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Sistemi Integrati di Produzione RELATORI

Ing. Mariangela Quarto

SEDE

Scuola di Ingegneria

DATA

23-10-2019

Corso di laurea Magistrale inINGEGNERIA GESTIONALESimulation Software

3D simulation software that models, simulates, predicts, and visualizes systems in manufacturing, material handling,

healthcare, warehousing, mining, logistics, etc. It helps to optimize current and planned processes, identify and decrease

waste, reduce cost, and increase revenue.

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Simulation

SIMULATION is the imitation of a system

• Based on knowledge or assumption about the behaviour of the parts of the system.

• The purpose is obtaining insight in the behaviour of the whole system.

SIMULATION MODEL is an abstraction of a real life system which can be used to answer questions or solve problems

• Contains only the elements that are needed to answer the question or solve the problem.

FlexSim terminology

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FlexSim Family Tree

Queue

Sink

Rack

Fixed Resource Visual ToolDispatcher Network Node

FlexSim Object

Operator

Transporter

Crane

ASRS Vehicle

Source

Traffic Control

MultiProcessor

Processor

Task Executer

Robot

Elevator

TaskExecuter

Object Classification

• FIXED RESOURCES: send and/or receive FlowItems.

• TASK EXECUTERS: perform assigned tasks.

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Fixed Resource

Fixed resource are the backbone of a simulation model: they are used to define the product flow.

• Push/pull FlowItems;

• Process FlowItems (forced delay);

• Queue up FlowItems (accumulate up to a max content);

• Call for an operator to be utilized (for process/setup);

• Call for a transport to carry FlowItems to next resource;

• There is NO transfer time.

Task Executers

Task Executers execute Task Sequences.

• Task sequence is a list of tasks which have to be completed in the order listed.

• Task is an activity such as loading, unloading, traveling, delaying, or simply being utilized.

• When a Task Executer receives a Task Sequence, it will start executing the Tasks one afteranother until the Task Sequence is finished.

• Task Sequences are created and dispatched automatically when the Use Transport or UseOperator flags are checked on a Fixed Resource.

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FlowItems

FlowItems are entities that are passed from one fixed resource to another within a model.

• FlowItems are actually FlexSim Objects.

• FlowItems hold information that can be setand queried in the model. this informationcan do anything from defining processtimes to making routing decisions, andanything in between.

Model Units

• Before creating a new model, you have to define what will be the model units used for: • Time; • Length; • Fluid.

• If you unselect the option to not show this window anymore you then could find these options in:

File > Global Preferences > Environment

• It is recommended to do units change only before starting to create anew model.

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Simulation execution

• Simulation execution commands and “accelerators” keys thatyou could use instead to control simulation execution.

• It is important to Reset the model each time you want to restartand to apply the changes.

• It shows the current run time and allowssetting a simulation stop time.

• It controls the run speed with the slide control (it has noeffects on the simulation results).

Object Port Connections

OUTPUT → INPUT Ports

• Define possible FlowItem routes to/from Fixed Resources.

CENTER Ports

• Used for referencing purposes.

• Typically used to point to a Task Executer to be called for the processing or transportation of a FlowItem.

• Objects can have an unlimited number of ports.

OUTPUT TO

INPUT

CENTER TO

CENTER

CONNECT A S

DISCONNECT Q W

VIEW V C

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Mouse Operation

• View Window Navigation

• Translate:

• Tilt and Rotate:

• Zoom:

+ DRAG

+ DRAG

+

• Object:

▪ Translate in X, Y and Z:

▪ Highlighted:

▪ Selected:

+ DRAG on object

Shift or CTRL+

Create a layout

• A model background layout or picture can be imported.

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Edit the objects

• Quick properties are shown in the right panel when you click on a object.

• Object properties → click on MORE PROPERTIES in quick properties or on the selectedobject.

General panel

Position, rotation and size of the 3D

shape in the bounding box

PORTS CONFIGURATION

Port rank is important in defining object

behaviour

Scale contents: contents position and size based on

this object sizeProtected: cannot be deletedNo select: cannot be selected

on 3D view

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Source

• It is used to introduce FlowItems into the model.

• You can decide what type of FlowItem is created.

• It creates copies of FlowItem class selected object.

• The arrival style of FlowItems can be based on: • Inter-Arrival Time → it can be the result of a distribution.• Arrival Schedule → define times and quantities for very arrival.• Arrival Sequence → define the quantities in sequence.

Queue

• It is used to stage FlowItems for downstream operations.

• Queues are used wherever WIP exists between process steps.

• Queue may be a table, basket, line or waiting room.

• You can set:▪ Max content.▪ FIFO or LIFO▪ If it is performs batching by releasing items only when target batch size or max wait time are

reached.▪ How to place FlowItems in it.

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Processor

• It is used anytime an operation is performed on a FlowItems.

• Can be represented anything would take time to manipulate a FlowItem.

• FlowItems must stay in the Processor for the sum of:▪ Setup Time▪ Process Time▪ Any Blocked Time.

• The dwell time may also include:▪ Time waiting for an operator▪ Time waiting for a transporter▪ Time waiting for the Processor to be repaired if broken down.

Sink

• It is used as an exit point for FlowItems.

• FlowItems normally can only exit the model via the Sink.

• Your last chance to record information about the FlowItems is in theOnEntry trigger of the Sink.

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Set run time statistics

• There are many ways to explore run-time statistics in FlexSim:▪ Statistics menu in Quick Properties for every object.▪ Dashboard▪ Visual Tool object▪ Object triggers to write personalized data.▪ Personalized interface.

Flow Panel

• Every Fixed Resource has the Flow Panel.

• It is used to decide where to send FlowItems next (output) or some condition on FlowItems toreceive (Input).

Send to Port

• Called when FlowItem is ready to be released.

• It allows to decide the output port where to send the FlowItem next.

• Here you can return:▪ The port number (e.g. 2 to send FlowItem to Processor2)▪ 0: to send the FlowItem to the first object in output (following the

output ports order) having room to receive it▪ -1: to avoid FlowItem to exit

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Model 1

• People arrive at a post office every 60 seconds, on average. The statistical probabilitydistribution which best simulates the inter-arrival pattern is an exponential distribution with alocation value of 0 and a scale value of 60.

• The service time at the one and only service window in the post office is lognormal2(31, 31,0.5) seconds.

• If the queue for the service window exceeds 20 people, new arrivals are routed out of themodel as “unhappy customers”.

What is the percentage of “unhappy customers”?

Purpose:

Introduction to the basic steps model building using a single queue and a single server system.

Model 2

• Begin from model 1.

• Add another service window to the post office with the same characteristics of the first one.

• The windows differ by the type of service they can provide:▪ 40% of the people need to use window 1▪ 60% of the people need to use window 2

How the service has changed?

How does the queue time increase if the windows differ by the type of service provided?

Purpose:

Learn how to duplicate objects

See effects of adding a second service window

Use the “Send to port” field

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Build Model in Phases

1. Create Flow• Create and verify flow with Fixed Resource Class object only• Verify if model works correctly.

2. Add Tasks executers• Add all necessary Task Executers• Verify dispatching rules and tasks sequences.

3. Network Node Paths• Add Network Node path to control travel path of the Transporters.

4. Reporting• Add appropriate reporting.

Global Tables

• By the Toolbox you can create Global Tables.

• These tables are useful to be read and written by all objects in the model.

Right click to edittable

Setup the table(name, rows and

column number…)

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Edit selected objects

• Groups of objects editing can be performed on selected objects using the Edit SelectedObjects menu.

• Only one object can be highlighted by a yellow box.

• Multiple objects can be selected by a red box.

Triggers

• They are an opportunity to define and customize system behaviour at a specific eventoccurance.

• Write/read information to/from a FlowItems

• Change visual properties of FlowItems or objects

• Send messages to other objects

• Change behaviour of other objects.

• Each types of objects have a unique set of triggers.

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Model 3

Where is the bottleneck?

Can you colour the parts on type basis?

Purpose:

Learns how to use empirical distribution and Global Table to assign item Types.

Create routing based on item types.

• Parts arrive in a queue exponentially every 30 s. thare are 4 types (1, 2, 3, 4) distributed (20%,30%, 40%, 10%) respectively.

• Parts are worked on one of 4 machines. Each machine is dedicated to a single part type. Theprocessing times at each machine is uniform (100, 120) s.

• Raw and semi-finished parts can be stored in a max capacity of 10 buffer.

• After the parts are worked, they are stored in a queue (max capacity: 10) and wait to betested. The test time always takes 10 s.

Labels

• Information can be stored any object (included FlowItems) in the form of labels.

• Objects can have an unlimited number of labels.

• Labels have a name and data. The data may be:• Numeric• String• Array• Pointer to objects or nodes• Table• …

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Conveyors basics

It is used to stretch/shorten theconveyors.

It is used to increase/decrease thecurvature of the conveyors.

Conveyors basics

• When connecting Fixed Resources to conveyors Entry Transfers and Exit Transfers are created.

• Decision Point: let you introduce logic;

• Station: Let you introduce a delay on the FlowItem (Same behaviour as the Processor);

• Photo Eye: let you introduce a time to block or to clear can bedefined; an angle and a height on the conveyor can be defined, a gapfrom FlowItems can be required.

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Model 4

• Begin from model 3

• At the test machine, parts that pass the test can leave the system, failed parts are routedback to the first queue to be reworked.

• 10% of the parts fail the test.

• The processing times at each machine is uniform (100, 120) s, but for reworking parts theprocessing time follows uniform (120, 130).

• Parts being reworked are given priority in machines working.

Can you change the shape of worked parts?

Purpose:

Learns how to use labels on FlowItems for routing and processing purposes.

Define more personalized logic trough the Triggers.

Use the FlowItem Bin Menu

Use the Conveyors Module.

Dispatcher Superclass

• The Dispatcher receives Task Sequences and either: • Queue them up• Dispatchers the Task Sequences immediately to other Dispatchers and/or Task

Executers connected to its output ports.

• Task Sequences can be sorted by their priority.

• Task Sequence may pre-empt the current Task Sequence part way through the current list of tasks.

• Task Executer is a subclass of the Dispatcher, so it can act as a Dispatcher and can be connected through its output ports or other Task Executers.

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Operator

• It can model human tasks such as machine setup or manual assembly.

• It can be used to transport FlowItems from one Fixed Resource to another.

• No additional functionality beyond the Task Executer except the animation used to walk and to walk loaded.

• It can move in x, y and z directions.

Network Nodes Path

• It is used to define the path a Task Executer will follow when executing its travel tasks.

• A Path is made up of a group of interconnected Network Nodes.

• A Task Executer is assigned to move on the network by connecting it to any NetworkNode in the path.

• The connected node becomes the Task Executer’s “home” node.

• The Fixed Resource, visited by the Task Executer assigned to travel on the network,must be connected to at least one Network Node.

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Connecting Network Nodes

1. Drag and drop the first NetworkNode.

2. Connect NetworkNode with Output-Input connection (A).

3. 2 green arrows show that there is now a 2-ways connectionbetween the 2 network nodes.

4. Disconnecting (Q) you clear the connection in the way you aredisconnecting. So, you have a 1-way connection.

5. Disconnecting in both ways you will see no connection betweenthe network nodes.

6. Connect the Fixed Resources that send or receive FlowItems toNetworkNode using A connection. A blue line will show theconnection (it does not connect to any port).

7. Connect the Task Executers to NetworkNode. This will be the resetposition. A red line shows that now the Task Executer has to followthe NetworkNodes path.

No Connection Passing

Connecting Network Nodes

• Right click on the arrow allows to set different status and modified the NetworkNodespath.

• Set the direction of the path.

• The disabled direction will be identify by a yellowarrow.

• Yellow arrow indicates that a Task Executer cannotovertake another one in this connection, in this way.

Non-Passing

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Connecting Network Nodes

• Right click on the arrow allows to set different status and modified the NetworkNodespath.

• It corresponds to the use of connection Q.

• It delete the 2-way connection.

No Connection

Connecting Network Nodes

• Right click on the arrow allows to set different status and modified the NetworkNodespath.

• It allows to switch between straight and curved path.

• Selecting Curved more NetworkNodes will be createdon the path and with drag and drop one of them it ispossible modify the path.

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NetworkNode Options

NetworkNode Options

• Change how A connection acts the first time you connect 2 NetworkNodes.

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NetworkNode Options

• Increase or decrease the size:• Increase

• Decrease

CTRL + L

CTRL + K

Dispatcher

• It is used to coordinate a term of Task Executers connected to the output ports.

• It receives the Task Sequence from the Fixed Resources connected through the centralports.

• Dispatcher choose the Task Executer that will execute the Task Sequence using the ruledefined in the Pass to function.

• If no Task Executer is available it queues Task Sequences using Queue Strategy logic.

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Visual Tool

• Can be used to display planes, cubes, columns, spheres, imported objects (2D CAD or 3Dshapes), 3D text and even presentation slides (bmp, jpg).

• Can act as a container for other objects.

Model 5

• Begin from model 4

• Add 2 Operators to carry parts from the test processor to their destination.

• Insert an obstacle loading the Wall.skp 3D file.

• Make a path in order to avoid the collision between the Operators and the wall.

Make the 2 Operators walk around the Wall moving in a circular way.

Purpose:

Import a 3D shape into a Visual Tool

Create a work team through the Dispatcher

Make a path for the Task Executers

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Views, Find Objects and Measure/Convert

VIEWS

• Quick Properties Views Section is shown clicking on a 3D View.

• Move and rotate in the view and Add a new view or Update an existingone.

• You can then select a view trough the panel or right clicking on 3D viewand choosing it from Model Views.

FIND OBJECTS

• View > Find Objects

• Find an object by a part of its Category, Group, Class or Tree Level.

MEASURE/CONVERT

• View > Measure/Convert

• Measure by clicking on button then on 2 points.

Fly Path

• The Fly Path is a “camera path” that permits to develop a fly-through presentation ofthe model.

• Toolbox: Visual > Fly Path

• Click on the New Fly Path button to create a new Fly Path.

• Then just move your visual and add Fly Points.

• The run control panel let you test fly paths that you have created.

Fly Points

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Video Recorder

• It allows the user to record multiple output files at one time.

• You can choose mainly:• The destination file to be created;• Frames per second (30 is a good fps rate);• Video size;• Start and end time;• Speed multiplier;• A perspective view to record on and if to show it while recording;• Eventually a Fly Path to run.

• Toolbox: Visual > Video Recorder

Push vs Pull

• In every Fixed Resource, under the Flow tab there are 2possible actions:• Output: you can decide where to send a FlowItem from the

current Fixed Resource.This represent a PUSH logic.

• Input: here you define where to get a FlowItem, choosingbetween the input Fixed Resources (Pull Strategy) andwhat kind of item can be accepted (Pull Requirement).

This represent a PULL logic.

• Push and Pull logics can coexist.

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Model 6

• Electronic components need to be testes after manufacturer.

• There are 2 types of components that arrive in queue at random with thw mix being 40% ofone and 60% the other.

• The inter-arrival time of components is exponential(0, 30).

• There are 2 testers for component 1 and 3 testers for component 2.

• Components will go to the first available tester.

• Testing times are all between 120 and 150 s uniformly distributed.

Are all tester equally utilized?

Can you model this with push?

Purpose:

Learn how to use pull logic in defining routings based on a FlowItem’s itemtype.

Lists

• Lists is a list of values that may be either numbers, strings or references to objects inthe simulation model.

• It work on the power of SQL for searching, filtering and prioritizing values.

• Lists are composed of:• Entries: represent the entire record that is placed on removed from the list;• Value: the primary value associated with a given entry;• Fields: secondary value to be stored with each entry.

• Values are Pushed into the Lists by a Pusher Object.

• Values are Pulled from the Lists by a Puller Objects.

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Lists types

• Toolbox: Global List >• Item List: Items are pushed onto the list, and Fixed Resources usually pull from it.• Fixed Resource List: Fixed Resources are pushed onto the list, and FlowItems usually

pull from it.• Task Sequence List: Task Sequence are pushed onto the list, and Task Executers

usually pull from it.• Task Executer List: Task Executers are pushed onto the list, and Task Sequence usually

pull from it.• General List.

Model 7

• Start from Model 6.

• Build the same model using a List instead of using connections.

Purpose:

Use the Lists to search for an item through a query

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Source Schedule

Define Arrivals number and Labels to be inserted

on the created Items

Do not create a repeated schedule with only 0 Arrival Times to avoid

FlexSim crash

Model 8

• 3 different products, uniformly distributed, enter a 5 station work cell every 10 s in average.

• Products are processes at the following stations in the order specified:• P1 needs to be processes at station 1, 3 and 2.• P2 needs to be processes at station 1, 2 and 4.• P3 needs to be processes at station 2, 4, 3 and 5.

• A queue having maximum capacity of 10 takes all work in progress items.

• Every working machine have a 10 s processing time.

Use an Arrival Schedule to test the routes for each product type separately.

Purpose:

Small example of using Global Table to dfine product routings.

Learn how to use a label to keep track of what step the FlowItem is on.

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Global Variables

• Toolbox: Modeling Logic > Global Variables

• Variables ca contain Integer number, Double number, Treenode (reference tosomething in FlexSim), String or Array.

• These variables can be read and written everywhere in the model.

Model 9

• Parts arrive at queue every 20 s exponentially distributed and need to be carried by anoperator to one of 3 machines, whichever is first available.

• Queue has 10 parts of max capacity.

• The operator needs to setup the part which takes 10 s.

• The part will then process for 20 s on its own.

• When the part finishes, it will leave the system.

Get the operator to stay for setup once he has carried the production to the machine.

Can you create the same model without center port connection?Purpose:

Learn how to use an Operator to both carry and process FlowItems.

Use Global Variables.

Prioritize Task Executer tasks.

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Combiner

• Combiner is used to pack, join or batch FlowItemsthrough 3 options:• Pack: FlowItem which enter ports 2 and higher are

placed inside the FlowItem which entered port 1.(PACKAGING)

• Join: FlowItem which enter ports 2 and higher aredestroyed, and the FlowItems which entered port 1represents the “assembled” part.

• Batch: when all the requested Items has arrived, afterprocessing they are released.

Rows are added automatically for

each input port connections

made for ports 2 and higher. The

first input port is always reserved

for the container or main part.

Separator

• Separator is used to:• Unpack: separate from container FlowItems that were

previously combined using the Combiner.• Split: make a specific number of copies of FlowItem.

Multiprocessor• Allows to perform several operation steps at one location.

• Each operation can have a different process time and usedifferent number of operators.

• It is good object to use when you large number ofFlowItems that move to a spot where several operationsare performed before it moves again.

• Only 1 FlowItem at a time is allowed in the MultiProcessor.

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Time Tables

• Toolbox: Time Tables

• Task executers shifts are created trough Time Tables.

• Time Tables can simulate machine stops for preventive maintenance.

• Select members that follow the TimeTables.

• Set stopping/resume times to objects.

• Use Graphical Editor to edit daily or weeklywork shift.

Experimenter

• Statistics > Experimenter

• To compare different solutions and find the best one, different scenarios must becompared.

• Using stochastic data into the model the result of the simulation may change at every model run.

• You must have a set of replications in order to obtain a sufficient set of our model KPIs.• You need to define Variables and their values for each scenarios.• Define Performance Measures to control. • In Experiment Run tab define Run Time, Warmup Time and the number of Replications

to run for each scenario.• Choose if to save the Dashboard and the State File.

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