The Locator System is composed of two parts: mobile
terminals called
Locator Terminals and a base
system called .
The Locator System is designed with the
concept that the action takes place on the warehouse floor. The
operator is given suggestions about
what should be done and where pallets should go. The supervisor
can set all parameters within the software to automatically
schedule shipping and storage moves. If the operator however
decides that he wants to do something else, he can refuse the
suggested task or move and enter what actually was done.
Optimize
Warehousing with VNA technology |
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As
an example Warehousing costs may be distributed in the
following manner:
- 40% - Building
- 40% - Personnel
- 10% - Rack Structure
- 10% - Forklift Vehicles
It follows that space reduction to the absolute
minimum requires a more detailed and precise planning.
It is equally important to minimize the traffic
aisles and staging areas as well as reducing the storage
areas.
The Planning also requires a balance between various
related factors to achieve a comprehensive solution.
- Building: Height
vs. Area - depending on the geographical region -
the same building volume with a reduced surface area
and higher ceiling height can be less costly to
build.
- Fire Protection: at
certain storage heights a sprinkler system may be
required
- Safety: corporate
and insurance concerns as well as a general safety
awareness drive the safety system requirements -
most narrow aisle systems have included a planned
safety profile while general traffic contends with
rules of the road
- Vehicles: the
forklift truck selection is based on lift height,
capacity, throughput capability and aisle
requirements all other items being equal
To what depth
does the forklift selection have an influence on the
overall warehouse design
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Better Space
Utilization at a set warehouse height |
In the
following example a warehouse with 138' Long
x 95' Wide x 47.5' High yielded the
comparative storage found in the table
below: |
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Forklift Model
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Walkie Stacker
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Counter-balanced
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Reach
Truck
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VNA
Turret
|
|
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Working Aisle width
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90.5"
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122"
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106"
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64"
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Number
of Aisles
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6
|
5
|
6
|
7
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Pallet
Levels
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5
|
6
|
9
|
12
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Pallets on floor level
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540
|
450
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450
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630
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Rack
Units
|
180
|
150
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150
|
210
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Pallets stored
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2700
|
2700
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4050
|
7560
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Pallet
numbers %
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100%
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100%
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155%
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280%
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Rack Structures |
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Rack
Structure and Material Organization:
- size of the warehouse
- inbound / outbound pallet movement as well as
information on the average storage time of the
material
- floor conditions ( existing, type of floor,
condition, capacity, rebar, floor topping)
There are numerous solutions for each possible
condition.
In general the following applies: In order to
maximize warehouse capacity and throughput, one must
select a suitable rack structure with the appropriate
vehicle and logistics system. In other words a
comprehensive working system.
The in / outbound load movement and their average
storage times directly influence the rack structure
requirements.
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Guidance
Systems
Very Narrow Aisle
vehicles operate in aisles with little free space
between the vehicle and the rack or the overhanging
loads. Travel speeds can only be maintained if the
operator is free to concentrate on the hydraulic and
travel functions. Steering controls within the aisle are
part of the "Guidance System". Rail guidance via the
vehicle mounted guide rollers and angle iron mounted
within the aisle. Wire Guidance requires vehicle
electronics and a floor embedded wire to follow.
In general
there are two types of guidance: Rail Guidance and Wire
Guidance both have their benefits.
Rail
Guidance
As can be seen
in the picture, rail guidance is a method in which the
vehicle travels between angle iron rails mounted on both
sides of the working aisle. A set of four guide rollers
mounted on the vehicle maintain the path. The steer
wheel is centered electronically in order to prevent
oscillation back and forth between the rails; entry
guides assist the operator to enter the aisle and
optical sensors provide automatic aisle identification -
releasing optional travel and hydraulic functions.
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Wire
GuidanceIn the middle of the working aisle a
small 1/8" wide x 3/8" deep groove is cut. A flexible
and durable wire is embedded in the floor and sealed
with epoxy. The wire is installed as a loop with a
connection to the LDU "Line Driver Unit" which sends a
low voltage RF frequency through this loop. Antenna
mounted on the vehicle utilize this magnetic field and
steer the vehicle along its path.
Advantages:
- additional floor clearance without guide rollers
- beneficial on uneven floors
- larger systems tend to be more cost effective
with wire guidance - NO additional bottom rack level
to compensate for the floor guide rails
- NO mechanical stress on vehicle or floor
structures (rails)
- floor level storage without rail interference or
structural compensation (raise floor level or
install lower rack shelf level)
- increased flexibility to change the layout - wire
can stay in the floor simply cut new path disconnect
area or aisle not to be used
- reduced overall system installation times
- adaptable to full automation
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Floor
System
The following
criteria should be utilized with a narrow aisle
forklift system:

- Floors should meet or
exceed a minimum of an F - 50 "FACE floor
rating"
- The sub floor should be
capable of supporting the racks and rolling
loads
- Floor joints
should run parallel to the working aisle under
the rack structure. If unavoidable the floor
joints should cross the working aisle
perpendicular and when possible outside of the
working aisle only.
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Tolerance in mm
allowed
between measurement positions |
Floor Covering |
0,1 m |
1 m |
4 m |
10 m |
ab 15 m |
Floor coverings may be added as self levelling toppings |
2 |
4 |
10 |
12 |
15 |

|
absolute height
difference h allowable between the wheel track in
widths shown |
|
up to 1,0 m |
over 1,0 m
to 1,5 m |
over 1,5 m
to 2,0 m |
over 2,0 m
to 2,5m |
Vehicle Lift Height < 6,00
m |
2,0 |
2,5 |
3,0 |
3,5 |
Vehicle Lift Height > 6,01 m and
Automatic Operation |
1,5 |
2,0 |
2,5 |
3,0 |
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Test Positions
as indicated in the table below as absolute maximum
values |
1,0m |
2,0m |
3,0m |
4,0m |
for all applications |
2,0 mm |
3,0 mm |
4,0 mm |
5,0 mm |
4. In warehouse areas in which the
vehicles travel with raised loads, the following
exception table applies to the wheel track.
5. The floor should not flex or permanently deform
under the weight of the operation
6. Trenches, power conduits, cut off floor anchors
etc. should be avoided within the narrow working aisles
7. The floor should resist
absorbing oils and grease as this may have an adverse
affect on braking.
8. Floor grounding should conform
with current specifications and not exceed 106 W -
avoid static build up.
9. The floor should allow
sufficient adhesion to brake the vehicle according to
the manufacturers specification
10. Because the vehicles diagonal travel
capability, it is advisable to avoid floor deviations
when ever
possible.
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Safety Systems |
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A safety
distance or border generally accepted between forklift
and pedestrian traffic is not obtainable in the very
narrow aisle configuration. Therefore pedestrians should
only have restricted access to the VNA aisles. If
customer requirements specify pedestrian access to the
narrow aisle area, it is recommended to install a
personal detection system. The systems are designed to
warn both the vehicle operator and pedestrian early
enough in case of danger. NOTE ultimately this a
customer decision, the best solution remains to avoid
pedestrian traffic in operational machine aisles.
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Wide Span
Shelving |
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Application
Storage of all types of goods that are not normally
stored on pallets and that may require individual
pick and storage capability.
Structure A
frame work supports of uprights supports a shelf of
sheet metal or wood
Advantages
- Good space utilization
- Variable to suit specific loads
- Can be serviced manually or with vehicles
- Handles Automated AS/RS - tote boxes
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Pallet Racks |
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Application
Storage for pallets.Rack Options include:
- Drum Storage
- Front to Back support / shelving
- Load stops prevent pushing pallets to far
- P&D stands
Application These racks vary from
shelving in that they are designed with carrying
beams to support more weight.
Practical applications up to 45 feet to be
serviced by Very Narrow Aisle Forklifts.
Higher rack systems are available and require
special attention to rack upright design making them
suitable for AS/RS systems.
The rack configuration may vary depending on load
weights and warehouse design. A single rack row may
stand on its own or require support from walls /
ceiling or over the top of the working aisle with
other rack rows (some aisle will have back to back
rows). Rack heights, floor conditions, seismic
zones, sprinkler requirements, load types, load
weight, customer application and servicing vehicle
type will influence the rack design.
Rack designs include structural steel, formed
channels, hanging beams, clamped beams, bolted and
welded components. Some rack systems are have
flexible beam locations and their levels may be
altered. Usually the placement of the first beam
level has the greatest effect on the overall
stability and capacity of the upright supports.
Advantages
- Flexible applications suitable for various load
types and material flow concepts
- Ability to add or modify the rack structure
after the initial installation
-

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Drive-In and
Drive-Thru Racks |
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Application
- Storage of larger quantities of the same item
- Pallets not suitable for block storage
Design This Storage system allows
maximum cube utilization for like pallets without
placing pallets on top of one another (block
storage). Rails placed perpendicular to the work
aisle allow for multiple deep pallet storage.
This configuration will reduce the number of
aisles but will also restrict pallet or load
selection.
The Drive-in Rack works on the principal of
"First in-Last out". The Drive-Thru Rack works on
the "First in-First out" principal.
Advantages
- Maximum Storage and limited selection
- Limited number of pallet face openings
- Limited to specific types of forklift equipment
-

Loads are placed in storage lanes. Vehicles must
enter these lanes to store & retreive loads
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Moveable Racks |
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Application
- Storage with limited load movement and limited
space availability
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Space
Comparison between a stationary and mobile rack system
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Flow Racks |
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Application
Pallet picking / large scale distribution
Description Racks are based on standard
rack component uprights with engineered load support
beams that to provide a specific angles to the flow
lane. The loads are placed on the inbound (higher) side
and flow (gravity) to the outbound (lower) side. Loads
are slowed via brakes located in the lanes. Some flow
racks are manual in nature, others have controlled
lanes. Each lane is FIFO - first in - first out - only.
Advantages
- Compact Storage
- FIFO
- Segregation of shipping / storage / and inbound
load
- Shorten
transportation distances for load distribution
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Application
as distribution rack
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Cantilever Rack |
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Application
Storage of long loads such as bar stock, pipes, lumber
etc.
Description Cantilever Racks are specially
constructed storage racks for long loads, either single
sided or double sided. The design may incorporate fixed
arms (welded construction) or moveable arms (bolted or
clamped).
Advantages
- Versatile in configuration and storage
capability
- Self
supporting, the heavy duty construction also lends
itsself to outdoor applications
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Cantilever Rack
shown in single and double sided construction
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Personnel Detection
Personnel Detection
Laser-Scanner-System. The
complete system is integrated on the vehicle. The Laser Scanners
face both travel directions forward / reverse, the units are
mounted under the rear cover and on top of the front axle.
Advantages of the Laser Scanner System:
- NO faulty error conditions caused by environmental
conditions (light, temperature)
- Individual zones can be configured to meet the exact in
customers requirements
- the system is designed as a collision avoidance
- not only pedestrians are detected, also objects are
recognized within the detection zone
Functional
Description of the Laser Scanner |
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The Laser
scanner is a light sensor, that measures light
distance in time. A short laser pulse is emitted. A
rotating mirror reflects the light around a 180
degree half circle. At the same time an electronic
stop watch is started. If the light hits an
obstruction, the difused light is returned to the
receiver and the timer stopped. The distance
measurement is calculated by subtracting the time
between the sent pulse and the received light.
Together with the detection angle and the distance
the exact position of the object can be determined.
If the position falls within the predetermined
safety zone "warning" the automatic speed reduction
is initiated. If the position falls within the
safety zone "danger" an e-stop is initiated to bring
the vehicle to a complete halt..

When entering the working aisle in the forward
direction the front scanner becomes active when the
vehicle enters the aisle (eg. guide rail detection -
wire guidance detection - magnetic codes at the
beginning of the aisle). The laser scanner detecting
reverse travel direction, even though active will
only be evaluated once its travel direction is
selected within the aisle.
The control aspect assures for
redundant
detection in a fail safe manner. The switching of
the active scanning device ensures authentic
obstacle detection avoiding as an example pedestrian
and traffic in the intersecting aisle when the
vehicle is heading away from this zone. The working
aisle detecting scanner always remains active until
the absolute end of the aisle has been obtained.

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