Fr

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Modelling, Simulation and Optimization of a
Shipbuilding Workshop

• Frédéric Bair, ANAST (University of Liege),
  Belgium, F.Bair_at_ulg.ac.be
• Yves Langer, n-Side, Belgium, Yves.Langer_at_ulg.ac.b
  e
• Philippe Rigo, ANAST (University of Liege),
  Belgium, Ph.Rigo_at_ulg.ac.be

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• Summary
• Welding Shipbuilding Workshop (ALSTOM,
   Chantiers de lAtlantique )

• Software used eM-Plant (Tecnomatix)

• Treatment of the huge database (Access)

• Very detailed model

• Stochastic

• Optimization Genetic Algorithm

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Welding Workshop
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Side B - Assembly m1 - Assembly m2 -
Assembly m3 - Assembly m4 - Assembly
m5 - - - - - - - -

• Side A
• - Assembly 1
• - Assembly 2
• - Assembly 3
• - Assembly 4
• - Assembly 5
• -
• - Assembly n-1
• - Assembly n
• -
• -
• -
• -
• -
• - Assembly m

Kit j
Kit 1
Group k1
Kit 2
Group 1
Kit j1
Kit i
Group k2
Group 2
Group l
Group k
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• Objective minimize production time
• with following characteristics
• Assemblies belong to fixed Kit
• Kits belong to fixed Group
• Orders of groups fixed
• Can optimize only position of kits among Groups
• Sequence optimization
• Useful for Genetic Algorithm (GA)

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• 2 different sequences (functioning)
• half-workshop sequence ? avoid stack up

Half-Cell 1
Half-Cell 2
Half-Cell 3
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• Half-cell sequence ? better to equilibrate both
  sides (saturation of welding robot)

Half-Cell 1
Half-Cell 2
Half-Cell 3
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Operation Time for each Kit Preparation
Tacking Welding Finishing
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• Other possible results of one simulation
• Occupation Times of welding robots, mechanized
  gripper, crane bridges, workers
• Gantt diagram (for each half-cell)
• Total times of each operation (by assembly, by
  kit, by group)
• Storage Times

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• Optimization
• Genetic Algorithm 1 individual by a given
  sequence

• Low variance
• Not necessary to multiply simulations

• Half-cell sequence better than half-workshop
  sequence

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Evolution of the population
Gain gt 8 between a random sequence and best
solution
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• Conclusion and perspectives
• Simulation useful even without optimization
• Optimization development Time lt Modelling
  development Time
• Not optimal solution but interesting gains
• Automatic Kits creation