Monitoring system of large flows of TAG movement by RFID technology.

Description

[0001] This invention refers to a monitoring system for large flows of moving TAGs, using RFID technology and the relative system that implements a decisional algorithm that manages TAG movement.

[0002] Currently, in order to manage access methods, RFID - HF at 13,56 MHz and RFID-UHF with the frequency of UHF 865 - 870 MHz EU are the most widely used.

[0003] RFID-HF technology by inductive and electromagnetic coupling. The typical configuration includes a wound antenna, preferably copper. The dimension and number of spiral winds is determined by sensitivity and operative distance.

[0004] The HF band is the more widely used for the so-called "smart TAG" used in logistics and the management of objects, even if for this latter application the UHF band system will prevail in the long term. In this frequency "contactless Smart Cards" are used, such as intelligent cards without contact, which constitutes the most technologically active sector in the producers of chips. Almost entirely passive, the cards are covered by the ISO/IEC 14443 international standard - known as 'proximity', for a distance of between 10 to 30 cm - and the ISO/IEC 15693 l international standard, 'vicinity', for an operative distance of between 30 to 90 cm. Used for ticketing, access of personnel, baggage tracking in airport systems, contactless smart cards have become commonplace as intelligent and secure replacements to magnetic cards used for transactions such as credit or ATM cards.

[0005] The main fuction of TAG RFID is to identify an object and to assist with its logistics (identification of baggage, pallets, containers or any other element or place in the distribution chain). The standards for this type of application comes from two organisms, whose work is going towards the same direction:

- EPC Global, started and operated as a private association;

- ISO (and its connected organisms), is the global body concerning standards in almost all technology fields.

[0006] As a source of energy for circuits and to trasmit, passive TAG uses the field generated from the signal of the Reader. This results in a reduced operating distance (a few metres maximum) and other operative issues. TAGs contain a certain amount of secure memory. This type of TAG is the most common and used in large applications.

[0007] Battery Assisted Passive (BAP) TAG, so-called semi- passive (or semi active) have been developed for use in situations in which active TAGs cost too much or their batteries do not last long or passive TAG does not ensure sufficient performance. [0008] Active TAGs are self sufficient in energy, tipically they have a battery and a radio frequency transmitter/receiver.

[0009] Passive TAGs are fed by the radio frequency energy that they receive, and subsequentely they spread the energy

modulating part of the energy transmitted by the Reader that is in contact them.

[0010] To receive energy and communicate with the Reader, the operation of passive TAGs is based on one of the following physical principles:

• Inductive coupling (magnetic) in conditions of "near-field";

• Electromagnetic coupling in conditions of "far-field" with backscatter effect.

[0011] Systems that exploit inductive coupling in 'near field' conditions are based on the fact that the distance is relative to the length of the wave emitted by the Reader antenna.

[0012] Systems that use electromagnetic coupling in conditions of "far-field" with backscatter effect are based on the principle that, for relatively long distances, relative to the length of the wave emitted by the antenna of the reader, the effects of electromagnetic field prevails in the antenna of the TAG, and they vary periodically in time.

[0013] In passive RFID systems, a critical role is played by the antennae of the TAGs and by those of the Reader. The antennae are the primary energy source for the TAGs and problems of orientation and polarisation significantey influence the performances.

[0014] Concerning the materials of construction of the antennae of the passive TAGs, these are generally made of engraved metal or with deposition of conductive ink on the substrate.

[0015] Concerning the dimension of coiled antennae, major influencing factors are the area of the coiled antennae and the number of coils. The tension induced at the ends of the antenna of the TAG is directly proportional to the number of coils and to the flow of the magnetic induction vector.

[0016] It is possible to use small antennae with a single coil that can be created by printing processes using condictive inks.

[0017] Finally, in order to be albe to operate at larger distances, the same UHF TAG can have two separate antennae allowing it to operate both from a far field and from a close field. The majority of the antennae for RFID must be tuned on resonance at the operating frequency. This puts the system at the mercy of external factors that can de-tune the antenna from the resonant frequency, reducing the operating distance. There are many causes of this and it depends on the frequency (skin effect, losses due to the proximity of metallic masses, fading of the signal, proximity to other antennae of the Reader, environmental changes, etc.). [0018] Readers are a key element of RFID systems, and their characteristics must be assessed carefully in order to achieve the benefits provided for in the system.

[0019] Until the recent wave of pervasive applications in the distribution chain, Readers of passive TAGs were primarily used for access controls and other applications (anti-theft systems, etc.). These could involve both a low number of TAGs recorded for each query, and a low number of data coming from the TAGs. Nowadays the situation is changing, for the needs of the supply chain, for the applications of which all the TAGs (even thousands) contained in packages in which the goods are stored, are read simultaneously (boxes, pallets, racks, containers).

[0020] The operating distance in an RFID system can be defined as the maximum distance at which the reading of a TAG reaches a specified percentage of success.

[0021] TAGs are made of a wide variety of containers, designed for different environments and applications. Among the most common assembly formats are: cards (credit card type), flexible adhesive labels, paper TAGs, TAGs injected or molded into containers and plastic products, TAG wrist straps, key-TAGs, large containers TAGs (pallets, containers, etc.).

[0022] Main features to be considered when selecting a TAG in the context of a particular RFID system: size and shape, mutual distances of the TAGs, durability, reusability, resistance in critical environments, polarisation, intervals of temperature in which the TAG is intended to function, communication distance between TAG and Reader, influence of any metallic materials and liquids, operating environment, speed within the field of the Reader, support of the Reader.

[0023] Currently, to monitor the access passages this technology is utilised through the use of devices that have the most widespread use on the band 13.56 MHz and which make use of photocell sensors. One of the major limitations is the limited distances in the monitoring process and the limited number of simultaneously detectable TAGs .

[0024] The purpose of the present invention is to solve the problem of the limited number of simultaneously detectable TAGs.

[0025] An added purpose of the present invention is to solve the problem of limited size of the PASSAGES which the TAGs pass through.

[0026] Another purpose is to avoid the identification of a static TAG as an infinite number of passages across a gap.

[0027] The present invention uses a system that involves the monitoring of a massive flow of TAGs associated with people or objects in motion across a gap along which two antennae of the RFID UHF frequency band 865 ÷ 870 or 2.4 GHz are arranged and oriented in appropriate directions. They need to be at a certain distance from each other which can vary depending on the environment in which they are installed. The choice of the frequency band 865 ÷ 870 MHz UHF EU is dictated by the need to avoid interferences with normal radio frequencies used by mobile operators. The decision not to use the 2.4 GHz band is due to the fact that this band is very crowded by other technologies (Wi-Fi, Bluetooth, ZigBee)

[0028] To achieve the purpose of the present invention, a system was used made with the latest generation of RFID devices designed and manufactured by the American company Impinj, in particular: Impinj Speedway Revolution R220 RFID Reader (IPJ- REV-R220-EU11M) and related antennae with the specifications given by the manufacturer, coupled with a common PC.

[0029] The antennae can be equipped with reflective side rails in order to avoid interferences between them, as the order of detection of the TAGs is important.

[0030] In a stable condition, meaning in absence of a TAG, the antenna of the Reader emits the electromagnetic field and "recaptures" it noting the absence of perturbations of the same field.

[0031] Once a TAG enters the electromagnetic field, the condenser supplies power to the chip of the TAG. The chip modulates perturbations of the field that the antenna of the Reader picks up through its antenna. But a TAG does not communicate with the reader only once: once it remains within the range of emanation of the magnetic field it continues to communicate and therefore there may be tens or hundreds of interactions.

[0032] It should be noted that this is an object in a given position rather than an indefinite number of detections of the same object.

[0033] This task is performed by the system in the PC connected to the reader. If the TAG moves, it is necessary to detect the direction of the displacement, in this case, the system in the PC, which implements the decision algorithm and be connected to the Reader and will be able to decide the direction of motion, communicating it to the upper application layer afterwards.

[0034] The system used for the purpose of the present invention, thus shows an increased amount of TAGs read simultaneously in input and output in relation to the radius of emanation of the electromagnetic field.

[0035] Such a system also allows to increase the width of the access/output passages up to 6 meters or more.

[0036] Therefore, to reach the purpose of the present invention, use is made of an algorithm that is based on the association to each antenna of a buffer to keep track of detected TAGs by storing them during their passage. Consider as an example a TAG input denoted by TAG 1.

Initially, near the entrance, TAG 1 will be detected by Antenna 1 and then stored in its relative buffer (buffer Antenna 1) and after detection by Antenna 2 will be stored in (buffer Antenna 2). As long as TAG 1 is present in the illuminating mirror of Antenna 1 , the software will update the time of detection of TAG 1 in buffer Antenna 1 ; advancing along the passage TAG 1 will also be detected by Antenna 2 and stored in buffer Antenna 2. As long as TAG 1 is present in the illuminating mirror of Antenna 2, it will be detected by this software and update the time of detection of TAG 1 in buffer Antenna 2 and perform a number of tasks, namely: if TAG 1 was taken over by Antenna 2 that has been stored in buffer A2 (meaning that Antenna 2 buffer was added to the first detection of Antenna 2) and by Antenna 1 (stored in buffer Antenna 1) then the system checks whether the time of the last check of TAG 1 by Antenna 2 is greater than the last detection of TAG 1 by Antenna 1 and stored in buffer Antenna 1 increased by an interval 'Dt' (variable and depends from the model of Reader used). If this condition is verified then it checks if the time of detection of TAG 1 by Antenna 1 is less than the time of detection of TAG 1 by Antenna 2, through comparison of the values previously stored in the respective buffers, if such conditions are verified then it inserts information in the database of interest as shown in Figure 5, the UML Activity Diagram.

[0037] Java SE has been utilised to develop this software. In particular, the communication with the Reader is made via LLRP (Low Level Reader Protocol standard EPCblobal). The tests were conducted in indoor environment using various TAGs and considering the various use cases: one inflow, one outflow, two concurrent streams, opposite input-output, obtaining satisfactory results.

[0038] It was possible to optimise the use of the following invention designing an integrated system in a single solution that includes two antennae, a Reader and a mini PC with decisionmaking within the system (Figure 4).

Description of the figures:

[0039 The representations of the system of the present invention is described thus in the following drawings :

• Figure 1 shows a graph that shows the functionality of the chip according to the supplied memory chip itself;

• Fig 2 shows a simulation of the application of the system;

• Figure 3 shows Buffer generated by the software, together with their antennae;

• Figure 4 shows an integrated system consisting of two antennas, a reader and a mini PC with intgrated decisionmaking system.

• Fig. 5 shows the UML Activity Diagram of the algorithm; Numbered reference figures

- Tab 2 Fig.3:

Entrance phase: For every TAG, the algorithm has the following conditions: Antenna 1 - Antenna 2 - 0 Exit phase: For every TAG, the algorithm has the following conditions: Antenna 2 - Antenna 1 - 0

The TAG detected by Antenna X is intended where Antenna X is indicated.

- Tab 2, Fig.4:

1 - Antenna 1

2 - Antenna 2

3 - Reader

4 - Mini PC unit containing monitoring management software

D - Minimal usable distance without interference between the Antennae

- Tab 3, Fig.5:

A = Activity T = Transaction Dt = Time variable in sec

• Al Activity of TAG detection by Reader

• A2 Receiving method of detected TAG

• A3 Entrance in Buffer 1

• A3.a Update detection of TAG X in Buffer 1

• A4 Entrance in Buffer 2

• A4.a Update detection of TAG X in Buffer 2

• A5 Removal of TAG X from buffer 1

• A6 Removal of TAG X from buffer 2

• A7 Updating DB

• A8 Updating DB

• Tl TAG X not detected • T2 TAG X detected

• T3 TAG X detected by Antenna 2

• T4 TAG X detected by Antenna 1

• T5 TAG X not present in Buffer 1

• T6 TAG X present in Buffer 1

• T7 TAG X in Buffer 1 & TAG X in Buffer 2

• T8 Time detecting TAG X > time detecting TAG X in Buffer 2 + Dt

• T8.a Time detecting TAG X in Buffer 2 < time detecting TAG X in Buffer 1

• T9 TAG X in Buffer 1 & NO TAG in Buffer 2

• T10 TAG X not present in Buffer 2

• Til TAG X present in Buffer 2

• T12 TAG X in Buffer 2 & TAG X in Buffer 1

• T13 Time detecting TAG X > time detecting TAG X in Buffer 1 + Dt

• T13.a Time detecting TAG X in Buffer 1 < time detecting TAG X in Buffer 2

• T14 TAG X in Buffer 2 & NOT TAG X in Buffer 1

• T15 Reader active

• T16 Reader disactivated