IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.

1. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 02 Issue: 10 | Oct-2013, Available @ http://www.ijret.org 489
DESIGN OF AN AUTONOMOUS ORNITHOPTER WITH LIVE VIDEO
RECEPTION FOR MILITARY SURVEILLANCE
Aditya Tandon1
, Ankit Vajpai2
, Aadi Nath Mishra3
1, 3
Mechatronics Department, SRM University, SRM Nagar, Kattankulathur, Chennai – 603203, India
2
Quad Systems, SRM University, Chennai, India
Aditya.quad@gmail.com, Aadinath.quad@gmail.com, Ankit.quad@gmail.com
Abstract
In recent years flying by propelled wings, also called as Ornithopter, has been an area of interest because of its application to Micro
Aerial Vehicles (MAVs). In the field of Defence and during the war of Iraq, a need for live surveillance within a close distance was
felt, which lead to research of various techniques for live surveillance in the battle ground to provide the necessary intelligence to the
troops in the line of action. These miniature vehicles seek to mimic small birds to achieve never before seen agility in flight. In order
to better study the control of flapping wing flight we have researched and modelled a large scale ornithopter called the ‘Garuda’. The
‘Garuda’ is capable of carrying a microcontroller, sensor package and an on board surveillance camera to transmit live video feed to
the receiver in real time. The design takes special care to optimize payload capacity, crash survivability, and field repair abilities.
This model has applications in the field of defence spy surveillance over enemy territories without being detected or arousing
suspicion.
Keywords: Ornithopter, Military, Surveillance, Autonomous, Video
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1. INTRODUCTION
Natural fliers like birds and insects have captivated the minds
of human inventors through history. The ease and grace with
which they take to the air vastly surpasses the state of the art
in aircraft and their control systems. This is not to say that
modern aircraft designs are ineffective, they are excellent in
many respects. Propellers and turbines are very efficient
methods of producing thrust and air foils efficiently produce
lift. A Boeing 747 achieves a dimensionless cost of transport
(energy used divided by weight times distance) of 0.1,
equivalent to a soaring albatross, and does it with amazing
reliability, but it will never match the manoeuvrability of the
albatross. Interest in the design and control of ornithopters has
grown in recent years as interest has grown in the area of
Micro Aerial Vehicles or MAVs. These small flying machines
have struck the imaginations of many as ideal platforms for a
variety of tasks including systems monitoring and surveillance
where a swarm of tiny agents would be unobtrusive and have
better access to confined areas than larger flying vehicles.
Fig 1: An ornithopter called the ‘Smart Bird’ developed by
Festo, a German company specialising in the field of
Automation and Bionics.
2. TECHNICAL REQUIREMENTS
2.1 Microcontroller
Fig 2: An Arduino Mega Development Board used as the
microcontroller for the Ornithopter Project.

2. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 02 Issue: 10 | Oct-2013, Available @ http://www.ijret.org 490
The selection of the microcontroller to base the rest of the
system on is one of the most defining decisions of the design
process because it makes up the largest amount of additional
payload weight. Because the scaling of the robot depends on
the payload capacity needed the computer choice will have a
long chain of effects down the design process.
The Arduino based controller has been used because of its
versatility and user friendly control system development.The
single board Arduino Mega has on board analog to digital
converter, several I/O boards to interface with servos and
wireless communication.The controller itself weighs around
100gms but with servos and wireless module the weight
increases to roughly 400g. The Arduino itself is an open
source hardware which has a large range of use and is much
more compact and lightweight. The software development
environment has a steep learning curve and all of the software
is to be written in C.
2.2 Battery
Fig 3: An 11.1 V, 1550mAh Lithium Polymer high discharge
battery.
The battery used is a three cell lithium polymer pack, the
standard for high performance machines like airplanes on this
scale because it has the best power and energy to weight ratios
available. Power density is the main concern at the initial
stages of the project because flights aren't expected to last for
long which would make power output the limiting factor for
the battery. A lithium polymer battery can be discharged at up
to 10 times its capacity (commonly referred to as 10C) with
specially selected batteries capable of continuous discharge up
to 25C which makes it able to deliver the short bursts of power
that the ornithopter needs to flap during short test flights.
Lithium phosphate batteries produced by A123 were also
investigated because they have similar characteristics but the
cell sizes available are too large to make a suitably lightweight
pack at the correct voltage. The cell price of the lithium
phosphate batteries works out to a pack at about half the price
of the lithium polymer pack. In addition to this the lithium
phosphate cells are much less sensitive to overcharging which
causes lithium polymer batteries to violently explode. Because
of potential cost and safety advantages of the lithium
phosphate cells over the lithium polymer cells they may be
further investigated in the future. As the current drawn from
the motor wasn't yet known a standard battery, 1200mAh at
11.4V and 93 grams, is chosen for the weight calculation.
2.3 Sensors
Fig 4: An MPU-9150 9 Axis Inertial Mass Unit module with
Analog Output. Courtesy: Spark fun Electronics
2.4 MPU – 9150
A 9 Axis Inertial Mass Unit to know the exact orientation of
the Ornithopter at any instance and to also quantitatively
measure all physical forces acting on the payload The IMU
package consists of a 3 Axis Accelerometer, a 3 Axis
Gyroscope, a Digital Motion Processor and a 3 Axis Digital
Compass. Using these values of Acceleration, Force and
Direction we are able to estimate the orientation of the
Ornithopter in space and hence manoeuvre it in the requisite
manner.
2.5 Data Logging – Micro SD Card
Arrangement put to use to record and store all sensor and
flight data of the Balloon Sat from launch to recovery. The
recovered data is thus used to support theoretical experiments
and help infer results as well as plot useful information graphs.
2.6 Battery Level Monitor
A voltage divider is created and thus the Battery levels on
board are mapped and data is stored for further studies on
battery consumption and the Ornithopter flight time.

3. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 02 Issue: 10 | Oct-2013, Available @ http://www.ijret.org 491
2.7 Ls20031 GPS 5HZ Receiver
The LS20031 GPS receiver is a complete GPS smart antenna
receiver that includes an embedded antenna and GPS receiver
circuits. This low-cost unit outputs an astounding amount of
position information 5 times a second. The receiver is based
on the proven technology found in LOCOSYS 66 channel
GPS SMD type receivers that use MediaTek chip solution.
3. HARDWARE INTERFACE
Fig 5: A CC2500 Serial Transceiver Module with SPI
Interface as shown. Courtesy: iLabs
Conventional hobby servos like those used on model aircraft
use a pulse width modulated signal with a period of about
40hz and a pulse width of between 1 and 2 milliseconds which
corresponds to the desired absolute position of the servo's
output drive. Because the computer system's main interface is
over RS232 serial, a conversion system is needed. For the
network communication, a CC2500 serial transceiver is used
which has an RS232 interface. The CC2500 transceiver could
also be connected to the Arduino microcontroller using an
Arduino shield or else be coupled with an SPI Interface. The
drive motor controller sits between the serial to PWM servo
controller and the motor and uses that signal to control a high
current driver suitable for the power requirements of the large
motor. This is again a standard radio control airplane part and
a JETI Model Advance 30 brushless motor speed controller
was chosen for this application because of its past use in the
lab. The speed controller is designed to handle 30 amps of
current which was considered to be an upper bound of power
required, about 300 watts at the 11.4 volts the battery pack
runs at.
Figure 6: Main drive motor speed controller. Converts the
PWM control signal into the appropriate waveform to drive
the high current brushless motor
Fig 7: Block diagram of the overall electronics system
configuration.
4. MOTORS AND GEAR RATIO
Figure 8: A BLDC Motor
The motor used in the flapping mechanism of the Ornithopter
is a Brushless DC Motor with 5000 RPM. A gear reduction
ratio of 24:1 is to be used, giving a shaft speed of roughly 210
RPM.

4. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 02 Issue: 10 | Oct-2013, Available @ http://www.ijret.org 492
Figure 9: Side view of the complete gearbox showing the
motor mounted and the configuration of the transmission
gears.
5. TAIL AND WING
The tail section of the ornithopter is responsible for both of the
controllable degrees of freedom aside from the ability to
throttle the drive motor. The tail of the Garuda is set up with
one servo directly connected to the tail at an angle and another
further up the body which rocks it via a linkage. Mounting the
rudder servo at an angle is important because with a single
control surface the elevator and rudder are naturally coupled,
moving the rudder servo makes the tail also move in the
vertical direction unless it's at zero angle where it doesn't have
any control authority anyway.
Figure 10: The tail section of the Kestrel. The tail uses a
clever configuration to decouple the elevator and rudder
actions
With the tail at an angle to the rudder servo it allows the servo
to be held into the zero angle position with respect to the
ornithopter body and while the tail stays near the trimmed
position for horizontal light. This causes the tail to move in a
bowl shaped trajectory decoupled from the elevator action and
is much easier to control by a human pilot. It does not solve
the problem when the elevator servo moves the tail out of the
trimmed horizontal position, but being able to exploit that is a
big advantage where it applies. The wings have a triangular
support structure made from carbon rods. A main spar runs
along the leading edge of the wing and a strut connects from
the rear of the ornithopters body to a point near the tip of the
main spar. From this strut there are several smaller carbon
rods that project to the edge of the wing which are somewhat
free to move. This results in a fanning motion from the trailing
edge of the wing that produces thrust while the leading edge is
aping up and down which directly contributes a part of the lift
in addition to the conventional lift coming from airflow over
the wing.
Figure 11: An image showing the flapping of the wings of
‘Kestrel’, an ornithopter whose design is similar to ‘Garuda’
6. MAIN FRAME
The main frame of the ornithopter is a surprisingly simple
component from a design standpoint. Because the aping
mechanism is contained fully within the gearbox frame the
main frame of the machine serves mainly to provide mounting
locations for the rear wing mounts, electronic components,
battery, and tail assembly. There are two directions to go with
the frame design, either a single at plate which relies on its
own thickness for stillness, or a three dimensional design
made from much thinner material that gets its stillness from
the truss-like structure. If the frame had to be very still the
second option would make for a much lighter and stronger
option, but in this case the frame really doesn't have to be very
still in all directions. The rear wing mount actually holds the
frame from flexing in the direction a sheet would be most
weak because the wing spars form a very large and still
triangle. What this amounts to is that while the more
complicated structure is often the higher stillness and lower

5. IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 02 Issue: 10 | Oct-2013, Available @ http://www.ijret.org 493
weight option it doesn't come with much advantage in this
case. The frame is vastly easier to design and fabricate and
may even be lighter.
Because the frame is really just a collection of mounting
locations for the rest of the components it's relatively easy to
design. The one major specification that must be paid attention
to is the location of the center of gravity. Because the data
needed to work out the correct location theoretically isn't
available this was also scaled up from the Kestrel where the
location was experimentally determined from flight testing to
be about 4 inches behind the main wing spar. The material to
be used for the space frame tubular structure is carbon fibre
and the external profiling of the ornithopter is done using
polyurethane foam or aluminium mesh..
Figure 12: An image showing the space frame structure with
the motor and gear assembly of ‘Kestrel’, an ornithopter
whose design is similar to ‘Garuda’.
7. LIVE VIDEO RECEPTION
A micro camera compatible with the controller has been
mounted the ornithopter to provide live surveillance. The live
feedback from the ornithopter will be obtained off board on an
LCD display. The surveillance system has a transmitter that
will transmit the live video feed over to the receiver and the
video feed can be used for surveillance or as an aid with the
GPS location to effectively maneuver the ornithopter.
Figure 11: A camera with a wireless transmitter to transmit
live video feed.
ACKNOWLEDGMENTS
We would also like to convey our heartfelt gratitude to Mr.
Sivanathan, Assistant professor, Dept of Mechatronics, SRM
University for his invaluable guidance throughout the research
of the project.
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