2. AGV’S DEFINATION
High Tech material handling systems that uses self
independent and propelled vehicles guided along definite
pathways.
Unlike other rail guided and conveyor system vehicles their
pathways are Un-obtrusive.
They are most prominent to areas suitable for automated
material handling system for batch production and mixed
model production.
TYPES OF AGV’S:- *Towing vehicles *Assembly line vehicles
*Unit load transporters/carriers *Robotic arm
vehicles
* Flexible machining vehicles *Autonomous
vehicles
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3. AGV’S GUIDANCE
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Guidance is a method by which AGV’S pathways are
defined and vehicle are controlled to follow that
pathways.
Generally three technology are used-
* IMBEDDED GUIDE WIRES-
1.Electrical wires are placed in a small channel in or out
the surface generally 3 to 12mm in width and 13-
26mm deep
2.Guide wire is connected to a frequency generator which
emits a lo voltage and current signal with frequency in
the range 1-15 KHz.
4. CONTD…
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AGV
Floor space
Guide wire
Sensor coil
EM Field
Two sensor coils are mounted
on both side of guide wires.
Intensity of magnetic field
measured by each coil is equal
when guide wire is in between
the two coil.
If vehicle strays to one side of or
the other guide wire path changes magnetic field
intensity changes
This difference is used to control the steering motor
which makes the required changes in vehicle
5. PRINCIPAL METHODS OF ROUTING IN
GUIDE WIRE SYSTEM
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Frequency Select Method-: 1.Guide wire leading to
different paths have different frequencies and requires
different frequency generator for each different
frequency used
2.As the vehicle enters the switch it reads an identification
code on the floor to determine its location and
depending upon its programmed destination, the vehicle
selects the correct guide path.
Path switch select method-: 1. Operates with single frequency
though out the guided path
2.Guide path layout is divided into blocks that are electrically
insulated from each other
3.For vehicle control power is turned off in all other branches
6. PAINT STRIP GUIDANCE
TECHNOLOGY
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In this method the vehicle uses an optical sensor system
capable of tracking the paint.
The paint contain fluorescent particles which reflect UV
light received by the sensor on the vehicle.
The strips can be taped, sprayed or painted on the floor.
System uses an 1 inch wide paint strip containing
fluorescent particle that reflect an UV light source from
the vehicle.
7. CONTD…
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An onboard sensor detects the reflected light in the
strip and control the steering mechanism to follow it.
Useful in environment where electrical noise renders
the guide wire system unreliable or installation of
guide wire in the floor surface is not practical
Disadvantage with paint strip us that the paint strips
deteriorates with time.
Must be kept clean and replaced periodically.
8. SELF/AUTO GUIDED VEHICLES(SVG)
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Latest AGV guidance technology.
Uses a combination of dead reckoning(capability to
follow a given route in absence of a defined pathways
on floor) and beacons located through the plant and
can be controlled by onboard sensors.
Movement of vehicle is accomplished by computing
the required no. of wheel rotation in a sequence of
specified steering angles.
The most common type of beacons used are:-
1.Bar coded beacons 2.Magnetic beacons
These beacons are preinstalled in the entire factory
that will actually send signal received by a rotating
laser scanner on vehicle or vice versa.
Accuracy of dead reckoning decreases over long
distances
9. AGV’S MANAGEMENT
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Management needed for efficient working of AGV, allocation
of delivery tasks for minimising waiting times at load/unload
stations.
There are TWO aspects of vehicle management-
1. TRAFFIC CONTROL-To minimise interference between
vehicles and to prevent collision between vehicles.
Two Methods of traffic control are-
1. ONBOARD VEHICLE SENSING(FORWARD VEHICLE
SENSING)-
* Have one or more sensor’s on each vehicle to detect
obstacles ahead on the guided path and stops the vehicle if
an obstacle is encountered.
10. 2.Zone
control
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Guide path
ZONE
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ZONE 2 ZONE 3 ZONE 4
•AGV’s layout is divided into different zones and the rule is that
no vehicle is allowed to enter a zone already occupied by
another vehicle.
•Allowance is given for length to sufficiently hold one vehicle
and allowance for safety, no. of vehicles in the system, size and
complexity of the layout.
•When one vehicle occupies a given zone ,any trailing vehicle is
not allowed to enter that zone, the leading vehicle must proceed
into the next zone before the trailing vehicle can occupy the
current zone.
11. CONTD…
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When a vehicle enters a given zone, it activates a block in
that zone to prevent any trailing vehicle from moving
forward and colliding with the present vehicle.
VEHICLE DISPATCHING:-
Dispatching to the point in the system where they are
needed.
1.On board control panels-*Dispatching through Onboard
computer control panels.
*Used for manual vehicle control vehicle programming and
other functions
*Lowest level of sophistication but flexible.
*Changes in delivery requirements are easy.
2.Remote call stations -:*Call stations is a push button
mounted on the load/unload stations
12. CONTD…
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*It transmit a hailing signal to any available AGV
within the dock and either pick/drop a load.
*A more automatic dispatching method capable of
automatically loading/unloading operations
3. Central computer control-:*Have a central
computer control for automatic dispatching of
vehicle
*Central computer issues a command to the vehicle
and the operations they must perform
*Vehicle is always communicating with the central
computer controller.
* Radio frequency is commonly used for
