ryukoku university, japan dr. wataru uemura - leuphana.de · about communication • we use three...

Ryukoku University, Japan Dr. Wataru Uemura

About communication

About communication

• We use three robots on RCLL. • They need to communicate with each other

in order to make cooperative actions. • In multi-agents system,

it is difficult to select the leader from all robots because they are equal as a role.

• Sharing information is very important.

Ryukoku University Wataru UEMURA

Sharing information system

• Carologistics proposed BlackBoard. • I proposed the Sharing Information System

for the disaster scene on ad-hoc network


Tim. N., et al., “Decisive Factors for the Success of the Carologistics RoboCup Team in the RoboCup Logistics League 2014”, RoboCup 2014: Robot World Cup XVIII, p. 158, (2014).

Black Board proposed by FAWKES

• Sharing the same information – on Virtual Black Board

• If one node is down – the remain nodes can hold the

information still. • Nodes need not to consider

– the network topology • because this runs over the application layer.

– the confliction of information • because all nodes connects to the same

network.

Virtual Black Board

Robot #1

BlackBoard

Robot #2

BlackBoard

Robot #3

BlackBoard


Robot communications and Ad hoc network communications • Robot Communications

– All robots can communicate with each other via one access point.

– No conflict information because the network is not down.

• Ad Hoc Network Communications – All nodes cannot

communicate directly, so internal nodes need to relay packets.

– Some conflict information because the network is distinguished.


September 30,2009 Sumatra-Andaman earthquake March, 11, 2011 Great eastern Japan earthquake

http://seattletimes.nwsource.com/html/picturethis/2014480706_pt_japan_earthquake.html http://www.tfd.metro.tokyo.jp/hp-dai6honbu/6hr/index.htm

Wireless networks are down because access points are broken.

Large-scale disasters accidents


http://seattletimes.nwsource.com/html/picturethis/2014480706_pt_japan_earthquake.html

http://seattletimes.nwsource.com/html/picturethis/2014480706_pt_japan_earthquake.html

http://www.tfd.metro.tokyo.jp/hp-dai6honbu/6hr/index.htm



Sharing between doctors and rescuers •Triage (priority) Information •Position of Injured people •Delivery situation

rescuers

Injured people and doctors

Delivery troops

Information aggregation and distribution

Sharing triage information system with our proposed protocol (2011).


Notebook NetWalker

OS Ubuntu9.04

CPU Freescale i.MX515(800MHz)

About our prototype system

• NetWalker made by SHARP is used as ad-hoc mobile node.


Conventional wireless networks

• An access point (base station) is required. • A node communicates with an AP. • A network cannot work if an AP is down. • An AP must cover all of its communication area.


About ad-hoc network

• The network consists of only nodes. • No AP is required.

– Peer to Peer communication (p2p) • Intermediate nodes relay packets

from the source node to the destination node. – Routing Protocol – Multi-Hop


Applications on ad-hoc network

• Ad hoc network applies to – the place where a wired network is constructed difficulty. – the place where an infrastructure is damaged.

• Apply to the local area. – Military service – Disaster relief – Vehicle networks – And so on…


Routing protocols for ad hoc network

• Reactive type – AODV

• Send control packets to make a route.

• Proactive type – OLSR

• Send control packets to maintain a route. • Flooding • MPR (Multipoint Relay)


Ad hoc network is maintained by routing protocols • Routing protocols run over

– the network layer. • A software runs over

– The application layer.

• Using my proposed protocol a software sharing information runs network layer in order to decrease the network traffic.

7 Application Layer

6 Presentation Layer

5 Session Layer

4 Transport Layer

3 Network Layer

2 Data Link Layer

1 Physical Layer

OSI Model


Proposed routing protocol

• We use control packets of network layer as broadcasting packets of application layer.

• In other words, node sends control packets including information to share among all nodes.

• Then nodes can maintain the route, and share the information at the same time.


Overview of proposed protocol

1. A node splits the information into the packets, and broadcasts it to neighboring nodes.

2. After receiving a packet, the node add it to the sending queue.

3. If the node receives the same packet, it is ignored.

4. A node takes one packet from the sending queue, and broadcasts it to neighboring nodes.

※A node announces the message and reports its status.

1. A node receiving the packet records which node sent it.

2. If the node wants to send the message to the source node, the packet can be delivered using the reverse path.

1. Broadcast the packet to neighboring node.

Node #1

Node#2

2. Add the receiving packet to the sending queue.

● ■ ▲ ●

● ▼ ■ ▲

Node#3

▲ ■ ◆ ▲

Node#n

※ ◆ ▲ ▼

●

●

4. Relay the packet.


• Nodes do not keep the information. • They only broadcast packets to neighboring

nodes.

• Now I would like to modify my protocol like as Black Board. – How to avoid the conflict.

About our proposed protocol (2011).


Experiments

• There are 11 nodes including 1 sender node and 10 receiver nodes.

• All nodes in 1 hop communication • All nodes in multi hops communication


1 hop experiment • We set n nodes in all

communication area. • So they can communicate

with each other in 1 hop. • Find the time at which the

sender gets ACK packet from the receiver.


Result - 1 hop

0

0.01

0.02

1 2 3 4 5 6 7 8 9 10

Del

ay T

ime(

s)

The number of nodesRyukoku University Wataru UEMURA

Multi hops experiment • We set n nodes, each node has

only 1 or 2 neighboring nodes. • So they cannot communicate

with each other in 1 hop except for their neighboring nodes.

• Find the time at which the sender gets ACK packet from the receiver.


Result - multi hops

0

20

40

1 2 3 4 5 6 7 8 9 10

Del

ay T

ime(

s)

The number of hopsRyukoku University Wataru UEMURA

Discussion

• 1 hop environment – The constant broadcasting time.

• Multi hops environment – The broadcasting which has below 8 hops are fast.

• Our protocol makes ad-hoc network efficiently.


Conclusion

• Routing protocol for ad-hoc network – Both network layer and application layer are

independent • Our proposed protocol

– Both network layer and application layer use the same control packet as broadcasting information.


Acknowledgement

• This work was supported in part by MEXT Grant-in-Aid for Young Scientists (B) 21710188.


But I did not implement this protocol

• I thought that I can implement a communication class to robots in not only Leuphana but also Ryukoku.

• So I should implement another class. – I don’t have enough space to run a robot. – I must implement

• a drive class in order to run a robot. • a sensor class in order to estimate a robot’s location.


ryukoku university, japan dr. wataru uemura - leuphana.de · about communication • we use three...

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