Abstract:
Methods, systems, and apparatuses for tracking and monitoring tagged objects in an RFID environment is described. By varying RFID reader antenna output power levels and detecting RFID devices in the vicinity, data about position and orientation of the RFID devices can be gathered. This gathered data is used to correlate with pre-stored data about RFID devices&#39; position and orientation. Such a correlation then can be used to infer data about neighboring RFID devices based upon data stored in the database. Such an inferential technique also results in a faster analysis of position and orientation data of RFID devices, and also leads to faster tracking of RFID enabled devices. Unnecessary reads and high power operations of the RFID reader are also avoided.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to radio frequency identification (RFID) reader technology, and in particular, to a system and method to track RFID devices. 
         [0003]    2. Background 
         [0004]    The monitoring of workforce and inventory movement is a major concern for businesses today. A slight modification in the path taken by an employee when taking inventory may increase efficiency and result in significant savings for a company. To achieve a complete knowledge of when and where an RFID tagged object or employee is located, conventional RFID readers utilize a brute-force technique of continuous reading of tags at constant power to gather position/orientation of RFID tags. The type and extent of data that can be obtained by these brute force techniques is limited. Additionally, these conventional real time tracking solutions generally require additional hardware installed at various workplace locations. 
         [0005]    Thus, what is needed are intelligent techniques and systems to track RFID enabled devices using minimal hardware to determine position and/or location and orientation of RFID tagged objects. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES 
         [0006]    The accompanying drawings, which are incorporated herein and form a part of the specification, illustrate the present invention and, together with the description, further serve to explain the principles of the invention and to enable a person skilled in the pertinent art to make and use the invention. 
           [0007]      FIG. 1  illustrates an exemplary environment in which RFID readers communicate with an exemplary population of RFID tags. 
           [0008]      FIG. 2  illustrates an exemplary system to determine location and/or orientation of RFID tagged objects/items by using power variation in an RFID reader and associated reader circuitry. 
           [0009]      FIG. 3  illustrates a flowchart for determining location and orientation using tag identification data. 
           [0010]      FIGS. 4A-4H  illustrate scenarios where power levels of an RFID reader are varied based upon inferred data relating to one or more tags&#39; orientation. 
           [0011]      FIG. 5  illustrates an exemplary computer system used to control power management of an RFID reader. 
       
    
    
       [0012]    The present invention will now be described with reference to the accompanying drawings. In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears. 
       DETAILED DESCRIPTION OF THE INVENTION 
     1.0 Introduction 
       [0013]    Methods, systems, and apparatuses for RFID devices are described herein. In particular, methods, systems, apparatuses, and computer program products for tracking RFID enabled devices, such as mobile employees carrying RFID readers, or RFID enabled inventory items, are described. 
         [0014]    The present specification discloses one or more embodiments that incorporate the features of the invention. The disclosed embodiment(s) merely exemplify the invention. The scope of the invention is not limited to the disclosed embodiment(s). The invention is defined by the claims appended hereto. 
         [0015]    References in the specification to “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. 
         [0016]    Furthermore, it should be understood that spatial descriptions (e.g., “above,” “below,” “up,” “left,” “right,” “down,” “top,” “bottom,” “vertical,” “horizontal,” etc.) used herein are for purposes of illustration only, and that practical implementations of the structures described herein can be spatially arranged in any orientation or manner. Likewise, particular bit values of “0” or “1” (and representative voltage values) are used in illustrative examples provided herein to represent data for purposes of illustration only. Data described herein can be represented by either bit value (and by alternative voltage values), and embodiments described herein can be configured to operate on either bit value (and any representative voltage value), as would be understood by persons skilled in the relevant art(s). 
       2.0 Example RFID Environment 
       [0017]    Before describing embodiments of the present invention in detail, it is helpful to describe an example RFID communications environment in which the invention may be implemented.  FIG. 1  illustrates an environment  100  where RFID tag readers  104  communicate with an exemplary population  120  of RFID tags  102 . As shown in  FIG. 1 , the population  120  of tags includes seven tags  102   a - 102   g.  A population  120  may include any number of tags  102 . Environment  100  includes any number of one or more readers  104 . For example, environment  100  includes a first reader  104   a  and a second reader  104   b  (also interchangeably referred to herein as a single RFID reader  104 ). Readers  104   a  and/or  104   b  may be requested by an external application to address the population of tags  120 . Alternatively, reader  104   a  and/or reader  104   b  may have internal logic that initiates communication, or may have a trigger mechanism (for example, an ON/OFF trigger) that an operator or a central controller of RFID reader  104  uses to initiate communication. Readers  104   a  and  104   b  may also communicate with each other in a reader network. 
         [0018]    As shown in  FIG. 1 , reader  104   a  transmits an interrogation signal  110   a  having a carrier frequency to the population of tags  120 . Reader  104   b  transmits an interrogation signal  110 b having a carrier frequency to the population of tags  120 . Each such transmission of an interrogation signal by the RFID readers  104   a  and  b  consumes power. By practice of this invention, power consumption of RFID readers  104  a and b is reduced. In addition, the ability to vary power levels of RFID readers  104   a  and  b  aids in avoiding tag misses and/or redundant tag reads. 
         [0019]    Readers  104   a  and  104   b  typically operate in one or more of the frequency bands allotted for this type of RF communication. For example, frequency bands of 902-928 MHz and 2400-2483.5 MHz have been defined for certain RFID applications by the Federal Communication Commission (FCC). 
       3.0 Example Embodiments 
       [0020]    According to an exemplary embodiment of the invention, RFID antenna output power level is set at a predetermined value. The output power level is then raised or lowered and data related to tags that enter or leave the antenna&#39;s field of view, and the order in which such tags move in or move out is recorded. By comparing which tags entered or left the antenna&#39;s field at various output levels, location and/or orientation of these tags can be inferred. 
         [0021]    Location and orientation information for a reader and/or tagged object can be obtained by systematically altering the output power level of reader  104  and performing a read of tags in the field of view of the reader. During such an operation, RFID reader  104  varies its output power, to detect one or more RFID tags in a vicinity or field of view of RFID reader  104 . Depending on various reflections from different tags and noting which tags enter or leave RFID reader  104  antenna field of view, and in what order, RFID reader  104  can then infer spatial orientation of tags and/or the location and orientation of the reader  104 . Such a determination location and orientation is performed by comparing data gathered from multiple reads of a tag population (at varying power levels). Once orientation is determined for one or more tags, RFID reader  104 &#39;s power level can be set back to a predetermined value for start of the next interrogation cycle can bring down its power levels before a next set of tag scans is performed, thereby saving battery and increasing time to recharge. 
         [0022]    These exemplary embodiments are described in detail below. It should be noted that one skilled in the art, after reading this disclosure, can contemplate other such techniques and systems where RFID reader  104  can be operated at varying power levels infer position and orientation data of tags by correlating data gathered during RFID reader reads with data existing in a database of known tag locations. Additionally or alternatively, though a single RFID reader  104  is described, one skilled in the art, after reading this disclosure, can easily extend the ideas embodied in this invention to multiple RFID readers, such as an array of RFID readers, for example. 
       3.1 Orientation/Location Determination 
       [0023]    Real time tracking provides valuable information to end users on customer habits and movement of the workforce. Current real time location monitoring solutions require additional hardware. In embodiments of the present invention, the output power level of the reader can be modified across reads of the tag population. The tag data gathered (e.g., which tags enter or leave the antenna field at various output levels) can be stored and correlated to determine location and orientation information for the reader. 
         [0024]      FIG. 2  depicts an exemplary system  200  for determining location and/or orientation of a device using RFID tag data, according to embodiments of the present invention. System  200  includes an RFID reader  204  and a centralized management system (CMS)  260 . 
         [0025]    Reader  204  includes one or more antennas  202 , a receiver and transmitter portion  220  (also referred to as transceiver  220 ), a baseband processor  212 , a network interface  216 , and a power control module  240 . These components of reader  204  may include software, hardware, and/or firmware, or any combination thereof, for performing their functions. Antennas  202 , transceiver  220 , baseband processor  212 , and network interface  216  are well known to those skilled in the art. 
         [0026]    Power control module  240  is configured to modify the output power level of reader  204 . In an embodiment, power control module  240  modifies the power level based on signals received from CMS  260 . In addition or alternatively, power control module  240  may also include an algorithm to systematically modify the output level of the reader over a series of read cycles for the reader. 
         [0027]    Although a single RFID reader  204  is depicted in  FIG. 2 , one skilled in the art can easily contemplate that system  200  may include multiple RFID readers. CMS  260  is configured to receive tag data from one or more readers  204 . In an embodiment, CMS  260  includes location/orientation determination module  265 . Location/orientation determination module  265  is configured to receive data from reader  204  for a read of a tag population and associate the data with reader power level used to obtain the received tag data. The power level/tag data is stored in a record in database  270 . Location/orientation module  265  is further configured to cause reader  204  to vary the output power level and perform a subsequent read of the tag population. Location/orientation module  265  is also configured to correlate the data obtained across multiple reads to derive location and orientation for reader  204  and/or objects in the tag population. 
         [0028]    Database  270  stores a set of records for one or more readers. Exemplary record  272  includes an identification of the reader, one or more read entries, and a timestamp for the record. A read entry includes the power level used for the read and associated tag data obtained during the read. Each reader may have multiple records. Database may also include details related to the antenna configuration of the reader. Database can be any form of data store. For example, database  270  can be an SQL database provided by IBM Corporation of Armonk, N.Y. 
         [0029]    In an embodiment, location/orientation module  265  can correlate data from multiple records for a reader (or multiple readers) to generate a report of reader movement or object movement within a predetermined period of time. 
         [0030]      FIG. 3  depicts a flowchart  300  of an exemplary method for determining location and orientation using tag identification data, according to embodiments of the present invention. Flowchart  300  is described with continued reference to the embodiment of  FIG. 2 . However, flowchart  300  is not limited to those embodiments. Note that the steps depicted in  FIG. 3  do not necessarily have to occur in the order shown. 
         [0031]    In step  310 , the output power level of the RFID reader is set to a first level. In an embodiment, the reader power level may be set to a minimum level then subsequently increased. Alternatively, the reader power level may be set to a maximum level then subsequently decreased. In a further alternative, the reader power level may be set to a value in the midpoint and then increased or decreased according to a predetermined method. 
         [0032]    In step  320 , reader  204  performs a read of the tag population at the established output level. 
         [0033]    In step  330 , reader  204  transmits the tag identification data obtained during the read performed in step  320  to CMS  260 . 
         [0034]    In step  340 , the tag data is associated with the output level used by the reader  1104  to obtain the tag data and stored in a database accessible by the location/orientation determination module. 
         [0035]    In step  350 , a determination is made whether additional reads of the tag population are to be performed. If additional reads are required, operation proceeds to step  355 . If no additional reads are required, operation proceeds to step  360 . 
         [0036]    In step  355 , the output power level of the reader is set to a different level. In an embodiment, location/orientation module  265  sends a signal causing power control module to alter the output power of reader  204 . Alternatively, power control module  260  alters the output level in accordance with a predetermined technique. 
         [0037]    In step  360 , location/orientation determination module  265  compares the tag data obtained at each read power level for the reader to determine location and/or orientation of the reader device at a specific time or period of time. Location/orientation determination module  265  may also take into consideration the type of antenna and the resulting antenna pattern of reader  204  when making the determination. 
         [0038]    In step  370 , location/orientation determination module  265  compares historical data for a reader  204  over a time period (e.g., a work shift) to develop a report of device movement during that period. 
         [0039]      FIGS. 4A-4H  illustrate the above method in more detail. 
         [0040]    Consider a scenario with 7 tags, A-G, and RFID reader  104  shown as “R” in  FIGS. 4A-4H . Also in  FIGS. 4A-4H , outwardly radiating ovals represent antenna output power levels. For example, larger ovals represent a higher antenna output level and smaller ovals represent lower output power levels. 
         [0041]    As shown in  FIG. 4A , RFID reader  204  antenna output power is set to 25% of its maximum output level. In this scenario, RFID reader  204  sees tag E first. In  FIG. 4B , antenna output power is increased to 50% and tags D and F enter RFID reader  204  field of view. Based on this data, RFID reader  104  knows that tag E lies between tags D and F and knowing that tag E was detected first, RFID reader  104  estimates that a tagged object is at tag E&#39;s location, and is pointing towards tag E. 
         [0042]      FIG. 4C  shows RFID reader  204  turned in a different direction as compared to  FIGS. 4A and 4B . In  FIG. 4C  the antenna power is set to 25% again, and RFID reader  204  sees tags C. Then, as shown in  FIG. 4D , RFID reader  204  increases its antenna output power level to 50% and tag D also enters RFID reader  104 &#39;s field. At this point, it can not be determined if RFID reader  104  is facing tag C or tag D. In  FIG. 4E , RFID reader  204  power is increased to 100% of its output level and at this point tag B becomes visible to the antenna. Therefore, using information gathered in  FIG. 4C and 4D  and by having another tag enter RFID reader  204 &#39;s field of view as in  FIG. 4E , it can now be determined that RFID reader  204  is indeed facing tag C. If RFID reader  104  were facing tag D instead of tag C, then tag E could have become visible to RFID reader  104  when output power was increased to 100% in  FIG. 4E . 
         [0043]    In yet another scenario shown in  FIGS. 4F to 4H , RFID reader  204  is close to tag F. As shown in  FIG. 4F , when RFID reader antenna power is set to 25%, the device sees only tag F. Then, as shown in  FIG. 4G , RFID reader  204  antenna power is increased to 50% and tag E enters RFID reader  204 &#39;s field of view. Once again, at this point it can not be determined if RFID reader  204  is facing tag F or tag C. To determine this, as shown in  FIG. 4H , RFID reader  204  increases the antenna output power to 100% to check which tags now enter the field. As shown in  FIG. 4H , when the RFID reader  104  antenna power is 100%, tag D and tag C become visible and it can subsequently be determined that the device is facing tag C. If it were facing tag F, then tags D and C would not have become visible when power was increased to 100%. Those knowledgeable in the RFID reader antenna radiation patterns would quickly recognize that antennas for different radiation patterns or RFID tags arranged in different patterns could use similar power management techniques to determine tag orientation by comparing tags entering or leaving the field with a known database of tag orientation. 
       4.0 Computer Embodiments 
       [0044]    In an embodiment of the present invention, the system and components of the present invention described herein are implemented using well known computer systems, such as a computer system  500  shown in  FIG. 5 . Computer system  500  can be any commercially available and well known computer capable of performing the functions described herein, such as computers available from International Business Machines, Apple, Silicon Graphics Inc., Sun, HP, Dell, Compaq, Digital, Cray, etc. Alternatively, computer system  500  can be a custom built system. 
         [0045]    Computer system  500  includes one or more processors (also called central processing units, or CPUs), such as a processor  504 . This processor may be a graphics processor in an embodiment of the invention. Processor  504  is connected to a communication infrastructure or bus  506 . Computer system  500  also includes a main or primary memory  508 , such as random access memory (RAM). Primary memory  508  has stored therein control logic (computer software), and data. 
         [0046]    Computer system  500  also includes one or more secondary memory storage devices  510 . Secondary storage devices  510  include, for example, a hard disk drive  512  and/or a removable storage device or drive  514 . Removable storage drive  514  represents, for example, a magnetic tape drive, a compact disk drive, an optical storage device drive, etc. 
         [0047]    Removable storage drive  514  interacts with a removable storage unit  518 . Removable storage unit  518  includes a computer useable or readable storage medium having stored therein computer software (control logic) and/or data. The logic of the invention as illustrated in various flowcharts above, for example, may be embodied as control logic. Removable storage unit  518  represents, for example, a floppy disk, a magnetic tape, compact disk, DVD, optical storage disk, or any other computer data storage device. Removable storage drive  514  reads from and/or writes to removable storage unit  518  in a well known manner. 
         [0048]    Computer system  500  may also include input/output/display devices  530 , such as monitors, keyboards, pointing devices, etc. 
         [0049]    Computer system  500  further includes a communication or network interface  527 . Network interface  527  enables computer system  500  to communicate with remote devices. For example, network interface  527  allows computer system  500  to communicate over communication networks or mediums  526  (representing a form of a computer useable or readable medium), such as LANs, WANs, the Internet, etc. Network interface  527  may interface with remote sites or networks via wired or wireless connections. 
         [0050]    Control logic may be transmitted to and from computer system  500  via communication medium  526 . More particularly, computer system  500  may receive and transmit carrier waves (electromagnetic signals) modulated with control logic via communication medium  526 . 
         [0051]    Any apparatus or manufacture comprising a computer useable or readable medium having control logic (software) stored therein is referred to herein as a computer program product or program storage device. This includes, but is not limited to, computer system  500 , main memory  508 , hard disk  512 , and removable storage unit  518 . Carrier waves can also be modulated with control logic. Such computer program products, having control logic stored therein that, when executed by one or more data processing devices, can cause such data processing devices to operate as described herein, represent embodiments of the invention. 
       5.0 Conclusion 
       [0052]    While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims and their equivalents.