Transcript Folie 1

HEINZ NIXDORF INSTITUTE
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Ad-hoc network communication
infrastructure for multirobot systems in
disaster scenarios
IARP/EURON Workshop on Robotics
for Risky Interventions and
Environmental Surveillance
January 7th-8th, 2008 - Benicàssim
HEINZ NIXDORF INSTITUTE
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Ad-hoc network communication infrastructure
for multi-robot systems in disaster scenarios
Ulf Witkowski
Mohamed El-Habbal
Stefan Herbrechtsmeier
Andry Tanoto
Heinz Nixdorf Institute
University of Paderborn
Jacques Penders
Lyuba Alboul
Sheffield Hallam University
Microsystems and
Machine Vision Lab
Veysel Gazi
TOBB University of
Economics and
Technology, Dept.
Electrical and Electronics
Engineering
• Introduction: GUARDIANS’ scenario
• Objectives of the communication system
• Swarming and positioning
• Implementation – platform and features
• Results
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HEINZ NIXDORF INSTITUTE
Introduction
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Disaster Scenario: Burning large warehouse
 Building with huge dimensions (>100m)
 May be (partly) filled with black smoke
 Technical infrastructure destroyed
 Only local Communication between
firefighters (exchange of commands)
 Orientation of firefighters by applying ropes with nodes indicating direction to exit
Team of robots assisting firefighters by (excerpt)
 Searching and inspection of the building
 Providing communication infrastructure (between firefighters, to operator,
between robots and humans, robot-robot communication)
 Providing position and orientation data
 Guiding firefighters to the exit
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Objectives
of the communication infrastructure
and networking
HEINZ NIXDORF INSTITUTE
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
1. Robust ad-hoc communication system for
•
Communication between
• Humans (HSM – HSM, and HSM - operator)
• Humans and robots (HSM commands/asks robots)
• Robots (for cooperation)
•
to facilitate
• Primary communication
• Service discovery
• Positioning
• Navigational aid for fire fighters and robots
•
by
•
•
•
Combining three (and more) communication technologies
(WLAN, Bluetooth, ZigBee, Chirp-ISM, UWB)
Plus all necessary layers of ISO/OSI model
(including ad-hoc-networking, service discovery, and positioning)
Single antenna, multiple antennas, antenna arrays + MAC-Layer)
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HEINZ NIXDORF INSTITUTE
Objectives
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
of the communication infrastructure
Communication system provides and uses position data
 Useful data for the firefighters
 Eases maintenance of the communication network
 Enables position based / cell based service discovery
 Supports map building (data for operator)
Supports placement of nodes to
span the mobile ad-hoc network
Supports service discovery
(offering and accepting services)
[2]
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HEINZ NIXDORF INSTITUTE
Communication technologies
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Existing radio based communication technologies
WLAN:
• Max. number of nodes: not specified
• Range: 100m (300m), data rate: 54 Mbit/s
• Power consumption: high
Bluetooth:
• Piconet: 8 nodes, Scatternet: Network of Piconets
• Range: 100m, data rate: 2.1 Mbit/s
• Power consumption: low
• Cell forming by adapted frequency hopping
ZigBee:
• Up to 255 nodes
• Range: 75m, data rate: 250 kbit/s
• Power consumption: very low
UWB: Excellent for positioning BUT bad availability
Nanoloc: Two way ranging in ISM band by using chirp signals
• Accuracy of distance measurements: 1-2 m
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HEINZ NIXDORF INSTITUTE
Communication test platform
HNI Minirobot
System
• Processor PXA270 520MHz
• SDRAM 64MB
• NOR Flash 64MB
• FPGA Spartan3E 1600k
Wireless Communication
• ZigBee (UART)
• Bluetooth (UART)
• WLAN (USB-Adapter)
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
static hardware
sensors /
µC /
(motors)
reconfigurable hardware
I2C
GPIO
extensions /
ext. HW /
WLAN
USB
processor
Marvell
PXA270
Bluetooth /
ZigBee /
debug
UART
AC97
Cam
camera
Displ.
touchscreen
Proz.Bus
CPLD
(Config)
FPGA
Spartan 3E
1600
GPIO /
extensions
Powering
SD-/MMCMemory
SDRAM
Flash
Software
• Linux Kernel 2.6.23
• Device Manager (udev)
• GNU C Library (Glibc) 2.5
• Complete Linux environment (Debian like)
• Automated build and packet system (OpenEmbedded)
This robot together with Khepera III is used for experiments
 transfer to large robot (Robotnik)
68 mm
86 mm
93 mm
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HEINZ NIXDORF INSTITUTE
Communication architecture
•
Implementation of a mobile ad-hoc communication
framework for the Linux operating system
on the HNI-minirobot
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Application / Services
Service
Discovery
Data
Exchange
Quality of
Service
Communication Framework
Communication Framework
• Service Discovery: manage, publish and
subscribe of services (data)
• Data Exchange implement data communication
• Quality of Service (and Positioning) interact with
application (swarming) to achieve stable networks
Network
Network
Abstraction
Layer
NetworkAbstraction
AbstractionLayer
Layer
Network
Bluetooth
Bluetooth
(WLAN, Bluetooth, ZigBee, Nanotron, ...)
Network Abstraction Layer
• One common of interface to different networks
•
Development of a hardware module for integration into
other systems (Khepera III and later on Robotnik system)
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Spanning a (mesh of) nodes
for a robust network
Static nodes placement
HEINZ NIXDORF INSTITUTE
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Mesh of equilateral triangles (advantageous area coverage)
Communication cell for mobile robots
 hand over between cells if required
L
60
L
quasi static node
(mobile robot, or
dropped
communication relay)
where L depends on :
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Maximum radio range supported by the communication standard used
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Maximum detection range supported by the distance sensor
(Radar, ultrasonic, LRF or LIDAR, Radio ToF)
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HEINZ NIXDORF INSTITUTE
Swarming
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Swarming is used to (among others) distribute the robots to span a robust
communication network
Non communicative swarming
• Loosely coupled entities with
local interaction
• Used as fall back if communication fails
Communicative swarming
• as standard control mode for robots and the team
• distribution of robots in a triangular grid
for supporting
• Various cooperative behaviors (e.g. navigation, search/exploration,
sensing, area coverage, gradient following, formation control, localization)
by
• Heuristic/ad-hoc, artificial potential functions,
gradient based, probabilistic, game theory, etc.
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HEINZ NIXDORF INSTITUTE
Static nodes placement
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Placement modes
Mode1
Mode1
d1
d1
d2
d2
Mode2
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HEINZ NIXDORF INSTITUTE
Static nodes placement
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Placement modes
Mode1
Mode2
d2
d1
Mode3
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HEINZ NIXDORF INSTITUTE
Experiments - Overview
Hybrid solution for node control/placement:
(1) Distance control <-> signal quality
(2) Distance measurements
(3) Laser range finder (LRF) and comm.
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
L
60
L
Aim: Place the third of three robots to
the correct position to span a
equi-lateral triangle (part of the robot distribution scheme)
Experiments:
(1) Signal quality measurements vs. distance (+obstacles)
WLAN, Bluetooth, ZigBee
(2) Radio based distance measurements
(Several point to point measurements and calculation of robot’s psosition)
(3) Angle measurements with LRF supported by communication
(‘Third’ robot measures its angle to fixed robots by using LRF that can be rotated)
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HEINZ NIXDORF INSTITUTE
Experiment 1
Signal quality measurements
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
100
90
80
70
60
Link Quality [%]
50
Signal Level [%]
40
30
20
10
0
1
15 29 43 57 71 85 99 113 127 141 155 169 183 197 211 225
Time [s]
Signal quality measurements for
WLAN, Bluetooth, and ZigBee
Path length: approx. 90 m, area with path (30m x 15m)
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Experiment 2
Positioning system
HEINZ NIXDORF INSTITUTE
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Scenario: 4 mobile robots, 3 of these are
‘infrastructure’ robots with known positions,
position of the 4th robot has to be
determined  all data is sent to
local server, that display calculated
and actual path of the 4th robot
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HEINZ NIXDORF INSTITUTE
Experiment 3
LRF + communication
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Static node 1
60
Active laser sensor
(ifm-efektor LRF,
rotatable)
Required position
Static node 2
Laser detector
Robot base with
communication module
Mobile Robot
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Experiment 3
LRF + communication
HEINZ NIXDORF INSTITUTE
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
• Mobile robot seeks to move to the desired
position to complete the triangle
• It sends the request to the other static nodes
• Robot initiates wireless connection with
the 2 static nodes using Bluetooth.
• After connection establishment, laser
sensor on robot starts rotating and scanning
for the 2 static nodes. Robot gets feedback
if nodes are hit by the laser beam
• As the 1st node is hit, it sends a reply to
the robot, which stores the distance
at that instant, and inverses its rotation
to search for the other node.
• As the 2nd node is hit, same procedure occurs. Afterwards, using the necessary
triangulation algorithm, the robot calculates the desired angle to rotate and the
desired distance to move to reach its goal.
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HEINZ NIXDORF INSTITUTE
Conclusion and Outlook
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
• Ad-hoc communication network to support firefighters
• Distribution of robots to span the network
(infrastructure robots and mobile nodes)
• Hardware platform combing WLAN, Bluetooth, ZigBee, and
Chirp-ISM
• Experiments for node placement
• Accuracy analysis vs. requirements
• Communication protocol
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HEINZ NIXDORF INSTITUTE
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Thank you for your attention!
Ulf Witkowski
Mohamed El-Habbal
Stefan Herbrechtsmeier
Andry Tanoto
Heinz Nixdorf Institute
University of Paderborn
Jacques Penders
Lyuba Alboul
Sheffield Hallam University
Microsystems and
Machine Vision Lab
Veysel Gazi
TOBB University of
Economics and
Technology, Dept.
Electrical and Electronics
Engineering
http://www.shu.ac.uk/mmvl/research/guardians/
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HEINZ NIXDORF INSTITUTE
Minimizing interference
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
FCC and ETSI radio rules for Bluetooth
•
v1.0 and v1.1:
Hopping channels: 78 (full spectrum)
Hopping rate: 1600 hops/s
•
v2.0:
Hopping channels: 15 (AFH)
Hopping rate: 1600 hops/s
- By using Bluetooth v2.0, spectrum can be divided into 5 channel groups
- 4 groups for intra-cell, and 1 group for inter-cell communication (static nodes)
- A cell that requires more traffic can request the use of more channel groups
from adjacent cells if they are free to use.
1
3
1
2
4
3
2
4
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Experiment 3
LRF + communication
HEINZ NIXDORF INSTITUTE
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Used Hardware
• Laser sensor : ifm-efektor LRF
• Laser detectors : near visible Red photo-transistors
• Communication devices : Mitsumi Bluetooth chips class-1
• Processing Board :
FPGA Virtex-E board with ADC
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Experiment 3
LRF + communication
HEINZ NIXDORF INSTITUTE
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Static node 1
60
Required position
Mobile Robot
Static node 2
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HEINZ NIXDORF INSTITUTE
Experiment 3
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Procedure
•
Mobile robot seeks to move to the desired position to complete the equilateral
triangle.
•
It sends the request to the other 2 static nodes, which should guide him to the
correct position.
•
Robot initiates wireless connection with the 2 static nodes using Bluetooth.
•
After connection establishment, Laser sensor on Robot starts rotating and scanning
for the 2 static nodes. For each rotated step, it requests info from static nodes whether
they are hit by the Laser beam or not.
•
As the 1st node is hit, it sends a positive reply to the Robot, which stores the distance
at that instant, and inverses its rotation to search for the other node.
•
As the 2nd node is hit, same procedure occurs. Afterwards, using the necessary
triangulation algorithm, the Robot calculates the desired angle to rotate and the
desired distance to move to reach its goal.
In our demo, the Laser sensor just rotates with the desired angle and points at its goal.
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Example for determining the position with
Nanotron‘s nanoLOC RF Module
HEINZ NIXDORF INSTITUTE
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
• R1, R2 and R3 are the robots
•
with known coordinates
•
(infrastructure robots)
• They drive to their position from
•
a common start point and
•
get their coordinates by
•
odometry
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HEINZ NIXDORF INSTITUTE
Atmel ATmega128L implementation
University of Paderborn
System and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
• Apart from a package switching process
displayed in the following picture, a driver for
•
controlling the nanoLOC transceiver is
running on the Atmel of the DK – boards
• This driver is written by nanotron and contains
some time critical passages for
•
ranging and it provides the ranging
capabilities
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