1. No category

Tutorial on how to modify a real attitude
indicator to be used with IOCards and servo
motors.
Author: Carlos López
Translation by Manolo Hdez-Peña M.
Revised by Jaime Pirnie
Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
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Intro
Building the instrument
Connecting the servos card (by Borja Perera)
Software configuration
Working with MS Flight Simulator
Working with X-Plane
Intro
Using the servo motors card, we can make any analog instrument work like a real
instrument in a real airplane. Although in the modern cockpits there are less and less
analog instruments, there always will be the stand-by gauges. In the case of the Boeing
737 and Airbus A320 (the most popular cockpits) the stand-by gauges are: attitude
indicator, altitude indicator, IAS indicator, and RMI. UIT these stand-by instruments, we
could fly anywhere in the case of a general failure in the glass cockpit system. Other
gauges that can be simulated using servo motors are: flaps position indicator, brakes
hydraulic pressure indicator, etc.
This winter ’04 I was gifted with an un-calibrated attitude indicator, so I decided to make
my simulated gauge using it. I would like to thank the company “Flight Training Europe”
(Xerez) and especially to Manuel Represa for this real gauge.
If you want to know how the real gauge works, try these links:
Gyroscope: http://www.ciencia-ficcion.com/glosario/g/giroscop.htm
Gyro properties: http://inicia.es/de/vuelo/INS/INS22.html
Attitude indicator: http://inicia.es/de/vuelo/INS/INS26.html
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Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
Building the instrument
Since our simulated cockpit has no movement, instead of keeping the horizon fixed and
moving the body/shell of the gauge (the real gauge acts this way), we will move the horizon
inside the fixed position body/shell of the gauge.
This is the gauge we are taking apart. Here
you see the front of the gauge. The picture
to the right shows the rear of the gauge.
Looking at the rear, we see the hole in the
center. This is the axle for the inner body
and the air intake (the inner gyro turns with
an air stream). The air outtake is the upper
left hole, which is connected to an air pump.
Lets take out the rear lid using a small
screwdriver.
With an allen wrench, we will take out the
center piece. We can now see the axle with
its bearings. This is where the inner body is
mounted.
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Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
Side view where we can see the inner body...
Now we will take out the front piece (with
the crystal) and the needle that indicates
the bank angle.
The gyro is still mounted in the inner body.
... and the mechanism for pitch indication.
All the pieces in the order that we have
taken them outo.
Another view of the pieces that indicate our
flight attitude.
Page 4 of 20
Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
Another view of the flight attitude indicator
pieces.
We can see some counterweights and screws
to calibrate the instrument.
This is a closer view of the inner body. We
can see how the piece move to indicate pitch.
We can now take out the inner body (with
the gyro on it).
The red line indicates the air circuit that
makes the gyro turn.
We can now take out the gyro and place a
servo in its place.
Page 5 of 20
Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
Here we can see the body (we will use it) and
the gyro (we can discard it).
Lets remake our attitude indicator. We have
to mount a servo on the inner body. This
servo will control the pitch movement.
We will mount these pieces in this position.
Here are all the pieces that have no use. We
can see the inner blade that moves the gyro
by the air stream.
We will use a Hitec servo, model HS-311.
This servo includes different gears and
accessories. We will use a piece with a cross
shape.
A closer view. All the elements except the
servo and the plastic piece are the original
ones. Only the gyro is substituted by a servo
motor.
Page 6 of 20
Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
The mechanism that will move the pitch
indicator.
The servo already mounted. It has been
fixed to the body with a plastic zip tie.
Another picture showing the mounted servo.
Next step is to mount the rest of elements.
Here we see the inner body inside the outer
one.
Now we fix the reference horizon and then...
... the horizon moved by the servo.
Page 7 of 20
Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
A side view.
And the mechanism in a levelled flight
position,
while a descent,
and while ascending.
Now we will fix the bank scale which will be
moved by the second servo motor.
To backlight the gauge we will use four little
12 volts light bulbs.
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Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
This is how it looks when backlit.
Once we have finished with the inner part,
we will mount a second servo motor that will
turn when rolling.
We will use a board (with the corresponding
holes) where to mount the second servo.
Now we will use a Futaba servo motor, model
S3001.
A closer view of it. The hole must be in line
with the inner body axle.
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Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
We can now calculate the final position of
the servo and an extra hole for the cables.
This picture shows all the elements mounted.
A side view of everything mounted.
Not all the servo motors have the same
connections, so we’ll have to check them.
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Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
Now we are finished. This is the final look of our simulated attitude indicator. The final step
is to connect the servos to the servos cards and see if everything works ok.
If you want to see some videos with the gauge working, try these links:
http://www.micabinadevuelo.com/periodo-3-servo/Servos_3_L.wmv
http://www.micabinadevuelo.com/periodo-3-servo/Servo_0001.wmv
http://www.micabinadevuelo.com/periodo-3-servo/Attitude_Indicator_L.zip
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Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
Connecting the servos card (by Borja Perera)
We have two options: build our own card or buy it from Opencockpits. If you choose the
first option, you can download all the information from Opencockpits. We are using a card
bought from Opencockpits. The servos card is connected to 8 master card outputs per
servo (two servos can be controlled with one card).
To control the first servo, we will use the connector below that has 10 pins. Pin #1 is not
used; pin #2 is a common GND (common outputs GND to avoid noise); the rest of pins are
connected to eight consecutive master card outputs. Now we will connect servo number 1
to this card by the upper left connector. It has three pins: yellow (servo control), red (+),
and black (GND).
If we want to connect a second servo, we will proceed the same way but will use the 8 pin
connector on the right hand side and the other three pin connector above.
We will feed the card with 4.8 volts (4.5 to 5 volts is OK) through the connector on the
left hand side (positive and GND is shown in the picture).
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Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
Software configuration
We are going to use the IOCards software in
the following order:
We start with the controller software to see if what we have done up until now works
properly and to check the movement limits of our servos. Once started, we will click Start
and activate the checkbox Servo Control. In my configuration, servos are connected to
outputs numbers 11 to 18 for pitch and from 19 to 26 for bank. We write in the field First
Output the first output where the servo is connected and in the field Value a number
between 0 and 255. First we look for the centered position of the servo. In my case the
centered values are 145 for servo-1 and 131 for servo-2:
Now we write down the values for the limit positions (90º for bank and 60º for pitch, once
the real gauge has been modified) and start the second program.
We will define two variables S_PITCH and S_BANK. We will assign two IOCGauges
addresses (#2 y #3) and we will associate them with the functions PITCH and BANK:
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Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
Under the functions tab we will define the following values:
Then we will define the servos under the MOTORS-S tab with the values obtained from
the controller software:
Once this is made, we can save the file and we are ready to calibrate our attitude
indicator and to test it with our favourite flight simulator.
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Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
Working with MS Flight Simulator
We will download first the file IOCGauges from www.opencocpits.com, follow the
installation instructions and open the file IOCGauges.ini where we will set the values for
maximum pitch and bank angles. In my case:
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Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
We will open iocard.ini file checking the following values:
We will start the simulator and the IOCard and IOCGauges programs:
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Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
Checking that both have connected with the simulator and one with the other via IOCP
protocol (FSUIPC must be installed in the folder ‘modules’ in FS).
We can make a test flight to see if the movements on the screens are the same as in our
new analog gauge. If not we can make small changes in the IOCGauges.ini.
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Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
Working with X-Plane
We don’t need FSUIPC nor IOCGauges if we use X-Plane. The control for analogue gauges
is included in the XPLUIPC, library developed by Alberto Beaterio. For additional
information on this DLL you can download it from www.opencockpits.com or directly from
this link: XPLUIPC Ver. 1.1 Release 1
Once the library is installed, we just have to set the values for the maximun angle of pitch
and bank in the XPLUIPC.ini. In my case:
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Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
We will open iocard.ini checking the following values:
Finally we will run the simulator and the IOCards software:
Note that FSUIPC is disabled and IOCP enabled.
Then, from X-Plane menu, we can check the connection this way:
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Tutorial on how to modify a real attitude indicator to be used with IOCards and servo motors
IOCards Project
We can make a test flight to see if the movements on the screens are the same as in our
new analog gauge. If not we can make small changes in the XPLUIPC.ini.
I would like to aknowledge the members of the developers of analog gauges
(Fernando Brea, Borja Perera, David Pousada and Manuel Vélez) and to the
software developers (Alberto Beaterio and Manuel Vélez) that make all this
possible.
Links to other pages related with analog gauges.
Gyro principles
Gyro properties
http://www.ciencia-ficcion.com/glosario/g/giroscop.htm
http://inicia.es/de/vuelo/INS/INS22.html
Attitude indicator
Video of an attitude indicator
driven with servos. By Carlos
López:
http://inicia.es/de/vuelo/INS/INS26.html
http://www.micabinadevuelo.com/periodo-3-servo/Servos_3_L.wmv
http://www.micabinadevuelo.com/periodo-3-servo/Servo_0001.wmv
http://www.micabinadevuelo.com/periodo-3-servo/Attitude_Indicator_L.zip
Tutorial on how to build a dual
flaps indicator. By Fernando
Brea and Borja Perera
Video of a dual flaps indicator
driven by servos. By Fernando
Brea
http://www.opencockpits.com/modules.php?name=Downloads&d_op=getit&lid=117
http://fernandobrea.eresmas.net/flaps/flaps1.wmv
http://fernandobrea.eresmas.net/flaps/flaps2.wmv
Carlos López: carloslopez@micabinadevuelo.com
http://www.micabinadevuelo.com/
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