Karin Thörnblad Industridoktorand Tillämpad optimering Logistikutveckling, Volvo Aero
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Transcript of Karin Thörnblad Industridoktorand Tillämpad optimering Logistikutveckling, Volvo Aero
Karin Thörnblad
Industridoktorand Tillämpad optimering
Logistikutveckling, Volvo Aero
Oktober 2010
Optimal schemaläggning vid produktion av flygmotorkomponenter
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9510KT, Karin Thörnblad
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Slide 2
Samarbete med Ann-Brith Strömberg, Matematiska Vetenskaper, Chalmers
Tekniska Högskola och Göteborgs Universitet
Michael Patriksson, Matematiska Vetenskaper, Chalmers Tekniska Högskola och Göteborgs Universitet
Torgny Almgren, Volvo Aero, Trollhättan
Volvo Aero
Vetenskapsrådet
NFFP (Nationella flygforskningsprogrammet)
Stöd från
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Slide 3
Multitaskmaskiner
Gradningsrobot Incheckning/Utcheckning
Setupstationer
Transportkran
Centralt verktygslager
Manuell gradning
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Multitaskcellen på Volvo Aero
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Slide 4
TransportkranTransporter mellan lagerplats och arbetsstationer
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Slide 5
3 setupstationerMontering/demontering i och ut ur fixturer
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Slide 6
5 multitaskmaskinerBorrning, fräsning och svarvning
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Slide 7
GradningsrobotAutomatisk gradning
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Slide 8
Den logistiska verkligheten på Volvo Aero
•Dyra svårflyttbara maskiner
•Högvärda lågvolymsprodukter
•Dyra fixturer
•Extremt höga krav på kvalitet och mått-toleranser
Supply chain Tillverkning - Kunder
Divergerande/parallell produktion
Komplexa produktflöden Multitaskcellen:
•8 olika produkter
•30 olika jobb
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Slide 9
Routing av en produkt
Multitask job
Job processed elsewhere
Varje produktionsorder följer en sk ”routing” i planeringssystemet
Ett jobb i multitaskcellen ↔ 3-5 ruttoperationer
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Slide 10
Produktkön
MT-cell
Planned order
Processed elsewhere
vjq , planerad ledtid från avslut av jobb j till ankomst till multitaskcellen för jobb q
v0j, planerad ledtid från aktuell position till ankomst till multitaskcellen
Stock checked-in
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Slide 11
Deburring and setup stations
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MC1
MC2
MC3
MC4
MC5
ManGr
DBR
MDM1
MDM2
MDM3
Nuvarande detaljplanering av multitaskcellen
Multitask- maskiner
Time (h)
Manuell planering baserad på• ”Earliest Due Date” prioritetslista• Andra prioriteringar p g a den rådande logistiska situationen• FIFO prioriteringsregel (First In First Out) används i andra delar av fabriken
Ruttoperationerna i de övriga resurserna läggs ut i ett möjligt schema.
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MC1
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ManGr
DBR
MDM1
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MDM3
Real production case
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Slide 12
Discrete machining model8
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The time horizon of the schedule is divided into T+1 discrete time steps.
Variables:
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Slide 13
The discrete machining problem
Job q may be started after completion of job j + planned lead time between the jobs on the same part
Only one job at a time can be processed on resource k
Each job can only be assigned to an allowed resource k
One job is scheduled only once
Objective: Minimize the sum of completion times and tardiness.
Definition of completion time
Definition of tardiness
Binary variables
Release date Resource availability
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Slide 14
Testresultat21 scenarier verkliga produktionsdata
Insamlade under april – augusti 2010
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Weekday
Real scenarios April - August 2010Time distribution for data collections
Mo Tu We Th Fr
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Slide 15
GenomförandeSchemaläggning av de första 20 jobben i kön m h a
•Matematisk optimeringsmodell med målfunktion
Minimera summan av sluttiderna och totala förseningen
Jämförelse med schemaläggning enligt
•Earliest Due Date (EDD) prioriteringsregel
•First In First Out (FIFO) prioriteringsregel
•Shortest Processing Time (SPT)prioriteringsregel
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Slide 16
Varierande beläggningVariationen i antal incheckade jobb indikerar hur beläggningen varierat under perioden.
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# jobs checked-in
Scenarios
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Slide 17
Computation times
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Full engineer's model
Divided engineer's model
Discrete machining + engineer's feas model
Number of jobs
All computations have been carried out on a 4 Gb quad-core Intel Xeon 3.2 GHz system using AMPL-CPLEX12
Comparison of CPU times (seconds)(s)
~3 months
~8 hours
~15 min
Medelvärde av21 verkliga scenarier< 2 min
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Slide 18
Scheduling algorithm Throughput time (h)
Difference from optimal solution (h)
Tardiness difference (h)
OPT#jobs checked-in ≤ 10#jobs checked-in > 10
27.729.126.4
0 0
EDD#jobs checked-in ≤ 10#jobs checked-in > 10
31.131.630.6
3.42.54.2
2.92.43.3
FIFO#jobs checked-in ≤ 10#jobs checked-in > 10
34.236.232.4
6.57.16.0
6.57.35.8
SPT#jobs checked-in ≤ 10#jobs checked-in > 10
29.430.628.3
1.71.51.9
2.11.72.4
Computational resultsResults given as a mean per job.
Throughput time = Completion time – Release date
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Slide 19
0%
5%
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15%
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30%
Mean all jobs Mean - # jobs checked-in <= 10
Mean - # jobs checked-in > 10
EDD (tardiness diff)
EDD (compl time diff)
FIFO (tardiness diff)
FIFO (compl time diff)
SPT (tardiness diff)
SPT (compl time diff)
Tardiness and completion time differences to optimal solution(percentage of mean throughput time of the opt solution
Ca 3 h
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Slide 20
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Opt
EDD
FIFO
Job tardiness resultsTardiness results from a high volume long jobs scenario
Job number
Tar
dine
ss (
h)
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Slide 21
Shortsighted scheduling
Job 3 - MC 2Job 3 - MC 2
Job 1 - MC1 & MC2Job 1 - MC1 & MC2
Job 3 – MC 2Job 3 – MC 2
t0 t1 t2 time
MC1
MC2
t0 t1 t2 time
Job 1 - MC 1 & MC2Job 1 - MC 1 & MC2
Job 2 – MC1 & MC 2Job 2 – MC1 & MC 2
Job 2 - MC1 & MC 2Job 2 - MC1 & MC 2
No knowledge about which jobs are on the way to the multitask cell (or further down in the priority list)
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Slide 22
Looking into the future…
Job 3 - MC 2Job 3 - MC 2
Job 1 - MC1 & MC2Job 1 - MC1 & MC2
t0 t1 t2 time
MC1
MC2
t0 t1 t2 time
Job 1 - MC 1 & MC2Job 1 - MC 1 & MC2
Job 2 - MC1 & MC 2Job 2 - MC1 & MC 2
Job 2 – MC 1 & MC 2Job 2 – MC 1 & MC 2
Job 3 – MC 2Job 3 – MC 2
The optimization model takes all jobs in the queue into account
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Slide 23
Looking into the future…
Job 3 - MC 2Job 3 - MC 2
Job 1 - MC1 & MC2Job 1 - MC1 & MC2
Job 3 – MC 2Job 3 – MC 2
t0 t1 t2 time
MC1
MC2
MC1
MC2
t0 t1 t2 time
t0 t1 t2 time
Job 1 - MC 1 & MC2Job 1 - MC 1 & MC2
Job 1 - MC 1 & MC2Job 1 - MC 1 & MC2
t3
t3
t3
Job 2 – MC1 & MC 2Job 2 – MC1 & MC 2
Job 2 - MC1 & MC 2Job 2 - MC1 & MC 2
Job 2 – MC 1 & MC 2Job 2 – MC 1 & MC 2
Job 3 – MC 2Job 3 – MC 2
Job 4 - MC1 & MC2Job 4 - MC1 & MC2
Job 4 - MC1 & MC2Job 4 - MC1 & MC2
Job 4 - MC1 & MC2Job 4 - MC1 & MC2
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9510KT, Karin Thörnblad
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Slide 24
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MC1
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MC1
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Scenario: 2010-08-12
Shortest Processing Time
Opt results
OPT SPT
Mean completion time 28.1 h 27.2 h
Tardiness diff (%) 0 % 17.1 %
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Slide 25
Handskas med förändringar
Väntade händelser– Nya produkter i kön– Varianser i ledtid
Oväntade händelser– Maskin går sönder– Operatör blir sjuk– Produkt lämnar kön p g a kvalitetsavvikelse– etc.
Optimized schedule
Reschedule
Frequency: shift
CPU time < 15 min
Expected eventsUnexpected events
when necessary
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Slide 26
Fortsatt forskning Fler beräkningar med realistiska högvolymsscenarier Jämföra resultat med mer sofistikerade schemaläggnings-
algoritmer Utvärdera resultat med en befintlig simuleringsmodell
Constraint programming Lagrangian relaxation Column generation Development of heuristics
Mer realistisk modell: fixturer,bemanning etc.
Förbättra målfunktionen
…
Mer tester
Mer teori
Bättre modell
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Slide 27
Frågor eller kommentarer?
Karin Thörnblad, industridoktorand
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Slide 28
Flygteknik 2010
Day month year
Thank You for your attention
and welcome to