Control Architecture for Flexible Production Systems

CONTROL ARCHITECTURE FOR FLEXIBLE PRODUCTION SYSTEMS

Bengt Lennartson, Martin Fabian, Petter FalkmanAutomation Laboratory, Department of Signals and SystemsChalmers University of TechnologyGöteborg, Sweeden

From the Proceedings of the 2005 IEEE International Conference on Automation Science and Engineering Presented byB. Taylor Newill12 November 2007

I – BACKGROU

ND AN

D STRATEGY (PG307)Flexible Production System

Easy to change production volume and flow Easy to modify and upgrade production equipment

Hardware Software

Simultaneously produce different products in a single production cell or unit

Current Capabilities

Highly flexible resourcesRobotsMachine toolsHumans

Non flexible resourcesSoftwareController hardware

Desired Capabilities

“Generic system architecture”Create one model that can be applied to all

processes and then optimize the modelParallel Execution

Benefits

DiagnosticsInformation HandlingOptimizationVerification

II – CON

TROL ARCHITECTU

RE FOR FPS (PG307-

308)Generic System Architecture

Production system where both hardware and software are flexible

Separation of resources – simplify handling changes to the system

Enables parallel execution

Scalable

Architecture Hierarchy

Architecture applicable to all levels

Applicable throughout the lifecycle

III – RESOU

RCES (PG308-309)Generic Resource Models (GeRMs)

ProducersMachine-toolsTanksReactors

MoversRobotsAGVsPipesPumps

LocationsBuffers

Generic Message-Passing Structure (GeMPS)

State Machine Structure Command Messages Handshake Messages

Capabilities

Coordination

IV – CON

TROLLER (PG 310-311)

The Controller

Three Controller TasksSupervisionSchedulingDispatching

Supervisor

Scheduler

Dispatcher

Chooses which product route accesses which resourceChooses an algorithm

Uses GeRMs to control with GeMPSTracks individual productsComputes the algorithm

Synchronize object utilization of common available resourcesAvoid blocked statesCreates algorithms

V – CON

TROLLER (PG 310-311)

Example Process Tree

5 Resource Models E.g. Parts of a paint

2 Product Specifications E.g. Colors, Red and Green

bxpy = “book” resource x for product yuxpy = “un-book” resource x for product y

VI – APPLICATION

(PG 311-312)Example Applications

Scania Trucks and BusesRear-axle manufacturing cell

Multi Purpose Batch Plants (MPBP)

Complex Robot Cells

State Based Control

Volvo CarsParallel operation listsBoolean resources

Product flow is sequential

Often multiple robots in a single cellResource is physical space

VII – CON

CLUSIO

NS

Conclusions

Enables Parallel Execution

Architecture for flexible production systems

Separates resources and processesEasier to diagnose and/or optimize systemsCreate better modelsTheoretically basedParallel execution

Adaptable to environment changes

Respects life-cycle

Highly resilient to disturbances (both internal and external)

Self proclaimed efficiency exceeds Holonic, Fractal, Bionic architectures