COMMUNICATION SYSTEM FOR AUTONOMOUS HELICOPTER

1
COMMUNICATION SYSTEM FOR AUTONOMOUS HELICOPTER

• Group 736
• Control engineering, Aalborg University, December
  2005
• Jeppe Søndergaard Larsen
• Martin Holm Pedersen
• Per Horn Petersen
• Kenneth Sparre Sørensen
• Örn Viðarsson
• Kasper Winther

2
Agenda

• Semcon presentation (Kasper)
• Alternative methods (Örn)   
• SCTP (Kenneth)
• GUI (Per)
• Test (Jeppe)
• Poster presentation (Martin)

3

• International Aerial Robotics Competition (IARC)
• Mission example

4

• International Aerial Robotics Competition (IARC)
• Mission example

- Nuclear reactor melt down
5

• International Aerial Robotics Competition (IARC)
• Mission example

- Nuclear reactor melt down
- Quarantine zone radius 3 km
6

• International Aerial Robotics Competition (IARC)
• Mission example

- Nuclear reactor melt down
- Quarantine zone radius 3 km
- Pictures of control gauges needed
7

• International Aerial Robotics Competition (IARC)
• Mission example

- Nuclear reactor melt down
- Quarantine zone radius 3 km
- Pictures of control gauges needed
- Radiation destroys Unmanned Aerial Vehicle
(UAV) within 15 minutes
8

• Unmanned Aerial Vehicle

9
Helicopter

• The Communication System
• requirements

Application
Ground Station
Application
10
Helicopter

• The Communication System
• requirements

Application
Minimum range 3 km
Ground Station
Application
11
Helicopter

• The Communication System
• requirements

Application
Minimum range 3 km
Minimum bandwidth 8320 bps
Ground Station
Application
12
Helicopter

• The Communication System
• requirements

Application
Minimum range 3 km
Minimum bandwidth 8320 bps
Ground Station

• Challenge
• Maintain high bandwidth (min. 11 mbit/s) within
  close range

Application
13
Helicopter

• The Communication System
• requirements

Application
Minimum range 3 km
Minimum bandwidth 8320 bps
Ground Station

• Challenge
• Maintain high bandwidth (min. 11 mbit/s) within
  close range
• Present data in a comprehensible way on the
  ground station

Application
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Helicopter
Server application
Ground Station
Client application
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Helicopter

• Communication
• Close range WLAN

Server application
WLAN
Rated range 300 m, bandwidth 54 mbit/s
Ground Station
WLAN
Client application
16
Helicopter

• Communication
• Close range WLAN
• Long range Radio modems

Server application
WLAN
Modem
Rated range 300 m, bandwidth 54 mbit/s
Rated range 5 km, bandwidth 19 200 bps
Ground Station
Modem
WLAN
Client application
17
Helicopter

• Communication
• Close range WLAN
• Long range Radio modems
• Serial Line IP (SLIP)

Server application
WLAN
SLIP
Modem
Rated range 300 m, bandwidth 54 mbit/s
Rated range 5 km, bandwidth 19 200 bps
Ground Station
Modem
WLAN
SLIP
Client application
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Helicopter

• Communication
• Close range WLAN
• Long range Radio modems
• Serial Line IP (SLIP)

Server application
WLAN
SLIP
Modem
Rated range 300 m, bandwidth 54 mbit/s
Rated range 5 km, bandwidth 19 200 bps
Ground Station
Modem
WLAN
SLIP
Client application
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Helicopter

• Communication
• Close range WLAN
• Long range Radio modems
• Serial Line IP (SLIP)

Server application
WLAN
SLIP
Modem
Rated range 300 m, bandwidth 54 mbit/s
Rated range 5 km, bandwidth 19 200 bps
Ground Station
Modem
WLAN
SLIP
Client application
20
Helicopter

• Communication
• Close range WLAN
• Long range Radio modems
• Serial Line IP (SLIP)

Server application
WLAN
SLIP
Modem
Rated range 300 m, bandwidth 54 mbit/s
Rated range 5 km, bandwidth 19 200 bps
Ground Station
Modem
WLAN
SLIP
Client application
21
Helicopter

• Communication
• Close range WLAN
• Long range Radio modems
• Serial Line IP (SLIP)

Server application
WLAN
SLIP
Modem
Rated range 300 m, bandwidth 54 mbit/s
Rated range 5 km, bandwidth 19 200 bps
Ground Station
Modem
WLAN
SLIP
Client application
22
Helicopter

• Communication
• Close range WLAN
• Long range Radio modems
• Serial Line IP (SLIP)

Server application
WLAN
SLIP
Modem
Rated range 300 m, bandwidth 54 mbit/s
Rated range 5 km, bandwidth 19 200 bps
Ground Station
Modem
WLAN

• Stream Control Transmission Protocol (SCTP)

SLIP
Client application
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• SCTP features
• Connection-oriented

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• SCTP features
• Connection-oriented
• Reliable

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• SCTP features
• Connection-oriented
• Reliable
• Multistreaming (multiple independent data
  streams)

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• SCTP features
• Connection-oriented
• Reliable
• Multistreaming (multiple independent data
  streams)
• Multihoming (multiple IP addresses at each
  endpoint)

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• Client application

Data
Shared memory
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• Client application

Data
Shared memory
3D data representation thread
SCTP client thread
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• Client application

Data
Shared memory
Semaphore
3D data representation thread
SCTP client thread
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• Client application
• 3D representation thread
• Irrlicht API (C)

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• Client application
• 3D representation thread
• Irrlicht API (C)
• OpenGL hardware acceleration

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• Client application
• 3D representation thread
• Irrlicht API (C)
• OpenGL hardware acceleration
• Initialization process
• Create scene elements

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• Client application
• 3D representation thread
• Irrlicht API (C)
• OpenGL hardware acceleration
• Initialization process
• Create scene elements
• While loop
• Draw elements and update scene

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3D representation thread
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Range test
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Range test - Radio modems may need Radio
Line-of-sight
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• Conclusion
• SCTP provides the functionality needed for this
  communication system

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• Conclusion
• SCTP provides the functionality needed for this
  communication system
• Other long-range communication devices should be
  acquired

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• Conclusion
• SCTP provides the functionality needed for this
  communication system
• Other long-range communication devices should be
  acquired
• Data representation may be extended to e.g. 2D
  graphs, and the user interface further developed

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• Conclusion
• SCTP provides the functionality needed for this
  communication system
• Other long-range communication devices should be
  acquired
• Data representation may be extended to e.g. 2D
  graphs, and the user interface further developed
• A fully functional communication system is
  developed
• Using two redundant connections, enabling
  transparent transition between long-range and
  high bandwidth communication

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• Conclusion
• SCTP provides the functionality needed for this
  communication system
• Other long-range communication devices should be
  acquired
• Data representation may be extended to e.g. 2D
  graphs, and the user interface further developed
• A fully functional communication system is
  developed
• Using two redundant connections, enabling
  transparent transition between long-range and
  high bandwidth communication
• Reliable

42

• Conclusion
• SCTP provides the functionality needed for this
  communication system
• Other long-range communication devices should be
  acquired
• Data representation may be extended to e.g. 2D
  graphs, and the user interface further developed
• A fully functional communication system is
  developed
• Using two redundant connections, enabling
  transparent transition between long-range and
  high bandwidth communication
• Reliable
• Portable to other applications

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Alternative methods

• Örn Viðarsson

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Agenda

• Bridging
• Custom packet forwarding
• TCP sockets

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Bridging

• Spanning Tree Protocol (STP)
• 12s transition time
• Rapid Spanning Tree Protocol (RSTP)
• Transition time in order of -
• milliseconds

-Both ethernet devices have to be initialized to
IP 0.0.0.0 -Virtual Ethernet Device on top of
SLIP
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Custom packet forwarding
SSH
Socket
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(No Transcript)
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TCP Socket
OSI model
TCP/IP model
sockets
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-The socket is initialized to -Family IPv4
(IPv6, Unix domain protocols) -Type Stream
socket (datagram socket, raw socket) -Protocol
0, means that the default combination of
family and type is selected (TCP, UDP,
SCTP) -Bind() function -Binds the well known
port to the socket -Listen() function -Moves the
socket from the closed to listen state -Accept()
function -Accepts a connection from a client and
returns a new socket descriptor
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TCP server client application
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SCTP

• Stream Control Transmission Protocol
• Kenneth Sparre Sørensen

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SCTP-Agenda

• Overview of SCTP
• Features of SCTP
• Comparison with other protocols

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Overview of SCTP

• SCTP is a reliable transport protocol (RFC2960)
• Has built-in support for multi-homed hosts
• Is message-based
• Classifies messages as
• Sequenced delivery of user message within
  multiple streams
• With an option for un-ordered delivery of
  individual user messages
• Additional security mechanisms

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Overview of SCTP

• Message Format

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Features of SCTP

• Connection setup (four-way handshake)

INIT
INIT-ACK
COOKIE-ECHO
COOKIE-ACK
Client
Server
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Features of SCTP

• Multi-streaming

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Features of SCTP

• Multi-homing

Internet
X
Client
Server
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Features of SCTP

• SACK in Data sending

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Features of SCTP

• Connection close

SHUTDOWN
SHUTDOWN-ACK
SHUTDOWN-CMPL
Client
Server
No Half Closed State
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Features of SCTP

• Comparison of features with TCP and UDP

Courtesy Addison Wesley
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GUI for GS

• Graphical User Interface for Ground Station
• Per Horn Petersen

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GUI-Agenda

• Overview of GUI
• 3D engine Irrlicht
• Why Euler Transformation
• Update frequency

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Overview of GUI

• 3D representation shows the
• Current Position (x,y,z)
• Current Speed
• Current Rotation (Roll, Pitch and Yaw)
• Current Rotation rates
• Flightpath in 2D (3D long distance view)
• 2D Graphs could show these develop in time
• (not implemented)

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Rear view
Position window
Roll view
Pitch view
Yaw view
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3D engine Irrlicht

• Open Source
• Platform independent
• C
• Looking at the existing classes as data types,
  makes it possible to look at C just as if is it
  was C
• Irrlicht utilizes the Open GL

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Why Euler Transformation

• BECAUSE OF TWO COORDINATE
• SYSTEMS
• The helicopter rotates around its own coordinate
  axes, that rotates along with the helicopter
• The method used is a so called 3-2-1
  transformation, which means first the 3D model
  is rotated around the Z-axis, then the Y-axis and
  last the X-axis
  (different order gives different result)
• Rotations in the GUI must be consistent to the
  helicopters rotations and these are given in
  Euler angles.
• An example that shows the difference between
  Euler transformation and no Euler transformation

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Without the Euler Transformation Notice Other
angles are zero
Axis to pitch around
Axis to roll around
Axis to yaw around
Axis to pitch around
Axis to roll around
With the Euler Transformation
Axis to yaw around
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Update frequency

• The 3D model only moves when new helicopter data
  is present in shared memory
• The 3D model moves non continuous
• It could be possible to estimate a route so the
  3D model could move continuously in non real time
  (delayed at least one sample)
• A higher update frequency (than 5 Hz) could make
  it possible to fly the helicopter by looking at
  the GUI if the scenery was more real

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TEST

• of Radio Modems and WLAN
• Jeppe Søndergaard Larsen

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Requirement specification

• Radio Modem
• Transmission range at least 3 km.
• Transfer 208 bytes with 5 Hz (8320 bps).
• WLAN
• Transmission range at least 200 m.
• 54 Mbps

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TEST

• Two test for the Radio Modems
• Along Limfjorden
• On the beach in Blokhus
• One test for the WLAN

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Radio Modem Test along Limfjorden
Level crossing
Flydedokken
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Results of Radio Modem test

• Only every ninth ping packet received.
• A second test with SCTP package was canceled.
• SCTP was tested on a shorter distance of 500 m
• Transmission frequency of 4,43 Hz.
• 56 of the maximum rate of 19 200 bps.
• The requirement specification is not fulfilled.
• Possible because of The Fresnel Zone, or poor
  Radio Modems.

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The Fresnel Zone

• Radio LOS
• A least 60 must be free for obstacles
• Radius

• d2.4km, f2.4GHz gt r8.66m
• Only 60 has to be free gt 5.2m

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Radio Modem Test in Blokhus

• Worse than expected.

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Results of WLAN test

• Better than expected.