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Tools for Rapid Simulation Modeling for the ‘Paper Switching’ Application
Presented for RASIG
by
John Carson
AutoSimulationsRail ApplicationsSpecial Interest Group
RASIG
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”– 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
• 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?
• 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
• 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
AutoMod Model
Control systemUI s/w
• Excel• VB and Java UI
AutoMod ModelsAutoSched ModelsOther simulation package
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
Ergonomics orRobotic Cell Model
AutoMod Model
MMS Controller
Interactive custom UI• Excel• VB• Java UI
AutoSched AP Model
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
letters
parcels
flats
Conveyor
AG
VS
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– 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• 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?– 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– 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.
Rail ApplicationsSpecial Interest Group
RASIG