Claims:We claim,
1. A system for tracking and localising objects using a network of passive and active energy radio devices and a GPS enabled base station comprising the steps of:
Tagging each object with a passive energy RFID receiver herein referred to as tags, periodically detecting the presence and absence of each user tag and also of tag IDs on a Special List, providing the user with the means to measure the distance between the band and a specific tag, sounding an alarm in case of a tag displacement and in the case of a tag getting lost providing means for locating the tag using anonymous tracker systems herein referred to as the community feature.
2. A method as claimed in claim 1, wherein the user interface provided as part of the said base station provides the user with the said means to register new tags with the said tracker system.
3. A method as claimed in claim 1, where said bands working in said tracking mode, polls the presence of said RFID tags using a low powered RF beam mirroring technique.
4. A method as claimed in claim 1, for increasing the power of the said bands in gradual steps, having a count equal to five(5), for tags which have failed to respond to the method as claimed in claim 2. At the end, a presence summary is prepared after every said poll cycle and checked for abnormalities, wherein if an anomaly is detected, the said base station is immediately alerted by the said band using a Bluetooth low energy uplink.
5. A method as claimed in claim 1, wherein the base station being alerted activates a beeper to draw user attention to the said anomaly in the said tracker system.
6. A method as claimed in claim 1, wherein the said user can put the said band into a locator mode, to measure the distance between the said band and the said tags using a granular power tuning technique.
7. A method as claimed in claim 1, wherein if a said tag is found to be lost, the said user can choose to put up the said tag’s details, including the said tag’s UID, last known GPS

location and timestamp of last contact, on a global said Special List maintained on a said distributed cloud server.
8. A method as claimed in claim 1, wherein a gradual geographically localised flooding of the said information is performed as described. The said anonymous localisers upon receiving information, starts working in locator mode to track down the said lost tag.
9. A method as claimed in claim 1, wherein an iterative time independent Area of

Confidence refinement technique is used to estimate the location of the said lost tag.

10. A method as claimed in claim 1, wherein upon reaching a Mean Confidence Index threshold using data as claimed in claim 9, a GPS extrapolation technique is used to estimate the location of said lost tag.The estimated GPS location is relayed to the owner of the said lost tag. , Description:Wireless data communication technology including Radio Frequency Identification tags can be used to identify and locate misplaced objects within a specified vicinity. This object tracking system is an efficient conglomeration of a base station carried by the user, a system server, radio bands and radio frequency tags which interact in an ad-hoc inter-network, facilitating and monitoring the locations of objects.

This passive energy ecosystem comprises of RFID tags which are affixed to those items whose location needs to be tracked. The tag is an integrated circuit chip which comprises an internal patch antenna and a non-volatile storage buffer pair as shown in fig. 1. A unique serial number known as the Unique Identifier(UID) value is associated with every tag. This unique Identification number is saved inside two storages inside the device jointly known as the “first means” and the “second means”. The second data being complementary to the first and both being connected to the antenna provides a redundancy check needed to protect the tag against

possible corruption. When the tag is triggered, this UID value is used to exclusively identify a particular object.

The second part of the system consists of what we call the “Band” as depicted in fig. 2. It consists of a RFID interrogator/reader and a Bluetooth(low energy) module connected to a microcontroller(MCU). The RFID reader is a supervisor component of the system consisting of a transceiver. It performs in two modes of operation, the finder mode, and the locator mode, the finder mode being the default operating state. In the finder mode, the reader uses a multiplexer(as shown in fig. 2) to daisy chain among all the concerned tags and also a Special list of tags(described later in the text) to check their presence using a radio energy mirroring technique common to RFID systems. It receives the signal mirrored and fingerprinted by the tags and converts the incoming radio waves into an accessible form of data. To conserve power the reader is kept at a minimum power, high attenuation state. During the poll cycle if it is detected that a certain tag failed to respond, the attenuation factor for it is lowered, or in other words, the reader uses more power to search for the tag. This is done in five stages until the maximum possible power range for the reader is reached, or the tag responds back to the reader. After every successful poll cycle, a presence summary is prepared by the MCU. The presence summary is a string of binary values, indicating if a particular tag is within the specified vicinity or not. A change in the presence summary arises in two scenarios, firstly, when an unknown tag is detected for the first time, and it’s UID appears on the special list or secondly, when one or more target tags fail to respond to five(5) poll cycles, indicating a possible unwarranted displacement. The second mode or the locator mode is activated only under the specific supervision of an active base station. Users can use this mode to locate nearby tagged objects. A simple way to perform radio-based localisation is to use the Received Signal Strength Indicator(RSSI), however, since most RFID tags fail to respond to RSSI triggers due to their working mechanism we again employ the RF attenuation described above to provide localisation. We start by targeting the tag with the lowest attenuation factor and consequently with the highest power and gradually decrease it until it stops responding. The point where we lose contact is used to calculate the distance of the RFID tag from the band. This entire band architecture is housed

within a shock resistant substrate of mostly plastic or cellulose origins in the shape of a wristband, making it inexpensive and portable and durable, which can be easily worn on a wrist like a watch.

The third part of the invention is the base station which provides the user with the first point of interaction with the system. We built the base station in two different forms, as a standalone hardware device with an inbuilt Bluetooth module, a GPS module and a GSM module and another as a software application to be run on third party devices like cell phones with GPS capabilities. On first interaction, the user inputs the tag IDs of her concern into the base station, which is then sent to the band via a Bluetooth downlink and the tracker system starts working. The base station also runs a broadcast listener in the background for updates in its Special list, received from the server. If a new address is received on the Special list, it is immediately sent to the band for localisation.

If a tagged user object is signaled to be out of reach from the tracking zone, an alarm system(beeper) incorporated in the base station, notifies the user of a possible displacement or aberration in the spatial positioning of the tracked object. In the unlikely event, a user misses the beeper or for unforeseen reasons lose a tagged target, she can put the tracker in localiser mode. This immediately puts the band in the locator mode and it starts locating the device according to the process mentioned above, with special importance being given to the tagged object’s last known GPS location. If even this method fails, our community feature acts as the last line of defense. In this feature, the user can opt to activate a community lookout for the lost device. This puts the device’s ID, last known location, timestamp and related data on a watch list known as the Special List maintained on the server end. This information is used to attempt community localisation as detailed below. This whole system consisting of tags, bands and base-stations jointly consist of the tracing ecosystem depicted in fig. 3.

The last part of the tracking system features a community-based application, shown in fig. 4, which has a wider prospect of utilization. It is based on the RFID Bluetooth active transceivers

present in the bands and GPS present in the base station, termed as localisers in short, for finding lost tags. Once a tag UID is put on the Special list we perform a geographically controlled flooding on the data, wherein the contents of the list is sent to base stations active in the vicinity of the last known tag position. This data is then subsequently transmitted by the base station to its corresponding band. The band then starts looking for the UID as mentioned above. According to general laws of Radio-triangulation, it takes a minimum of three stations to coordinate a target with reasonable confidence. However since it might not be feasible to have multiple localisers to be present in the same locality, at the same time to perform a proper triangulation we use a confidence building procedure, where we keep on refining our estimated Area of Confidence(AoC) as more localisers enter the region of interest. It is however completely allowable for the localisers to have different temporal alignments since we perceive lost objects to be constant on the time axis. As we refine our Area of Confidence, we have an exponential decrease in its three-dimensional volume, as shown in fig. 4, with an increase in the Mean Confidence Index(MCI). After a threshold MCI is reached, the AoC is extrapolated w.r.t available base station GPS data to obtain the most probable GPS coordinates of the lost tag, which is then sent back to the concerned user. All the above-mentioned data packets are time stamped and encrypted using the localiser’s fingerprint for authentication and nonrepudiation purposes. This is done to prevent localisation spoofing attacks from adversarial entities. However, if the lost tag localisation fails within a given time-period, we perform a secondary flooding with an increased area of dispersal. The number of times the cycle is performed is dependent upon individual customer profiles before which a tag is labeled as untraceable.

Although the present invention has been described keeping in contention with the description given above and the diagrams attached to this document certain changes can be made owing to new ideas and methods. These will be incorporated from time to time to make our invention as feasible as possible solving real life problems.