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006Architectural Design & Evaluation Architectural Design & Evaluation

Of An Industrial AGV Transportation System Of An Industrial AGV Transportation System With A Multiagent System ApproachWith A Multiagent System Approach

SATURN, 2006

Danny Weyns

DistriNet, Dept. Computer Science,

Katholieke Universiteit Leuven Belgium

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OverviewOverview

• AGV Transportation System

• Software Architecture, ADD

• ATAM o Utility tree

o Analysis of architectural approach

• Some lessons learned

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AGV Transportation SystemAGV Transportation System

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Main FunctionalitiesMain Functionalities

• Transport assignment

• Execution transports

• IO with machines

• Collision avoidance

• Deadlock prevention

• Battery charging

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Main Quality GoalsMain Quality Goals

• Performance o Transports/hour – bandwidth

• Flexibilityo Deal with change autonomously, exploit opportunities

• Opennesso Deal with AGVs that dynamically leave and enter the

system

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• Centralized architectureo Server assigns transports to AGVs, plans routes etc.

o Low level control AGVs is handled by E’nsor software

• Main quality attributeso Configurability (server is central configuration point)

o Predictability (server manages execution of functionality)

Traditional Traditional approachapproach

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EMCEMC2 2 ProjectProject

• Collaboration Egemin – DistriNet

• Project: 2004 – 2006 (4 FT)

• Main Goal o Cope with quality requirements: flexibility and openness

o Investigate feasibility of applying decentralized architecture for AGV transportation system

• Approach: Situated Multiagent System

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Situated Multiagent SystemSituated Multiagent System

• What is a situated multiagent system (MAS)? o Set of autonomous entities (agents) explicitly situated in a

shared structure (an environment)

o Agents select actions “here and now”, they do not use long term planning (locality in time and space)

o Interaction is at the core of problem solving (rather than individual capabilities)

Decentralized control

Adaptive behavior

Collective behavior

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OverviewOverview

• AGV Transportation System

• Software Architecture, ADD

• ATAM o Utility tree

o Analysis of architectural approach

• Some lessons learned

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Software ArchitectureSoftware Architecture

• Architectural design processo Principles from Attribute Driven Design (ADD)

Recursive decomposition: select drivers, apply architectural approaches

o Guided by: Reference architecture for situated MAS

ObjectPlaces middleware

• Documentationo Architectural views / view packets

Deployment -- Module -- Component and Connector

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Overview of the reference architectureOverview of the reference architecture

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Deployment View: SystemDeployment View: System

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Module Uses View: AGV Control SystemModule Uses View: AGV Control System

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Communicating Communicating Processes View:Processes View:Move action AGVMove action AGV

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AttributeAttribute--Driven DesignDriven Design

• ADD with reference architectureo Reference architecture

blueprint for architectural design

provides build-in mechanisms

o ADD is helpful

as a design approach

for refinement

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OverviewOverview

• AGV Transportation System

• Software Architecture

• ATAMo Utility Tree

o Analysis of architectural approach

• Some lessons learned

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Architecture TradeArchitecture Trade--Off Off Analysis MethodAnalysis Method

• Goals ATAMo Articulation of business goals

o A concise presentation of the architecture

o Utility tree

o Mapping architectural decisions to quality requirements

o Tradeoff points, risks, non-risks

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ATAM for AGV ATAM for AGV Transportation SystemTransportation System

• AGV Software Architectureo Developed independent of concrete system (Product Line like)

o Evaluation in context of particular project (tobacco warehouse)

• Preparation o Preparation utility tree (+ 4 days / 3 stakeholders, 1 evaluator)

• ATAM o June 16th, 2005 -- 10 stakeholders, 2 evaluators

o Presentations: ATAM, business goals, architecture, approaches

o Generation utility tree - analysis architectural approaches

o Round-up

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OverviewOverview

• AGV Transportation System

• Software Architecture

• ATAM o Utility Tree

o Analysis of architectural approach

• Some lessons learned

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Utility treeUtility tree(fragment)(fragment)

relative importance complexity to realize

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OverviewOverview

• AGV Transportation System

• Software Architecture

• ATAM o Utility Tree

o Analysis of architectural approach

• Some lessons learned

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Analysis Architectural approachAnalysis Architectural approach

S3AD 5 Unicastcommunication in Middleware

R3AD 4 Two steps deadlock prevention mechanism

T3AD 3 Dynamic Contract-Net protocol for transport assignment

R2T2AD 2 Agent located on machine controls E’GV

NR3S2AD 1 Choice for .NET remoting

NonrisksRisksTradeoffSensitivityArchitectural decisions

Scenario: The amount of communication, with maximal 12 E’GVs and a maximal load of 140 transports per hour, does not exceed 60% of the bandwidth of the 11Mbps communication channel.

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OverviewOverview

• AGV Transportation System

• Software Architecture

• ATAM o Utility Tree

o Analysis of architectural approach

• Some lessons learned

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Some Lessons LearnedSome Lessons Learned

• Software architectureo We gained a better insight in

Role of SA in building complex systems

Relationship between MAS and SA

o Qualities trade off (flexibility versus performance)

o SA constraints the system implementation

o Lack of tool support to document SA

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Some Lessons LearnedSome Lessons Learned

• ATAMo Utility Tree = most important instrument, yet time

consuming -> good preparation is necessary

o A complete evaluation of a complex system such as the AGV system is not manageable in one day

o Evaluation of specific case versus product line like basic architecture hindered the discussions

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Thanks!

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Analysis Architectural approachAnalysis Architectural approach

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