (what pilot see) or more correct low
dynamic pressure.

Ok, no one here on RAH build jet liner, some fly them, and some build high
performance aeroplanes that have the capability to cruise at high altitude,
other aeroplanes can benefit from improvements of winglets too, if you fly
very long distances and want most economic, you would like to cruise near
(high side of) speed for best L/D ( at alt it will still go fast) here
winglets will help a lot.
other situations is to improve take off and climb and roll stability AND
roll rate, better aileron efficiency.

In this case Dick want more stability on a ? small big M ? plane, with
winglets he get a wing that "think" that the dihedral is grater then it is,
and improve the short wings low speed performance. don correct it would not
hurt cruise performance.

Jan in ME
www.jcpropellerdesign.com
Propeller and Performance software


"Morgans" > skrev i meddelandet
...
>
> "Jan Carlsson" > wrote in message
> ...
> > Dick,
> >
> > I think that winglets would improve roll stability, and L/D, climb
> > performance and high alt. performance.
> >
> > Jan Carlsson
>
> At the speeds we fly, winglets do little to nothing. They only become
> useful at higher speeds.
> --
> Jim in NC
>
>

[Morgans]

"Jan Carlsson" > wrote in message

> When I said "I think" I was very humble...

I also attempt to be humble. You can always find someone smarter, or
bigger, or stronger or ..... than yourself.

> Regarding winglets I am an "expert" (definition of an expert is someone
that
> have read what other have don :-)

Perhaps I have more reading to do.

> Peter Masak did a great pioneer work on effective winglets. result was
> winglets that didn't decrease performance at high speed as the large
earlier
> winglets.

> Winglets make the wing act like it was of greater span,

This I know.

the improvement is
> larger then if the wing was lengthened the amount of the winglets height.
> And the increase in bending moment is smaller then the longer wing will
> produce.

This I did not know.

> Winglets and longer wings reduce the induced drag (that come from the work
> of producing lift) that work is harder at low indicated speed, =slow speed
> at low altitude, low indicated speed at high altitude and getting there.
>
> So even an "high speed" jetliner will be helped by using winglets, it
spend
> a long time at high weight climbing to economical cruising altitude, there
> it cruise at low indicated speed (what pilot see) or more correct low
> dynamic pressure.

Do you have any suggestions that I could do some more reading? I hate it
when I am wrong! :-)
--
Jim in NC

[Jan Carlsson]

My humour doesn't always come to its right in English not even Swedish. Some
people recognise it as humor. :-)

There was an article by Peter Masak on the net some years ago, I have saved
it on the puter at my office.

As an Captain you can always ref. to §1= Captain is always right. or
§2=if Captain is wrong, §1 is what rules. (not a good one in a plane)

Jan
www.jcpropellerdesign.com


"Morgans" > skrev i meddelandet
...
>
> "Jan Carlsson" > wrote in message
>
> > When I said "I think" I was very humble...
>
> I also attempt to be humble. You can always find someone smarter, or
> bigger, or stronger or ..... than yourself.
>
> > Regarding winglets I am an "expert" (definition of an expert is someone
> that
> > have read what other have don :-)
>
> Perhaps I have more reading to do.
>
> > Peter Masak did a great pioneer work on effective winglets. result was
> > winglets that didn't decrease performance at high speed as the large
> earlier
> > winglets.
>
> > Winglets make the wing act like it was of greater span,
>
> This I know.
>
> the improvement is
> > larger then if the wing was lengthened the amount of the winglets
height.
> > And the increase in bending moment is smaller then the longer wing will
> > produce.
>
> This I did not know.
>
> > Winglets and longer wings reduce the induced drag (that come from the
work
> > of producing lift) that work is harder at low indicated speed, =slow
speed
> > at low altitude, low indicated speed at high altitude and getting there.
> >
> > So even an "high speed" jetliner will be helped by using winglets, it
> spend
> > a long time at high weight climbing to economical cruising altitude,
there
> > it cruise at low indicated speed (what pilot see) or more correct low
> > dynamic pressure.
>
> Do you have any suggestions that I could do some more reading? I hate it
> when I am wrong! :-)
> --
> Jim in NC
>
>

[Wayne Paul]

Jim,

In addition the to article I mentioned earlier,
http://www.soaridaho.com/Schreder/Technical/Winglets/Masak.htm, take a look
at the series posted on
http://www.soaridaho.com/Schreder/Technical/Winglets/PSU_Ref.htm

Wayne
http://www.soaridaho.com/Schreder


"Morgans" > wrote in message
...
>

> Do you have any suggestions that I could do some more reading? I hate it
> when I am wrong! :-)
> --
> Jim in NC
>
>

[UltraJohn]

Morgans wrote:

>
> Do you have any suggestions that I could do some more reading? I hate it
> when I am wrong! :-)

I thought I was wrong once, But I was mistaken!.
John

[[email protected]]

>From the model airplane world here is a product that controls both
pitch and roll.

http://www.futaba-rc.com/radioaccys/futm0999.html

It operates by optically referencing the horizon. So your day VFR
application would be a coincident limitation.

I don't know how current autopilots mechanically couple to the flight
controls but there are very large hobby servos that could probaby be
powerful enough to nudge the controls back and forth in response the
the control unit.

You could either just use their sensor and build your own controller or
attempt to use their controller.

BTW- The vibrating piezo gyros used for RC helecopters have some slow
drift so you can't use them directly but they do have a lot of promise
still for a stabization system. In the hobby application they act more
as dampers than absolute references as the horizon would be for the
earlier mentioned method. So the hobby gyro could counteract bumps but
the steady state error would have to be maintaned by the pilot.

Regards

Dick wrote:
> Sitting around the hanger and discussing the possibility of somehow
using
> off-the-shelf electronic/computer components or gadgits for
semi-automatic
> wing leveling on lightly loaded, short wingspans.
>
> Not being computer guys, the current thought is that something should
be out
> there that is available cheaply and modifiable to use a simple wing
> leveler.
>
> Having heard someplace that automotive computers, as an example,
sense data
> millions of times leads us to believe that sensing the wing tip
initial
> movement and counteracting very very quickly would be a good thing.
>
> As an example: One fellow pictured a rolling ball bearing inside a
tube
> somehow activating a magnetic switch which in turn pulses a dc linear
motor
> to operate the aileron minutely.
>
> We are not sure how to detect the very earliest initial wing tip
movement or
> drive the small trim type motor and would appreciate some thoughts
or site
> recommendations to investigate.
>
> Thanks, Dick

[Pete Schaefer]

Ah. You might consider pursuing developing a "rate damper". This would be
much simpler than trying to control attitude, as it would only require
sensing of rate. This would not act as a wing leveler (well, not exactly,
but it might provide some attitude stabilization without correcting for
drift), but it would respond to bumps. You'd still fly attitude, but the
damper would handle the transients due to turbulence, etc.

Being a flight controls engineer, I won't advise you further on this project
(not willing to assume any liability on a project I don't control), but I
will provide the following advice:
(1) Incorporating such capabilities on an aircraft is LOADED with very
serious potential hazards, all of which can be mitigated by a very careful
and conservative system buildup. These include:
- PIO susceptibility
- runaway servos that can make it difficult/impossible for the pilot to
fly the airplane
- high transient electrical loads
- high mechanical loads on your airplane
(2) Set things up so that you can always turn it off quickly and revert to a
normal airplane (i.e. no mechanical load on flight controls from an
unpowered servo. Set it up so you can always mechanically trim out what you
get from a stuck, hard-over servo.
(3) Instrument the system thoroughly during development and test so that you
know how hard you're working your airplane.

Check with some R/C modelers to get the idea on how to set something like
this up.

"Dick" > wrote in message
m...
> Trying to make summer flying in chop somewhat easier. We didn't plan on
> turning over controls to the device and would still keep a light grip on
the
> stick; just wouldn't have to constantly play the stick.

[Dan, U.S. Air Force, retired]

wrote:

>>From the model airplane world here is a product that controls both
> pitch and roll.
>
> http://www.futaba-rc.com/radioaccys/futm0999.html
>
> It operates by optically referencing the horizon. So your day VFR
> application would be a coincident limitation.
>
> I don't know how current autopilots mechanically couple to the flight
> controls but there are very large hobby servos that could probaby be
> powerful enough to nudge the controls back and forth in response the
> the control unit.

The servos you describe would be strong enough in a small aircraft since
autopilots I have worked on don't move the primary control surfaces
directly. They move trim tabs.
>
> You could either just use their sensor and build your own controller or
> attempt to use their controller.
>
> BTW- The vibrating piezo gyros used for RC helecopters have some slow
> drift so you can't use them directly but they do have a lot of promise
> still for a stabization system. In the hobby application they act more
> as dampers than absolute references as the horizon would be for the
> earlier mentioned method. So the hobby gyro could counteract bumps but
> the steady state error would have to be maintaned by the pilot.

There are pizeo gyros out there that are less drifty. If you have the
money go look at Crossbow. Their systems are interesting. Among other
things they make AHRS and INS modules.

Dan, U.S. Air Force, retired

[Roger]

On Fri, 25 Feb 2005 12:10:45 -0500, "Peter Dohm"
> wrote:

>In an effort not to go too far beyond my own knowledge, I'll avoid detail.
>
>My best recollection, being about twenty years from being current as either
>a pilot or a technician, is that "wing leveler" is a very missleading term
>applied
>to a single axis auto-pilot. Typically, the single axis would be yaw
>(heading)

Try a Cherokee. They turn just fine using the ailerons with very
little adverse yawh.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
>and would have been accomplished be slaving to either a rate gyro (such as
>a turn coordinator or turn and slip) and a potentiometer, or a system of an
>air jet and heated resistors, to provide a correction signal with
>considerable
>integration (a/k/a damping or low pass filtering). Although it would seem
>intuitive to have the wing leveler steer the plane with the rudder and have
>the dihedral roll the wings, the only systems that I have seen used the
>ailerons and depended on the vertical stabilizer to keep the resulting yaw
>within reason.
>
>If you are still interested in learning more about how autopilots work, I
>would
>suggest trying to obtain some of the factory trianing manuals for the
>technicians who will work on them. Try Bendix/King, S-Tech, and others.
>Some books may also be available at college bookstores on booksellers
>like Borders or Barnes & Noble.
>
>
>
>
>"Dick" > wrote in message
om...
>> Sitting around the hanger and discussing the possibility of somehow using
>> off-the-shelf electronic/computer components or gadgits for semi-automatic
>> wing leveling on lightly loaded, short wingspans.
>>
>> Not being computer guys, the current thought is that something should be
>out
>> there that is available cheaply and modifiable to use a simple wing
>> leveler.
>>
>> Having heard someplace that automotive computers, as an example, sense
>data
>> millions of times leads us to believe that sensing the wing tip initial
>> movement and counteracting very very quickly would be a good thing.
>>
>> As an example: One fellow pictured a rolling ball bearing inside a tube
>> somehow activating a magnetic switch which in turn pulses a dc linear
>motor
>> to operate the aileron minutely.
>>
>> We are not sure how to detect the very earliest initial wing tip movement
>or
>> drive the small trim type motor and would appreciate some thoughts or
>site
>> recommendations to investigate.
>>
>> Thanks, Dick
>>
>>
>

[[email protected]]

Trim tabs you say- Well that makes a lot of sense then. Some nice big
servos embedded in the wing and horizontal stab could do double duty as
conventional trim and with addition of controller, an automatic
stabilazation system.

[Dan, U.S. Air Force, retired]

wrote:
> Trim tabs you say- Well that makes a lot of sense then. Some nice big
> servos embedded in the wing and horizontal stab could do double duty as
> conventional trim and with addition of controller, an automatic
> stabilazation system.
>

As has been already pointed out the devil is in the details. The theory
is simple when thinking of damping. Think of a child swinging on a
swing. You want to stop him. At what point do you apply influence? Not
at the bottom where the swing there is the most kinetic energy you have
to fight. You want to apply force at the end of each swing.

Simple, ain't it? If it really were that simple you could use a rate
sensing gyro hooked more or less directly to your servo. The gyro would
have to be mounted near the center of motion in your aircraft. I worked
on autopilit systems on several types of aircraft and none was simple.

One thing that you need to figure out is how to install your servo in
such a way as you can still manually trim without damaging it. Another
thing that would be handy is a quick disconnect button on your yoke or
stick. You'd be surprised how fast a malfunctioning power steering
system can get out of hand if it wants to.

Dan, U.S. Air Force, retired

Dan, U.S. Air Force, retired

[[email protected]]

Thats what is done on RC Heli's, the rate gyro directly sums into the
normal command. The only control you have is the gain on the gyro and
I'd guess you'd have to adjust this to particular aircraft and
preference of the pilot.

I assume the gyro(s) would be pretty near the center of motion along
with the pilot, but why is this a requirement? Doesn't any ridged part
of the aircraft experience the same yaw,pitch,roll accelerations? One
possible implimentation could be a gryo co-located with the actuator
(servo) that controls that axis.

I think this would replace manual trim because if you could do the
stability control, you sure as heck could make it move back and forth
in response to a 3 position toggle switch.

If it breaks you fly without trim till you land. I think there is some
rule that the aircraft must be controllable with any trim to it's full
limit.

[Dan, U.S. Air Force, retired]

wrote:

> Thats what is done on RC Heli's, the rate gyro directly sums into the
> normal command. The only control you have is the gain on the gyro and
> I'd guess you'd have to adjust this to particular aircraft and
> preference of the pilot.
>
> I assume the gyro(s) would be pretty near the center of motion along
> with the pilot, but why is this a requirement? Doesn't any ridged part
> of the aircraft experience the same yaw,pitch,roll accelerations? One
> possible implimentation could be a gryo co-located with the actuator
> (servo) that controls that axis.

Take a 12" ruler rotate it around 4" mark. Imagine you have rate gyros
at the 4" and 11" marks. The one at the 4" mark senses only rotational
rate, the one at the 11" mark senses rotational rate plus a G force. If
you read the specs on pizeo rate gyros they are G limited. You can buy
them with G limits in excess of 50G but they can be pricy. Exceding the
G limit on a pizeo gyro won't neccesarily kill it, but you will get an
error which defeats the purpose.

None of the aircaft I worked on had pizeo gyros, but the theory still
holds. The power steering rate gyros on the F-4E are mounted in the
wings near the roots. It's not my idea of fun to change them either.

Sometimes design considerations preclude mounting near the axis, but if
you can do it it will reduce induced errors.
>
> I think this would replace manual trim because if you could do the
> stability control, you sure as heck could make it move back and forth
> in response to a 3 position toggle switch.

To be really cool install a coolie hat switch.
>
> If it breaks you fly without trim till you land. I think there is some
> rule that the aircraft must be controllable with any trim to it's full
> limit.

I used to fly R/C way back in the dark ages. Unless servos have
radically changed you shouldn't have problems unless they don't provide
enough force to the tabs near the limits of the servo's travel.

Dan, U.S. Air Force, retired

[Roger]

On Fri, 25 Feb 2005 00:12:06 GMT, "Dick" > wrote:

>Sitting around the hanger and discussing the possibility of somehow using
>off-the-shelf electronic/computer components or gadgits for semi-automatic
>wing leveling on lightly loaded, short wingspans.

To paraphrase the manual for my auto-pilot. When encountering more
than moderate turbulence, turn off the autopilot. I believe Pete
touched on this as well.

The same is true for altitude excursions.

Mine can do a much better job of holding altitude and attitude than I
when the going gets really rough.

That's when I turn it off and manually hold the attitude (more or
less).

Yes it can be done and I'd think the simplest would be to get a solid
state gyro, or turn coordinator... and build around that.

>
>Not being computer guys, the current thought is that something should be out
>there that is available cheaply and modifiable to use a simple wing
>leveler.

All it takes is money. The less ingenuity, the more money.

>
>Having heard someplace that automotive computers, as an example, sense data
>millions of times leads us to believe that sensing the wing tip initial
>movement and counteracting very very quickly would be a good thing.

Counteracting very quickly with a lightly loaded wing could possibly
break something very quickly as well.

>
>As an example: One fellow pictured a rolling ball bearing inside a tube
>somehow activating a magnetic switch which in turn pulses a dc linear motor
>to operate the aileron minutely.

Rule number one...no... sorry that one is already taken. An airplane
and any thing in it does not know up from down in anything except
straight and level flying. However a gyro tends to stay in the same
position you put it when starting out, so it makes a good reference
platform. (as long as you don't do anything drastic to confuse it such
as causing it to tumble)
I haven't seen any prices on the components for a solid state gyro.

>
>We are not sure how to detect the very earliest initial wing tip movement or
>drive the small trim type motor and would appreciate some thoughts or site
>recommendations to investigate.

Find an old DG, or TC and experiment from there.
Build in sufficient disconnects so if it goes TU you can put the
greasy side on the bottom again.

You can over-ride a wing leveler or AP, but it always gives me a
strange feeling to be telling the airplane to do one thing when it's
fighting me to do something else and its attempt is readily apparent.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com
>
>Thanks, Dick
>

[Pete Schaefer]

"Roger" > wrote in message
...
> To paraphrase the manual for my auto-pilot. When encountering more
> than moderate turbulence, turn off the autopilot. I believe Pete
> touched on this as well.

Driving an auto-pilot too hard can put your servos on the rate limit. On a
rate limit, a servo develops serious amplitude-dependent lag, which can
destabilize your loop closures. THe way arount this problem? Big, huge,
powerful, fast servos. This solution opens up a whole other can of worms.

> All it takes is money. The less ingenuity, the more money.

Being intimate with the hazards associated with such a project, I would
never recommend this as a casual development project. In this case, less
ingenuity means great exposure to serious hazards. It all seems so simple in
concept, but the devil.......

> Counteracting very quickly with a lightly loaded wing could possibly
> break something very quickly as well.

And that's just one of the hazards.

> I haven't seen any prices on the components for a solid state gyro.

The ones the R/C guys use, which are, in my opinion, quite rugged and
accurate enough for this kind of an application, pretty innexpensive. I
think I saw one model that sold for under $200. Systron-Donner makes
single-axis chips for (working from memory) under $500. Full 6-dof Motion
Packs go for around $20k. I think Crossbow has a 6-dof package for under
$12k.

> Build in sufficient disconnects so if it goes TU you can put the
> greasy side on the bottom again.

Yup. On the stick. Fly it with a gun to it's head.

[Dan, U.S. Air Force, retired]

Pete Schaefer wrote:

<snip>
>I think Crossbow has a 6-dof package for under
> $12k.

Crossbows prices have dropped over the past 2 years. The AHRS they had
at $10K is now under $8K per UI of 1.

Now if the made and interface to drive synchro instruments....

Dan, U.S. Air Force, retired

[Dan, U.S. Air Force, retired]

Pete Schaefer wrote:

> "Dan, U.S. Air Force, retired" > wrote in message
> news:IfyVd.20906$Sn6.20727@lakeread03...
>
>>Crossbows prices have dropped over the past 2 years. The AHRS they had
>>at $10K is now under $8K per UI of 1.
>
>
> Probably still a bit too pricey for a home-brew rate damper, autopilot,
> etc., to be built by a novice.
>
>
>>Now if the made and interface to drive synchro instruments....
>
>
> All that effort to package up accurate solid-state measurement devices and
> you want to drive synchro instruments?

I am a tad old fashioned. Besides, I have yet to see a glass display I
like.

>
> Isn't there some PDA software that uses a Crossbow AHRS to drive a set of
> displays?

I think there is such software at Crossbow's site. I can imagine a PDA
as a back up device or temprary upgrade. That is if you want to spend
$8K for something temprary. The PDA can be mounted ona a panel or yoke
clip. Where do you put the AHRS? Strap in to a seat and you have lost a
passenger. I don't know if it would be worth it.

Dan, U.S. Air Force, retired

[Pete Schaefer]

"Dan, U.S. Air Force, retired" > wrote in message
news:MUAVd.21080$Sn6.16679@lakeread03...
> I am a tad old fashioned. Besides, I have yet to see a glass display I
> like.

I'm kinda liking the looks of the Blue Mountain EFIS Sport these days. I
think it can even support a slave display. Would be nice to spread out the
data and declutter the individual displays. A lot of the EFIS type products
out there just look too damned busy for my tastes. Gonna order the Blue
Mountain for a work project pretty soon. I'm using my current project at
work to evaluate stuff I'd eventually like to stick in an RV-8.

> I think there is such software at Crossbow's site. I can imagine a PDA
> as a back up device or temprary upgrade.

I haven't seen a PDA that I'd want in the cockpit, myself.

> clip. Where do you put the AHRS?

They're not very big. You would probably build a small shelf and mount it
behind the firewall. You typically have to mount devices like that at a
structural node - right under the pilot's ass is often a good spot.
Otherwise, structural vibration will clutter up your data.

> passenger. I don't know if it would be worth it.

I don't think I'd ever bother to mess around with such an expensive device,
especially when there are complete instrument packages for less.

[[email protected]]

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

[Dan, U.S. Air Force, retired]

Pete Schaefer wrote:

> "Dan, U.S. Air Force, retired" > wrote in message
> news:MUAVd.21080$Sn6.16679@lakeread03...
>
>>I am a tad old fashioned. Besides, I have yet to see a glass display I
>>like.
>
>
> I'm kinda liking the looks of the Blue Mountain EFIS Sport these days. I
> think it can even support a slave display. Would be nice to spread out the
> data and declutter the individual displays. A lot of the EFIS type products
> out there just look too damned busy for my tastes. Gonna order the Blue
> Mountain for a work project pretty soon. I'm using my current project at
> work to evaluate stuff I'd eventually like to stick in an RV-8.

When you get a chance to play with it I'd like to hear your impressions.
>
>
>>I think there is such software at Crossbow's site. I can imagine a PDA
>>as a back up device or temprary upgrade.
>
>
> I haven't seen a PDA that I'd want in the cockpit, myself.

I have never used a PDA for anything. Then again I don't have a cellular
phone, FAX, etc. Retired life is SO rough:)
>
>
>>clip. Where do you put the AHRS?
>
>
> They're not very big. You would probably build a small shelf and mount it
> behind the firewall. You typically have to mount devices like that at a
> structural node - right under the pilot's ass is often a good spot.
> Otherwise, structural vibration will clutter up your data.

I was thinking along the lines of a temporary installation which I
assumed was the whole idea of a PDA system.
>
>
>>passenger. I don't know if it would be worth it.
>
>
> I don't think I'd ever bother to mess around with such an expensive device,
> especially when there are complete instrument packages for less.
>
>
Agreed.

Dan, U.S. Air Force, retired

[Dan, U.S. Air Force, retired]

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

[Roger]

On Wed, 2 Mar 2005 08:30:27 -0800, "Pete Schaefer"
> wrote:

>
>"Roger" > wrote in message
...
>> To paraphrase the manual for my auto-pilot. When encountering more
>> than moderate turbulence, turn off the autopilot. I believe Pete
>> touched on this as well.
>
>Driving an auto-pilot too hard can put your servos on the rate limit. On a
>rate limit, a servo develops serious amplitude-dependent lag, which can
>destabilize your loop closures. THe way arount this problem? Big, huge,
>powerful, fast servos. This solution opens up a whole other can of worms.

Ahhh... That's not what I was getting at.
They have you disconnect to protect your airplane as the servos can do
too good a job of holding altitude. It wasn't lag they were worried
about.

Just as the question asks on the FAA exam. What do you do when
entering an area of moderate to severe turbulence?
The AP doesn't know the correct answer for that one and it's going to
hold altitude, and/or attitude even if it has to break something to do
it. (depends on the AP)

There really is such a thing as "too much of a good thing".

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

[Ernest Christley]

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.

[Pete Schaefer]

"Dan, U.S. Air Force, retired" > wrote in message
news:g%KVd.21109$Sn6.5222@lakeread03...
> > I'm kinda liking the looks of the Blue Mountain EFIS Sport these days. I
> When you get a chance to play with it I'd like to hear your impressions.

Will do. Not sure when we'll actually get it delivered (prolly in April).
Sure looks good on paper, though. I looked at their smaller unit (the Lite).
Pretty small display, but bright. Too much info crammed in too small a space
for my tastes. Might be able to declutter it a bunch, though. THe EFIS One
is just too damned big. It eats most of an instrument panel. I don't like
the idea of using one piece of equipment for so many functions when it's so
big that I have no room for backups. The Sport seems just about right.

> I have never used a PDA for anything. Then again I don't have a cellular
> phone, FAX, etc. Retired life is SO rough:)

I don't have any of the above, either. Clutters up life and desk space too
much. The only portable electronic device I own (besides a watch), is my
hand-held GPS.

> > They're not very big. You would probably build a small shelf and mount
it
> I was thinking along the lines of a temporary installation which I
> assumed was the whole idea of a PDA system.

Oh. I was thinking of where to mount the sensor unit (Crossbow or other
6-dof sensor package), not the display. Need to level them (or do a bunch of
calculations for correcting for off-level installation).

[Pete Schaefer]

"Dan, U.S. Air Force, retired" > wrote in message
news:rhLVd.21112$Sn6.10965@lakeread03...
> The hard part is the electronics package between the two.

It wouldn't be that bad, really. At least not for just a rate damper. The
R/C gyros put out pulse-width modulation signals, which are pretty easy to
work with. Also, there are a lot of decent servos out there that can read
it.

I think the hard part of the rate damper project is making sure you don't
overtorque something important in your airplane, and setting things up so
that, when the damper servo goes haywire, that you can turn it off and
revert to a normal airplane quickly and without hurting anything/anybody,
and that while you're busy figuring out that something is going wrong, that
you can overpower anything it's doing that you don't like.

More than a few people and quite a few airplanes have gotten killed in the
process of engineers trying to figure out how to do all this automatic
stabilization and fly-by-wire stuff. It's not something approached casually,
unless it's for a toy that's OK to crash (R/C model). In my somewhat short
career as a flight controls engineer (12 years), I've seen 3 airplanes lost
and more than a couple of close calls due to control design issues. Even
when everything works as designed, there are man-machine interaction
problems that can kill you. Even apparently innocuous things. Think back to
that Airbus that busted up a couple of years ago in New York. I think
there's an article in Flying this month about it. Nothing there that jumps
out at you as an obvious hazard, but it got a couple hundred people real
dead.

I'd really hate to see someone on this newsgroup go out and get himself
killed trying to invent something without full cognizance of the hazards.

Pete

[Pete Schaefer]

"Roger" > wrote in message
...
> Ahhh... That's not what I was getting at.
> They have you disconnect to protect your airplane as the servos can do
> too good a job of holding altitude. It wasn't lag they were worried
> about.

Yeah, there are a couple of issues there. The autopilot might command
surface deflections beyond what is safe for the control surface. Could rip a
surface off. And, as I already said, the autopilot could get into an
oscillation if it rides a rate limit.

> Just as the question asks on the FAA exam. What do you do when
> entering an area of moderate to severe turbulence?

Yup.

> There really is such a thing as "too much of a good thing".

Roger that...uh..Roger.

[Pete Schaefer]

"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

[Dan, U.S. Air Force, retired]

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

[[email protected]]

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

[Blueskies]

> 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.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F006%5F011%5F000%5F000&product%5Fid=276%2D625

[Jughugs]

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.asp?catalog%5Fname=CTLG&category%5Fname=CTLG%5F006%5F011%5F000%5F000&product%5Fid=276%2D625
>
>

[Predictor]

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

[Robert Bonomi]

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.

..

[Matt Whiting]

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]

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.

[Predictor]

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/apgdst/aifac/aicontent/fuzzy/fuzzy...
http://www.fpk.tu-berlin.de/~anderl/epsilon/fuzzyintro4.pdf
http://www.phys.ufl.edu/docs/matlab/pdf_doc/fuzzy/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]

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/apgdst/aifac/aicontent/fuzzy/fuzzy.pdf
http://www.fpk.tu-berlin.de/~anderl/epsilon/fuzzyintro4.pdf
http://www.phys.ufl.edu/docs/matlab/pdf_doc/fuzzy/fuzzy_tb.pdf
http://www.faqs.org/faqs/fuzzy-logic/part1/
http://www.fuzzy-logic.com/ch3.htm


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

[Tim Ward]

"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/apgdst/aifac/aicontent/fuzzy/fuzzy.pdf
> http://www.fpk.tu-berlin.de/~anderl/epsilon/fuzzyintro4.pdf
> http://www.phys.ufl.edu/docs/matlab/pdf_doc/fuzzy/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



>

[Ron Webb]

"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%2C2877%2CADXL203%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..

[Predictor]

Tim Ward suggested:
"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."


In this thread, the only strong claims made about fuzzy logic have been
that it is "risky" (which has gone unexplained) and that it is
non-deterministic, which is simply false.

Fuzzy logic has an extensive, published record of successful
applications on which to stand, both in control and elsewhere. I am
familiar with Bob Pease's criticism of certain published fuzzy control
applications, and he makes some good points. No one here, as I read
it, has made miraculous claims, nevertheless fuzzy logic has been used
to good effect to solve real-world problems.

You have apparently encountered some uncritical, starry-eyed fans of
fuzzy logic, for which you have my sympathy. Nonetheless, a technology
should be judged on its technical merits, not its adherents.


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

[Dan, U.S. Air Force, retired]

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%2C2877%2CADXL203%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

[Big John]

Dick

Check developments in Israel. They have a lot of UAV's that have
systems in them that might fit your requirement right off the shelf?

Big John
`````````````````````````````````````````````````` ``````


On Fri, 25 Feb 2005 00:12:06 GMT, "Dick" > wrote:

>Sitting around the hanger and discussing the possibility of somehow using
>off-the-shelf electronic/computer components or gadgits for semi-automatic
>wing leveling on lightly loaded, short wingspans.
>
>Not being computer guys, the current thought is that something should be out
>there that is available cheaply and modifiable to use a simple wing
>leveler.
>
>Having heard someplace that automotive computers, as an example, sense data
>millions of times leads us to believe that sensing the wing tip initial
>movement and counteracting very very quickly would be a good thing.
>
>As an example: One fellow pictured a rolling ball bearing inside a tube
>somehow activating a magnetic switch which in turn pulses a dc linear motor
>to operate the aileron minutely.
>
>We are not sure how to detect the very earliest initial wing tip movement or
>drive the small trim type motor and would appreciate some thoughts or site
>recommendations to investigate.
>
>Thanks, Dick
>

[Ron Webb]

"Dan, U.S. Air Force, retired" > wrote in message
news:wtJWd.24485> >

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

Dan

I agree 100% that any amateur designed auto pilot would be a risky
proposition. That's one reason I'm still in the parts accumulation stage 2
years after I started thinking about it. The part I'm having the most
trouble finding is a couple of big brass BALLS ;^}

Control systems engineering is perhaps THE most feared course in any
undergrad EE program, and for good reason. It's not an easy subject.

Having said that, I think it can be done. My own precautions will include:


1) The servos are coupled to the controls with springs - easily overpowered
by the manual controls which are left in place. And of course a big red
"DISENGAGE" button on the stick.

2) Thorough testing using X-Plane simulator. I'll use a custom designed
interface between the autopilot and the simulator.. That's one reason I'd
want more than one person on the project - the simulator test "pilot" should
be independant of the designer.

3) All control equasions will be radically over-damped. No "Auto-Pilot
Induced Oscillations".

4) The pitch control will only be controlling the trim tab.

[Blueskies]

>

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

[George A. Graham]

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>

[Dan, U.S. Air Force, retired]

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

[UltraJohn]

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.
Myaccommodatejection 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


I don't know Dan you must be flying a pretty tight plane. The unit
referenced is only 3.25" square by 2.75" deep for the panel mount part, the
servo which isn't panel mounted is a bit bigger. Most homebuilts can
accommodate that. Now all I need to do is get to work on this KR-2 in the
garage!
John

[Dan, U.S. Air Force, retired]

UltraJohn 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.
>
> Myaccommodatejection 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
>
>
>
> I don't know Dan you must be flying a pretty tight plane. The unit
> referenced is only 3.25" square by 2.75" deep for the panel mount part, the
> servo which isn't panel mounted is a bit bigger. Most homebuilts can
> accommodate that. Now all I need to do is get to work on this KR-2 in the
> garage!
> John
>

I'm building an airplane I personally will never fly (can't pass the
physical). The only thing I could do to install the system in question
is remove the TAS indicator.

Dan, U.S. Aie Force, retired

[Frank van der Hulst]

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

[Ron Webb]

> 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

[AINut]

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
>
>

[Ernest Christley]

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*)

[Ernest Christley]

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.

[Pete Schaefer]

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"?

[Pete Schaefer]

"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.

[Ron Webb]

"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 here:
http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=327629&Row=213180&Site=US

The data sheet is here:
http://www.analog.com/en/prod/0%2C2877%2CADXL202%2C00.html


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


Ron Webb

[Dave Hyde]

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

[Dan, U.S. Air Force, retired]

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

[Pete Schaefer]

"Dave Hyde" > wrote in message
...
> I wonder if we've crossed professional paths sometime over the years.
> Dryden?

Yup. I was at Dryden from 1993 to 1997 (internship, then as a Research
Associate on a grant with USC, then as a contractor after waking up one day
and realizing that I didn't really want a PhD after all), then went to work
at Lockheed in Palmdale, where I've been ever since. At Dryden, I was in
that Integrated Controls group over in code R.

> PSFCC ring a bell?

It tickles my memory. Is that the processor upgrade that was put in one of
the Dryden F-18's? I never worked much with that gang, but I know a lot of
those guys.

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

I feel like I'm trying to get a kid to put his dad's gun down. The guys on
this group know enough to get themselves is a whole lot of trouble.

[Dave Hyde]

Pete Schaefer wrote...

> I was at Dryden from 1993 to 1997...

I was there a few times over the years, mostly
in that time range.

> Is that the processor upgrade that was put in one of
> the Dryden F-18's?

Well, 'upgrade' is debatable, but we're talking about the
same program. <g>

> I never worked much with that gang, but I know a lot of
> those guys.

OK, there was another 'Pete' on that program, but I've
since remembered his last name, and it wasn't you. :-)

> I feel like I'm trying to get a kid to put his dad's gun down.

At least no one's said they've already tested it in 'X-Plane',
so it *has* to work :-)

Dave 'phase margin' Hyde

[GeorgeB]

On Mon, 7 Mar 2005 18:41:35 -0800, "Pete Schaefer"
> wrote:

>> 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.

I am not sure what he has in mind, but I've found that using preloaded
(tight wound) springs, when the "inputs" are applied via them,
introduce only the additional mass. If they are not preloaded ... the
mathematics gets beyond me.

Example ... take an old style screen door spring (sounds redundant,
doesn't it <g>), cut it to a lenght of an inch (for example only), use
an anvil to pop out a turn, pull on it ... some reasonable force is
applied before the spring begins stretching (macro level coils
separating ...not counting the tiny bits of stretch in the ends)

I used a similar method with shear load cells to protect them; the
first 10 pounds was applied to the cell with "no" deflection. The
next 2 compressed a spring and applied load to the cell. After that,
I had metal-metal preventing further load on the cell. Keeps the 15
pound cell from being destroyed when a man stepped in the weigh
hopper.

[Morgans]

"Pete Schaefer" wrote

Lots of primary research was going on.
> These days, I talk to people out there, and it sounds like they've got
> NOTHING going on of any significance anymore. Sad.

That's cause there is nothing significant to discover, anymore! ;-o
--
Jim (grinning and ducking and running) in NC

[Pete Schaefer]

It's wierd. When I was out there, it was still a really happenin' kind of
place. Lots of stuff was flying. Lots of primary research was going on.
These days, I talk to people out there, and it sounds like they've got
NOTHING going on of any significance anymore. Sad.

"Dave Hyde" > wrote in message
...
> I was there a few times over the years, mostly
> in that time range.

[Frank van der Hulst]

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?

Nope... I finished on my MTech thesis the year before last, designing a
system to automatically measure ocean waves. I used the ADXL202
accelerometers you've mentioned here, plus 3 magnetometers to measure
attitude, plus some digital filtering and stuff. Ocean waves, being in
constant variable motion, is probably a tougher environment than an
aircraft. And, as someone else suggested, I guess that an aircraft
system could be designed as a pilot aid rather than pilot replacement.

Your GPS can't tell you whether you're straight and level, only whether
you're straight. Whilst we're talking GPS, some interesting work was
done using GPS to measure attitude using 3 antennas about a foot apart.
This sounded like it had real promise.

Maybe we have bumpier bumps here, or maybe you fly something with a high
wing loading, or whatever, but in the circumstances where an active wing
leveler would be useful, I think it would need to react accurately and
correctly within (say) 0.1 seconds to be useful. And would need to not
need to be reset more than (say) once in 20 minutes. I just can't see
that with a 1-second GPS update of position and track (not airspeed or
heading). If there's no bumps, then manual aileron trim will do the
trick just as well.

Frank

[Ron Webb]

> Your GPS can't tell you whether you're straight and level, only whether
> you're straight.

Agreed.

But if the GPS says I'm straight (over a 10 second average) and the
accelerometer says the roll axis vector is pointed toward the floor of the
aircraft, then it seems to me I'm straight (otherwise the heading would be
changing) and level - since if there is no heading change the only vector
remaining is G.

[Evan Carew]

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Hash: SHA1

Ron,

Try adding in some cross controll input & acelerometer error Bzzzzt. The
deal is that over time, any acelerometer, even 3 axix will accumulate
error, and ignoring your idea of non-realtime GPS directional input for
the moment, what you need is a leaky integrator. To accomplish this, you
need to be able to sense the horizon in an accelerated frame of
reference. You can accomplish this in a number of ways. The two that
come readily to mind are magnetometers & solid state or otherwise steam
gage type gyros. Sadly, this last requirement for instrumentation is
often where the expense for your system will come in to play.

Evan Carew

Ron Webb wrote:
>>Your GPS can't tell you whether you're straight and level, only whether
>>you're straight.
>
>
> Agreed.
>
> But if the GPS says I'm straight (over a 10 second average) and the
> accelerometer says the roll axis vector is pointed toward the floor of the
> aircraft, then it seems to me I'm straight (otherwise the heading would be
> changing) and level - since if there is no heading change the only vector
> remaining is G.
>
>

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[Roger]

On Tue, 08 Mar 2005 00:33:00 GMT, Ernest Christley
> wrote:

>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.

It's that "bumpy ride" that takes a quick response.

You need response (and sensing) times in milliseconds.
By far the simplest I can think of would be to tie into a gyro for
both pitch and roll. Then if you have the time and inclination, add
the output from the blind altitude encoder for altitude hold.

For an experiment, feed the gyro signals into a lap-top and process
them. You could even use an old AI for a test. Just let the
calculated outputs drive bar graphs, or position indicators and record
the functions. It'd be nice to be able to record the actual control
inputs as well for comparison. When the outputs look good then move
on to driving servos for trim tabs.

All failure modes should be neutral. Failure of any signal should
drop the system off line and that would put the servos at neutral.

A while back a friend had the elevator trim tab break. This
immediately put them into a 6-G pull up. Only a good pilot (who's
hand was on the stick) saved their bacon. BTW that was in IMC.

There is no need for an amateur built AP to be a dangerous exercise,
but the risk depends solely on how much foresight is put into the
system. Never leave a control system with a single point failure
mode.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

[Dale Larsen]

> 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.

Ron-Using accelerometers in 3d space will soon become inaccurate due to
small errors in the accelerometers, math rounding errors and drift. How do
you propose to 'erect' such a device to keep the shiny side up?

[Dan, U.S. Air Force, retired]

Dale Larsen wrote:

>>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.
>
>
> Ron-Using accelerometers in 3d space will soon become inaccurate due to
> small errors in the accelerometers, math rounding errors and drift. How do
> you propose to 'erect' such a device to keep the shiny side up?
>
>
Add a VG.... let's see the second integral....
OK, too complicated...keep a cat in the cockpit, periodically drop it on
the floor, since cats always land feet first.....
No, cats tend to get cranky when you do that.....

Dan, U.S. Air Force, retired

[Ron Webb]

>>
>> Ron-Using accelerometers in 3d space will soon become inaccurate due to
>> small errors in the accelerometers, math rounding errors and drift. How
>> do you propose to 'erect' such a device to keep the shiny side up?

The only constant acceleration is the acceleration of gravity. A "leaky
integrator" with a 2 or 3 second Tau should work fine.

If it can be done mechanically, it can be done electronically.

[Roger]

On Mon, 14 Mar 2005 16:50:34 -0900, "Ron Webb"
> wrote:

>
>>>
>>> Ron-Using accelerometers in 3d space will soon become inaccurate due to
>>> small errors in the accelerometers, math rounding errors and drift. How
>>> do you propose to 'erect' such a device to keep the shiny side up?
>
>The only constant acceleration is the acceleration of gravity. A "leaky

How so? the plane doesn't know if it's right side up or not.
You can do a barrel roll, or loop and always keep "down" through the
bottom of the seat.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com

>integrator" with a 2 or 3 second Tau should work fine.
>
>If it can be done mechanically, it can be done electronically.
>

[Ron Webb]

>>The only constant acceleration is the acceleration of gravity. A "leaky
>>integrator" with a 2 or 3 second Tau should work fine.


> How so? the plane doesn't know if it's right side up or not.
> You can do a barrel roll, or loop and always keep "down" through the
> bottom of the seat.
>
> Roger Halstead (K8RI & ARRL life member)
> (N833R, S# CD-2 Worlds oldest Debonair)
> www.rogerhalstead.com


Roger

That's a good question. I have run every other scenario over in my mind, and
it looks to me that the proposed system should deal with them under any
normal circumstances.

However, I had not considered a constant acceleration "barrel roll" while
maintaining the same heading.

How to sense that???
My original idea had included an electronic "Gyroscpe"

I had eliminated it when I discovered how hard the iMEMS ADXRS300
http://www.analog.com/en/prod/0,,764_801_ADXRS300%2C00.html
are to get, but I may have to put it back.

A homemade version is available.
http://home.comcast.net/~scottxs/piezogyro/piezindex.htm