Understanding AGVS
History of AGVS
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History of AGVS
1953 First AGV

The first AGV system
was built and
introduced in 1953( A
modified towing
tractor that was used
to pull a trailer and
follow an overhead
wire in a grocery
warehouse)
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History of AGVS
1973 Volvo Assembly Plant

In 1973, Volvo in Kalmar,
Sweden set out to develop
non-synchronous
assembly equipment as an
alternative to the
conventional conveyor
assembly line. The result
was 280 computercontrolled assembly
AGVs.
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History of AGVS
1970s First Unit Load

Introduction of a unit 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 AGVS
Smart Floors and Dumb Vehicles

In the 1970’s the principal
guidance technology was to
induce an electronic
frequency through a wire
that was buried in the floor.
‘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 AGVS
Dead Reckoning Capability

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As the vehicles became more
intelligent, the path became
less sophisticated
Dead reckoning is a term that
describes the ability of a
vehicle to traverse steel
expansion joints on the
factory floor or to cross a steel
grate
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 AGVS
1980s Non-Wire Guidance

The introduction of laser and inertia
guidance.
Allow for increased system flexibility and
accuracy
 No need for floor alterations or production
interruption

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AGV NAVIGATION

The principles which make it possible for an
AGV to navigate its way between any two
locations are really quite simple. All navigation
methods use a path. The vehicle is instructed to
Follow a Fixed Path or Take an Open Path.
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Fixed Path Navigation
Following a Path



The paths are well
marked on the floor
The paths are
continuous
The paths are fixed, but
can be changed
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Fixed Path Navigation:
Creating a Path
The principle techniques for creating paths are to:




Apply a narrow magnetic tape on the surface of the floor
Apply a narrow photo sensitive chemical strip on the
surface of the floor
Apply a narrow photo reflective tape on the surface of the
floor
Bury a wire just below the surface of the floor
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Fixed Path Navigation:
Buried Wire Path

Bury a current-carrying
wire just below the
surface of the floor
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Fixed Path Navigation:
Steering Correction Coils

The vehicle steers itself to
FOLLOW the magnetic field
surrounding the buried wire.
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Fixed Path Navigation:
Path Selection

In this illustration, a vehicle at “A”
has two choices on how to get to
“B”. A computer either on board
the vehicle or at some central
location selects a path based on
established criteria.

Criteria:
 The shortest distance
 The path with the least traffic
at the present time

All of the “PATH FOLLOWING”
methods permit routing options
that include guide path switching
and merging.
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Open Path Navigation:
Taking a Path

Unlike “path following
navigation,” where the guide
paths are fixed, and more or
less permanent, vehicles
operating in the “Take a
Path” category are actually
offered more variation if not
an infinite number of ways to
navigate the open space
between two points.
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Open Path Navigation:
Navigation Methods

The three most common open space
navigation methods are:
Laser Guidance
 Inertial Guidance
 Cartesian Guidance

The choice of navigation method for a
particular application is often a simple matter
of preference.
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Navigation Methods - Laser
Guidance


Reference points are
strategically located
targets
A beacon on top of
the vehicle emits a
rotating laser beam
which is reflected
back to the vehicle
when it strikes (sees)
a target.
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Navigation Methods - Inertial
Guidance


An on board gyroscope establishes and maintains a vehicle’s heading.
Distance traveled is calculated by an on board encoder which counts wheel rotations.
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Navigation Methods –
Cartesian Guidance


Location precision is
accomplished by way of a
fixed grid pattern that
covers the entire floor
area.
The possible travel paths
in a given, unrestricted
operating area for a grid
based system are infinite
and most like that
provided by laser
guidance
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AGVS Dispatching

Dispatching AGVS is much the same as dispatching taxi
cabs.

The dispatch function makes sure that all customers get
timely services from the vehicle best able to service a
request.

Remote and local dispatch are most commonly described as
offboard and onboard dispatchers respectively.
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AGVS Communications

Communications include message commands such as:





where to go,
when to start,
when to slow down,
when to stop.
Four types of basic communication media:




Radio Communication
Infrared Communication
Guide Wire Data Communication
Inductive Loops Communication
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AGVS Communications
Radio Communication

Maximum flexibility in
system control

Vehicles can be programmed
“on the fly”

system speed of response to
changing load movement
demands is improved
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AGVS Communications
Infrared Communication

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
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Optical infrared communication is
highly reliable but has the
disadvantage of not being
continuous; it is point to point.
Vehicles may be stopped during this
data exchange which usually occurs
at load stations where the fixed and
mobile units are 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 Dispatching
The Dispatcher

The remote dispatch function generally resides in a



computer (PC),
Programmable Controller (PLC),
or 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 Monitoring

Types of monitoring :

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
System monitoring
Vehicle monitoring
The functions and
reporting capabilities of
each are important to
the safe operation of the
AGVs.
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Material Handling
Systems
Automatic Storage Retrieve Systems
AS/RS
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