FIELD OF THE INVENTION
The present invention relates to a Radio frequency based material tracking system
to store and track materials/ boxes in a storage area corresponding to received
signal strength indication values.
BACKGROUND OF THE INVENTION
Material can be stored in open yards, closed stores and sometimes in semi closed
stores in a typical manufacturing company or in construction site as well. Old
methods of keeping track of material was the use of bin card or a barcoded system
which will be linked to a system software to locate and to take stock for generating
reports etc.
Some new technologies are developed in this area of material tracking in which the
RFID has gained popularity and few successful implementations/deployments have
shown it is reliable and trust worthy adapting this technology.
In medium or large sized closed or semi-closed stores, materials are stacked for
dispatching them to various sites, based on the user's requirement. However, said
stored stock undergoes lot of internal transactions like adding/receipt of new
materials/boxes/crates which perforce stored in some respective locations based on
the floor space availability. Similarly, there are issues of materials dispatch from
stores to other sites or another production areas etc. In all the above cases,
physical adjustment/shifting of items from one physical location to another physical
location within the store is mandatory and the current new location of a particular
material need updating in the prior art system for every time/transaction.

US 7786844 B2 discloses a system and method for detecting RFID tagged items
being moved by a mobile asset/vehicle, the method comprising of actuating an RFID
reader coupled to the mobile asset/vehicle to read identifications of proximately
located RFID tagged items a first time at a first location after loading of the mobile
asset/vehicle and storing a first set of read RFID tagged items, the first set of read
RFID tagged items including RFID tagged items loaded onto the mobile
asset/vehicle and RFID tagged items not loaded on.
Even, US 6669089 B2 teaches a forklift RFID system, comprising of at least one
RFID antenna positioned on a fixed portion of the forklift, at least one RFID antenna
positioned on a portion of the forklift that is vertically movable with respect to the
fixed portion, a user interface including a touch-panel display; and software
adapted to provide information to the display describing which RFID tags have been
interrogated by the antennas.
WO 2007/023274 A2 of discloses an RFID portal arrangement for detecting the
passage of RFID tags past the portal arrangement, comprising first and second
antenna means operable to communicate with tags passing the portal arrangement,
and control means operable to conduct a sequence of transactions with each RFID
tag, while passing the arrangement, and to determine the sequence of antenna
means used for the sequence of transactions, the control means being further
operable to use the antenna sequence to recover information relating to the
direction of movement of the corresponding RFID tag relative to the portal
arrangement.
Even US 2008/0249883 Al discloses a Self-checkout kiosk for enabling a patron to
purchase product carrying an RFID identification tag, comprising a portal through
which the patron must exit from a vending area in which product is stored and

available for purchase, a self-checkout station within the vending area enabling the
patron to complete a purchase transaction prior to exiting the vending area through
the portal, said portal carrying at least one RFID reading means for detecting
product being transferred through the portal, and security means responsive to
transfer of the product through the portal without a patron completing a purchase
transaction using the self-checkout means.
None of the prior arts as discussed hereinabove, however provides a system for
tracking and self-assigning the RFID tagged material to an RFID fixed antennae
automatically.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a Radio frequency based
material tracking system to track materials/ boxes in a storage area corresponding
to received signal strength indication values.
Another object of the invention is to propose a Radio frequency based material
tracking system to track materials/ boxes in a storage area corresponding to
received signal strength indication values, which allows an automatic assignment of
physical location of a tracked material to the nearest antenna.
SUMMARY OF THE INVENTION
According to the proposed RFID based tracking system of the invention, complete
shed/store area is covered with RFID fixed antennae based system operating on the
read range of the antennae. Material/boxes/crates etc, are RFID tagged on receipt
and dumped in the store anywhere subject to floor space availability. A system

software interacts with all the tags/tagged material within the storage area through
a pre-addressed (i.e. Location area name of the fixed antennae or number and left
side, right side etc..) fixed antennae system and acquires the details of all the RFID
tagged material in their respective vicinity based on the RSSI (Received Signal
Strength Indication) value and the software automatically assigns tagged material to
the nearest antennae. Hence, at any point of time, the user knows the physical
location of the tagged material and it becomes easy for the user to go to the
location and use a handheld reader to exactly locate the tagged material/box etc.
With the use of this technology we can reduce the cycle time of search of material
can be reduced by 50% and human effort by 50%. There is no need for manual
accounting and physical verification of material.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig.1 Flow diagram of the method of the invention
Fig.2 box to be tracked
Fig 3. RFID Portal
Fig 4. A system to implement the method of figure 1.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
The boxes [10] of different size and shapes filled with material are stored in a
packing shed. To facilitate entry of new stock and removal/dispatch of old stock
based on the demand, position of all the boxes changes every time to meet the
space constraints within the store. The boxes are kept in parallel rows one over the
other using an overhead crane available in the shed.

RFID fixed antennae [9] are fixed at a certain height on the columns [11] of the
shed, with antennae facing down wards at 45 degrees and facing the stacked
boxes/material on the floor. Antennae on the left side and right side are grouped
separately and every two antennae mounted in on line are connected with one RFID
antenna.
All the antennas are connected to their respective readers, through co-axial cable ,
which are connected through LAN cables and in turn all the LAN cables are
connected to a LAN switch separately for left side and right side antennae. A
desktop PC with a printer is arranged in the control room which connected to the
RFID/LAN system.
All the boxes/material received in the store are RFID tagged [1] (The tags can be
screw mounted or tied to the material) and a database of all entries is created for
the existing and for the newly received items.
All the RFID tagged items/boxes can be dumped into the storage area as per the
requirement, convenience and based on the availability of the space within the store
[2].
RFID fixed antennae are enabled to interact with all the tags within their vicinity and
the RSSI (Receive Signal Strength Indication) value of all RFID tags in the vicinity of
a particular antenna are captured by the desktop PC through RFIF fixed reader
including an application software. The application software allows an automatic
assignment of the tags to a particular antenna out of all antennae, based on the
RSSI value (Higher RSSI value means closer to the tag location to the antennae)
and the system shows the number of tags available in a particular antennae area,
[3].

If a particular tag already exists then the system updates of the tag details and
assigns the tag to the respective reader automatically. The system refreshes
itself in a periodic way, and any addition, deletion, replacement, relocations etc.,
automatically get re-assigned to respective antenna.
User can check location of any item/box any time by logging in to the system by
using various search criteria like RFID Tag ID, Box Number, Item Number etc..
Which will available in software. [5]
Each antenna reads its own tag with a unique identity. Now suppose a box/tag
from the segment A has been misplaced to some other segment say segment E,
the reader A will give an error signal that a particular box/tag has been
misplaced from its territory [6]. And readers E and F (adjacent to reader E) it
read a new box/ tag which doesn't belong to their territory, Reader E will still
read the tag because the tag is found in its own territory and reader F will read
due to back scatter signal (as to find a perfect unidirectional antenna is difficult).
Now to exactly locate the tag/box, the RSSI (Received Signal Strength
Indication) value of the two readers [7], shall be compared, And definitely the
signal strength of reader E will be greater than that of reader F .So if the RSSI
value of reader E is greater than that of reader F then the misplaced tag is in
segment E otherwise in segment F.
And suppose if the two RSSI values are almost equal or comparable then the
approximate location of the tag will be known that it is either in E or in F. Now
the hand held reader can be used to determine exact position of the misplaced
tag. [8]

If the user want to issue any item/box for dispatch, the Tag location can be
identified from the desktop system and, the operator can go to the location
physically with the RFID handheld antenna. Handheld antenna can be triggered
using relevant search option so that respective Tag will respond to the query by
enabling LED/alarm feature in the Tag.
The User need to ensure that the Tag assigned has to be removed physically
from the box being dispatched and the same tag can be re-assigned to any other
item/box newly taken in to the stock.

WE CLAIM:
1. A Radio frequency based material tracking system to track materials/ boxes in
a storage area corresponding to received signal strength indication values,
the system comprising a hand-held (HH) RFID antenna, a plurality pair of
fixed antenna disposed at a height on the left and right sides columns of the
storage area, each antenna disposed on one side of the columns are
connected through Local Area Net (LAN) cables which cables connected to a
LAN-switch separately for antennas disposed at left and right side; a desktop
Personal computer (PC) located at the control room of the system, the PC
being connected to the RFID system, wherein all the incoming, outgoing and
stored items provided with RFID tags, the system is enabled to :-
- assign tag to each incoming and stored material using the HH antenna;
- segment the storage area into a plurality of segmented areas (A,B,C,D,E,F);
- map one antenna to one segment;
- automatically assign each particular box (material) to a specific antenna
based on the received signal strength indication (RSSI) value provided by
each antenna;
- identify tag location of a particular material for issuance out of the storage
area using the desk-top system; and
- allow an operator with the HH-antenna to physically locate the identified
tagged material for egress from the storage area.
2. The system as claimed in claim 1, wherein the number of tags available in a
particular antenna coverage as well as the total number of tags present at
any point of time within storage area can be determined by using the PC.

3. The system as claimed in claim 1, wherein any tag if misplaced from one
segment to the other, the RSSI value of each antenna is compared and the
highest value indicates the correct segment where the box is actually located.
4. The system as claimed in claim 3, wherein the HH antenna is used to locate
the exact location of a misplaced tag when the RSSI of the antenna provides
substantially equal values.
5. The system as claimed in any of the preceding claims, wherein the location
data of each of the existing or newly arrived tags is updated and re-assigned
to respective antenna.