Full Paper as a pdf file - INFORMS Simulation Society
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1. O Nu ANNC NI OAYD Figure 3 AutoMod Timeline Business Graph AutoView is a free program so users can create de tailed animation walk through graphics and can distribute the Auto View files freely to their customers AutoView also has single frame capture capability to AVI and MPEG format files This feature allows users to create animations that can be shared with others without the need for any additional software Also the single frame ca pability helps smooth the animation on larger models where hardware constraints may affect animation performance 6 GRAPHICS IN 3 D Both dynamic and static objects can be displayed during model execution Figure 1 shows a screen shot of a typical AutoMod model during a model run Dynamic objects rep resent loads vehicles resources queues and statistics The static layout is the background graphics of the plant such as columns aisle markings and walls Labels can identify specific areas in the facility There are several ways to create a layout of the system to be modeled AutoMod comes with a three dimensional graphics editor that allows the user to construct objects from standard graphics primitives Cone Box Hemi sphere Trapezoid Frustum Cylinder Arc Vector list Set Text and Triad are primitives that can be selected placed and scaled to create any static entity in the facility AutoMod supports the true to scale import of CAD format files under the IGES standard2. are not limited in any way so model logic can be of any size and complexity The power and flexibility of the AutoMod language makes is easy to model almost any real world situation Processes in AutoMod are the places where actions are performed or decisions are made For example an inspec tion operation could be represented as a process in Auto Mod From the final assembly process parts would be sent to the inspection process where an inspector re source would look at the parts Processes can have a physical location but it is not a requirement 4 2 Loads Loads are the active entities in AutoMod and can be created in many ways including deterministic or probabilistic gen eration The inter arrival rate for loads can be read from an external data file or attached to a statistical distribution AutoMod has predefined random distributions that can be used to fit most real world random events Loads are 211 given types such as RedCar or PartA and they can have attributes such as color stock keeping unit SKU priority and time in the system Attributes can be accessed and modified in AutoMod s action statements Loads have 3 D shapes and dimensions like most other entities in AutoMod Loads can also be changed on the fly in Auto Mod through actions like scale by x 2 scales load in x by 2 times set color to brown sets load color to brown 4 3 Resources Resources in AutoMod are used to
3. counters and container loading in ports With the release of AutoMod version 10 0 in 2001 graphics in AutoMod are even more realistic than before AutoMod s new VR Graphics allows modelers to create visually accurate 3D scenes in their models making them more convincing VR Graphics in AutoMod allows VRML and Open Inventor format files to be imported for entities in the model Additional graphical enhancements include templates for conveyors and path movers that provide real istic graphics for widely used material handling systems 209 The AutoMod Product Suite includes e AutoMod discrete and continuous simulation e Simulator manufacturing oriented interface for fast and easy modeling e AutoStat statistical analysis including optimiza tion e AutoView dynamic walk though of animation with AVI support e Model Communications Module MCM proto cols for linking to third party software notably for PLC emulation This tutorial gives an overview of the AutoMod prod uct Suite explaining the technical details of the products and how they interrelate to each other a Figure 1 AutoMod VR Graphics in a Filling Operation 2 INTRODUCTION AutoMod s strength is that it combines the ease of use of a simulator with the power and flexibility of a simulation Stanley language Simulators usually address specific real world problems with predefined constructs making model defini tion quick and eas
4. perform the same operation e Parts have complex routings including alternate steps setups and batching e Product is manufactured to customer order Figure 4 shows the main menu for the Simulator AutoS ched Factory Resources Products Demand Output Definition Run Control Customization Pictures Help Discrepancies Figure 4 Simulator Main Menu 8 1 Factory Resources Factory resources include the equipment operators fix tures and any other item required for the manufacturing of products Machines are grouped into families that can per form similar operations When a machine finishes the cur rent operation it looks at all the products available to proc ess and makes a decision about the next thing to do This decision is called a scheduling rule The Simulator allows the users to select from among many standard rules like first in first out highest priority or same setup Stanley 8 2 Products Products are the items that are being produced in the Simu lator model Products have a routing that defines the op erations required to manufacture them The routing de fines families of machines to visit and can also include alternated steps setup requirements processing time and batching requirements A bill of materials can also be de fined for sub assemblies which can be either produced or purchased 8 3 Demand Demand in the Simulator represents the customer orders In manufacturing many decis
5. represent machines op erators fixtures containers and any other finite capacity objects There are two default categories for a resource s state The first is the working category busy or idle and the second is the availability category up or down Dur ing the animation state colors indicate the status of each resource Statistics are automatically collected for every resource in a model Loads use resources for specified processing times These times can be deterministic or probabilistic using AutoMod s built in statistical distributions to simulate ran domness Processing times are either part specific or are applied to all parts using a particular resource Resources can also be preempted if a higher priority load needs im mediate attention Resources can have downtimes which are defined by MTTF mean time to fail and MTTR mean time to re pair These times can use AutoMod s statistical distribu tions to represent random failures Though MTTF is calcu lated by model simulated time by default it can also be based on parts processed or machine running time Resource cycles can be created and attached to spe cific resources to indicate when or how often events such as random failures or PM s occur for a resource 4 4 States The user can define states other than the default states These states might be used to represent conditions such as blocked starved PM offline etc The state of a resource can then be
6. system This allows control system designers to test the con trol logic using the simulation prior to going into the field which can result in considerable savings in terms of time spent on site performing routine logic testing and debugging Much on site work involves waiting for problems to arise during ramp followed by a difficult and slow investigation into the origins of the incident The resulting logic modifica tion is then hard to verify under a range of conditions with out major disruption to production Emulation provides a re Stanley liable way of verifying control code functionality offline training operators in a safe environment and of testing modifications to a control system before they get put into effect Furthermore the emulation model serves as a testbed for any further control system modifications throughout the life of the system so production is not disrupted In order to facilitate emulation and other linked application requirements MCM enables sockets Object Linking and Embedding for Process Control OPC and Dynamic Data Exchange DDE technologies Connecting across different platforms is achieved using sockets tech nology which allows communication via strings or C structures OPC is specifically designed to facilitate the convenient and efficient connection of Programmable Logic Controllers PLCs to other software through a stan dard protocol that is non proprietary Models may be easily linked to o
7. value Figure 6 shows the out put from an optimization run Across the X axis are the number of generations required to find the optimum and the Y axis gives the values for the user defined fitness function The fitness function can be defined as any com 215 bination of model inputs and outputs with user defined weighting factors applied to each value Very Aut Oper Figure 5 Example Graph From Auto Stat Oplinizalion Progress tor Opt 1 HB best Fires 664 00 PF et eo oar Pai 4 4 Beal Fires THE Fi re HA 4 here alion 481 30 abe E Fareri aaa ARRE IAA A Finne AMM 299 00 o Chikh aris MA averai mere Miner 15028 1530 ee nonton Figure 6 Optimization Run Graph 10 MODEL COMMUNICATIONS MODULE The Model Communications Module MCM is an exten sion to AutoMod that allows simulation models to commu nicate with other programs locally or on a network of ma chines Some of the applications of MCM include communications between e Two or more AutoMod models e Control systems and AutoMod models e Other applications and AutoMod models Communication between two or more models allows for parallel and distributed simulation MCM also includes Multi Model Sync MMS which keeps the event lists of the linked models synchronized The fastest growing application of communications is emulation where an AutoMod model is used to replace a real AMHS in order to test and debug an industrial control
8. Additionally with the release of version 10 0 Virtual Reality Modeling Language VRML and Open Inventor graphic format files can be imported directly into Auto Mod Most CAD systems and other solid geometry crea tion programs support VRML and there are many transla tors available that can convert from other file formats like IGES STEP and DXF to VRML VRML format files can be included as either static or dynamic shapes in the AutoMod model Stanley 7 RUN TIME ENVIRONMENT In keeping with AutoMod s interactive features the user has complete control of the model in the run time envi ronment The model can be viewed with the animation on or run with the animation off AutoMod uses concurrent animation the simulation progresses as the animation pic ture is being updated With animation off the simulation does not render the animation but it performs all simula tion calculations The user can suspend the simulation at any instant to review statistics through pop up windows to take resources down to set break points or alarms or to control the view of the animation without constraint 7 1 View Control AutoMod provides a comprehensive flexible and easy to use method of interacting with a model during model exe cution If the simulation project is in the experimentation phase where only parameter changes are made and the model needs to be re run several times AutoMod provides the ability to run in batch mode without anim
9. Proceedings of the 2001 Winter Simulation Conference B A Peters J S Smith D J Medeiros and M W Rohrer eds THE AUTOMOD PRODUCT SUITE TUTORIAL Brian Stanley Division Headquarters Brooks Automation AutoSimulations Division 655 Medical Drive Bountiful UT 84010 U S A ABSTRACT Whether designing a new system or modifying an existing one engineers want to take the guesswork out of finding the best possible solution While there are many analysis methods for designing industrial systems simulation re mains the method that provides the highest level of confi dence that a system will perform A well written simula tion model can be a valuable tool in the design analysis and operation of manufacturing and other complex sys tems The AutoMod Product Suite from Brooks Automa tion AutoSimulations Division has been used on 1000s of projects to help engineers and managers make the best de cisions possible 1 BACKGROUND The AutoMod Product Suite combines the ease of use of a simulator type tool with the power and flexibility of a simulation language As shown in Figure 1 3 D visualiza tion has been an integral part of the AutoMod product since its inception in 1984 The main focus of the AutoMod simulation software is on manufacturing and material handling systems AutoMod is flexible enough though to use in other non manufacturing applications for example fast food restau rants rental car lots airport ticket
10. acity the load will be delayed until another load decrements the counter Statistics for count ers are collected automatically 4 8 Functions Subroutines and Source Files Functions and subroutines are used to create modular mod els This allows the models to be extended more easily Users can define their own functions in the AutoMod or C languages and these functions can be called from any where in the AutoMod model Subroutines help eliminate duplication of action statements in the model Source files contain the logic for the model Any num ber of source files may be defined and they are processed differently depending on their file extension For example m files contain AutoMod logic and will be checked by AutoMod for correctness when edited Files with a c ex tension should contain C language and will be compiled with the model Users may also define other source files to contain input data or documentation for the model 4 9 Labels AutoMod provides the ability to use text labels to enhance model understanding Labels may be added to any location in the model s physical space and they can either be static or dynamic during the simulation Labels can rotate when the animation view changes or can be attached to a fixed position on the screen 4 9 1 Tables Tables in AutoMod supply the user with the means to col lect statistics on any model entity and to classify those sta tistics for better understanding
11. ation 7 2 User Interaction AutoMod provides advanced debugging and trace facilities A model can be single stepped at any time during the ani mation Also the ability to set breakpoints and alarms al lows the user to suspend the simulation when a certain event occurs or when a specific clock time is reached AutoMod also provides comprehensive reports The reports can be displayed on request at any time during the simulation Printed versions of the reports can also be specified in the Model Development Environment Re ports are configurable by the user who can choose be tween standard full and no report for all AutoMod enti ties AutoMod automatically keeps track of many statistics These automatic reports are linked to specific entity types such as Movement systems Processes Queues Resources Order Lists etc Vehicle states are tracked during the entire model run and reports are generated automatically Reports can be sorted alphabetically or numerically for easier analysis The user can also develop and generate custom reports from within process procedures 8 AUTOMOD S SIMULATOR INTERFACE In addition to AutoMod s standard interface already de scribed AutoMod also includes a manufacturing template called the Simulator The Simulator can be used to model problems where e Machines are grouped by capability For exam ple in a machine shop one might have sets of lathes mills and drill presses that can
12. changed using AutoMoa s actions so that sta tistics can be tracked for each state In addition state monitors can be defined and used to track states for entities other then resources such as vehicles conveyors or par ticular areas of a facility Stanley 4 5 Queues and Order Lists Queues in AutoMod are both graphical and statistical ele ments and they can have any user defined capacity When a queue has reached its capacity the next load trying to enter that queue must wait until there is space available Queue contents can be shown dynamically in the animation and loads can be stacked in any direction in the queue Loads that are at a queue or process may be sorted or delayed until they are explicitly ordered to leave To de termine which action should take place next the loads must place themselves on order lists An order list is not a physical entity like a queue but a logical element that pro vides a way to sort loads that have been delayed for any reason To remove a load from an order list another load must execute an order action Loads can be ordered to move to another process or order list or to simply continue where they left off in their processing Order lists can be sorted by load priority or other load attributes either in as cending or descending order 4 6 Blocks Blocks control the number of entities occupying a physical space making them very useful for controlling path mover vehicles Blocks may ha
13. facturing and material handling Mr Stanley re ceived a Bachelor of Industrial Engineering degree from Georgia Institute of Technology His e mail address is brian stanley brooks com
14. imation in an acceler ated time scale and select objects from the animation screen to gather detailed statistics about the system being modeled Statistics can be viewed at any time during a simulation run These model execution features make it easier to verify and validate models of complex systems and provide a forum for communication about system per formance among project team members 3 AUTOMOD INTERFACE An AutoMod model consists of one or more systems A sys tem can either be a process system in which flow and con 210 trol logic are defined or a material movement system Each model must contain one process system and may contain any number of movement systems Processes can contain com plex logic to control the flow of either manufacturing mate rials or control messages to contend for resources or to wait for user specified times Loads can move between processes with or without using movement systems All inter arrival and event times can be represented by deterministic values or be derived randomly from one of many statistical distributions AutoMod s interface is win dow oriented utilizing pop up and pull down menus dia log boxes selection lists and an editor for developing pro cess logic 4 AUTOMOD S WORLD VIEW Any number of movement systems can be defined in an AutoMod model and a process system connects the movement systems to the logical flow of products In the process system loads products par
15. ions need to be made includ ing how to allocate resources what each operation should do next and when to launch new orders into the facility The demand file in the Simulator defines each customer order start date and time and expected due date Reports from the simulator indicate which orders met their due dates and which were late The Simulator in AutoMod provides a quick and easy way to define models of a certain class of manufacturing problem Most Simulator models can be created without writing any code The spreadsheet interface to the simula tor is intuitive and very easy to use Data can be imported directly from other data sources like an MRP or ERP sys tem to facilitate even faster model building 9 AUTOSTAT The AutoStat product is the statistical analysis tool in the AutoMod product family AutoStat does extensive output analysis on an AutoMod model including Confidence intervals Warm up determination Sensitivity analysis Factor response analysis Design of experiments Optimization using evolution strategies AutoStat also has support for running scenarios across a network of machines Support for multiple machines and CPUs give users the ability to make many more runs of the simulation than was possible before Figure 5 shows an example graph from AutoStat The evolution strategies algorithm used by AutoStat is well suited to finding the optimum solution without getting trapped at a local optimal
16. of their distribution Tables automatically provide average standard deviation maxi mum and minimum for all values entered in the table Us ers can define the number of bins or categories and AutoMod adds values to the appropriate bin when directed by the user in the tabulate action statement Stanley 4 10 Types and Random Streams Types in AutoMod provide users with a powerful tool for creating among other things lists of entities such as re sources or stations and then making complex decisions based on the contents of the lists Some of the default types are integer real resource location etc But with user defined types it is possible to create for example a variable of type ResourceList whose data can then be ma nipulated in any number of ways to facilitate complex de cision making Random streams may be defined to give each element of randomness independence from other elements The number of different random streams used by AutoMod models is without limit The current version of the software 10 0 supports the Linear Congruential Generator LCG Commencing with the upcoming maintenance release Version 10 5 AutoMod will use the Combined Multiple Recursive Generator described by L Ecuyer 1999 4 11 Run Control Run control in AutoMod allows users to define the warm up and steady state periods for the model by resetting time persistent statistics Reports can be printed for any run con trol period o
17. on realism is also unmatched as AutoMod provides animation that facilitates faster model building and better communication of model results The AutoMod product suite including the AutoStat AutoView and MCM extensions provides a comprehen sive solution to the needs of the simulation user Through the use of AutoSimulations technologies models can be 216 come more than design tools being used to test controls operate the facility and plan for expansion REFERENCES AutoMod Beginning Class Notes 2001 Bountiful UT Brooks Automation AutoSimulations Division AutoMod User s Manual 2001 Bountiful UT Brooks Automation AutoSimulations Division Banks J 2000 Getting Started with AutoMod Bountiful UT Brooks Automation AutoSimulations Division Bowden R O and J D Hall 1998 Simulation Optimiza tion Research and Development In Proceedings of the 1998 Winter Simulation Conference ed D J Medei ros Edward F Watson John S Carson Mani S Manivannan 1693 1698 Piscataway New Jersey Institute of Electrical and Electronics Engineers L Ecuyer P 1999 Good parameter sets for combined mul tiple recursive random number generators Oper Res 47 159 164 AUTHOR BIOGRAPHY BRIAN STANLEY Eastern Regional Account Manager joined Brooks Automation AutoSimulations Division in 1998 Prior to Mr Stanley s account management respon sibilities he completed simulation projects in distribution manu
18. r snap Business graph output can be auto matically created Post processed animation periods used by AutoView an animation extension discussed in section 4 are also defined in the run control Run control also pro vides an entity tracing capability that gives the model builder an event by event account of the model run This informa tion is useful in verifying and validating a model 4 12 Business Graphics Graphs in AutoMod are easy to define and they update in real time with the animation Graph types include bar charts pie charts and timelines Figure 3 shows a typical timeline business graph Any model entity can be attached to a graph including transporter vehicle velocity number of loads on a conveyor section or average utilization of a machine Graphs can be printed or plotted to a variety of supported output devices and graph displays can be con trolled using the AutoMod language 5S AUTOVIEW AutoSimulations post processed animation extension can be used to view the animation records created by running an AutoMod model The AutoView product allows the user to pre define all views and time periods in the model animation and then play them back to generate presenta tion quality animation files 213 A Pack_Backup 10 00 00 00 SCALE gt SCROLL gt 5 t E oconudochirel Cur E cometdochine2 Qur conyhachine3 Cur E convMochined Cur E comehochineS Qur
19. ther applications using DDE Examples of this include Excel spreadsheets Access databases ergonomics programs as well as control programs 11 TEACHING AUTOMOD Teaching AutoMod has been greatly facilitated with the publication of the text Getting Started with AutoMod Banks 2000 PowerPoint slides have been prepared to accompany the text Additionally the electronic files are available for all of the example models in the text These are all downloadable from www autosim com as is the Student Version of AutoMod 9 1 Additionally professors can receive a file with the solutions to all of the exercises in the text 12 SUMMARY AutoMod is a state of the art simulation system that pro vides the ability to define the physical elements of a system using true to scale CAD like graphics and the logical por tion of the system using a powerful procedural language The results are that a typical user can be three to ten times more productive using AutoMod in comparison to using any other simulation tool The accuracy and degree of de tail with respect to model development is unequalled AutoMod allows the construction of very large com plex models In fact AutoMod provides an architecture that has proven that the larger the project the more bene fits AutoMod provides over other simulation systems AutoMod provides realistic 3 D visualization There are no limits to the views or the size of the picture to be shown The degree of animati
20. ts etc move between processes locations and compete for resources equip ment operators and queues The load is the active entity executing action statements that are connected to the proc esses Typical action statements give users the ability to Use machines operators Move into queues Clone new loads Change load types Wait on user defined delay lists Increment decrement counters Set variable values Read from data files Send to other processes Make conditional tests Figure 2 shows the process system pallet for AutoMod The pallet is organized in a top down manner with the most commonly defined elements at the top 4 1 Processes The process system is the backbone of an AutoMod model providing the general purpose simulation features required for modeling a wide range of real world problems While material movement is important it is not always critical in manufacturing No value is added to product while it is be ing moved around a manufacturing facility Machines and people perform value added operations The AutoMod process system is where the value added operations and control logic are defined Stanley Process System Figure 2 AutoMod s Process System Pallet AutoMod s process system includes a simulation lan guage based on action statements Action statements com bine the power of a structured language with the ease of use of English like manufacturing oriented syntax Auto Mod models
21. ve any capacity from one to infin ity Path mover vehicles lift trucks AGVs Electrified Monorails etc and loads increment blocks automatically when moving through the physical space defined by the block Loads can also claim blocks in process logic as di rected by the user Blocks can have any shape including combinations of the AutoMod supported shapes discussed in section 5 4 7 Variables and Counters Data may be stored in an AutoMod model using variables Variable values are changed using the set action as fol lows set Setup time to 123 456 Variables can be used in calculations or can be com pared to other variables In addition to integer real and string types variables can also be used to store references to other process system entities such as processes queues resources order lists counters loads and locations Stor ing these references gives the users more power and flexi bility to expand and extend models to match modifications 212 of the actual system AutoMod also supports the notion of arrayed entities making it easier to model real world sys tems that have some dimensionality for example a ware house with similar operations on two floors Counters are similar to variables except they can have finite capacity and they can only be positive integer values Counters have a maximum capacity making them useful for traffic control When a load tries to increment a counter that is at its cap
22. y AutoMod s movement systems aid users in defining the movement of material either manually or by automated equipment Material movement systems include e Path Mover path vehicle systems such as lift trucks AGVS and human movers e Conveyors including belt and roller types Automated Storage and Retrieval Systems ASRS Robots Bridge Cranes Power and Free Chain Conveyors Tanks and Pipes To define material movement systems the user simply defines movement elements such as paths and stations and then inputs the operating parameters such as velocity and acceleration AutoMod then automatically creates the corresponding model logic 3 D animation is created automatically as well providing a realistic picture of how a facility will look and operate Model animation can be viewed from any angle or perspective in real time provid ing visualization capabilities unmatched in other simula tion tools AutoMod s key strengths are Flexibility to model complex systems accurately Unlimited size of models High performance simulation engine Best in class statistical analysis features Graphic environment for creation of geometry True to scale import from CAD tools The animation provided in AutoMod models is concur rent meaning that the graphic pictures are running real time with the simulation model The model execution en vironment is very interactive allowing the user to stop and Start the simulation run without an
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