Tools for Rapid Simulation
Modeling for the ‘Paper
Switching’ Application
RASIG
Rail Applications
Special Interest Group
Presented for RASIG
by
John Carson
AutoSimulations
A Modest Proposal
• AutoMod can do it!
Who is this guy?
What is AutoMod?
• AutoSimulations
– founded in 1982
– 108 employees worldwide
• offices in USA, UK, Japan, Taiwan, Singapore
• distributors in UK, Europe, Far East, Brazil
– headquarters in Bountiful, Utah
– owned by Brooks Automation (almost)
– ASI offers simulation and scheduling software, training
and consulting
– main simulation product: AutoMod
AutoMod
• General purpose simulation package
– strong modern simulation language
– runs on Windows
• Templates to facilitate vehicle and material
handling applications
– vehicles, conveyors, ASRS, bridge crane, …
– “tanks & pipes” for liquid and bulk
– vehicle templates can be applied to:
• rail, trucks, ships
• Currently on version 9.0
AutoMod Applications
• “Bread ‘n butter”
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Manufacturing
Warehousing
Distribution Centers
Transportation/logistics
Transportation Applications
• AutoMod has been used for:
– rail yard simulation
• Norfolk Southern mixing centers
• Steel company train yard
• U.S. Navy explosives storage site (rail, ship, cranes)
– rapid transit
• Miami Metrorail and Portland TRI-MET
– ports
• Port of Singapore
– ships, tractor/trailer and agv, yard cranes, quay cranes
Demonstration:
A Rail Demo Model
Topics
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The Challenge
Example: Simulation Modeling in One Day
What’s in the AutoMod Toolkit?
An Approach to Rapid Modeling for the
‘Paper Switching’ Exercise
• Discussion
The Challenge
• Rapid Model Development
– Model must be ready to run in days
– Data should be standardized as much as
possible
• Rapid Experimentation
• Rapid Analysis
• Other aspects outside the simulation toolkit
– data collection & preparation, ...
Example: Rapid Model Building
• Taco Bell template model
– model of auto traffic in parking lot, adjacent streets and
drive-thru (0, 1 or 2)
– Taco Bell has applied the model to 80+ sites
– They develop a new model in one day
• import CAD drawing and develop new layout (“paths”) of
adjacent streets and parking lot
• enter site-specific data (traffic rates, …) in standardized format
• NO programming
• run and get standard reports (analysis may take a few days)
– Initial development took 6-8 weeks
Demonstration:
The Taco Bell Template Model
What’s a Template Model?
• Specific, narrow domain
– well-defined scope, boundary, level of detail
• Generic model
– everything is a “variable”, including the layout
– completely data-driven
• Standardized input files
• Standard output reports
– customized for the application (not standard AutoMod
reports)
Is a Template Model Possible for
the Paper Switching Application?
• Assumptions
– Man-machine simulator
• Needs to have an interactive front-end
• Humans provide the hard decision-making “logic”
• Model makes the basic moves, displays current
state, tracks standard statistics, tracks history
• Model needs to replay and allow restart at given time
– Needs to run on a network
• multiple front-ends, multiple simultaneous users
• multiple models (or multiple copies of same model)
What’s in the AutoMod Toolkit?
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MCM/MMS
Generic modeling support
Replay and Checkpoint/Restart
Tracking History
– Presentation
• Other requirements
– standard inputs and outputs
The AutoMod Toolkit:
MCM/MMS
• MCM
– Model Communications Module
– Facilitates messaging between models and other
applications, such as:
• Custom user interfaces written in Excel, VB or Java
• MMS (Multiple-Model Synchronization)
– Allows multiple AutoMod model to run together
• Simulation clocks automatically synchronized
• Works on 1 PC or over network
• MCM messaging to “send entities” or information model to
model
MCM/MMS:
Actual Applications
• MMS allows any number of AutoMod models to
run together with synchronized clocks, and to pass
messages
– USPS
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3 to 7 synchronized AutoMod models
simultaneous model development
easy swapping of one mh design for another
experimentation with an integrated model
– AutoMod + AutoSched AP
• uses AutoMod to add mh and animation quickly without
having to enhance the AutoSched product
MCM/MMS - Overview
Control system
UI s/w
• Excel
• VB and Java UI
AutoMod Models
AutoSched Models
Other simulation package
AutoMod Model
Demonstration:
MCM/MMS In Action
What is MMS?
• Provides time management
– offers 2 modes: exact and periodic synchronization
– models are event-driven and run as fast as possible, or with
animation, run with a display step
– repeatable
• Provides message passing
– automatic synchronization messages
– model dependent messages
• message is any no. of integers, reals and strings
• message usually represents an external event or data transfer
• each model has a callback function to process external events
What is MMS?
• Works on 1 PC or any no. over a LAN
– Based on sockets, so works with Windows, Unix
– On Windows LAN, MMS has low overhead
• Provides debugging support
– Ability to interact with all models while running
– Repeatable: capability to repeat run for debugging by re-run all models,
or only one model driven by a message file.
• Hardened, tested, used in large-scale industrial models
– Prototype in use for 3+ years
• MMS available now in commercial release
MMS Time Management:
Exact and Periodic Mode
• In exact mode, the simulation clocks are synchronized
perfectly
– only 1 model runs at a time
• appears as if all are running simultaneously
– MMS server controls which model runs
• In periodic mode, all messages are sent when desired, but
are received periodically, say every 10 simulated seconds
– between message updates, all models run simultaneously
– potential for large run-time gain
– downside is possible loss of accuracy
• suitable only for properly defined, loosely coupled submodels
– repeatable
MMS Applications
Interactive custom UI
• Excel
• VB
• Java UI
AutoMod Model
Ergonomics or
Robotic Cell Model
AutoSched AP Model
MMS Controller
Applications: US Postal Service
• USPS Processing and Distribution Center
– currently 3 AutoMod models in the suite
– soon to be 6+ models
– individual models for:
• equipment (LPE, FPE, IBS)
• MH (conveyor, agv)
• Facility control (scheduling, routing, dispatch, …)
– multiple model developers, geographically distributed
• each model can run standalone for debugging, V/V and initial
runs and analyses
Postal Model
Facility Control Model
Equipment Models
parcels
AGVS
flats
Conveyor
letters
Applications: Semi-Conductor
(Presented at ASI Symposium, June‘99)
• Integrated Mfg and MH Models for large
semi-conductor manufacturer
• AutoSched AP and AutoMod Models
• AP model does facility control, scheduling,
routing, processing…
– has all the “intelligence”
• AutoMod model is simpler, MH only
– receives commands to move a lot from A to B
– notifies AP model upon delivery
Applications: Ergonomics
• An ASI customer (a simulation consulting firm)
connected an AutoMod model to ergonomics
model produced by another s/w company
The AutoMod Toolkit: Variables
• For path-based models (incl rail), a standard classification
system for components and “control points” allows a
generic model to adapt to new layouts
– main track, leads, ladder, …
– “control points” can be variable
1 or more leads
Any no. of parallel tracks
The AutoMod Toolkit: Variables
• Generic logic to address the basic moves
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pull into track X
drop N railcars
pull forward past switch and back into track Y
…
• Conclusion: One AutoMod model can work with a range
of layouts
Replay and Checkpoint/Restart
• Human-made decisions transmitted from
the UI to the model can be recorded
– Allows play back of a complete shift or day
• Gives you a built-in way to do a presentation
– Allows checkpoint/restart capability
• Restart and play back to a specified point
• Pick up with interactive human decisions
– “we goofed, let’s back up 1/2 hour and try again”
– true back-up of time not feasible, but re-run is fast when
animation is off
AutoMod’s Train Template
• Provides some support for typical train modeling
– automatic detection of head of train passing a point
– automatic detection of train clearing a point (such as a
switch)
– dynamic acceleration and deceleration rates
– currently, it’s prototype but has been used by
AutoSimulations’ consulting group numerous times
Requirements for a Custom
Interactive Front-End
• Model must be driven by a custom UI
– Standardized, pre-written
• Will it require some customization on each project?
– Standard model controls
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Pause/continue
Animation on/off
View control (zoom)
Restart and re-run up to specified point
– Specific commands for train control
– Displays system state and standardized output reports
– Easy, quick to learn and use
Standardized Inputs and Reports
• How feasible to have standard inputs across
the range of anticipated applications?
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Train arrivals
Train characteristics (no. & types of railcars)
Speeds, acceleration, braking, delays
...
• Are there standard outputs?
– Can custom outputs be added quickly?
Standardized Set of Decisions
• The logic behind the decisions is provided by the
human users
– makes model simpler
– makes a generic model possible
• But can the actual decisions (or commands) be
standardized?
– Pull into track X (one of several parallel tracks)
– Stop with engine at point Y, or Stop with last car at
point Z
– Drop last N railcars
Limitations
• Model would move trains, drop off and pickup
railcars
– Animation would display trains and railcars only
• Other activities would be represented by time
delays and would not be shown visually
– automobiles unload and re-load (mixing center)
– container movement, unload and load
Summary: An Approach to Rapid
Modeling for ‘Paper Switching’
• Same model running on multiple machines
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synchronized in simulation time
runs real time, faster or slower
color-coded animation shows current state
allows different users to view different parts of
yard and different reports
• Standard interactive UI with model control
and reporting
Discussion: Q & A
• Is it feasible? Is it cost effective?
• Can the movement logic be modeled in a generic
fashion?
– The “hard” logic comes from human participants
– The model responds to commands
• Other modeling activities - data collection,
analysis, etc - must still take place.
RASIG
Rail Applications
Special Interest Group