Futaba GY611 User Manual

AVCS GYRO

NSTRUCTION MANUAL

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YAW-AXIS STABILIZER FOR MODEL HELICOPTER

(RATE GYRO)

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Thank you for buying a GY611 AVCS gyro.
Before using your new gyro, please read this manual thoroughly and use the
gyro properly and safely. After reading this manual, store it in a safe place.

FOREWORD

The GY611 gyro is an AVCS (Angular Vector Control System) rate gyro de
veloped for model helicopter competition.

[GY611 Features]

· Super narrow pulse (760μs) drive system substantially improves servo re
sponse. An S9256 digital servo is used.

· Microcomputer high-speed arithmetic processing substantially improves
gyro response.

· High resolution 12-bit A/D accurately converts the sensor output to a digi
tal signal.

· Newest SMM (Silicon Micro Machine) and low-back aeroform case im
prove vibration resistance and neutral characteristic.

· Amp mounts an LCD that allows accurate data setting.

[S9256]

· Special servo for the GY611. Compatible with super narrow pulse (760μs)
drive.

· High response realized. (0.06 sec/60˚)

· Alumite case w/heat sink effectively cools the motor heat.

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Always use the special S9256 servo with the GY611.

·The GY611 cannot operate with servos other than the super narrow pulse

(760μs) servo. The servo may be destroyed.

Warning: This product contains a chemical known to cause cancer and birth defects
or other reproductive harm.

· No part of this manual may be reproduced in any form without prior permission.

· The contents of this manual are subject to change without prior notice.

· This manual has been carefully written. Please write to Futaba if you feel that any
corrections or clarifications should be made.

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ABLE OF CONTENTS

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FOR SAFETY

· Meaning of Special Markings ---------------------------- 4

· Mounting/Operating Precautions ------------------------ 4

· Fuselage Maintenance Precautions ---------------------- 6

· S9256 Usage Precautions --------------------------------- 7

BEFORE USE

· Set Contents ------------------------------------------------ 8

· AVCS Gyro -------------------------------------------------

DATA SETTING

· Name and Function of Each Part -----------------------12

· LCD Display and Edit Keys ----------------------------- 13

· Function Map ---------------------------------------------- 14

· GY611 Functions Setting --------------------------------

· Remote Gain Function ----------------------------------- 21

· Initialization ----------------------------------------------- 30

INSTALLATION AND ADJUSTMENT

· Installing to Fuselage ------------------------------------- 32

· Flight Adjustments ----------------------------------------

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37

REFERENCE

· Specifications ---------------------------------------------- 40

· Definition of Abbreviations ------------------------------

· GY611 Parameters Sheet --------------------------------

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42

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OR SAFETY

OR SAFETY

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To ensure safe use, observe the following precautions.

Meaning of Special Markings

Pay special attention to the safety at the parts of this manual that are
indicated by the following marks.

Mark Meaning

Procedures which may lead to a dangerous condition and

cause death or serious injury to the user if not carried out
properly.

Procedures which may lead to a dangerous condition or
cause death or serious injury to the user if not carried out
properly, or procedures where the probability of superficial
injury or physical damage is high.

Procedures where the possibility of serious injury to the user

is small, but there is a danger of injury, or physical damage,
if not carried out properly.

Symbol: ; Prohibited ; Mandatory

Mounting/Operating Precautions

Insert the connectors fully and firmly.

·If a connector works loose due to vibration during flight, control may be

lost and result in a dangerous situation.

Always use the GY611 with a PCM proportional system.

·Using the GY611 with an FM proportional system, when noise enters,

the wrong neutral position may be memorized.

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OR SAFETY

Always use the accessory sensor tape to install the sensor

to the fuselage.

· This is necessary to securely fasten the sensor to the fuselage so that operation of
the gyro does not transmit unwanted fuselage vibrations directly to the sensor.

When mounting the sensor, provide a little surplus so that

the sensor connection cables are not too taut.

· If the sensor cables are too taut, the gyro will not display its full performance. If the
sensor peels, control will be lost and result in a dangerous situation.

Mount the sensor and control amp so that metals or other

conductive objects do not touch these cases.

· The GY611 uses a conductive resin case to reduce electromagnetic interference. Be­cause the surface of the case is conductive, metal objects may cause a short circuit.

Mount the sensor and servo at least 2cm apart.
When using a GV-1 governor, mount the sensor and GV-1

amp at least 5cm apart.

When using the GY611 with a motor-driven helicopter,

mount the sensor and drive motor at least 10cm apart.

· Noise from the servo motor, GV-1 amp and drive motor may cause the per­formance of an erroneously operated gyro to drop.

Precautions When Turning on the Power Switch

During initialization, the message --Hello-- appears on the GY611
LCD screen.

Do not move the helicopter until this message disappears

(in about 3 seconds).
Also, do not move the transmitter rudder stick from the

neutral position during this period.

Always check the direction of operation of the servos.

·If you attempt to fly the model when a servo operates in the wrong direction, the

fuselage will spin in a fixed direction and enter an extremely dangerous state.

When the rudder neutral position was changed by the link-

age, the rudder neutral position in the AVCS mode must
always be re-read before use.

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OR SAFETY

· Re-reading method:

Turn on the transmitter in the AVCS mode, then turn on the gyro . Or quickly switch (in­terval of within 1 second) the remote gain channel switch between the AVCS mode and
Normal mode at least three times and switch the AVCS side with the transmitter in the
ON state. This memorizes the new rudder position inside the GY611.

Avoid sudden temperature changes.

·Sudden temperature changes will cause the neutral position to change. For example,
in the winter, do not fly immediately after removing the model from inside a heated car
and in the summer, do not fly immediately after removing the model from inside an air
conditioned car. Allow the model to stand for about 10 minutes and turn on the power
after the temperature inside the gyro has stabilized. Also, if the gyro is exposed to direct
sunlight or is mounted near the engine, the temperature may change suddenly. Take suit­able measures so that the gyro is not exposed to direct sunlight, etc.

Check the remaining receiver/gyro/servo nicd battery op-

erating time during the adjustment stage and decide how
many flights are remaining.

Never use the transmitter rudder trim in the AVCS mode.

·When the rudder is trimmed during flight, the neutral position will change.

When using the GY611 in the AVCS mode, set revolution

mixing to OFF.

Fuselage Maintenance Precautions

Use a tale rotor drive tube or other part with a high torsion

performance for the tail drive.

Take the strength of the tail into account during inspection

and adjustment.

· The amount of improvement of gyro performance has a considerable effect
on the fuselage vibration level or the size, type, linkage method, looseness,
etc. of the tail rotor.

Since a higher gain than usual can be used then the tail rotor is more effec

tive, the load on the tail is also greater.

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OR SAFETY

Always perform proper maintenance for ultimate perfor-

mance.

· The rigidity of the fuselage tail has a large effect on gyro performance.

Make the fuselage vibration as small as possible.

·Fuselage vibration has an adverse affect on gyro operation.

S9256 Usage Precautions

Do not use the S9256 with applications other than the

GY611 gyro.

· The S9256 is designed to be used with the GY611 only, and will not operate
in other applications. Trouble may also occur.

Immediately after flight, do not touch the S9256 case.

·The heat sink section of the case is extremely hot, and may cause burns.

When mounting in the fuselage, install the S9256 so that it

does not touch the servo case and metal parts of the heli
copter frame.

· The middle case has an aluminum heat sink construction, and will generate
a large amount of noise if touched. In this case, it will become impossible to
receive and is extremely dangerous.

· Current Drain:

The S9256 is designed to be used with the GY611 gyro only, especially to

operate at high speed. Therefore, the servo starts, a correspondingly large
current flows and the current drain is, therefore, large. Constantly pay atten­tion to the remaining capacity of the Nicd battery and decide the number of
safe flights. Always pay attention to the following points:

· Always use an Nicd battery. A dry cell battery will not display the spspecified
performance.

· When using the S9256 in a system with a battery fail safe function, the cut­off voltage is set to a high value. Shortening of the flight time due to this
must be included in calculation.

· Install the servo so that it does not get caught on the push rod or does not
loosen even when operated over its full travel. If unreasonable force is ap­plied, the current drain will increase tremendously and shorten the life of the
servo and accelerate battery consumption.

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EFORE USE

EFORE USE

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Set Contents

After unpacking the GY611 set, first check if the following parts are
provided:

GY611 sensor (x1)

GY611 control amp

(x1)

Sensor tape (x3)

Mini screwdriver (x1)

S9256 servo (x1)

(Only a set w/servo)

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B

EFORE USE

• Drifting stop

Forward

Side wind

AVCS Gyro

Differences Between AVCS Gyro and Conventional Gyro

Compared to a convention gyro, the AVCS gyro has a substantially
improved tail control capacity. Gyro operation also differs from that
of conventional systems in a number of ways.

The following sequentially describes the conventional gyro and the
AVCS gyro.

Conventional gyro

The conventional gyro detects movement of the helicopter's tail and controls
the rudder servo so that movement of the tail stops.

Now, consider hovering when the helicopter is exposed to a side wind, the
tail drifts. When the tail drifts, the gyro detects the tail rotation angular veloc
ity and operates the servo in the direction that stops the tail from moving.
Drifting of the tail is stopped by control from the gyro. When the tail stops
drifting, the control amount from the gyro becomes zero. Since the helicop­ter is always exposed to side wind, even in this state, the tail starts to drift
again. When the tail drifts, the gyro tries to stop it again. The "drifting stop"
operation is repeated and the tail continues to drift in the wind direction in
this manner. The higher the gyro sensitivity, the smaller the amount of this
drift. However, if the sensitivity is high, hunting will occur and, therefore, the
sensitivity amp has a limit.

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EFORE USE

• The tail remains extremely stable.

Forward

Side wind

AVCS gyro

This following describes how the AVCS system works when the helicopter
is exposed to a side wind while hovering, the same as the preceding item.
When the helicopter is exposed to a side wind, the tail begins to drift. The
gyro controls the servo so that the movement of the tail stops, the same as
a conventional gyro. At the same time, a sensor is controlled so that the tail
is rotated in the opposite direction (returns to the original position). In short,
the conventional gyro performs an operation known as "drifting stop", but
the AVCS system performs an operation that "stops drifting and returns to
original position". The "return to original position" operation added to the
AVCS system improves rudder trim operation. In other words, the gyro can
automatically trim the rudder against side winds. This also applies to reverse
flight. When a helicopter is flying in the forward and reverse directions, the
rudder trim is changed to advance, but with the AVCS system, this trim
change is performed automatically and instantaneously so that the tail re­mains extremely stable even during high-speed reverse flight.

The AVCS system requires a high-precision angular velocity sensor. The
GY611 realizes a high-precision angular velocity detection function and ex
tremely small output drift by using a new type of gyro sensor. This minimizes
rudder neutral position drift during flight and eliminates the need to trim the
rudder during flight.

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Differences in rudder control method

The following describes the differences between conventional gyro
and AVCS gyro rudder control.

The conventional gyro sends the rudder control signals from the
transmitter to the rudder servo and starts to move the tail. When the
tail moves, the gyro detects this movement and generates a signal to
stop it. If the tail continues to move even in this state, a rudder con

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EFORE USE

trol signal larger than the signal from the gyro must be applied from
the transmitter. That is, the difference between the rudder control sig
nal from the transmitter and the control signal that attempts to stop
this from the gyro becomes the actual amount of movement of the
tail. Ordinarily, the rudder control signal is amplified several times
over by the gyro amp and is balanced with the gyro control signal so
that the transmitter can be used at the normal steering angle.

The AVCS system uses a different rudder control method. As de
scribed in the preceding section, it has additional functions that "at
tempt to return movement by external force to the original position"
and that generate an angular velocity proportional to the rudder con
trol signal. That is, it functionally controls the speed of rotation of
the tail. The original AVCS (Angular Vector Control System) came
from this.

· In the AVCS mode, when the transmitter rudder stick is moved when the heli­copter was stopped, the rudder servo controls operation until the tail reaches
the specified rotational speed.

· Trim deviation of the rudder control signal also becomes a signal that causes
the tail to turn so that even a little trim deviation causes the tail to move.
Therefore, the rudder trim is made the same in all flight states and must
match the neutral reference signal at the gyro. The method of reading the
rudder neutral signal at the gyro will be described separately.

· Since the rudder mixing signals from the transmitter also become a tail rota
tion signal, all the rudder mixing functions must be disabled.

· In the AVCS mode, the gyro automatically trims the rudder so that linkage
changes cannot be verified. Initially, the GY611 trims the rudder by flying in
the Normal mode to take the rudder linkage neutral position. This centers the
linkage. At this time, this rudder neutral reference point is read to the GY611.

Giving the gyro the rudder neutral reference signal and performing
tail operation by referring to this signal in the AVCS mode in this
way is how the AVCS system differs from the conventional system.

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D

ATA SETTING

ATA SETTING

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Name and Function of Each Part

GY611 control amp

LCD display

· Displays the set data. (8 characters x 1 line)

(Input/output terminals)
Gyro sensor input

Rudder servo output

· Use d when s et ti ng data.

Edit keys

Operated by pushing with
the accessory mini screw­driver.

LCD contrast trimmer

· Allows adjustment of the contrast so that the LCD display is easiest to see.
It is adjusted with the accessory mini screwdriver.

GY611 gyro sensor

· Stick to the body using the accessory
sensor tape.

(Receiver connectors)
Remote gain input
Rudder input

· To control amp

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D

ATA SETTING

LCD Display and Edit Keys

LCD display

· Set data disp lay and o perat io n
status monitoring are possible.

Edit keys
Setup screen call

· The setup screens can be sequen­ti a lly call e d w i th t h e F U NC+ or
FUNC- key. For the order in which
the setup screens are called, see
the function map.

Data setting

· Pe rf o r m dat a se tti n g with th e
DATA+ or DATA- key. When setting
a value, the data is increased when
the DATA+ key is pressed and is
decreased when the DATA- key is
pressed. The mode can also be se­lected using either the DATA+ or the
DATA- key.