Ad-hoc network communication infrastructure for multi- robot systems in disaster scenarios
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Transcript of Ad-hoc network communication infrastructure for multi- robot systems in disaster scenarios
HEINZ NIXDORF INSTITUTE
University of PaderbornSystem and Circuit Technology
Prof. Dr.-Ing. Ulrich Rückert
Ad-hoc network communication infrastructure for multi-
robot systems indisaster scenarios
Ad-hoc network communication infrastructure for multi-
robot systems indisaster scenarios
IARP/EURON Workshop on Robotics for Risky Interventions and Environmental Surveillance
January 7th-8th, 2008 - Benicàssim
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
2
Ad-hoc network communication infrastructurefor multi-robot systems in disaster scenarios
Ulf Witkowski Mohamed El-Habbal
Stefan HerbrechtsmeierAndry Tanoto
Heinz Nixdorf InstituteUniversity of Paderborn
Jacques PendersLyuba Alboul
Sheffield Hallam UniversityMicrosystems and
Machine Vision Lab
Veysel Gazi
TOBB University ofEconomics and
Technology, Dept. Electrical and Electronics
Engineering
• Introduction: GUARDIANS’ scenario
• Objectives of the communication system
• Swarming and positioning
• Implementation – platform and features
• Results
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
3
Introduction
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
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
4
Objectives of the communication infrastructureand networking
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)
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
5
Objectives 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 tospan the mobile ad-hoc network
Supports service discovery(offering and accepting services)
[2]
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
6
Communication technologies
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
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
7
Communication test platformHNI Minirobot
System• Processor PXA270 520MHz• SDRAM 64MB• NOR Flash 64MB• FPGA Spartan3E 1600k
Wireless Communication• ZigBee (UART)• Bluetooth (UART)• WLAN (USB-Adapter)
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)
processorMarvellPXA270
I2C
USB
Powering
sensors /µC /(motors)
GPIO
AC97
Cam
extensions / ext. HW /WLAN
SDRAM
CPLD(Config)
Flash
Proz.-Bus
UART
camera
Bluetooth /ZigBee /debug
GPIO /extensions
SD-/MMC-Memory
static hardware reconfigurable hardware
FPGASpartan 3E
1600Displ. touchscreen
86 mm93 mm
68 mm
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
8
Communication architecture
• Implementation of a mobile ad-hoc communicationframework for the Linux operating systemon the HNI-minirobot
Communication Framework
• Service Discovery: manage, publish andsubscribe of services (data)
• Data Exchange implement data communication
• Quality of Service (and Positioning) interact withapplication (swarming) to achieve stable networks
Network Abstraction Layer
• One common of interface to different networks
• Development of a hardware module for integration intoother systems (Khepera III and later on Robotnik system)
BluetoothBluetoothNetwork(WLAN, Bluetooth, ZigBee, Nanotron, ...)
Communication Framework
ServiceDiscovery
DataExchange
Quality of Service
Application / Services
Network Abstraction LayerNetwork Abstraction LayerNetwork Abstraction Layer
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
9
where L depends on :• Maximum radio range supported by the communication standard used• Maximum detection range supported by the distance sensor
(Radar, ultrasonic, LRF or LIDAR, Radio ToF)
Mesh of equilateral triangles (advantageous area coverage)
L
L
60
Spanning a (mesh of) nodesfor a robust network Static nodes placement
quasi static node(mobile robot, ordroppedcommunication relay)
Communication cell for mobile robots hand over between cells if required
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
10
Swarming
Swarming is used to (among others) distribute the robots to span a robustcommunication network
Non communicative swarming•Loosely coupled entities withlocal 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.
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
11
Static nodes placement
Placement modes
d1 d2
Mode1
Mode2
Mode1
d2
d1
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
12
Static nodes placement
Placement modes
Mode1 Mode2
Mode3d1d2
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
13
Experiments - Overview
Hybrid solution for node control/placement:
(1)Distance control <-> signal quality(2)Distance measurements (3)Laser range finder (LRF) and comm.
Aim: Place the third of three robots tothe correct position to span aequi-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)
L
L
60
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
14
Experiment 1Signal quality measurements
Path length: approx. 90 m, area with path (30m x 15m)
0
10
20
30
40
50
60
70
80
90
100
1 15 29 43 57 71 85 99 113 127 141 155 169 183 197 211 225
Time [s]
Link Quality [%]
Signal Level [%]
Signal quality measurements forWLAN, Bluetooth, and ZigBee
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
15
Experiment 2Positioning system
Scenario: 4 mobile robots, 3 of these are‘infrastructure’ robots with known positions,
position of the 4th robot has to bedetermined all data is sent tolocal server, that display calculatedand actual path of the 4th robot
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
16
Experiment 3LRF + communication
60
Static node 1
Static node 2
Mobile Robot
Required position
Active laser sensor(ifm-efektor LRF,rotatable)
Ro
bo
t b
ase
wit
hco
mm
un
icat
ion
mo
du
le
Laser detector
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
17
Experiment 3LRF + communication
• Mobile robot seeks to move to the desiredposition to complete the triangle
• It sends the request to the other static nodes
• Robot initiates wireless connection withthe 2 static nodes using Bluetooth.
• After connection establishment, lasersensor on robot starts rotating and scanningfor 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 tothe robot, which stores the distanceat that instant, and inverses its rotationto search for the other node.
• As the 2nd node is hit, same procedure occurs. Afterwards, using the necessarytriangulation algorithm, the robot calculates the desired angle to rotate and the desired distance to move to reach its goal.
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
18
Conclusion and Outlook
• 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
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
19
http://www.shu.ac.uk/mmvl/research/guardians/
Thank you for your attention!Thank you for your attention!
Ulf Witkowski Mohamed El-Habbal
Stefan HerbrechtsmeierAndry Tanoto
Heinz Nixdorf InstituteUniversity of Paderborn
Jacques PendersLyuba Alboul
Sheffield Hallam UniversityMicrosystems and
Machine Vision Lab
Veysel Gazi
TOBB University ofEconomics and
Technology, Dept. Electrical and Electronics
Engineering
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
20
Minimizing interference
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 2
3 4
1 2
3 4
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
22
Experiment 3LRF + communication
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
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
23
Experiment 3LRF + communication
60
Static node 1
Static node 2
Mobile Robot
Required position
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
24
Experiment 3
Procedure
• Mobile robot seeks to move to the desired position to complete the equilateraltriangle.
• It sends the request to the other 2 static nodes, which should guide him to thecorrect position.
• Robot initiates wireless connection with the 2 static nodes using Bluetooth.
• After connection establishment, Laser sensor on Robot starts rotating and scanningfor the 2 static nodes. For each rotated step, it requests info from static nodes whetherthey 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 distanceat that instant, and inverses its rotation to search for the other node.
• As the 2nd node is hit, same procedure occurs. Afterwards, using the necessarytriangulation 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.
• Laser detectors : near visible Red photo-transistors
• Communication devices : Mitsumi Bluetooth chips class-1
• Processing Board :FPGA Virtex-E board with ADC
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
25
Example for determining the position withNanotron‘s nanoLOC RF Module
• 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
• T is the robot which position• has to be calculated
• The distance between R1 & T,
• R2 & T and R3 & T is measured
• with the Nanotron Transceiver
• The position of T can be• calculated by solving a system• of equations.•
HEINZ NIXDORF INSTITUTEUniversity of Paderborn
System and Circuit TechnologyProf. Dr.-Ing. Ulrich Rückert
26
Atmel ATmega128L implementation
• 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
• The package switching process forwards communication packages in both direction and• filters ranging package from the PDA processor to start a ranging process