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Modeling and Analysis of Picking Warehouses Using Simio
Jeff Smith
Industrial and Systems EngineeringAuburn University
Simio Learning Resources
• Videos (http://www.simio.com/videos)• Publications
– Introduction to Simio (Included PDF and downloadable seven-part video series)
– Joines, J.A. and Roberts, S.D., Simulation Modeling with SIMIO: A Workbook
– Kelton, W.D., J.S. Smith, and D.T. Sturrock Simio & Simulation: Modeling, Analysis, Applications
Key Simio Object Concepts
Object: Defines data, logic, behavior, view, events, and interaction with other objects.
Model: An object that is executable.
Project: A collection of models/objects. A project can be loaded as a library.
Properties: Static inputs to an object.
States: Changeable values associated with an object
Events: Supports communication between objects. Fired when key things happen.
Resource: Constrains the system. Any object (even an entity) may be a resource.
Entity: A dynamic object that may move through system
Transporter: An entity that can “work on” or carry other entities. Vehicles and Workers are entities (and resources).
Simio User Interface
• Files Menu• Ribbons• Project Tabs• Libraries• Project• Current
Model• Properties• Facility View
Standard Library
Source: Generate entities of a specified type and arrival pattern.
Sink: Destroy entities.
Server: Capacitated process, such as a machine.
Workstation: Capacitated process, includes setup, process, tear-down.
Combiner: Batches entities with a parent entity (e.g., pallet).
Separator: Splits batches or copies entities.
Resource: Seized/Released by objects.
Vehicle: Fixed route or on-demand pickups/drop-offs.
Worker: Moveable resource, for stationary and non-stationary tasks.
BasicNode: Simple intersection, fixed object input.
TransferNode: Change destination/get rides, fixed object output.
Connector: Zero travel time.
Path: Entities independently move at their own speeds.
TimePath: Entities complete travel in a specified time.
Conveyor: Accumulating/non-accumulating conveyor devices.
Simple Flow Line
Server 1Arrive Server 2 Depart
Object Hierarchy - The Family of “Objects”
Object Definition
Object Instance
Object Runspace(Realization)
Simple Flow Line - Details
Server 1Arrive Server 2 Depart
Tandem Queueing Model Arrival Rate 25.00 entities/hr
Mean IAT 0.04 hrMean IAT 2.40 min
Server 1 Server 2Service Rate 30.00 35.00 entities/hr
Mean ST 0.03 0.03 hrMean ST 2.00 1.71 min
r 0.83 0.71L 5.00 2.50 7.50 entities
W 0.20 0.10 0.30 hrs
Editing Object Properties
• Displayed in Properties Window• Defined by object builder• Integers, Booleans, rules, expressions, …• Expression editor (down arrow at right):
“Top 10” Expressions
• X (a number – integer or real)
• Random.Exponential(mean)• Random.Triangular(min, mode, max)• Random.Uniform(min, max)
• ServerName.Capacity.ScheduledUtilization• ServerName.InputBuffer.Contents• DefaultEntity.Population.TimeInSystem.Average• DefaultEntity.Population.NumberInSystem.Average• SinkName.InputBuffer.NumberEntered• SinkName.TimeInSystem.Average
Simple Flow Line – Expressions• Source1
– Interarrival Time: Random.Exponential(2.4)• Server1
– Processing Time: Random.Exponential(2)• Server2
– Processing Time: Random.Exponential(1.7)
Simple Flow Line - Experiment
Server 1Arrive Server 2 Depart
Simple Flow Line – Responses
Server 1Arrive Server 2 Depart
Simple Flow Line – SMORE Plots
Server 1Arrive Server 2 Depart
Simple Flow Line – Throughput Response
Server 1Arrive Server 2 Depart
Buffers and Referenced Properties
Server 1Arrive Server 2 Depart
Buffers and Referenced Properties
Server 1Arrive Server 2 Depart
Buffers and Referenced Properties
Server 1Arrive Server 2 Depart
Simple Picking Warehouse
• Pickers– Walk speed: 1 meter/sec– Pick time: Uniform(10, 20) sec– Pack time: Triangular(.5, 2, 3.5) min
• Fork Lift– Travel speed: 1.5 meters/sec– Load time: Uniform(5, 10) sec– Unload time: Uniform(20, 30) sec
Racks45 m
30 pick positions in each rack (approximate using 15 evenly spaced locations)
Decisions:• Number of pickers• Number of pack stations• Number of forklifts
