Kiel Graham, Josh Kramer and Eric
Sabourin, Department of Mechanical
Engineering, University of Ottawa
For our project
we created a
quad copter. The
quad copter is a
type of
rotorcraft,
which means that
it uses rotors
instead of fixed
wings to
generate lift.
This type of
aircraft was one
of the first
configurations
to successfully
implement a
vertical
takeoff.
Rotorcraft have
a wide variety
of applications
and uses, and
one of their
most useful
features is the
ability to take
off and land
vertically,
eliminating the
need for a
runway.
Advantages
For our project,
we decided to
create a 4 rotor
rotorcraft, a
quad copter. The
quad copter
offers several
advantages in
its design.
First of all it
is relatively
simple and cheap
to build and
maintain due to
its simple
mechanical
design. This
simplicity
allows for easy
field repairs
when required.
Furthermore the
quad copter has
very stable
flight
characteristics,
which make it
useful for
capturing images
or lifting loads
safely. With
modern
advancements
quad copters can
now perform
highly complex
aerial
manoeuvres,
which further
increase the
range of
applications of
quad copters.
Some
applications for
quad copters in
today’s society
are real estate
photography,
military
surveillance and
transport, and
exploring unsafe
places.
Transmitter and
Receiver
The Transmitter
and receiver
used had the
following
specifications:
a 2.4 GHz 4
channel
transmitter with
a 6 channel
receiver.
We needed 4
output channels
from the
transmitter to
control the
thrust, rudder,
ailerons, and
elevators
respectively.
The thrust
channel controls
how much uniform
power is
supplied to all
4 motors and is
used to control
the altitude of
the quad copter
(left), and he
ailerons channel
controls the
roll of the quad
copter (right).
The rudder
channel controls
the yaw of the
quad copter
(left), and the
elevators
channel controls
the pitch of the
quad copter
(right).
The block
diagram
demonstrates how
the quadcopter
transmitter
signal goes to
the receiver on
the quadcopter,
which then goes
to the Pulse
Width Modulator
(PWM) and the
Pulse Position
Modulator (PPM)
which converts
the signal that
the gyros and
accelerator can
understand to
self-level the
quadcopter and
provide power to
the motors.
There is also
the diagram of
the go-pro
camera and
receiver used on
the quadcopter.
The Frame
The frame was
constructed
mainly out of
aluminum. 6061
Aluminum has a
mass of 2.7
g/cm3. The
mechanical
properties are
desired from the
aluminum and
they are offered
in a light-
weight material.
The aluminum is
rigid enough to
resist flexing
when the rotors
are operating at
full throttle
and strong
enough to resist
breaking when
the quadcopter
crashes. The
aluminum is
relatively easy
to machine and
fairly cheap to
purchase.
For our design
the frame is an
X configuration.
The X
configuration
was chosen over
a +
configuration
for smoother
flight and a
better mix of
motor
integration from
each channel.
The Lengths of
the X arms are
24” end to end
and are made of
1” x 0.25”
rectangular
bars. There is
one full-length
bar and two
half-length bars
to keep the
motors on the
same plane. The
bars are
sandwiched
between two 4” x
4” x 0.125”
aluminum plates.
The plates are
used to keep the
X configure
rigid and to
mount the
controller and
camera mount to
the bottom. The
camera mount is
made from the
same aluminum
bars as the arms
and was bent
into shape to
give a slight
downward view
for the camera
for better
filming angles
when in flight.
Below are the
design drawings
for the quad
copter.
The weight of
the quadcopter
was minimized in
multiple ways.
The components
of the
quadcopter were
assembled with
small machine
screws instead
of bulkier nuts
and bolts. Holes
were drilled in
areas of the
frame that would
not be used for
mounting
components to
reduce weight,
reduce drag and
hold parts in
place by running
wires though the
holes.
Microcontroller
The
microcontroller
used for our
quadcopter is
the Hobbyking
KK2.0 flight
controller. The
controller takes
signals from the
channels and
transmits the
signal to the
necessary motors
to make the
desired action
happen. The
quadcopter
flight would not
be very smooth
without the use
of a
microcontroller.
The flight
controller has
fixed channels
of throttle,
rudder, aileron
and elevator. If
the throttle is
increased all
four of the
motors speed up
at the same
rate, if the
rudder stick is
moved to the
left or right
either both the
clockwise motors
or
counterclockwise
motors speed up
to rotate the
quadcopter. If
the aileron is
increased left
or right either
the left half
motors or right
half motors
speed up to move
sideways. If the
elevator stick
is moved up or
down the back
two motors or
front two motors
speed up to move
forward or
backward.
The
microcontroller
has an
incorporated LCD
screen, which
makes it very
simple to see
that the user
commands are
inputted
properly. The
gains of each
channel, other
than thrust, are
adjusted on
screen, as
opposed to
turning
potentiometers
on controllers
without LCD
screens. The
ESC’s are easily
calibrated
through the
microcontroller
and the LCD
screen shows
that the
calibration was
successful. The
status of the
sensors are
displayed on the
LCD screen as
well so it is
simple to
problem solve
instead of
guessing where
your errors may
come from. The
controller
firmware was
updated and
slightly altered
by connecting
the controller
to a laptop
using aUSBasp
adapter to flash
the ATMEL
Mega324PA chip
on the
controller.
The Motor
The motors used
were the
MT2213-935KV
MultiStar Motor
and Propeller
Combo 10-4.5 CW
CCW. This comes
with 4 motors
and 4
propellers. Each
motor generates
583g of thrust.
When added
together, the
four motors can
generate 2332g
of thrust. When
compared to the
weight of the
quadcopter,
1360g, it is
evident that the
motors provide
enough thrust to
lift up the
quadcopter and
move it around.
The rotors spin
at a rate of
935rpm/V and
gives 200W of
power.
Battery
The battery used
was the Turnigy
2200mAh 3S 25C
Lipo Pack, as it
gave the
required amount
of power, was a
relatively light
battery for the
power it
provides, and it
was cost
effective. It
discharges 25C
and has a
capacity of
2200mAh. The
battery is
composed of 3
cells. Each cell
has a max
voltage of 3.7V,
which gives
11.1V for the
entire battery.
Battery
Elimination
Circuit
In the Turnigy
PLUSH – IBA
speed
controllers
used, there are
Battery
Elimination
Circuits (BEC),
which regulate
the dispersion
of battery
power. It allows
the use of 1
battery to power
both the motive
part of the
motor and the
steering part.
It also has a
Low-Voltage
Cutoff (LVC)
sensor that
diverts power
away from the
motive part of
the motor and
sends more to
the steering
application when
the battery
power gets low.
This allows the
controller time
to bring the
quadcopter back
when in the
event of low
battery. The LVC
for the speed
controllers is
2.6V per battery
cell or 7.8V for
the entire
battery