Practical applications for mobile robots based on Mecanum wheels - a systematic survey

Abstract

In this paper a literature review concerning practical applications for mobile robotic platforms based on special wheels (in this case, Mecanum wheel) is presented. Mobile robots equipped with four Mecanum wheels have the omnidirectional property, which means, they have the ability to move instantaneously in any direction, from any configuration. Therefore, compared to conventional platforms, these vehicles possess multiple advantages in terms of their mobility in narrow spaces or crowded environments. They have the ability to easily perform certain tasks in congested environments foreseen with static obstacles, dynamic obstacles or narrow areas. Usually, such environments are found in factory workshops, warehouses, hospitals, etc. Hence the resulting needs to create this kind of robotic platforms to satisfy the requirements of various fields, such as: industrial, military, naval, medical and last but not least, the educational field (as the basis for research). The characteristics of the Mecanum wheel, a short comparison between this type of wheel and a conventional wheel, as well as the constructive and design solutions previously developed are described in the first part of this paper. Then, some application fields and the related systems based on Mecanum wheel are presented.

Full text

Practical Applications for Mobile Robots based on Mecanum Wheels - A Systematic Survey
The Romanian Review Precision Mechanics, Optics & Mechatronics, 2011, No. 40 21
PRACTICAL APPLICATIONS FOR MOBILE ROBOTS
BASED ON MECANUM WHEELS - A SYSTEMATIC SURVEY
Florentina Adăscăliţei, Ioan Doroftei
”Gh. Asachi” Technical University of Iasi, Mechanical Engineering Faculty, Theory of Mechanisms and
Robotics Department, B-dul D. Mangeron, 61-63, 700050, Iasi, Romania
E-mail: adascalitei_florentina@yahoo.com, ioan_doroftei@yahoo.com
Abstract: In this paper a literature review concerning practical applications for mobile robotic
platforms based on special wheels (in this case, Mecanum wheel) is presented. Mobile robots
equipped with four Mecanum wheels have the omnidirectional property, which means, they have
the ability to move instantaneously in any direction, from any configuration. Therefore, compared
to conventional platforms, these vehicles possess multiple advantages in terms of their mobility in
narrow spaces or crowded environments. They have the ability to easily perform certain tasks in
congested environments foreseen with static obstacles, dynamic obstacles or narrow areas.
Usually, such environments are found in factory workshops, warehouses, hospitals, etc. Hence the
resulting needs to create this kind of robotic platforms to satisfy the requirements of various fields,
such as: industrial, military, naval, medical and last but not least, the educational field (as the basis
for research). The characteristics of the Mecanum wheel, a short comparison between this type of
wheel and a conventional wheel, as well as the constructive and design solutions previously
developed are described in the first part of this paper. Then, some application fields and the
related systems based on Mecanum wheel are presented.
Keywords: Mecanum wheel, omnidirectional mobile robot, AGV
1. Introduction
Omnidirectional wheels have been used in robotics,
in industry, and in logistics for many years. By
reviewing and analyzing systematically the existing
literature concerning this type of wheels, it was
revealed that systems based on Mecanum wheels
detain omnidirectional capabilities, whereas systems
based on conventional wheels do not. Specifically,
these capabilities make the vehicle extremely
maneuverable, which could be very helpful in
different indoor and outdoor applications. Therefore,
compared to conventional vehicles, omnidirectional
robotic vehicles possess multiple advantages in
terms of their mobility in narrow spaces and
crowded environments. They have the ability to
easily perform certain tasks in congested
environments foreseen with static obstacles,
dynamic obstacles or narrow areas. Usually, such
environments are found in factory workshops,
warehouses, hospitals, etc. Hence the resulting needs
to create this kind of robotic platforms to satisfy the
requirements of various fields, such as: industrial,
military, naval, medical and last but not least, the
educational field. Furthermore, to prevent the
shortcomings presented by Mecanum wheel,
researchers have focused on its optimization,
developing new constructive solutions, thus
allowing their implementation in new applications,
such as planetary explorations, mine operations.
2. Mecanum wheel
2.1. Mecanum wheel characteristics
Mecanum wheel was designed and invented in
Sweden, in 1975, by Bengt Ilon, an engineer with
the Swedish company Mecanum AB [1]. Mecanum
wheel is based on the principle of a central wheel
with a number of rollers placed at an angle around
the periphery of the wheel. The angle between
rollers axis and central wheel axis could have any
value, but in the case of conventional Mecanum
wheel it is 45° (Figure 1). The rollers are shaped
such that the silhouette of the omnidirectional wheel
is circular. The angled peripheral rollers translate a
portion of the force in the rotational direction of the
wheel to a force normal to the wheel direction.
Depending on each individual wheel direction and
speed, the resulting combination of all these forces
produces a total force vector in any desired
direction, thus allowing the platform to move freely
in direction of the resulting force vector, without
changing the direction of the wheel.
A Swedish omnidirectional wheel has 3 DOF’s

Practical Applications for Mobile Robots based on Mecanum Wheels - A Systematic Survey
The Romanian Review Precision Mechanics, Optics & Mechatronics, 2011, No. 40
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composed of wheel rotation, roller rotation and
rotational slip about the vertical axis passing through
the point of contact (Figure 2). In the
omnidirectional wheel, the wheel velocity can be
divided into the components in the active direction
and in the passive direction. The active component is
directed along the axis of the roller in contact with
the ground, while the passive one is perpendicular to
the roller axis [2]. When the wheel rotates, a force
vector along the wheel and a force vector
perpendicular to the wheel are created. By a simple
control of each wheel rotation, the vehicle moving
direction can be changed instantaneously.
Figure 1: Mecanum wheel
Figure 2: DOF’s in a Mecanum wheel [2]
When a Mecanum wheel is rotating, at least one
roller (maximum two rollers) is (are) in contact with
the ground. Only a small surface (theoretical, one
point) of the roller is in contact with the ground. The
area of this surface traverses the roller from one side
to another, depending on the sense of wheel rotation.
The direction of the traction force will be done by
the traversing sense of contact surface. It means, if
we look to the wheel from the top side, the traction
force will be perpendicular to the roller axis [3].
2.2. Mecanum wheel vehicle vs. Conventional
wheel vehicle
The benefits of a vehicle with Mecanum wheels
relative to one with steered wheels have been
presented by [4]. Usually, robotic vehicles are
designed to perform planar motion. In a two
dimensional space, a body has three degrees of
freedom, being capable of translating in both
directions and rotating about its centre of gravity.
However, most conventional vehicles do not have
the ability to control every degree of freedom
independently, because conventional wheels are not
capable of moving in a direction parallel to their
axis. These so called non-holonomic constraints of
the wheel prevent vehicles using skid-steering from
moving perpendicular to its drive direction. To reach
every location and orientation in a two dimensional
space it can require complicated maneuvers and
complex path-planning. Non-holonomic vehicles can
move in some directions (forward and backward)
and can describe some curved trajectories, but
cannot crab sideways. For example, to realize a
parallel parking, a differential drive vehicle should
make a number of maneuvers (Figure 3).
Figure 3: Lateral parking of a differential drive
mobile robot [6]
A vehicle without non-holonomic constraints it can
travel in any direction under any orientation. This
capability is widely known as omnidirectional
mobility. Omnidirectional vehicles have great
advantages over conventional platforms, with car-
like Ackerman steering or differential drive system
in terms of moving in tight areas [5]. They can crab
sideways, turn on the spot and follow complex
trajectories. These vehicles are capable of easily
performing tasks in environments with static and
dynamic obstacles and narrow spaces.
Usually, vehicles based on Mecanum wheel have a
square or a rectangular configuration, with two
wheels on each side of the chassis. Using four of
these wheels provides omnidirectional movement for
a vehicle without needing a conventional steering
system. When Mecanum wheels are actuated, the
angled peripheral rollers translate a portion of the
force in the rotational direction of the wheel to a
force normal to the wheel direction.
Figure 4: Vehicle motion according to the direction
and angular speed of the wheels [6]

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The Romanian Review Precision Mechanics, Optics & Mechatronics, 2011, No. 40 23
Table 1: Comparison between different types of drives
Mecanum drive Holonomic drive Swerve drive
Description
Wheels with angled rollers
Wheels with “straight”
rollers (omniwheels)
Independently steered drive
modules
Advantages - compact design
- high load capacity
- simple to control
- less speed and pushing
force when moving
diagonally
- low weight
- compact design
- simple to control
- less speed and pushing
force when moving
diagonally
- simple conceptually
- simple wheels
- continuous wheel
contact
- high load capacity
- robust to floor conditions
Disadvantages
- very complex
conceptually
- discontinuous wheel
contact
- high sensitivity to floor
irregularities
- complex wheel design
- more complex
conceptually
- discontinuous wheel
contact or variable
drive-radius
- sensitive to floor
irregularities
- lower traction
- complex mechanical
design
- heavy and massive
design
- complex to program and
control
- high friction and
scrubbing while steering
Depending on each individual wheel direction and
velocity, the resulting combination of all these
forces produce a total force vector in any desired
direction thus allowing the platform to move freely
in the direction of the resulting force vector, without
changing of the wheels themselves. The vehicle is
able to translate on any direction, forward/backward
but also sideways left/right and turning on the spot,
thanks to its special wheels (Figure 4). This is
especially helpful when having to maneuver in tight
environments [5]. A short comparison between
Mecanum drive, holonomic drive and swerve drive
is presented in Table 1.
2.3. Mecanum wheel constructive solutions
Omnidirectional wheeled vehicles with Mecanum
wheels have some shortcomings. According to [7], a
vehicle with Mecanum wheels is susceptible to
slippage, and as a result, with the same amount of
wheel rotation, lateral travelling distance is different
from longitudinal travelling distance. In addition, the
ratio of longitudinal travelling distance over lateral
travelling distance with the same amount of wheel
rotation, changes with ground condition. The second
drawback is that the contact point between the wheel
and the ground moves along a line parallel to the
wheel axis, even though the wheel is always in
contact with the ground. The lateral movement
produces horizontal vibrations. The last drawback is
that its ability to overcome obstacles is not
independent of travel direction.
The slippage of the wheels prevents the most
popular dead-reckoning method, using rotary shaft
encoders [5], [8], from being performed well on a
vehicle with Mecanum wheels. In order to solve the
problem, visual dead-reckoning was used as a slip-
resilient sensor [7], [9]. This technique, also used in
optical mice, makes use of an on-board video-
camera continuously capturing frames of the ground
beneath and image processing hardware on the robot
determining the speed and direction in which the
current frame has moved relative to the previous
frame thus allowing the speed and direction of that
point of reference to be calculated.
A traditional Mecanum wheel with the peripheral
rollers held in place from the outside is presented in
Figure 1. This design, although having a good load
carrying capacity, has the disadvantage that, when
encountering an inclined or uneven surface, the rim
of the wheel can make contact with the surface,
instead of the roller, therefore preventing the wheel
from operating correctly (Figure 5.a). A simple
alternative design, also proposed by Ilon, which
alleviates the problem, consists in having the rollers
split in two (or in three) and centrally mounted as
shown in Figure 5.b. This design ensures that the
rollers are always in contact with the work surface,
thus allowing a better performance on uneven
surfaces [10].

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(a)
(b)
Figure 5: a) Traditional Mecanum wheel on inclined
surface; b) Mecanum wheel with centrally mounted
rollers
One disadvantage of the Mecanum design is the
inefficient use of the kinetic energy supplied to the
wheels by the motors. Due to the rotation of the
exterior rollers, only a component of the force at the
perimeter of the wheel is applied to the ground and
the resulting force only partially contributes to the
motion of the vehicle. [11] proposed two designs to
improve the Mecanum wheel efficiency. The first
design is the Mecanum wheel with lockable rollers
illustrated in Figure 6. This design was conceived to
overcome the losses of efficiency due to energy lost
in a direction normal to that of travel through the
peripheral rollers (they bleed off energy as they
rotate), when the vehicle is travelling in a straight
line (forward/backward). Simple actuators are used
to rotate the brake activation disc, therefore to lock
and unlock the roller, when the vehicle is moving.
When driving in longitudinal motion, the peripheral
rollers will be locked and they will act as a heavy
thread, but when driving in sideways motion the
rollers will be unlocked. This design is effective in
reducing any lost forces in the forward direction to
zero, but does not improve the losses in any other
directions.
Figure 6: Mecanum wheel with lockable rollers [11]
Figure 7: Mecanum wheel with rotatable rollers
[11]
The second design is Mecanum wheel with rotatable
rollers illustrated in Figure 7. Compared to the first
design, this one is more effective, but mechanically
more complex. The peripheral rollers are split and
centrally mounted on an axle which can be pivoted
through 135°. This allows the rollers to be adjusted
from a straight position (in which they are locked so
the rollers cannot rotate on their axles), thus
effectively forming an almost normal treaded tire, to
an angle of 45° in which case they act as a
traditional Mecanum wheel, or to an angle of 135°,
making diagonal travel easier as it overcomes the
resistance given by the traditionally immobile
wheels. The angle of the rollers on each wheel is
controlled through all the roller shafts, which are
connected through a bevel gear system in such a way
that a rotary actuator on one of the shafts controls all
the other simultaneously.
[3] proposed a new Mecanum wheel constructive
solution in terms of its performance on various
surfaces and concluded that the size of the peripheral
rollers has a great effect upon this performance
(Figure 8.a). The larger the rollers are, the greater
the range of surface deviations can be overcome.
Also, as the size of rollers increases, the slower they
spin, resulting in lower friction losses in the driving
of the wheel. In conclusion, when designing a new
drive system for a vehicle, there exist a certain
number of rollers that makes the ideal compromise
between having a small number of large rollers per
wheel, and having a large number of small rollers
per wheel (Figure 8.b).
(a) (b)
Figure 8: a) New constructive wheel design; b)
Rollers number according to their size.
Large size of rollers means a small number of them.
This has as effect a very small radius to the rollers
extremities and, in this case, it could be difficult to
use ball bearings in order to decrease the friction
between the roller and its axis. The new constructive
solution not only facilitates the use of big bearings,
but also makes possible the approximation of the
roller shape with a circle, because the roller length
becomes smaller than the one used in a traditional
Mecanum wheel – it is half of the normal roller.
In order to overcome the Mecanum wheel
difficulties when moving on rough terrain, [12] has
developed two new concepts of this type of wheel,
using the principle of “steeping on obstacles”. The
first one is the concept of “elliptical Mecanum

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The Romanian Review Precision Mechanics, Optics & Mechatronics, 2011, No. 40 25
double wheel” (Figure 9). The wheel itself consists
in two elliptically Mecanum wheels, 1 and 2,
coupled with a special mechanism in between 3. The
role of the mechanism 3 is to move (rotation and
relative translation to each other) the components 1
and 2 in such a way that the resulting motion would
provide the same movement (in terms of speed,
direction, smoothness) to the vehicle as a traditional
Mecanum wheel would. For practical purposes,
components 1 and 2 are not truly elliptical, when
viewed sideways, but rather an approximation of an
ellipse is used. The designed wheel includes a total
number of 12 rollers (8 of type 1 and 4 of type 2).
The maximum obstacle height that this wheel can
overcome is 75% of the wheel largest radius.
Figure 9: Assembled elliptical Mecanum double
wheel [12]
The second concept is the “semicircular Mecanum
double wheel”. The idea was to modify the
elliptically shaped wheel seen in Figure 9, and
replace it with a wheel having half circular and half
elliptical profiles as shown in Figure 10. In this case,
as the double wheel rotates, the smooth motion of a
regular Mecanum wheel is achieved, while the
ability of overcoming small obstacles when
travelling laterally is kept. In contrast to the elliptical
wheel, the semicircular wheel includes three types of
rollers (4 of type 1, 2 of type 2 and 7 of type 3) and
the total number of rollers is 13. The flatter the
elliptical part is the greater clearance can be
achieved for overcoming higher obstacles. This type
of wheel is capable of overcoming obstacles of
height up to 37.5% of the wheel’s radius. Also, both
of these types of wheel have the ability of moving in
soft dirt. The wheel would pile up a small amount of
dirt and then step on it, thus avoiding being blocked
by large amounts of dirt.
Figure 10: Assembled semicircular Mecanum
double wheel [12]
3. Practical applications in various fields
3.1. Military field
The manoeuvrability provided by omnidirectional
vehicles can be utilized and can be very important in
numerous outdoors applications, such as search and
rescue missions, military activities, planetary
explorations and mine operations.
This wheel is commonly used in robotic applications
requiring a high degree of maneuverability, such as
those experienced by NASA for hazardous
environment exploration [13]. The objective of the
OmniBot project (Figure 11) is to develop a
hazardous duty mobile base as an advanced
development test bed to research alternate technical
approaches for remotely controlled operations in
hazardous areas. In addition, this base will be used
to test various automated umbilical technologies for
autonomous mobile vehicles.
Figure 11: NASA OmniBot mobile base [14]
Figure 12: Mecanum wheel vehicle for USA Navy
[15]
In hazardous environments where it is too dangerous
to send in unprotected personnel, a mobile base
could be used to perform remote inspections, site
surveys, and operations. The OmniBot is driven with
four brushless servomotors connected to
omnidirectional wheels (Mechanum). This allows
for complete 2-degree-of-freedom motion, which
results in extremely high maneuverability. The
benefit of this motion profile can truly be
appreciated when the vehicle is operated in a
teleoper-ational mode.The vehicle can be controlled
with a radio frequency (RF) control box or with a
hardwired joystick. With the video transmission gear
installed, teleoperation is possible up to a distance of
1,800 feet [14].

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Omnix Technology Systems, Inc. had developed
Mecanum wheel vehicle for U.S Navy for inspection
of areas inaccessible to humans and vehicles capable
of transporting very heavy loads in military
environments [15]. These vehicles can be seen in
Figure 12 are especially adaptable for autonomous
or teleported operations due to the unrestricted
manoeuvrability and simplicity of control.
MarsCruiserOne is a pressurized, habitable rover,
designed to allow exploration of the Moon and Mars
during future space missions (Figure 13).
Characterized by omnidirectional wheels especially
suited to tackle rocky terrain, it travels at a speed of
5-10 km/h [16]. This design incorporates: hubless
wheels (which allowed ingress/egress for the
astronaut crew for extra-vehicular activities and
access to other surface modules and rovers),
Mecanum wheels, a linear motor drive and a single
point rotary shock absorber/suspension system [17].
Figure 13: MarsCruiserOne [16]
3.2. Industrial field
Airtrax ATX-3000 industrial forklifts (Figure 14)
excel in applications requiring tight manoeuvring or
transporting long loads sideways through standard
sized doors or narrow aisle ways. The ATX’s
unique, Omni-Directional movement allows it to
travel in all directions thus making it an ideal vehicle
to work in tight spaces where turns are not possible
and finite control is a necessity. The truck features
48 volt transistor controls with state-of-the-art
technology, infinitely variable travel, lift and lower
speeds, excellent visibility, ergonomic controls and
operator comfort [18].
The unique design of the four 21x12 independently
driven Mecanum wheels enables the ATX’s
OmniDirectional capabilities. Each wheel is directly
driven by individual transaxles. The wheels consist
of a large, heavy-duty hub with 12 uniquely
designed polyurethane rollers. The wheel and roller
design provides the Omni-Directional movement of
the vehicle based on the speed and direction of each
wheel as determined by the operation of the traction
joystick. Each roller incorporates bearings that do
not require periodic greasing or maintenance under
most conditions. Since each roller rotates freely,
scrubbing against the floor is minimized while
turning or moving sideways [18].
Figure 14: Airtrax Sidewinder lift truck [19]
[20] developed an Automated Guided Vehicle as a
drive-under tractor in very compact dimensions. The
development and realization of the vehicle are
optimized for the transportation of small goods
(Figure 15.a) [21]. The primary goal was a small
vehicle at low cost [22]. Furthermore the vehicle has
to be able to transport variable amounts of
containers in an economic way. An innovative
approach was to accomplish accumulated and single
transports by towing a trolley (Figure 15.b) or by
carrying one container with the same vehicle. For
transport and providing of small goods, the
following applications were found to be the most
promising: Floor block storage, order picking,
assembly and production. The vehicle has an
omnidirectional drive, using four independently and
electrically driven Mecanum wheels. The
accomplished prototype is smaller than any vehicle
that is available at the market in Europe. As a result
the needed space for logistic operations, like the
width of the track and stations, could be minimized
compared to common solutions. Especially the
height of the vehicle is very low so that an efficient
use as a drive-under tractor is possible. The results
showed an efficient approach for an automated
transportation of trailers and small load carriers.
(a) (b)
Figure 15: a) Vehicle with small goods container; b)
Vehicle with trolley [20]
3.3. Medical field
Powered wheelchairs are known to provide benefits
for older adults by enabling them to have a means of
independent mobility. These benefits include:
participation in self-care, productivity, and leisure

Practical Applications for Mobile Robots based on Mecanum Wheels - A Systematic Survey
The Romanian Review Precision Mechanics, Optics & Mechatronics, 2011, No. 40 27
occupations; as well as, socialization opportunities,
and positive self worth [23] [24]. Overall powered
wheelchairs are linked to an improved quality of life
for older adults who have a reduced ability to walk
and do not have the stamina, strength, or ability to
propel themselves in a manual wheelchair [23].
Without a powered wheelchair these older adults
would be dependent on others to complete life tasks
[25], and unable to have independent mobility.
The OMNI (Office Wheelchair for High
Manoeuvrability and Navigational Intelligence for
People with Severe Handicap) is a standalone
wheelchair developed with two goals in mind: 1) to
allow high mobility in complex environments; and
2) to have modes of operation that will help the user
have higher degrees of independence [26]. This
wheelchair has been designed for individuals with
severe mental and physical disabilities. It consists of
Mecanum wheels that provide 3-DOF (degrees of
freedom) for the wheelchair; a specialized joystick
for 3-DOF movement; a sensor ring around the
wheelchair that has IR (infrared) and ultrasound
sensors to provide obstacle detection capabilities; a
bumper sensor for fail-safe detection of collisions;
wheel odometers for knowledge of the wheelchair’s
location; an elevating seat to raise the user; and a
specialized display for the user select modes of
operation (Figure 16).
The omnidirectional wheelchair being developed at
the University of Western Australia’s Centre for
Intelligent Information Processing Systems (CIIPS)
allows the user to easily manoeuvre in what would
otherwise be an extremely complicated environment.
This project made improvements to the Mecanum
wheels, batteries, motor driver cards, human
interface, control software, chassis and suspension
system. These improvements transformed the
partially working prototype into a fully usable
wheelchair (see Figure 16). The result is much
higher driving accuracy and a greatly improved
overall experience for the user in both comfort and
ease of use. On the whole, the project was extremely
successful and will provide a very solid test bed for
advanced driving and mapping projects in the future
[19].
Figure 16: Omnidirectional wheelchairs: OMNI
[26], CIIPS wheelchair [19], iRW [27] (from left to
right)
Another example of an omnidirectional wheelchair
is iRW [27], which provides a telehealth system with
easy-to-wear, non-invasive devices for real time
vital sign monitoring and long-term health care
management for the senior users, their family and
caregivers (Figure 16). A joystick controller is used
to control the iRW to move forward/backward, sway
right/left, and spin clockwise/counter clockwise. The
maximum forward speed of the iRW is set at 3km/h,
which is close to walking speed of human, and the
maximum backward and sideways speed is set at
1.5km/h.
3.4. Educational field
Uranus (Figure 17) was the first mobile robot with
Mecanum wheels, designed and constructed in
Carnegie Melon University [28], [29]. It was built to
provide a general purpose mobile base to support
research in to indoor robot navigation. As a base, it
provides full mobility, along with support for a
variety of payloads, such as sensors and computers.
It had not a suspension system, which is absolutely
necessary if the ground is not completely flat.
Figure 17: Uranus omnidirectional mobile robot [28]
Other researchers, such as Braunl from University of
South Australia have developed two different
Mecanum wheel omnidirectional mobile robots,
Omni-1 and Omni-2 [30], [31]. Figure 18 shows the
structure of Omni-1 and Omni-2. The first design,
Omni-1 used the Mecanum wheel design with rims
that only leave a small gap/clearance for the roller.
The motor and wheel assembly tightly attached to
robot’s chassis. The Omni-1 can drive very well on
hard and flat surface but it loses the omnidirectional
capability on soft surface.
Figure 18: Mecanum Wheel Mobile robot Omni-1
and Omni-2 from University of Western Australia
[31]
Omni-2 was develop using rimless and with

Practical Applications for Mobile Robots based on Mecanum Wheels - A Systematic Survey
The Romanian Review Precision Mechanics, Optics & Mechatronics, 2011, No. 40
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centrally mounted roller. The motor and wheel
assembly attach to cantilever wheel suspension with
shock absorbers. The rimless Mecanum wheel and
shocks absorbers encounter the sinking-in on softer
surface and uneven work surface as a result allows
omnidirectional driving for Omni-2.
The Mechatronics and Robotics Research Group
(MR2G) at Massey University have developed all
terrain Automatic Guided Vehicle (AGV) using a set
of Mecanum wheels combined with a set of
conventional wheels [11]. Any terrain change is
automatically detected and a set of pneumatics
actuators used to change from Mecanum wheels for
indoor and high mobility requirement to
conventional wheel for outdoor and rough terrain.
This new driving mechanism of AGV has been
implemented on Mapped Environment Guided
Autonomous Navigator (MEGAN). Figure 19
illustrates the structure of MEGAN.
Figure 19: Mapped Environment Guided
Autonomous Navigator (MEGAN) [11]
3.5. Other fields
The main goal of the CommRob project was to
develop scientific methods or technologies to
introduce robots in human environments. The
Interactive Behavior Operated Trolley (Figure 20)
InBOT addresses several everyday problems.
Among other possibilities this means helping the
customer to find the desired products without
extensive search in big supermarkets, or relieving
the customer from the burden of pushing the
shopping cart using his own force all the time,
especially if the cart is heavily loaded or the
customer is elderly or handicapped. Especially for
these groups of customers it could be very
interesting that InBOT is able to avoid collisions on
its own, even with objects that are moving
themselves. InBOT has the ability to perform special
local maneuvers and a flexible task-planner. It
provides four different modes of operation to assist
the user in the best way. First InBOT can be steered
like an ordinary shopping cart by the haptic handle
[32], including assistance functionalities like
obstacle avoidance. Second and third it can follow or
lead the user. Therefore the robot has to
continuously track the user’s position, to perform
adaptive distance management and finally to
estimate the user’s intentions. And fourth the robot
can be commanded to act independently until
ordered otherwise [33].
Figure 20: The interactive shopping trolley [33]
4. Conclusions
In this paper, an overview over the Mecanum wheels
and their practical applications is presented. The
main advantage of this type of wheel is represented
by the omnidirectional property that it provides,
allowing extreme maneuverability and mobility in
congested environments. Also, some research that
was carried out in Mecanum wheel mobile robots in
order to improve the wheel design is described. The
manoeuvrability provided by omnidirectional
vehicles can be utilized and can be very important in
both outdoors applications, such as search and
rescue missions, military activities, planetary
explorations and mine operations, long loads
transportation, and indoor applications, like small
goods transportation, powered robotic wheelchairs
or shopping carts.
5. Acknowledgement
This paper was realized with the support of
POSDRU CUANTUMDOC “DOCTORAL
STUDIES FOR EUROPEAN PERFORMANCES
IN RESEARCH AND INOVATION” ID79407
project, funded by the European Social Found and
Romanian Government.
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