［ Transportation ］

Development of Side-Fork TypeAGVKeywords

AGV, Forklift, Reach function

Abstract

At the logistics system project sites, forklift type Automatic Guided Vehicle(AGV) are being introduced for transporting pallets. We already released automatic guided low lift (Model: 2APLB) but has reviewed the load capacity, liftingheight and lift system. We newly developed side-fork type AGV. Since the sidefork type AGV (Model: 3ML-M11) can move in all directions, it can move even if
the path width is narrow and has a reach function. In addition, since the load canbe drawn into the AGV body by the reach function, it is possible to detect obstacles around the entire body and to travel safely. This AGV was awarded the Good
Design Award 2014 because of its excellent design and functionality.

1 PrefaceIn the manufacturing industry, pallets are often
used to transport materials from warehouses to production lines. In addition, a lot of pallets are used forthe storage of the stock in the distribution warehouse. In logistics using such pallets, pallets areoften loaded and unloaded to different heights suchas ﬂoor and shelf.
Conventionally, there were many transportation
by manned forklifts, but now Automatic Guided Forklift(AGF) are being widely used due to the difﬁculty of
securing of drivers and for accident prevention.
However, existing AGF have the following
problems.
( 1) It is necessary to change the orientation of thefork by 90°when placing the pallet after AGF travels
through the passage. It takes time and a path widthof 3m or more is necessary.
( 2 ) Since AGF approaches the pallet or shelf byrunning in the direction of the fork, there is a dangerof pinching people.
( 3 ) When traveling with the fork lifted, there is adanger that loads will fall due to a sudden stop.
In this paper, we introduce side-fork type
Automatic Guided Vehicle (AGV) developed to solvethese problems.

2 Product Speciﬁcations
Table 1 shows the speciﬁcations. The forward

14

Nobuhito Mori,
Toshiyuki Ueno,
Yasuhiro Nishizawa,
Nobuo Okazaki

MEIDEN REVIEW Series No.172 2018 No.1

Table 1 Specifications
It shows the speciﬁcations of 3ML-M11.
Items

Specifications

Guidance system

Magnetic guidance or laser-type radar

Driving for traveling

2-wheel differential drive unit × 3 units

Traveling driection

Forward/backward traveling, traversing,and spin turnMax. traveling speed 60m/min
Max. lifting hight

1000mm or 1800mm for optional

Max. lifting speed

250mm/s

Reach stroke

1350mmReach speed

250mm/sTransport pallet size Max. 1200 × 1200mm
Max. load capacity

1100kg (Cargo center 600mm, deviationfrom the center of gravity ±50mm)

Stopping accuracy

Machine base end ±10mm, fork end±30mm

Vehicle dimensions

W2278 × H1738 × L1748mm

Min. turn radius

1500mm (Forward/backward traveling
15m/min)Self-weight

2050kgand backward direction is a direction orthogonal tothe fork direction. The load capacity is 1100kg at themaximum, and it targets pallets up to 1200 × 1200mm.
Fig. 1 shows the outline drawing.

3 Features
3.1 Application to Narrow Paths
Fig. 2 shows the path width required for travel-

Emergency stop switch

2400

Fork tip sensor

Front

Pallets

1748

3ML-M11
RightLeft
Wireless
LAN unit
Touch
panel

Walls orshelves

Walls orshelvesObstaclesensorRear

Obstacle sensor
Emergency stop switch

BumperTransfer area

Detection area of obstacle sensor

Walls orshelvesMoveable10001738

Unit: mm

Contactor for automatic charging
2278

Outline Drawing

It shows the standard outline drawing of 3ML-M11. The verticaldirection of the top view is the front-rear direction.

3000
Load2APLB

3ML-M11 Path WidthBlinker (4 places)
Unit: mmFig. 1Fig. 3

It shows the required path width for 3ML-M11. The side-fork typecan be transferred immediately after going forward and backward.

Walls orshelves

3.2 High Drive Performance
The driving wheel of 3ML-M11 is a 2-wheel differential drive, and it is arranged in 3 places. Thedrive wheels of the drive units have a swing mechanism to prevent slipping of the drive wheels due toundulation of the ﬂoor of the wheel axle of the wheel.
Because this AGV is three-wheel drive, it can move
forward and backward, traverse, skew, and spinturn.

Drive unit

3.3 Improved Safety
Walls orshelves

Transfer area
Space is necessary
to remove pallets
Walls orshelvesTraveling driection

Fig. 2

Unit: mm2APLB Path Width

It shows the required path width for 2APLB. The conventional
fork type AGV turns 90 degrees and approaches the shelf.

ing by automatic guided low lift (Model: 2APLB), andFig. 3 shows the path width of side-fork type AGV(Model: 3ML-M11). 3ML-M11 can be carried out froma ﬁxed shelf placed at a path width of 2400mm.
Since the path width can be narrowed by 600mm
compared to the conventional way, the storage area
can be expanded.

AGV has the greatest merit that can be operated
without a dedicated path. As a result, here are cases
where the AGV travels on a walking path, anddesigning must be made with safety so that the AGV
will avoid collision with people.
Particular points to be considered about sidefork type AGV are “falling of the AGV main body”
and “collision with the person by the fork part ormovable part, etc.” In order to solve these safety
problems, 3ML-M11 has a reach function and several obstacle detection sensors for collision avoidance.
( 1) AGVʼs fall prevention
Fig. 4 shows the relationship between the center of gravity position and falling. In the conventional
fork type AGV, since load is applied to the outside of
the space surrounded by the wheels when pallets(loads) are loaded, there is a risk of falling down
depending on the load position and acceleration /deceleration. 3ML-M11 always moves with the fork
pulled in (reach-in), thereby preventing falls. By thereach operation of the fork, the center of gravity of
MEIDEN REVIEW Series No.172 2018 No.1

15

Since the center of gravity of the load is
between drive units, it does not fall over.

Detection area of obstacle sensor

Load center of gravity (Reach-in)
Load
3ML-M11

Detection area ofobstacle sensor

Load centerof gravity(Reach-out)

3ML-M11

There is a possibilityof leaning with point A
as a fulcrum.

Obstacle sensor

Point ASide view

Obstacle sensor

Front view

Driving wheel centerFig. 4

Load Center of Gravity

Fig. 5

Sensor Detection Area of Obstacle Detection
Sensor for Collision Avoidance with People

It shows the load center of gravity position of reach-in andreach-out.

It shows the detection area of the intrusion monitoring obstacle
sensor. Monitor penetration during reach operation.

the load is moved to the inside of the space surrounded by the wheel, and AGV is not inclined even
if the load is more than the allowable load, so thatthe vehicle can travel safely.
( 2 ) Avoiding collision with people
Because the tip of the fork is thin, people areunlikely to notice when empty. 3ML-M11 prevents
collision between the fork part and the person bybringing in the fork pulled in. The state in which thefork is out of the vehicle body is only when the AGV
is stopped, and since the reach operation is performed after approaching the pallet, the collisionrisk of the person to the fork is low.
The collision between the person and the AGVis more dangerous during on the move than during
the stop. In order to avoid collision during traveling,
3ML-M11 monitors all directions with obstacle sensors so that the AGV will stop even if a person
approaches from any direction.
In addition, since the reach operation involves
danger such as collision and nipping accident, as asafety measure during the reach operation, obstacle detection sensors for avoiding the collision withthe moving part were arranged so as to surroundthe work that was drawn.
Fig. 5 shows the sensor detection area ofobstacle detection sensor for collision avoidancewith people. These sensors stop the reach operation when there is a risk of a collision with people
outside the AGV and it is detected by the sensor,
and prevents the collision.

mance and reach function, but also considering
frame shape and color arrangement. In general
forklift trucks move forward and backward in thedirection of the fork, but 3ML-M11 has a fork on theside, so it is difﬁcult for the operator to predict thedirection of travel. As a countermeasure, we adopted
a body shape with a slope that is lower in the front
and higher in the back. The inclined cover is reminiscent of an arrow and clearly indicates “progressdirection” psychologically and visually. We arranged
a lavender color in the front, making it easier to recognize the front side in terms of color. It made thecenter of the bottom surface black color, so that it
looks compact. Also, consideration was given sothat the end of the car could be brightly colored andthe turning radius could be visually imagined. The
above-described design contributes to improvement of safety.
Improved workability such as reduction of necessary path width mentioned in Section 3.1 andrational design were highly appreciated, and received
the Good Design Award 2014.

4 Postscript
Unlike conventional automatic guided derived
from manned forklift, developed side-fork type AGV
with concept not conﬁned to existing concept.
For coexistence with people, it is an advanced
AGV that enhances design. We will continue toincorporate the demands from the market anddevelop AGVs that are friendly to people and load.

3.4 Design Excellence
3ML-M11 was designed not only for the parts
related to transportation such as traveling perfor-16MEIDEN REVIEW Series No.172 2018 No.1

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