extruder automation with learning control 2009 m. pandit 3 extruder automation with learning control...
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Extrusion 2009 Extrusion 2009 M. PanditM. Pandit1
Extruder Automation with Learning Control Extruder Automation with Learning Control
Extruder Automation with Learning ControlExtruder Automation with Learning Control
Madhukar Pandit, Madhukar Pandit, University of Kaiserslautern, 67653 Kaiserslautern, GermanyUniversity of Kaiserslautern, 67653 Kaiserslautern, Germany
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Extruder Automation with Learning Control Extruder Automation with Learning Control
AUTOMATION TASKS TO BE PERFORMED in EXTRUSIONAUTOMATION TASKS TO BE PERFORMED in EXTRUSION
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Means availableSensors
Methods and Algorithms for control
Hardware and Methods for signal processing andcommunication
Tasks involved
Control of motion, temperature, force etc.
Archiving and data evaluation
Monitoring Visualisation of Process variables
Alarms and Interlocks
Goal
Raise quality, increase productivity
AUTOMATIONAUTOMATION TASKS TASKS -- General General --
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Extruder
ram
billetpyrometer
profile
position-sensor
die
Ofen
hydraulics
PLC
PLC
billet billetbillet
pyrometer
Isothermal Isothermal –– IsorateIsorate ExtrusionExtrusion
For productivity:For productivity:Maximise extrusion rateMaximise extrusion rate
For product quality:For product quality:Extrude under prescribedExtrude under prescribed
conditions e.g. extrusion conditions e.g. extrusion
temperature and ratetemperature and rate
Goal:Goal: Increase productivity,Increase productivity,
enhance product qualityenhance product quality
To achieve both simultaneously:To achieve both simultaneously:Employ tight control ofEmploy tight control of
extrusion rate and extrusion rate and
temperaturetemperature
AUTOMATIONAUTOMATION TASKS in TASKS in EXTRUDERSEXTRUDERS
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ContentsContents
11 INTRODUCTIONINTRODUCTION
22 AUTOMATION TASKS TO BE PERFORMED AUTOMATION TASKS TO BE PERFORMED
33 IMPLEMENTATION: Measurement and ControlIMPLEMENTATION: Measurement and Control
44 CONTROL: Modelling CONTROL: Modelling Iterative Learning ControlIterative Learning Control
55 A STATEA STATE--OFOF--THE ART AUTOMATION SYSTEMTHE ART AUTOMATION SYSTEM
66 CONCLUSIONS AND PERSPECTIVESCONCLUSIONS AND PERSPECTIVES
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ExtrusionRam movement Control
2. AUTOMATION TASKS TO BE PERFORMED in EXTRUSION2. AUTOMATION TASKS TO BE PERFORMED in EXTRUSION
Billet HandlingBillet transportBillet loading Billet heating Control
Profile Handling Assess profile properties Image processingCool profilePuller movement Control
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For optimal production:
Prescribe values of relevant process variables appropriately
Extrude such that the variables takeon the prescribed values
Process variables:
Billet temperature,
Extrusion force, Ram speed, Profile speed
Profile exit temperature,
Cooling of Profile
2. AUTOMATION TASKS TO BE PERFORMED in EXTRUSION2. AUTOMATION TASKS TO BE PERFORMED in EXTRUSION
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For choosing values appropriately
• Use experienceUse experience
•• Gather data, analyse it and store Gather data, analyse it and store optimal values in a dataoptimal values in a data--bank andbank andretrieve when requiredretrieve when required
To extrude such that values of the variables are
held in prescribed ranges• Display process variables and let the Display process variables and let the
operator control inputs manually operator control inputs manually
•• Use automatic controlUse automatic control
•• Use a combination of bothUse a combination of both
Data Acquisition Task
ControlControl TaskTask
VisualisationVisualisation TaskTask
2. AUTOMATION TASKS TO BE PERFORMED in EXTRUSION2. AUTOMATION TASKS TO BE PERFORMED in EXTRUSION
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Extrusion Extrusion Control TaskControl Task
Adjust billet temperature and ram speed such that the process Adjust billet temperature and ram speed such that the process
variables variables
Billet temperature, Billet temperature,
Profile exit temperature, Profile exit temperature,
Profile speed Profile speed
Max. extrusion forceMax. extrusion force
Cooling rateCooling rate
lie within the prescribed ranges and extrusion speed is maximumlie within the prescribed ranges and extrusion speed is maximum
3 IMPLEMENTATION: Measurement and Control 3 IMPLEMENTATION: Measurement and Control ……
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2. Feed2. Feed--back controlled extrusion:back controlled extrusion:
Measure Measure process variables and adjust the input variables process variables and adjust the input variables
such that the desired runs are obtained.such that the desired runs are obtained.
Direct FeedDirect Feed--backback FeedFeed-- back over the cyclesback over the cycles
1. Simulated extrusion:1. Simulated extrusion:
Make calculations using simulation studies and calculate billet Make calculations using simulation studies and calculate billet
temperature and ram speedtemperature and ram speed ((Profile temperature not Profile temperature not
measured during extrusionmeasured during extrusion))
Methods of performing the Extrusion Control TaskMethods of performing the Extrusion Control Task
…… 3 IMPLEMENTATION: Measurement and Control3 IMPLEMENTATION: Measurement and Control
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-- for measurement and control systems for temperature of for measurement and control systems for temperature of billet and profile exit with nonbillet and profile exit with non-- contact radiation pyrometers contact radiation pyrometers
NonNon-- contact temperature measurementcontact temperature measurement
…… 3 IMPLEMENTATION: Measurement and Control3 IMPLEMENTATION: Measurement and Control
0 50 100 150 200 250 300510
520
530
540
Time t in s
Ou
tput of ca
usal filte
r y
0 50 100 150 200 250 300510
520
530
540
Time t in sO
utp
ut of n
on-c
au
sal filter
y
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Objectives: Isothermal Extrusion Control Isothermal Isorate Extrusion ControlRobustness of control
Control inputs: Extrusion velocityBillet temperature / - taperValve position of hydraulicsVelocity of billet/quench ring
hitherto: Feedforward control (simulated extrusion)Feedback control (on-line)
now: Employ control from cycle to cycle
Iterative Learning Control (ILR)
Strategy for Extrusion Control
…… 3 IMPLEMENTATION: Measurement and Control3 IMPLEMENTATION: Measurement and Control
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Learning algorithm( Predictive feedLearning algorithm( Predictive feed-- forward adaptive feedforward adaptive feed-- back) :back) :
uk+1(l) = uk(l) + ∆∆∆∆uk+1(l) (Optimal ram speed / billet temp.)
∆∆∆∆uk+1(l) = F[ϑϑϑϑd(l), ϑϑϑϑk(l), ϑϑϑϑk+1(l), ϑϑϑϑΒ Β Β Β k(l), ϑϑϑϑΒ Β Β Β k+1(l), pk+1(l), vk(l),vk+1(l), ∆ϑ∆ϑ∆ϑ∆ϑk+1 ]
with:ϑϑϑϑd(l) : Desired run of exit temperature uk(l) : Input as a function of extruded length of cycle k
vk(l) : Ram velocity in current cycle k
ϑϑϑϑk(l) : Run of exit temperature in previous cycle k∆∆∆∆uk+1(l) : Increment of input calculated for cycle k+1
ϑϑϑϑΒ Β Β Β k(l) : Billet temperature in cycle kpk+1(l) : Extrusion force in current cycle
4 CONTROL: Modelling and Iterative Learning Control 4 CONTROL: Modelling and Iterative Learning Control ……
F[F[……] to be chosen (based on] to be chosen (based on modelmodel ) for fast convergence. ) for fast convergence.
With With exact modelexact model convergence to optimal input in 1 cycle !convergence to optimal input in 1 cycle !
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Notation Notation
x : position of ram with respect to its starting point ,
t : time elapsed since the beginning of extrusion
v(x,t ) : velocity of the ram when it is at position x
ϑϑϑϑB(x,t): billet temperature
ϑϑϑϑP(x,t) : profile temperature
F(x,t) : extrusion force
ϑϑϑϑR(t) : temperature of the container
ϑϑϑϑdie(t) : temperature of the die
…… 4 CONTROL: Modelling4 CONTROL: Modelling
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ModellingModelling ApproachesApproaches
�� Model Model basedbased on on exactexact physicalphysical lawslaws ((structurestructure and and parametersparameters) )
–– exactexact analysisanalysis leadsleads to partial differential to partial differential equationsequations ((p.d.ep.d.e.).)((unsuitableunsuitable forfor controlcontrol))
�� Lumpend Lumpend parameterparameter approximationsapproximations ((suitablesuitable forfor controlcontrol))
•• Model Model fromfrom physicsphysics nonlinearnonlinear o.d.eo.d.e. .
•• Model Model withwith formal formal structurestructure fromfrom inputinput outputoutput data (data (‘‘blackblack box box modelmodel‘‘))
-- ArtificialArtificial NeuralNeural NetworkNetwork (ANN)(ANN)
-- NonlinearNonlinear--RegressionRegression, , fuzzyfuzzy setssets etc. etc.
•• Model Model withwith structurestructure derivedderived fromfrom physicsphysics + + parametersparameters obtainedobtainedusingusing measurementsmeasurements –– ((‘‘greygrey boxbox‘‘ modelmodel ) ) ourour choicechoice !!
…… 4 CONTROL: Modelling4 CONTROL: Modelling
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The profile temperature ϑϑϑϑP(t) depends on
- initial temperature in the deformation zone ϑϑϑϑI(t)
- the temperature rise ∆ϑ∆ϑ∆ϑ∆ϑD(t) :
dϑϑϑϑP(t)/dt = – ((((1/T2). ϑϑϑϑP(t) + (K2/T2).(ϑϑϑϑI(t)+ ∆ϑ∆ϑ∆ϑ∆ϑD(t)
K2 depends on ϑϑϑϑdie(t) , the ram velocity v(t ) force F(t),
ϑϑϑϑI(t) on temperature of billet ϑϑϑϑB(t), of receptacle ϑϑϑϑR(t) and v (t)
ϑϑϑϑI(t) = ϑϑϑϑB(t) + c1 ∫vRa(ττττ) dττττ + + + + c2(ϑϑϑϑB(t) – ϑϑϑϑR ).√t.
∆ϑ∆ϑ∆ϑ∆ϑD(t) in the deformation zone
d∆ϑ∆ϑ∆ϑ∆ϑD(t)/dt = – (1/T1). ∆ϑ∆ϑ∆ϑ∆ϑD(t) + (K1/T1)(c3.vk(t).exp(c4 .ϑϑϑϑI(t) ).
Relations Relations betweenbetween variables variables basedbased on on physicalphysical lawslaws
…… 4 CONTROL: Modelling 4 CONTROL: Modelling
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…… 4 CONTROL: Modelling4 CONTROL: Modelling
Block Block diagrammediagramme of of thethe modelmodel
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NonNon--linear models with Hammerstein structurelinear models with Hammerstein structure
Simplifying approximations for discretised model
a. The temperature change in the deformation zone is constant.
b. The recipient temperature ϑϑϑϑR is nearly equal to the billet
temperature ϑϑϑϑB .
c. The temperature of the profile ϑϑϑϑP follows changes of heat input instantaneously without lag.
d. A term is introduced to weight the influence of a ram speed
change v(n) depending on the billet temperature ϑϑϑϑB and ram
position LB(n).
…… 4 CONTROL: Modelling4 CONTROL: Modelling
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ϑϑϑϑP(n) =kB.ϑϑϑϑB(n) + kI .LB(n)+ kv ·
ϑϑϑϑP(k) =ϑϑϑϑB(k) + ϑϑϑϑB*(k)
ϑϑϑϑB*(k) = ϑϑϑϑ0 + ∑g1(n).f(ϑϑϑϑB (k-n))
f(.) is a non-linear function approximated by
f(ϑϑϑϑB (k))= a1.ϑϑϑϑB(k) + a2.ϑϑϑϑB2(k) + a3.ϑϑϑϑB
3(k)
3ϑϑϑϑB(0)
ϑϑϑϑB(n) – klLB(n)· vRa(n)
…… 4 CONTROL: Modelling4 CONTROL: Modelling
EquationsEquations depictingdepicting thethe relationshipsrelationships in in discretediscrete formform
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…… 4 CONTROL: Modelling4 CONTROL: Modelling
Block Block diagramdiagram withwith Hammerstein blockHammerstein block
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ix••••
= fi (x1, x2, xn, u1,u2, …up,t) , i = 1, 2, …, nyk = gk (x1, x2, xn, u1,u2, …up,t), k= 1, 2, …, q
NonNon--linearlinear modelmodel in in generalgeneral statestate spacespace representationrepresentation
u1
u2
up
y1
y2
yq
.
...
…… 4 CONTROL: Modelling 4 CONTROL: Modelling
Black box Black box modelmodel in in statestate spacespace representationrepresentation
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5 A STATE5 A STATE--OFOF--THE ART AUTOMATION SYSTEM THE ART AUTOMATION SYSTEM MoMASMoMAS®®
- Modular Measurement and Automation
Extruder press
Billet heating
PC with MoMAS-Software
Ram
BilletPyrometers
Furnace
Billet BilletBillet
Pyrometer
Commmunication
Link
PLC
Forcesensor
Positionsensor
Cooling
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MOMASE vent control
Main-Task
A D-Conversio nM-5B-1/U
Pyrometer
VelocityACC ON-AGLinkR S-232C
ExtruderE xtruder PLC control
Optimisati onWatchdo g
Data acquisiti on Para meter dialog
MoMASMoMAS®®
Display at Display at
operatoroperator
consoleconsole
…… 5 A STATE5 A STATE--OFOF--THE ART AUTOMATION SYSTEM THE ART AUTOMATION SYSTEM MoMASMoMAS®®
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Runs of die Runs of die exitexit temperaturetemperature and and ramram velocityvelocity
…… 5 A STATE5 A STATE--OFOF--THE ART AUTOMATION SYSTEM THE ART AUTOMATION SYSTEM MoMASMoMAS®®
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••measures and displays process variables profile exit measures and displays process variables profile exit temperature, extrusion force, ram velocity etc. during everytemperature, extrusion force, ram velocity etc. during everycycle cycle andand extrusion time per billet, idle times and the extrusion time per billet, idle times and the mean mean temperature over the cycles temperature over the cycles
••calculates the optimal process input functions and calculates the optimal process input functions and transfers this to the PLCtransfers this to the PLC
••determines best process inputs for an order, stores determines best process inputs for an order, stores them and retrieves them them and retrieves them autautomatically when neededomatically when needed
••provides the extruder managers and engineersprovides the extruder managers and engineerswith a data data base for monitoring and evaluation awith a data data base for monitoring and evaluation a
The functionsThe functions performed hitherto:performed hitherto:
…… 5 A STATE5 A STATE--OFOF--THE ART AUTOMATION SYSTEM THE ART AUTOMATION SYSTEM MoMASMoMAS®®
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Hardware and Software requiredHardware and Software required
-- PPyrometersyrometers forfor billetbillet and and forfor profileprofile exitexit
-- An Industrial PC with Windows operating system and An Industrial PC with Windows operating system and MoMASMoMAS
and OPC server software and OPC server software
-- A A sensor for measuring the position of the ramsensor for measuring the position of the ram
Prerequisite for the installationPrerequisite for the installation
availability ofavailability of
-- A hydraulically actuated ramA hydraulically actuated ram
-- A PLC (e.g. Siemens S5/S7, Allen Bradley 5/40 etc.)A PLC (e.g. Siemens S5/S7, Allen Bradley 5/40 etc.)
-- An inner velocity control loop and An inner velocity control loop and
-- Of advantage:Of advantage: An induction furnace for controlled taperAn induction furnace for controlled taper
…… 5 A STATE5 A STATE--OFOF--THE ART AUTOMATION SYSTEM THE ART AUTOMATION SYSTEM MoMASMoMAS®®
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Production Statistics of Extruder equiped with MoMAS MoMAS ®®
at SAPA Offenburg
No. of billetsextruded
Meanextrusion rate
RMS error of
exit temp. ϑϑϑϑ
Standard
deviation of ϑϑϑϑ
WithMoMAS 30 381 10,02 mm/s 12,1 °C 3.89 °C
WithoutMoMAS
26 180 9,29 mm/s (28,8 °C) 4,21 °C
Actual production statistics for the period
May – September 2001 of an extruder in Offenburg
Note Note increasedincreased meanmean extrusionextrusion rate of > 6%rate of > 6%
…… 5 A STATE5 A STATE--OFOF--THE ART AUTOMATION SYSTEM THE ART AUTOMATION SYSTEM MoMASMoMAS®®
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HowHow far far areare wewe withwith total total automationautomation ??????
AchievedAchieved !!!!!!
6 CONCLUSIONS AND PERSPECTIVES 6 CONCLUSIONS AND PERSPECTIVES ……
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Commercial viabilityIs extruder plant working at its full capacity ?Is there a demand for increased product output ?Is a new market sector being envisaged ?
Technical feasibilityAre the hydraulics and ram position / speed control adequate ?Is the billet furnace temperature control in order ?Is the puller control adequate ?Is the PLC capable of handling the data traffic ?
Acceptance by the crewIs the crew capable of coping with the new system ?
…… 6 CONCLUSIONS AND PERSPECTIVES6 CONCLUSIONS AND PERSPECTIVES
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ConclusionsConclusions
•• Contactless temperature measurement of extruded Contactless temperature measurement of extruded
aluminium with high accuracy is feasiblealuminium with high accuracy is feasible
•• Advanced extruder control based on exit temperature Advanced extruder control based on exit temperature
monitoring offers an useful tool for total automation monitoring offers an useful tool for total automation
•• Isothermal extrusion at constant extrusion rateIsothermal extrusion at constant extrusion rate has been has been
implemented employingimplemented employing MoMASMoMAS to achieve gains in to achieve gains in
productivity and qualityproductivity and quality
•• Improved models yield faster convergenceImproved models yield faster convergence
PerspectivesPerspectives
•• Fault detection and technical diagnosis using process modeFault detection and technical diagnosis using process model l
…… 6 CONCLUSIONS AND PERSPECTIVES6 CONCLUSIONS AND PERSPECTIVES
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Whether automation based on temperature measurement and control is expedient seems to be a dogma…
If you think it is not necessary, you may be right....
or- more likely -
you may be left behind
��
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INSTALLED SYSTEMSINSTALLED SYSTEMS
Presses which run with MoMAS MoMAS ®®
• 3 presses in Germany (SAPA , ALCANALCAN and
Research Centre for Extrusions, Berlin)
• 1 press in Sweden ( SAPA)
• 2 presses in Italy (ALEX and COMETAL)
• 2 presses in USA ( SAPA)
• 4 presses in Australia (CAPRAL)
• 2 presses in Russia (Minsk)