Erle-Copter, a smart drone powered
by Linux
Operation Manual
May 21, 2015
Contents
1 Introducing Erle-Copter
1.1 A marketplace for drone apps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
3
2 Parts
4
3 Safety and failsafes
6
4 Learn to ﬂy
9
4.1 Flying modes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5 First ﬂight
14
5.1 Attaching propellers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.2 Connecting to Erle-Brain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
5.3 Steps to ﬂight save . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
A Erle-Brain
16
B ROS
17
C Speciﬁcation
18
D Resources
18
E License
19
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1
INTRODUCING ERLE-COPTER
Erle-Copter is a Linux-based drone that uses robotic frameworks such as ROS (the Robot Operating System) and the award winning APM software autopilot to achieve different ﬂight modes.
It’s ideal for outdoor operations and it has been designed for an extended ﬂight time with a
takeoff weight of up to 2 kilograms.
Erle-Copter is the ﬁrst smart drone that ﬂies with Linux and includes ROS as the SDK for
drone app development.
1.1
A MARKETPLACE FOR DRONE APPS
Together with Canonical and the Open Source Robotics Foundation, we are pushing a new marketplace for robot and drone applications. An open platform that attracts innovators and experts to collaborate and compete in the future marketplace of drone and robot applications.
More at ubuntu.com/things.
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2
PARTS
Below the parts that Erle-Copter contains are described. Do not hesitate and ask questions in
our forum.
Radio controller
The Power Module incorporates both a way to power
your autopilot, accessories and report battery voltage
and current to Erle-Brain.
Erle-Copter makes use of rechargeable Lithium Polymer (LiPo) batteries. More about batteries and chargers here.
Provides WIFI connection to Erle-Brain
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Provides high gain WIFI connection to Erle-Brain
4 x Electronic speed controller (ESC).
4 x Brushless motors.
GPS + Compass
Radio communicatios in 2.4Ghz band
Telemetry 915MHz or 433MHz
Propellers 10×4.5
Propellers 10×4.5 (self-tightening)
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3
SAFETY AND FAILSAFES
• Always turn on the Remote Controller prior to turning on Erle-Copter
• Toggle all switches to the top
• Be sure there are no distractions when you are ﬂying.
• Fly in very large open area void of obstacles and away from trafﬁc and people. Be aware
of surroundings.
• Be sure you have calibrated the IMU’s and the compass and you hace GPS ﬁx (Slow continuous blue ﬂashing).
• When in doubt, pull down on the throttle stick and land.
Erle-Copter will not avoid obstacles on its own unless it has been programmed for
it. As the operator, it is your job to recognize and avoid obstructions while ﬂying.
Always ﬂy in an open area away from people and buildings; do not attempt to ﬂy
indoors or in a conﬁned space.
Erle-Copter has powerful motors and high-speed propellers. Never place your
hands near the propellers while Erle-Copter is armed.
All unmanned aerial vehicle (UAV) operators should abide by all regulations from such
organizations as the ICAO (International Civil Aviation Organization) and their own national airspace regulations.
FRAME 1: SAFETY
Environmental factors, such as wind and GPS irregularities, can cause instability in ﬂight.
Erle-Copter will attempt to compensate for these factors by triggering a failsafe if it detects an unsafe ﬂying condition due to loss of controller signal, loss of GPS signal, or low
battery (see below for details). If you observe any inconsistent behavior, land, and consult our team at forum.erlerobotics.com.
RADIO FAILSAFE
Always use the controller as a primary or backup control system when ﬂying. Ensure that the
controller is turned on any time Erle-Copter is powered. If this failsafe is enabled it will get
triggered under the following circumstances:
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• The pilot turns off the RC transmitter
• The vehicle travels outside of RC range (usually at around 500m 700m)
• The receiver loses power (unlikely)
• The wires connecting the receiver to the ﬂight controller are broken (unlikely).
Producing the following behavior:
• Nothing if the vehicle is already disarmed
• Motors will be immediately disarmed if the vehicle is landed OR in stabilize or acro mode
and the pilot’s throttle is at zero
• Return-to-Launch (RTL) if the vehicle has a GPS lock and is more than 2 meters from the
home position.
• LAND if the vehicle has:
– no GPS lock OR
– is within 2 meters of home OR
– the FS_THR_ENABLE parameter is set to “Enabled Always Land”
• Continue with the mission if the vehicle is in AUTO mode and the FS_THR_ENABLE parameter is set to “Enabled Continue with Mission in Auto Mode”.
More about radio failsafe here and here
LOSS OF GPS SIGNAL
Erle-Copter requires an active GPS signal before takeoff. If Erle-Copter loses GPS signal in
ﬂight, it will trigger a GPS failsafe indicated with a high-high-high-low tone, and automatically
switch to manual control (standard - altitude hold mode). Always be prepared to regain manual
control of Erle-Copter at any time while ﬂying and choose an unobstructed ﬂying area to improve GPS signal strength. When ﬂying a mission, we recommended changing the GPS failsafe
behavior to land.
• The GPS Failsafe is enabled by default but you can enable or disable it on the Mission Planner’s Standard Parameter List, by set the FS_GPS_ENABLE parameter to
0 (Disable) or 1 (Land) or 2 (switch to AltHold). It is highly recommended to leave it
enabled and no known reason why it should ever be disabled.
• If you lose GPS lock or experience a GPS Glitch for 5 seconds while in a mode that
requires the GPS (Auto, Guided, Loiter, RTL, Circle, Position or Drift) mode it will
initiate a Land (or AltHold if FS_GPS_ENABLE is set to 2).
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More about GPS failsafe here.
LOW BATTERY
When the battery reaches a low state (voltage under certain value), Erle-Copter will land with
a quick repeating tone. If Erle-Copter reaches the low battery limit during a mission, it will return to the launch point before landing.
This failsafe permits to you to minimize the risks of having a sudden death of Erle-Copter
and enables a better use of your LiPo batteries.
More about low failsafe battery here.
EKF CHECK & FAILSAFE
The EKF check runs on Erle-Brain and will trigger when the EKF’s compass and velocity “variance” are higher than 0.8 (conﬁgurable with EKF_CHECK_THRESH parameter) for one second.
This “variance” increases as the estimates become untrustworthy. 0 = very trustworthy, >1.0 =
very untrustworthy. If both variances climb above the EKF_CHECK_THRESH parameter (default is 0.8) the EKF/Inav failsafe triggers.
When the failsafe triggers, Erle-Brain’s tone-alarm will sound. If telemetry is attached
“EKF variance” will appear on the HUD. And EKF/DCM error will be written to the
dataﬂash logs.
If ﬂying in a ﬂight mode that does not require GPS nothing further will happen but
you will be unable to switch into an autopilot ﬂight mode (Loiter, PosHold, RTL, Guided,
Auto) until the failure clears. If ﬂying in a mode that requires GPS (Loiter, PosHold, RTL,
Guided, Auto) the vehicle will switch to “pilot controlled” LAND. Meaning the pilot will
have control of the roll and pitch angle but the vehicle will descend, land and ﬁnally
disarm it’s motors. The pilot can, like always switch into a manual ﬂight mode including
Stabilize or AltHold to bring the vehicle home.
The EKF check and failsafe can be disabled by setting the EKF_CHECK_THRESH to “0” through
the Ground Control Station’s Conﬁg/Tuning » Full Parameter List. Alternatively it can be made
less sensitive by increasing this parameter from 0.8 to 0.9 or 1.0. The downside of increasing
this parameter’s value is that during a ﬂyaway caused by a bad compass or GPS glitching, the
vehicle will ﬂy further away before the vehicle is automatically switched to LAND mode.
More about EKF failsafe here.
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4
LEARN TO FLY
THROTTLE
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YAW
Flight Tip
When adjusting orientation, move the left stick horizontally without changing its vertical
position.
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PITCH AND ROLL
Flight Tip
Erle-Copter moves according to its orientation. The yellow arms face forward, and the
black arms face backward. Before using the right stick, use yaw to keep Erle-Copter facing in outward orientation so that the black arms face towards you and the yellow arms
face away from you.
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4.1
FLYING MODES
STABILIZE
Stabilize mode allows you to ﬂy your vehicle manually, but self-levels the roll and pitch axes.
ALT HOLD
In altitude hold mode, the copter maintains
a consistent altitude using the internal pressure sensors while allowing roll, pitch, and
yaw to be controlled normally.
Altitude hold mode is used as the basis of au-
Note
In order to maintain the altitude in this
mode the throttle stick should be in the
middle (40% to 60%).
tonomous modes such as LOITER, AUTO, etc.
LOITER
Loiter mode automatically attempts to maintain the current location, heading and altitude using GPS. The pilot may ﬂy the copter in Loiter mode as if it were in manual. Releasing the sticks
will continue to hold position.
Note
Good GPS position, low magnetic interference on the compass and low vibrations are all
important in achieving good loiter performance.
RTL
RTL stands for ”Return to Launch” and when activated, Erle-Copter navigates from its current
position to hover above the home position. The home positioned is set as the point where the
copter was armed.
The copter will ﬁrst rise to RTL_ALT before returning home or maintain the current altitude
if the current altitude is higher than RTL_ALT. The default value for RTL_ALT is 15m.
GUIDED
Guided mode is not a traditional ﬂight mode that would be assigned to a mode switch like other
ﬂight modes. The guided mode capability is enabled using a ground station application and
telemetry radio. This capability allows you to interactively command the copter to travel to a
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target location by clicking on a point on the Ground Station Flight Data map. Once the location
is reached, the copter will hover at that location, waiting for the next target.
FOLLOW ME
The follow me mode makes it possible for you to have your copter follow you as you move, using
a telemetry radio and a ground station. it’s easiest to use a phone or tablet as your Follow Me
ground station . Follow Me mode uses dynamic waypoint feature.
AUTO
In Auto mode Erle-Copter will follow a pre-programmed mission script stored in the brain which
is made up of navigation commands (i.e. waypoints) and “do” commands (i.e. commands that
do not affect the location of the copter including triggering a camera shutter).
Note
Auto mode incorporates the altitude control from altitude hold mode and position control from Loiter mode and should not be attempted before these modes are ﬂying well.
All the same requirements apply including ensuring that vibration levels and compass interference levels are acceptable and that the GPS is functioning well including returning
an HDOP of under 2.0.
AUTOTUNE
AutoTune attempts to tune the stabilization algorithm to provide the highest response without
signiﬁcant overshoot. It does this by twitching the copter in the roll and pitch access which
means that the copter needs to be basically ﬂyable in AltHold mode before attempting to use
AutoTune.
FRAME 2: NOTE
This mode is just to optimize copter’s ﬂight, Erle-Robotics will deliver vehicle’s parameters list to the customers.
More modes and information at Erle-Copter gitbook.
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5
FIRST FLIGHT
5.1
ATTACHING PROPELLERS
Erle-Copter uses four propellers. Propellers generally come in pairs and there are classiﬁed by
the color of each central nut. One should turn in clockwise direction and the other in the opposite. Clockwise propellers are also known as ”pusher kind” propellers and are marked with an
”R” (sometimes it’s a ”P”). Each propeller has locking and unlocking direction symbols. To attach, spin the propeller in the direction of the locking symbol. The propellers will automatically
tighten onto the motors when you arm Erle-Copter before takeoff.
Propeller
Fastening/
Lock: Tighten the propeller
in this direction.
Un-fastening
Lock: Tighten the propeller
in this direction.
Unlock: Remove the pro-
Unlock: Remove the propeller in this direction.
peller in this direction.
FRAME 3: FLIGHT TIME
Damaged propellers should be replaced by purchasing new ones if necessary.
5.2
CONNECTING TO ERLE-BRAIN
FRAME 4: USING A WIFI DONGLE (5 GHZ FREQUENCY)
Make sure that your laptop/phone/tablet/... has 5 GHz support. You should look for
802.11 ac support. Erle-Copter creates a network called ”erle-copter”. The password
for the network is holaerle.
5.3
STEPS TO FLIGHT SAVE
Note
Ensure that the controller is always turned on while Erle-Copter is powered.
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Connect the battery
To activate the motors, hold the left stick down-right
until the motors spin. Now you’re ready for takeoff!
• Take off and gain altitude by raising the left stick
slightly above center.
• Rotate counter-clockwise and clockwise by moving the left stick left and right.
• Fly forward, backward, left, or right by moving the
right stick in the direction you want to ﬂy.
• Release the right stick to level.
• Lower the left stick below center to descend.
After landing, hold the left stick down-left until the
motors stop spinning.
Disconnect the battery
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A
ERLE-BRAIN
Erle-brain is an open hardware and open source Linux-based autopilot to make drones. It consists of a BeagleBone Black and a PixHawk Fire Cape and comes with a Debian image ﬂashed,
ROS preinstalled and the latest ready to ﬂy code.
We ship Erle-brain with the following characteristics:
• Debian Wheezy 7.5
• ROS Indigo Igloo
• APM
• Cortex-A8 @ 1 GHz 4 GB eMMC and microSD card capable - 512 MB RAM
• 12 PWM outputs
• RC Input using either PPM-SUM or S.Bus
• 1 USB Host, 1 UART, 3 I2C, Buzzer connector, Failsafe connector.
The hardware has many more peripherals and we are working hard to bring them out.
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B
ROS
ROS (Robot Operating System) is a BSD-licensed system for controlling robotic components
from a PC. A ROS system is comprised of a number of independent nodes, each of which communicates with the other nodes using a publish/subscribe messaging model. For example, a
particular sensor’s driver might be implemented as a node, which publishes sensor data in a
stream of messages. These messages could be consumed by any number of other nodes, including ﬁlters, loggers, and also higher-level systems such as guidance, pathﬁnding, etc.
Note that nodes in ROS do not have to be on the same system (multiple computers) or even
of the same architecture. You could have a Arduino publishing messages, a laptop subscribing
to them, and an Android phone driving motors. This makes ROS really ﬂexible and adaptable
to the needs of the user. ROS is also open source, maintained by many people.
More at http://wiki.ros.org/ or Gitbook
ROS Answers is a crowd-sourced resource for everything ROS.
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C
SPECIFICATION
Autopilot
Erle-Brain
Firmware
ArduCopter
GPS
uBlox GPS with Compass
Telemetry radio
Radio Telemetry (915 MHz or 433 MHz)
Motors
950 kV
Frame type
X
Propellers
PROPELLERS 10×4.5 counterclockwise (PAIR)
PROPELLERS 10×4.5 clockwise (PAIR)
Low battery voltage
10.5V
High battery voltage
12.6V
Battery cell limits
4S
Radio range
up to 1 Km
Flight time
15-20 minutes*
FRAME 5: FLIGHT TIME
Flight time depends on wind conditions, elevation, payload, temperature, humidity, ﬂying mode and pilot skill.
D
RESOURCES
Hardware
https://erlerobotics.com/blog/erle-copter/
Store
https://erlerobotics.com/blog/tienda
Forum
forum.erlerobotics.com
Online doc
Erle-Copter gitbook
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E
LICENSE
Unless speciﬁed, this content is licensed under the Creative Commons Attribution-NonComercial-Share Alike 3.0 Unported License. To view
a copy of this license, visit http://creativecommons.org/licenses/by-sa/3.0/ or send a letter to Creative Commons, 171 Second Street, Suite
300, San Francisco, California, 94105, USA.
If you plan on using this material for commercial purposes get in touch with us at [email protected]
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