BACKGROUND

[0001] Radio frequency tags, for example RFID tags, can be affixed to objects in order to identify an object using an electromagnetic field. When a radio frequency tag is triggered by an electromagnetic interrogation signal from a radio frequency tag reader, the radio frequency tag generates a return signal to transmit data to the radio frequency tag reader. The data transmitted by the radio frequency tag may include an identification number or similar.

[0002] Radio frequency tags have application in a range of industries. Radio frequency tags can be used for identification of an individual object, for example to identify a book on a library shelf. Radio frequency tags can also be used to track items, for example to track the progress of an object through an assembly line, or stocktaking, where a single interrogation signal from a radio frequency tag reader can trigger multiple return signals from multiple items to determine a quantity of items or a contents of a container. Another use of radio frequency tags is in security, both for tagging of products in retail shops to trigger an alarm if removed from the shop, or for personal identification cards. Radio frequency tags are also used in banking transactions to facilitate contactless payment.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Further details, aspects and embodiments of the invention will be described, by way of example only, with reference to the drawings. In the drawings, like reference numbers are used to identify like or functionally similar elements. Elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale.

[0004] Figure 1A illustrates an example operation of a radio frequency tag reader;

[0005] Figure IB illustrates an example operation of the radio frequency tag reader;

[0006] Figure 2 shows a block diagram of a system suitable for carrying out methods described herein;

[0007] Figure 3 is a sequence diagram illustrating a method of locating a target object from among a plurality of objects; and

[0008] Figure 4 is a sequence diagram illustrating a method 400 of locating a target object from among a plurality of objects illustrating further actions that may be performed when it is determined that an identification of the candidate object does not match an identification of the target object.

DETAILED DESCRIPTION

[0009] In the following description, for purposes of explanation, numerous specific details of certain examples are set forth. Reference in the specification to “an example” or similar language means that a particular feature, structure, or characteristic described in connection with the example is included in at least that example, but not necessarily in other examples.

[0010] Radio frequency tags are useful in identifying an object from a plurality of stored objects. Such radio frequency tags may include, by way of example only, Radio Frequency Identification (RFID) tags, Near-Field Communication (NFC) tags, high frequency (HF) radio tags, or ultra-high frequency (UHF) radio tags. A radio frequency tag may be affixed to each object of the plurality of objects.

[0011] A radio frequency tag comprises a radio transceiver. The radio frequency tag can be triggered by an electromagnetic interrogation signal from a radio frequency tag reader. When triggered, the radio frequency tag transmits a return signal comprising digital data. A passive radio frequency tag is powered by the energy of the electromagnetic interrogation signal from the radio frequency tag reader. An active radio frequency tag comprises a battery to power the tag.

[0012] For a plurality of radio frequency tags located in close proximity to each other, a single interrogation signal from a radio frequency tag reader may trigger return signals from more than one of the radio frequency tags. Some of the radio frequency tags may return a stronger or weaker return signal than those around them when measured with a radio frequency tag reader. Stronger or weaker return signals of a radio frequency tag may be due to the distance of the radio frequency tag from the radio frequency tag reader, manufacturing tolerances or manufacturing defects of the radio frequency tag, or may be due to the positioning of the radio frequency tag on the object with which it is associated.

[0013] Figure 1A shows an example situation in which a radio frequency tag reader 110 is used to read a first radio frequency tag 122a of a first object, the first object positioned between a second object comprising a second radio frequency tag 124a, and a third object comprising a third radio frequency tag 126a. In the example of Figure 1A, an interrogation signal 112 is transmitted from radio frequency tag reader 110. The interrogation signal 112 triggers a return signal 114a from first radio frequency tag 122a. The return signal 114a comprising an indication of an identity of the first object with which first radio frequency tag 122a is associated.

[0014] The interrogation signal 112 may also trigger a return signal 116a from second radio frequency tag 124a and a return signal 118a from third radio frequency tag 126a. Thus, three return signals 114a, 116a and 118a are received by radio frequency tag reader 110, in the example of Figure 1A. In this example, the return signal 114a from first radio frequency tag 122a is the strongest of the three return signals, due in part to the lower distance between the first radio frequency tag 122a and the radio frequency tag reader 110, compared to the distance between the second or third radio frequency tags 124a, 126a and the radio frequency tag reader 110.

[0015] Figure IB shows a second example situation in which the radio frequency tag reader 110 is used to read the first radio frequency tag 122b of the first object, the first object positioned between the second object comprising the second radio frequency tag 124b, and the third object comprising the third radio frequency tag 126b. In the example of Figure IB, an interrogation signal 112 is transmitted from the radio frequency tag reader 110. The interrogation signal 112 triggers a return signal 114b from first radio frequency tag 122b. The return signal comprising an indication of the identity of the first object with which first radio frequency tag 122b is associated.

[0016] The interrogation signal 112 may also trigger a return signal 116b from second radio frequency tag 124b and a return signal 118b from third radio frequency tag 126b. Thus, three return signals 114b, 116b and 118b are received by radio frequency tag reader 110, in the example of Figure IB. In this example, the return signal 116b from second radio frequency tag 124b is the strongest of the three return signals, despite the distance between second radio frequency tag 124b and radio frequency tag reader 110 being greater than the distance between first radio frequency tag 122b and radio frequency tag reader 110. This difference in the strength of the return signals may be due to the positioning of each radio frequency tag on the respective objects, manufacturing tolerances in the radio frequency tags, or other reasons. Accordingly, radio frequency tag reader 110 may incorrectly associate the identity of the second radio frequency tag 124b with the first object, based on an assumption that the strongest return signal would be associated with the nearest object, resulting in an erroneous identification of the first object. [0017] Some embodiments according to the teachings disclosed herein may aid in the identification of objects. In particular, the disclosed methods and apparatus may facilitate identification of an object of a group of objects arranged in close physical proximity.

[0018] Figure 2 shows a block diagram of a system 200 suitable for carrying out the methods according to some embodiments described herein. System 200 comprises a processor 210 communicatively coupled to a memory 212. Processor 220 is further communicatively coupled to a radio frequency tag reader 220, and an actuator 230. Optionally, processor 220 may be further communicatively coupled to an auxiliary sensor 240.

[0019] In operation, radio frequency tag reader 220 and optional auxiliary sensor 240 may be configured to provide input data or signals to processor 210, and actuator may be configured to operate in response to output data or signals from processor 210.

[0020] To locate a target object from among a plurality of objects, where each object comprises a unique radio frequency tag, a first measurement may be performed by the radio frequency tag reader 220 in order to identify a candidate object from the plurality of objects. This candidate object is an object of the plurality of objects which is determined to be a most likely match for the target object, based at least on the first measurement by the radio frequency tag reader 220.

[0021] Once a candidate object has been identified, the candidate object may be spatially displaced relative to the other objects of the plurality of objects. Spatially displacing the candidate object may be done by means of an electro-mechanical actuator, such as actuator 230 of Figure 2. In some examples, the actuator 230 may be a robotic arm. In some examples, the actuator 230 may be a bespoke actuator configured specifically for displacing one of the one or more objects. In some examples, the actuator 230 may comprise the radio frequency tag reader 220.

[0022] After spatially displacing the candidate object, a second measurement may be performed by the radio frequency tag reader 220 in order to confirm whether the candidate object is in fact the target object. Determining whether the candidate object is in fact the target object may comprise comparing an identification of the radio frequency tag of the candidate object to an expected identification of a radio frequency tag of the target object.

[0023] By spatially displacing the candidate object prior to performing the second measurement by the radio frequency tag reader 220, the effects of interference from other radio frequency tags may be reduced. [0024] In various examples, the second measurement may be performed by the same radio frequency tag reader as the first measurement, or by a different radio frequency tag reader to the first measurement. The specific arrangement of radio frequency tag reader, and whether multiple radio frequency tag readers are used, may depend on the specific arrangement or storage of the plurality of objects, and/or similar physical requirements.

[0025] An auxiliary sensor, such as auxiliary sensor 240 of Figure 2, may provide a sensor data that can be used to accurately position the actuator relative to individual objects, for example actuator 230, in order to spatially displace the candidate object. The auxiliary sensor may be, by way of example only, any one of an optical sensor, an inertial sensor, a camera module, an accelerometer, or a similar sensing means suitable for positioning the actuator to manipulate an individual object of the plurality of objects. In some embodiments, the auxiliary sensor 240 may comprise a plurality of sensing elements, configured to work in combination to determine the position, dimensions and/or orientation of the objects to allow the position of the actuator to be accurately controlled to manipulate a targeted object.

[0026] Figure 3 is a sequence diagram illustrating a method 300 of locating a target object from among a plurality of objects. According to method 300 illustrated in Figure 3, a candidate object is identified 310 based on a first measurement by a radio frequency tag reader, such as radio frequency tag reader 220 of Figure 2. Once a candidate object has been identified 310, the candidate object is spatially displaced 320 relative to the other objects of the plurality of objects. Spatially displacing 320 the candidate object may be done using an actuator, such as actuator 230 of Figure 2.

[0027] A second measurement 330 of the candidate object is then performed by the radio frequency tag reader. Following the second measurement 330 of the candidate object, it is determined 340 whether the identification of the candidate object determined based on the second measurement matches an identification of the target object. If the determination 340 indicates that the identification of the candidate object matches the identification of the target object, then it is concluded 350 that the candidate object is the target object. If the determination 340 indicates that the identification of the candidate object does not match the identification of the target object, then a newly selected candidate object may be identified 310 based on the previously obtained first measurement by the radio frequency tag reader, and the method returns to the spatial displacement step 320 in order to spatially displace 320 the newly selected candidate object and perform a second measurement 330 of the newly selected candidate object by the radio frequency tag reader. [0028] Figure 4 shows a sequence diagram illustrating a method 400 of locating a target object from among a plurality of objects illustrating further actions that may be performed when it is determined that the identification of the candidate object does not match the identification of the target object. According to method 400 illustrated in Figure 4, a candidate object is identified 410 based on a first measurement by a radio frequency tag reader, such as radio frequency tag reader 220 of Figure 2. Once a candidate object has been identified 410, the candidate object is spatially displaced 420 relative to the other objects of the plurality of objects. Spatially displacing 420 the candidate object may be done using an actuator, such as actuator 230 of Figure 2.

[0029] A second measurement 430 of the candidate object is then performed by the radio frequency tag reader. Following the second measurement 430 of the candidate object, it is determined 440 whether an identification of the candidate object determined based on the second measurement matches an identification of the target object. If the determination 340 indicates that the identification of the candidate object matches the identification of the target object, then it is concluded 450 that the candidate object is the target object. If the determination 440 indicates that the identification of the candidate object does not match the identification of the target object, then it is concluded 442 that the candidate object is not the target object, but is instead a second object. It is then determined 444 whether an actual location of the second object is at the expected location of the second object. If it is determined 444 that the actual location of the second object is the expected location of the second object, then the second object is returned 446 to an original position. Alternatively, if it is determined 444 that the actual location of the second object is different to the expected location of the second object, then the second object is moved 448 to be placed in the expected location for the second object. Following either returning 446 the second object to the original position or moving 448 the second object to the expected location, the method returns to step 410 to identify a new candidate object, based on the first measurement by the radio frequency tag reader.

[0030] In some embodiments the newly selected candidate object may be located proximate, e.g. adjacent to, a previously selected candidate object.

[0031] Certain embodiments may further comprise returning the candidate object to the original position if it is determined that the candidate object is not the target object. A second candidate object may then be identified, and the process of confirming whether the candidate object (in this case, the second candidate object) is the target object repeated. The second candidate object may be identified based on a second most likely object compared to the first candidate object. The second candidate object may be identified based on a most likely object based on updated parameters based on determining that the first candidate object is not the target object.

[0032] Certain embodiments may further comprise a database comprising data related to an expected location of each object the plurality of objects. The expected location of an object may be an absolute location, or the expected location may be a location of an object relative to the other objects of the plurality of objects.

[0033] If a target object is correctly identified, but is determined to be in a location that is different to the expected location of the target object according to the database (an ‘incorrect’ location), then the target object may be moved relative to the other objects of the plurality of objects to the expected location according to the database (a ‘correct’ location). If the second measurement 330, 430 determines that the candidate object is a second object different from the target object, and the second object is in the expected location of the target object according to the database or the second object is in a location that is different to the expected location of the second object, then the second object may be moved relative to the other objects of the plurality of objects to an expected location of the second object according to the database. Moving the target object may be done by means of an electro-mechanical actuator. In some embodiments the electro-mechanical actuator for moving the target object may be the same electro-mechanical actuator used for spatially displacing a candidate object. In some embodiments the electro-mechanical actuator for moving the target object may be a different electro-mechanical actuator to the electro-mechanical actuator used for spatially displacing a candidate object.

[0034] In some embodiments, one or more parameters associated with a radio frequency tag may be stored in a database. In response to one or more measurements by a radio frequency tag reader one or more of these parameters may be updated. For example, the one or more parameters may relate to an expected return signal strength for a particular radio frequency tag.

[0035] In some embodiments, when it is determined 340, 440 that the identification of the candidate object does not match the identification of the target object, one or more parameters stored in the database may be updated prior to determining a new candidate object.

[0036] In some embodiments, one or more weightings to be applied to measurements of return signal strength for each radio frequency tag may be stored in the database. These weightings may be adjusted over time increase the accuracy of identification of the target object. For example, a radio frequency tag associated with a specific object may always return a weaker return signal to the radio frequency tag reader, for example, due to a manufacturing defect in the radio frequency tag, or positioning of the tag on the object. Therefore, a weighting may be assigned to the specific object in order to apply a compensation factor to the strength of the return signal, in order to counteract the effects of the naturally weaker return signal.

[0037] In some embodiments, the one or more weightings may be adjusted using machine learning or artificial intelligence techniques.

[0038] In addition to a first measurement by a radio frequency tag reader, identifying a candidate object may be based on one or more of: an expected location of the target object based on the recorded database, a previous measurement of the target object by the radio frequency tag reader, a previous measurement by the radio frequency tag reader at the expected location of the target object based on the recorded database, or the one or more parameters associated with a radio frequency tag.

[0039] In some examples, identification of a candidate object may utilise various artificial intelligence, machine learning or neural network techniques, based on historical data of whether an identification of a candidate object matches the identification of the target object. By this, the accuracy of correctly identifying a candidate object that is the target object can be improved over time.

[0040] Certain methods and systems as described herein may be implemented by a processor, for example processor 210 of Figure 2, that processes program code that is retrieved from a non-transitory storage medium. Processors suitable for the execution of computer program code include, by way of example, both general and special purpose microprocessors, application specific integrated circuits (ASIC) or field programable gate arrays (FPGA) operable to retrieve and act on instructions and/or data from the computer-readable storage medium.

[0041] The computer-readable storage media can be any media that can contain, store, or maintain programs and data for use by or in connection with an instruction execution system. Computer-readable storage media can comprise any one of many physical media such as, for example, electronic, magnetic, optical, electromagnetic, or semiconductor media. More specific examples of suitable machine readable storage media include, but are not limited to, a hard drive, a random-access memory (RAM), a read-only memory (ROM), an erasable programable read-only memory, or a portable disc. [0042] In some examples, the computer-readable storage medium may comprise program code or instructions to perform the method illustrated in Figure 3 and discussed above.

[0043] The method and apparatus provided herein may be useful, by way of example only, in a library for identifying and organising a plurality of books, where each book has a radio frequency tag affixed. The strength of a return signal from a particular radio frequency tag may vary depending on the position of the tag inside the book, thickness of book cover or spine, or similar factors. Additionally, a return signal of a particular tag will be subject to interference from the tags of books either side of it, or even books on adjacent shelves. Thus, a first measurement by the radio frequency tag reader may be taken whilst the book is on the shelf, and a second measurement by the radio frequency tag reader may be taken with the book partially or wholly removed from the shelf. Identification of a book located at an incorrect position on a shelf may be remedied by use of an electro-mechanical actuator to reposition the book in a correct location. Thus, the methods and apparatus herein can be used for sorting unsorted objects, such as books.

[0044] The method and apparatus provided herein may also be useful, by way of example only, for identifying and picking parts, such as electronic components each comprising a radio frequency tag, for use in a production process. The disclosed methods and apparatus would enable verification of the part or component before installation in a product, based on a first measurement of a part or component on the shelf or in the storage bin, and a second measurement of the part or component once partially or wholly removed from the shelf or storage bin.

[0045] Other applications of the method and apparatus provided herein are envisaged, for example use in warehouse and logistic operations, document storage, archiving and retrieval, biological or chemical sample storage and retrieval, automated safety deposit box retrieval or similar banking operations, and the like.

[0046] According to examples of the present disclosure, there is provided a method for locating a target object from among a plurality of objects, each object of the plurality of objects comprising a unique radio frequency tag, the method comprising: identifying a candidate object from the plurality of objects based on a first measurement by a radio frequency tag reader; spatially displacing the candidate object relative to the other objects of the plurality of objects; and determining that an identification of the candidate object matches an identification of the target object based on a second measurement by the radio frequency tag reader. [0047] Some examples further comprise a recorded database, wherein identifying the candidate object is further based on identifying any radio frequency tag that is not positioned according to the recorded database.

[0048] In some examples, if it is determined that the identification of the candidate object does not match the identification of the target object, the method further comprises: returning the candidate object to an original position; and identifying a second candidate object from the plurality of objects based on a third measurement by the radio frequency tag reader.

[0049] In some examples, identifying a candidate object is further based on one or more parameters stored in a memory.

[0050] Some examples further comprise updating the one or more parameters based on at least one of the first measurement by the radio frequency tag reader and the second measurement by the radio frequency tag reader.

[0051] In some examples, spatially displacing the candidate object relative to the other objects of the plurality of objects comprises controlling an actuator.

[0052] In some examples, the plurality of objects are a plurality of items each with an associated RFID tag.

[0053] According to examples of the present disclosure, there is provided an apparatus for locating a target object from among a plurality of objects, each object of the plurality of objects comprising a unique radio frequency tag, the apparatus comprising: a processor; a radio frequency tag reader; and an actuator; wherein the processor is configured to: identify a candidate object from the plurality of objects based on a first measurement by the radio frequency tag reader; control the actuator to spatially displace the candidate object relative to the other objects of the plurality of objects; and determine that an identification of the candidate object matches an identification of the target object based on a second measurement by the radio frequency tag reader.

[0054] In some examples, if it is determined that the identification of the candidate object does not match the identification of the target object, the processor is further configured to: control the actuator to return the candidate object to an original position; and identify a second candidate object from the plurality of objects based on a third measurement by the radio frequency tag reader.

[0055] In some examples, the radio frequency tag reader is located on the actuator. [0056] In some examples, the plurality of objects are a plurality of books.

[0057] In some examples, the radio frequency tag is an RFID tag.

[0058] In some examples, the radio frequency tag is a high frequency (HF) or ultra-high frequency (UHF) radio tag.

[0059] In some examples, the actuator comprises a robotic arm.

[0060] In some examples, the processor is further configured to control the actuator to relocate the target object, if the target object is determined to be in an incorrect location relative to the other objects of the plurality of objects.

[0061] According to examples of the present disclosure, there is provided a computer- readable storage medium comprising instructions which, when executed by a computer, cause the computer to carry out the steps of: identifying a candidate object from a plurality of objects based on a first measurement by a radio frequency tag reader; controlling an actuator to spatially displace the candidate object relative to the other objects of the plurality of objects; and determining that an identification of the candidate object matches an identification of a target object based on a second measurement by the radio frequency tag reader.

[0062] All of the features disclosed in this specification (including any accompanying claims, abstract, and drawings) may be combined in any combination, except combinations where some features are mutually exclusive. Each feature disclosed in this specification, including any accompanying claims, abstract, and drawings, may be replaced by alternative features serving the same, equivalent, or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed in one example of a generic series of equivalent or similar features.

[0063] The present teachings are not restricted to the details of any of the foregoing examples. Any novel combination of the features disclosed in this specification (including any accompanying claims, abstract, and drawings) may be envisaged. The claims should not be construed to cover merely the foregoing examples, but also any variants which fall within the scope of the claims.