Mitsubishi Heavy Industries Technical Review Vol. 56 No. 2 (July 2019)
1New Electric Counter-balanced
Forklift Truck Equipped with 360° Steering

Rocla Oy

Rocla Oy (hereafter Rocla), one of the European arms of Mitsubishi Logisnext Co., Ltd., wasestablished as a heating apparatus manufacturer in 1942 in Finland. The company started themanufacture of indoor equipment for lifting and moving materials in the 1950s. In 1992, thecompany started supplying products under the MHI brand. In the field of electric counterbalanced
forklift trucks, the company had manufactured Japanese-designed products, but launched the EDiA
EX, the first Rocla-designed product, in November 2014. The product has been well-received bymany customers for its beautiful and functional design unique to Scandinavian products. (Refer to“Winning Red Dot Design Award for Forklift Trucks,” Mitsubishi Heavy Industries Technical
Review Vol. 54 No. 1.) This paper presents the new EDiA EM electric forklift truck released inAugust 2018 as a product of the same series as the EDiA EX, and explains its 360° steeringfunction, a first in the product segment.

|1. Concept of EDiA series
The concept of the EDiA series focuses most importantly on user experience. Based on thisconcept, we communicate with various customers to embody products that are rooted in eachcustomer's experiences and work culture. Customer usage environments vary widely (Figure 1),
and it is very important to understand their needs. As shown in Figure 2, we focus on features thatallow users to feel the beauty of the product during use, such as “work efficiency” for facilitating
work and reducing working time including the 360° steering function and the automatic tilt
centering function presented in the upper row in the figure, “safety” including the high visibility,
hill holding function, and automatic cornering speed control noted in the middle row in the figure,and “comfort” based on ergonomics including the ease of getting on and off and adjusting thefunctionality of various control equipment depicted in the lower row in the figure. The EDiA series
aims to be a product line that harmonizes these features with sophisticated design.

Figure 1

Usage examples of forklift truckMitsubishi Heavy Industries Technical Review Vol. 56 No. 2 (July 2019)
2Figure 2

Concepts of EDiA EM|2. Product features of EDiA EM
2.1

Vehicle design

By enlarging the cabin space and the entrance by 25 mm compared to the previous model, acomfortable operating environment even for physically large operators is realized. In addition, byimproving the height of the dashboard, the arrangement of the attachment hoses for the mast, etc.,
the front view is enhanced to improve operability (Figure 3). Figure 4 depicts the interior design.
A user interface based on the same series concept as the EDiA EX is adopted. The small-diameter
steering wheel, armrest-type cargo handling control lever, accelerator pedal, and brake pedal are
optimally positioned based on ergonomics and customer feedback, contributing to the reduction ofoperator fatigue. The multi-lingual color display has an easy-to-use design using as few charactersas possible and a large number of icons, the meaning of which can be understood at a glance. For
cabin interior equipment, which is a major feature in Scandinavia, operation switches of the heater,wiper, etc., are located at positions that are easy to see in the operator's field of view, and thevehicle adopts an easy-to-open/close long door handle, a large glass window and a low-position
wiper motor that does not interfere with the operator’s view. The cabin also features an interior
light, radio unit, etc., providing customers with a safe and comfortable environment similar to apassenger vehicle.

Figure 3 Improvement of cabin space and entranceMitsubishi Heavy Industries Technical Review Vol. 56 No. 2 (July 2019)
3Figure 42.2

Interior design

Assist control function

The operation assist control functions installed on the EDiA EM are inherited from the EDiA
EX. The first one adjusts the set speed according to the operating speed for cargo handling orvehicle travel (Figure 5). The corresponding vehicle action becomes quicker when the control
interface is operated quickly at full stroke, and slower when operated slowly. The second onefinely
and smoothly changes the travelling speed while turning according to the angle of the tire(Figure 6). Both control functions are set to simultaneously realize the safety and workability
reflecting customer opinions. The EDiA EX is equipped with many other control functions basedon the user experience design. The next chapter explains the 360° steering function newly adopted
for the EDiA EM.

Figure 5 Operating speed-sensitive control curves

Mitsubishi Heavy Industries Technical Review Vol. 56 No. 2 (July 2019)
4

Figure 6 Automatic cornering speed reduction control|3. 360° steering function
3.1

Explanation of 360° steering function

In the past, when switching the running direction of a forklift 180° for unloading or loading,it was necessary to perform turning while running backward, stopping, switching forward/backward,
starting, and turning while running forward as can be seen in Figure 7. In this switching ofdirection, the operator is required to turn back the steering wheel left to right. When the tire angle
reaches 90° left and right (180° in total), the steering angle reaches the limit, and the steering wheel
is not turned any more in the same direction. On the other hand, in the case of switching direction
with the 360° steering function, when the tire angle approaches 90°, forward/backward motion isswitched automatically simply by continuing to turn the steering wheel in the same direction
without turning back. Figure 8 illustrates the movement of the tire and the rotational speed ratio of
the left and right motors while switching direction. The movement of each component fromrunning straight backward to starting turning, continuing to turn the steering wheel, and runningstraight forward is as follows:(1) The tire continues to steer beyond 90° and reaches 180°, which is the straight forward
running position.
(2) The position of the knob on the steering wheel returns to the neutral position when the tire
reaches the straight forward running position.
(3) At the start of turning, the rotation speed of the backward running side of the left and right
driving motors starts to decrease, and when the tire angle reaches 90°, the left and rightmotors rotate in mutually opposite directions at the rotation speed ratio of 1:1, which enables
the minimum turning radius. After that, the rotation speed of the forward running sideincreases, and when the tire reaches the straight forward running position, both the left andright motors rotate fully forward.
To realize these control functions, the forklift truck is required to be equipped with driving
motors independently on the left and right wheels, a steering-by-wire system with no mechanicalconnection between the steering wheel and the tire, a steering wheel that can turn 360°, aforward/backward operation switch that returns automatically to the neutral position, etc. Inaddition, fine control tuning is performed so that the behavior becomes stable and continuous andsmooth direction change is possible even if any unexpected operation is performed. As a result,continuous and smooth automatic switching forward/backward motion in a series of operations
become possible.

Mitsubishi Heavy Industries Technical Review Vol. 56 No. 2 (July 2019)
5Figure 7 Comparison of 360° steering function and ordinary steering function

Figure 8 Tire movement and rotational speed ratio of left and right motors

3.2

Advantages of 360° steering function

Using the 360° steering function improves work efficiency by saving time for stopping andstarting for switching direction, and also enables easy turning in narrow spaces and reduces thecentrifugal force applied to the cargo and the load caused by acceleration and deceleration. In
addition, it is expected that the smooth behavior lowers the burden on the operator resulting in
fatigue reduction and reduces tire wear. For customers who prefer the conventional steeringfunction, the conventional system can be selected.

3.3

Application example of 360° steering function

Figure 9 presents an application example. When loading factory cargo onto a truck or othercarrier vehicle, the forklift truck reciprocates between the truck and the cargo pickup point. Thissection estimates how much the work time can be reduced by the 360° steering function in suchcases.
- Approximately 2 seconds per turn can be saved. (According to a result of a comparisonand verification by Rocla. This actually depends on the operator and environment.)- In this application example, which has 2 turns per work cycle, 4 seconds in total can besaved.
- Assuming that 60 seconds are required per working cycle, the time saving effect results in
6.7%.
- Assuming that the annual total actual operation time (including rest time, etc.) is 1000
hours (4 hours per day, 250 days per year), 16.7 days can be saved.

Mitsubishi Heavy Industries Technical Review Vol. 56 No. 2 (July 2019)
6Figure 9 Application example of 360° steering function

In addition to shortening the work time as shown above, the work becomes safer and theburden on the operator is reduced. Moreover, since loads such as centrifugal force applied to thecargo are reduced by the smooth turning, the risk of cargo collapse and product damage is also
reduced.

|4. Future development
Forklift manufacturers in Europe have developed products and logistics solutions that strive
to improve work efficiency, reduce the burden on workers and improve safety ahead of the world inresponse to user needs. Under these circumstances, we will actively propose solutions for customer
problems and the smarter use of forklifts, and continue to communicate with customers to provide
value based on the user experience design.