The Intelligent Conveyor Belt
Report 2005.TL.6973, Transport Engineering and Logistics.
The subject of this research project is the intelligent conveyor belt with
integrated RFID. This research assignment is issued by Ammeraal Beltech.
This is a conveyor belt company of belts for light and medium heavy
RFID, short for radio frequency identification, is a way to identify an
object by data transfer using radio waves. This data transfer takes place
between an electronic reading device and an electronic data carrier, the
transponder. They can communicate wireless because of the use of
electromagnetic (radio) waves. The RFID system consists of a transponder
(or tag) attached to the object that is to be identified and a reader.
Both the transponder and the reader use an antenna to be able to communicate with each other. The antenna of
the reader is large because it must create an energy field to power the
transponder and it also has to receive the weak signal of the transponder.
The components of the transponder are very small.
The operation of a common RFID system is as follows: The reader develops
an energy field (electromagnetic field) through its antenna. This field
excites energy (voltage) in the transponders antenna. This energy is used
to operate the transponder, which is sending back its data through its
antenna. This signal is received by the reader and processed further. The
reader powers and operates the transponder.
The transponder is an important item in a RFID system, because this is the
device that is placed on or in the product. With many different products
and different environments, the transponder often has to fulfill specific
requirements and this asks for different transponder designs. Areas of use
differ from animal identification to pallet tracking to automatic toll
collecting. Because of this, RFID uses four different radio frequencies:
LF, HF, UHF and microwave.
A RFID transponder is read only, write once/read many or rewriteable. The
transponder can be passive or active. In the passive type, all the power
for the operation of the transponder is delivered by the (electromagnetic)
field generated by the reader. To enlarge the read range there are active
transponders, which use a battery. This battery powers the microchip
and/or delivers the power for sending data to the reader.
The reader's main functions are to activate the transponder and structure
the communication sequence with the transponder. The reader enables
contactless data transfer between the application software and the
transponder. The reader can be stationary or handheld.
Standardization is important in the worldwide application of RFID.
Frequency bands must be determined globally. Governments and institutes
already designated the frequency bands available for RFID. The HF and
microwave frequencies are worldwide but the LF and especially the UHF
range differ per region. Organizations are trying to agree to one UHF
Not only the frequencies must be standardized, but also the power level of
the signal must be determined. It differs per region per frequency range
and the organizations are trying to straighten that out. Standard
organizations (such as ISO) designed standards concerning topics such as
communication protocols, field strength and interference. Besides the
hardware, the software must be developed. Organizations like GS1 (EAN) are
developing a uniform code that can be used in the FMCG (fast moving
consumer goods) sector: the EPC (electronic product code). The EPC is an
agreement about a code system like the barcode system and also involves
transponder type, frequency, etc.
Besides RFID, there are other automatic identification methods, such as
optical ID (barcode), magnetic ID (cards), smart cards and biometrical
(fingerprint). While RFID can compete with all techniques, for instance in
the access/security field, a comparison with the barcode (optical ID) is
the most interesting. It is important to notice that RFID can offer more
than the barcode. Although the barcode is a very efficient way to identify
an object, it can't do more than identifying. RFID, on the other hand, can
do more. For instance due to the larger data capacity, much more information
of the object can be stored. Also, the possible combination of sensors can
deliver even more information, for instance temperature
The RFID technology exists already for decades, but in the last few years
there were many technological developments. Components got smaller and
more efficient, read ranges and data capacities were expanded.
Improvements and innovations will continue in the future. From a very
small microprocessor to printed antennas and all polymer transponders. A
different approach in developing RFID is to make the RFID transponder
intelligent and communicate with each other.
While RFID still isn't a full-grown technology, it is being used for quite
some time. The most common applications nowadays: Access and security,
transport and logistics, tracking and tracing and authentification. The
main goal of the applications for Ammeraal Beltech is to enlarge the
reliability of its products by structuring and controlling operations,
such as maintenance (checks) or monitoring of belts, with RFID.
Interesting are identification of the belt and maintenance/monitoring with
the intelligent belt.
If a RFID transponder is integrated in the belt, every bit of necessary
information about the belt can be written to it and read from it any time,
even while it is running. This can be in the form of a unique code that is
linked to product information in a database. It means that all information
can be on-site and directly available and not somewhere in the
administration. In this manner data is collect more efficient, which can
reduce labor time and errors.
RFID is the selected technique because RFID is small enough to be integrated
in the belt so it is protected from the environment. It is clean what is
necessary in food applications. It is operated wirelessly, which simplifies
reading and reading can be done while the belt is running. RFID also has the
possibility to write to the transponder. Barcode, for instance, must be on
the surface because of the line of sight that is necessary to read it. This
means it is vulnerable to the environment and can get damaged or dirty.
A belt with an integrated transponder can be used for more than
identification only. The possibility to write to the transponder can be
used in maintenance applications. Each time the belt is serviced or
checked, it can be written to the transponder. With this information it is
not only possible to know the last service but also a history of the
maintenance is available. From this history, the behavior of the belt can
be analyzed. One step further in maintenance is to have the belt signaling
the operator that it needs service (for instance tensioning). The belt
monitors its own performance and gives a warning signal whenever there is
something wrong. Failure of the belt conveyor can be caused either by the
installation the belt runs on (drive) or by the belt itself. Preventing
failure of the belt is the responsibility of the user but also an
opportunity for AB. When the belt is installed and in use, maintenance
(monitoring) is important in order to maintain a good performing belt and
to prevent failure. This can be done by measuring and monitoring tension
However, measuring conditions inside the belt is very
complicated because of the environment with constant stressing and
bending. Because of this, accurate measuring is almost impossible. In
stead, measurements can be taken outside the belt, but this is also
immediately outside the territory of Ammeraal Beltech. However, the
measurements, although inaccurate, can indicate changes in the belt. If
the measured values (i.e. tension, temperature) are outside a certain
range, then something is happening to the belt and a warning signal can be
given: Check the belt for possible bad performance. In this way the
reliability of the system can be increased and sudden failures can be
With the transponder integrated in the belt, the transponder and the belt
influence each others behavior. Since the transponder is relatively small
and sensitive, the belt and environment will have much more influence on
the transponder than the other way around. Therefore the most important
subjects are: stress (varying normal stress, bending), temperature
(welding, process) and chemical interaction (adhesion, reactions).
The belt is only affected by the transponder because some belt material is
replaced with material with different behavior. This can in the worst case
lead to delamination or surface wear (there where the transponder is
placed). For these reasons it is always best to have the transponder as
small as possible. On the other hand, the movements of the belt put
serious stress on the integrated transponder. With this in mind, there are
actually two options:
Since all transponders, at least up to this date, consist of a fragile
microchip and copper or aluminium antenna, which cannot withstand constant
bending and large strain, first of all, it is best to try the very stiff
transponder approach. When a flexible, strainable transponder is available or
developed, that can withstand the stresses in the belt, then finally that is
the best compromise. The transponder to select for integration should be
passive and electronically operated. Currently, there are two usable
- A very flexible transponder that can withstand the bending and strain.
This is the best approach from a belt point of view.
- A very stiff transponder that is much stiffer than the belt, that can
withstand the stresses it is subjected to, with negligible deformations in
the transponder. This is the best approach from a transponder point of
view, because then the delicate components (microchip and antenna) are not
subjected to stress.
Although the UHF transponder is not full-grown yet, its performance is
much better than the LF transponder (range, speed). But since the belt is
a difficult environment for the delicate electronics, it is best to select
a very tough transponder. It is possible to encapsulate the UHF
transponder but then it will be too large to be integrated in the belt.
Data transfer speed becomes important when a large quantity of data needs
to be exchanged with a running belt. For identification only, with a
unique code linked to information in a database, the data speed is not
very important (LF should be fast enough). Together with durability and
current availability, the LF transponder is the best choice for now. This
transponder type is very tough and the only disadvantage is the estimated
short read range and slow read speed.
- The LF transponder, small stiff disc (Æ6
x 1,5 mm), 2-4 kb/s, range ~cm.
- The UHF/microwave transponder, straight flexible shape (150 x 10 x 0,5
mm), 20-150 kb/s, range ~dm-m.
Future developments can make the UHF transponder smaller or flexible and
more suitable to be integrated in the belt. This would offer possibilities
to store the data directly on the transponder and UHF is also more capable
to be combined with sensors. Still, it is strongly advised to make the
transponder stiff to withstand the stressing or completely flexible with
an other antenna material than copper or aluminum.
A practical test proves that with the currently available transponder
types, it is possible with LF to identify the belt. Both the belt and the
transponder remain undamaged. Downside is the very short read range (1-2
cm) and the restricted thinness of the belt. HF is not suitable with the
copper or aluminum antenna and too large when encased (>4mm). The
standard UHF/microwave transponder is to be tested with a handheld reader
but with a copper or aluminum antenna, it is also suspected to break due
to bending and stressing.
The costs of the transponders are important because in a normal (barcode
replacing) application, thousands of transponders are used. In this case
where a transponder is integrated in the belt only the cost of one
transponder is added to the cost of the belt (which is a fraction). But
besides the transponder, there is also the need for a reader. Readers can
be expensive, especially when they are used in this particular application
at Ammeraal Beltech. The reader is periodically used to identify the belt
and if it is used for one or a few belts only then the identification of a
belt with RFID is an expensive solution. The case where identification of
belts is interesting is in the large users, for example an airport. In
this case there are hundreds of belts where the costs of one or a few
readers are divided over. On top of that the reader will be used more
frequently and this justifies the cost of the reader.
It is concluded that identification with Lf is possible but the
performance is very limited and too restricted for in field use. Since HF
is unsuitable because of the shape, the UHF transponder is the best choice
performance-wise and with this transponder a combination with sensor(data)
is possible. Handheld UHF readers are expected soon (2006). For the
physical layout of the transponder there are two possibilities: fully
flexible (follow the belt's movements) or fully stiff (withstand the
belt's movements). Recommended is the flexible option because the antenna
is still relatively large (making it stiff results in a large transponder)
and this option will influence the belt the least. The antenna design can
be a next step in the development of the intelligent belt, followed by the
development or selection of tension and temperature sensors and the design
of an interface with the transponder.
With the current state of RFID it is not recommended to produce the
intelligent belt. The right transponder is not available yet and the
belting market is not asking for a belt with integrated technique.
Ammeraal Beltech is not risking much by waiting a few years to let RFID
proove itself and let the proper transponder being developed. In the mean
time real customers and applications for the intelligent belt can be
found. When the right transponder is available on the market is hard to
predict, since the RFID market is mainly focussed on logistical
applications (excluding constant bending applications), but it will take a
Reports on Transport Engineering and Logistics (in Dutch)
, TU Delft