1 understanding agvs history of agvs ie 447 - cim lecture notes - chapter 9 mhs

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Understanding Understanding AGVSAGVS

History of AGVSHistory of AGVS

IE 447 - CIM Lecture Notes - Chapter 9 MHS

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History of AGVSHistory of AGVS1953 First AGV1953 First AGV

The first AGV system The first AGV system was built and was built and introduced in 1953introduced in 1953( A( A modified modified towing towing tractortractor that was used that was used to pull a trailer and to pull a trailer and follow an overhead follow an overhead wire in a grocery wire in a grocery warehousewarehouse))


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History of AGVSHistory of AGVS1973 Volvo Assembly 1973 Volvo Assembly

PlantPlant In 1973, Volvo in In 1973, Volvo in

Kalmar, Sweden set Kalmar, Sweden set out to develop non-out to develop non-synchronous synchronous assembly assembly equipment as an equipment as an alternative to the alternative to the conventional conventional conveyor assembly conveyor assembly line. The result line. The result was was 280280 computer-computer-controlled controlled assembly AGVsassembly AGVs..


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History of AGVSHistory of AGVS1970s First Unit Load1970s First Unit Load

IIntroduction of a ntroduction of a unit load vehicleunit load vehicle

They have the ability to serve several functions;

a work platform,

a transportation device, and

a link in the control and information system

They transport material in warehouses, factories, mills, hospitals, and other industrial and commercial settings.


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History of AGVSHistory of AGVSSmart Floors and Dumb VehiclesSmart Floors and Dumb Vehicles

In the 1970’s the In the 1970’s the principal guidance principal guidance technology was to technology was to induce an electronic induce an electronic frequency through a frequency through a wire that was buried in wire that was buried in the floor.the floor.

‘‘floor controller’floor controller’

•These first generation navigation schemes were expensive to install.

•All floor cuts needed to follow the exact path of the AGV.


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History of AGVSHistory of AGVSDead Reckoning CapabilityDead Reckoning Capability

As the vehicles became As the vehicles became more intelligent, the more intelligent, the path became less path became less sophisticatedsophisticated

Dead reckoningDead reckoning is a is a term that describes the term that describes the ability of a vehicle ability of a vehicle to to traverse steel expansion traverse steel expansion joints on the factory joints on the factory floor orfloor or to cross a steel to cross a steel grategrate

The biggest advantage was that dead reckoning eliminated the need to make the cut radius turns at intersections. (Installation was greatly simplified).


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History of AGVSHistory of AGVS1980s Non-Wire Guidance1980s Non-Wire Guidance

The introduction of The introduction of llaser aser andand inertia inertia

guidanceguidance..

AAllow for increased system flexibility and llow for increased system flexibility and accuracyaccuracy

NNo need for floor alterations or production o need for floor alterations or production interruptioninterruption


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AGV NAVIGATIONAGV NAVIGATION

The principles which make it possible for an The principles which make it possible for an AGV to navigate its way between any two AGV to navigate its way between any two locations are really quite simple. All navigation locations are really quite simple. All navigation methods use a path. The vehicle is instructed to methods use a path. The vehicle is instructed to FollowFollow a Fixed Path a Fixed Path or or TakeTake an Open Path an Open Path..


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Fixed Path NavigationFixed Path NavigationFollowing a PathFollowing a Path

The paths are well The paths are well marked on the floormarked on the floor

The paths are The paths are continuouscontinuous

The paths are fixed, but The paths are fixed, but can be changedcan be changed


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Fixed Path Navigation: Fixed Path Navigation: Creating a PathCreating a Path

The principle techniques for creating paths are to:The principle techniques for creating paths are to: Apply a narrow Apply a narrow magnetic tapemagnetic tape on the surface of the floor on the surface of the floor Apply a narrow Apply a narrow photo sensitive chemical stripphoto sensitive chemical strip on the on the

surface of the floorsurface of the floor Apply a narrow Apply a narrow photo reflective tapephoto reflective tape on the surface of the on the surface of the

floorfloor Bury a wireBury a wire just below the surface of the floor just below the surface of the floor


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Fixed Path Navigation: Fixed Path Navigation: Buried Wire PathBuried Wire Path

Bury a Bury a current-carrying current-carrying wire just below the wire just below the surface of the floorsurface of the floor


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Fixed Path Navigation: Fixed Path Navigation: Steering Correction CoilsSteering Correction Coils

TThe vehicle steers itself to he vehicle steers itself to FOLLOWFOLLOW the magnetic field the magnetic field surrounding the buried wire.surrounding the buried wire.


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Fixed Path Navigation: Fixed Path Navigation: Path SelectionPath Selection

In this illustration, a In this illustration, a vehicle at “A” has two vehicle at “A” has two choices on how to get to choices on how to get to “B”. A computer either on “B”. A computer either on board the vehicle or at board the vehicle or at some central location some central location selects a path based on selects a path based on established criteria.established criteria.

Criteria: Criteria: TThe shortest distancehe shortest distance TThe path with the least he path with the least

traffic at the present traffic at the present timetime

All of the “PATH All of the “PATH FOLLOWING” methods FOLLOWING” methods permit routing options permit routing options that include guide path that include guide path switching and merging.switching and merging.


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Open Path Navigation: Open Path Navigation: Taking a PathTaking a Path

Unlike “Unlike “path following path following navigationnavigation,” where the ,” where the guide paths are fixed, guide paths are fixed, and more or less and more or less permanent, vehicles permanent, vehicles operating in the “operating in the “Take a Take a PathPath” category are ” category are actually offered more actually offered more variation if not an variation if not an infinite number of ways infinite number of ways to navigate the open to navigate the open space between two space between two points.points.


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Open Path Navigation: Open Path Navigation: Navigation MethodsNavigation Methods

The three most common open space The three most common open space navigation methods arenavigation methods are:: Laser GuidanceLaser Guidance Inertial GuidanceInertial Guidance Cartesian GuidanceCartesian Guidance

The choice of navigation method for aThe choice of navigation method for a particular particular application is often a simple matter of preferenceapplication is often a simple matter of preference..


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Navigation Methods - Laser Navigation Methods - Laser GuidanceGuidance

RReference points are eference points are strategically located strategically located targetstargets

A beacon on top of the A beacon on top of the vehicle emits a vehicle emits a rotating laser beam rotating laser beam which is reflected back which is reflected back to the vehicle when it to the vehicle when it strikes (sees) a target.strikes (sees) a target.


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Navigation Methods - Inertial Navigation Methods - Inertial GuidanceGuidance

AAn n on board gyroscopeon board gyroscope establishes and maintains a vehicle’s heading establishes and maintains a vehicle’s heading.. Distance traveled is calculated by an Distance traveled is calculated by an on board encoderon board encoder which counts wheel rotations. which counts wheel rotations.


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Navigation Methods – Navigation Methods – Cartesian GuidanceCartesian Guidance

LLocation precision is ocation precision is accomplished by way of a accomplished by way of a fixed grid pattern that fixed grid pattern that covers the entire floor covers the entire floor area.area.

The possible travel paths The possible travel paths in a given, unrestricted in a given, unrestricted operating area for a grid operating area for a grid based system are infinite based system are infinite and most like that and most like that provided by laser provided by laser guidanceguidance


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AGVS DispatchingAGVS Dispatching

Dispatching AGVS is much the same as dispatching Dispatching AGVS is much the same as dispatching taxi taxi cabscabs..

The dispatch function makes sure that all The dispatch function makes sure that all customers get customers get timely services from the vehicle best able to service a timely services from the vehicle best able to service a requestrequest..

RemoteRemote and and local dispatchlocal dispatch are most commonly described as are most commonly described as offboardoffboard and and onboard dispatchersonboard dispatchers respectively. respectively.


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AGVS CommunicationsAGVS Communications

Communications include message Communications include message ccommandsommands such assuch as:: where to go,where to go, when to start,when to start, when to slow downwhen to slow down,, when to stop.when to stop.

FFour types of basic communication mediaour types of basic communication media:: Radio CommunicationRadio Communication Infrared CommunicationInfrared Communication Guide Wire Data CommunicationGuide Wire Data Communication Inductive Loops CommunicationInductive Loops Communication


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AGVS Communications AGVS Communications Radio CommunicationRadio Communication

MMaximum flexibility in aximum flexibility in system controlsystem control

Vehicles can be Vehicles can be programmed “on the programmed “on the fly”fly”

system speed of system speed of response to changing response to changing load movement load movement demands is improveddemands is improved


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AGVS Communications AGVS Communications Infrared CommunicationInfrared Communication

Optical infrared communication Optical infrared communication is is highly reliablehighly reliable but has the but has the disadvantage of not being disadvantage of not being continuouscontinuous; it is point to point. ; it is point to point.

Vehicles may be stopped during Vehicles may be stopped during this data exchange which usually this data exchange which usually occurs at load stations where the occurs at load stations where the fixed and mobile units are fixed and mobile units are aligned and in close proximity. aligned and in close proximity.

Or, the vehicle communicates at fixed points along its guide path as the vehicle travels through a given zone.

Infrared communication is best suited for small systems with few vehicles and load stations.


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Remote DispatchingRemote DispatchingThe DispatcherThe Dispatcher

The remote dispatch function generally resides in a The remote dispatch function generally resides in a

computer (PC),computer (PC), Programmable Controller (PLC),Programmable Controller (PLC), or other microprocessor, known as the Dispatcheror other microprocessor, known as the Dispatcher..

The Dispatcher accepts input from the various system Components (generally transport requests) and directs the AGVS to fulfill the command in the most efficient manner.

Remote dispatch can occur with vehicles at single or various dispatch points.


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AGVS MonitoringAGVS Monitoring

TTypes of monitoringypes of monitoring : : System monitoringSystem monitoring Vehicle monitoringVehicle monitoring

The functions and The functions and reporting capabilities of reporting capabilities of each are important to each are important to the safe operation of the the safe operation of the AGVs.AGVs.


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Material Material Handling Handling SystemsSystems

Automatic Storage Retrieve Automatic Storage Retrieve SystemsSystems

AS/RSAS/RS


26IE 447 - CIM Lecture Notes - Chapter 9

MHS


MHS

1 understanding agvs history of agvs ie 447 - cim lecture notes - chapter 9 mhs

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