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