Method and system for locating the position of items in a storage system

Abstract

A method for locating a plurality of tagged items in a storage system includes scanning the tags at a plurality of power levels with a first antenna (540), identifying each tag of interest found by the first antenna at each of the plurality of power levels (560), scanning the tags at the plurality of power levels with at least one further antenna (540), identifying each tag of interest found by each of the plurality of power levels (560), identifying an antenna that identified each tag of interest at a minimum power level, and estimating a location of each tag of interest using the identified antenna and the minimum power level at which each tag of interest was identified (580).

Description

Technical Field

[0001] The present disclosure generally relates to identifying the position of tags placed within a storage cabinet, and more particularly to a system and method for identifying the position of items with radio frequency identification (RFID) tags within a multi-shelf cabinet.

Background Art

[0002] Radio frequency identification (RFID) is one of the radio frequency identification methods. Here, data is electronically stored on a tag, and the data can be read by an RFID reader to identify, locate, and / or track the item to which the tag is attached. The RFID system does not necessarily provide the exact position of the tagged item. Instead, it often provides the general position of the tagged item. For example, when a tagged item is placed within a cabinet, the RFID reader often confirms the presence of the tag within the cabinet. In this case, it is not necessarily possible to confirm which shelf or drawer within the cabinet the tagged item is placed in.

[0003] The RFID reader operates by generating an electrical signal, generating an electromagnetic field that interacts with the antenna coil of the RFID tag to interrogate the tag, and obtaining identification information from the tag.

Summary of the Invention

Means for Solving the Problems

[0004] Any consideration of the documents, acts, materials, devices, articles, etc. included in this specification is not to be received as an admission that any or all of these matters form part of the prior art base in the field related to the present disclosure that existed prior to the priority date of each claim of this application, or that it was common general knowledge.

[0005] In one embodiment, a method is provided for locating a plurality of tagged articles within a storage system. This method includes the steps of: scanning tags at a plurality of power levels using a first antenna; identifying each tag of interest found at each of the plurality of power levels using the first antenna; scanning tags at a plurality of power levels using at least one further antenna; identifying each tag of interest found at each of the plurality of power levels using each of the further antennas; identifying the antenna that identified each tag of interest at the lowest power level; and estimating the location of each tag of interest using the identified antenna and the lowest power level that identified each tag of interest.

[0006] The step of scanning tags at multiple power levels using the first antenna may include activating the antenna coil of the first antenna at each of the multiple power levels. The step of identifying each tag of interest found at each of the multiple power levels using the first antenna may include receiving response signals from at least some of the tags of interest at each of the multiple power levels. The electric field strength radiated from each antenna may vary by a predetermined amount depending on each power level. The power levels may be logical power levels corresponding to the actual power levels required for a given antenna range. The method may include deriving the logical power levels of each antenna corresponding to the actual power levels required to reach a given distance.

[0007] The method may further include a step of calibrating the antenna power levels in the storage system. The step of calibrating the antenna power levels in the storage system may include a step of placing a plurality of calibration tags in the storage system; a step of scanning the calibration tags at a plurality of different power levels using each antenna; a step of identifying the minimum power level at which each antenna discovers each calibration tag; and a step of setting one or more calibration values ​​for each antenna from the identified minimum power level. The step of calibrating the antenna power levels in the storage system may be repeated with the calibration tags placed at a plurality of different levels in the storage system. The step of calibrating the antenna power levels in the storage system may compensate for differences in antenna coils so that each logical power level of each antenna corresponds to substantially the same antenna coil range.

[0008] The method may include a step of setting the tag to a low-power mode that reduces the number of activated tags in the storage system before scanning the tag. The tag may include memory. The method may further include a step of storing a value representing the power level at which the tag was first discovered. The memory may be a timestamp field. The value representing the power level at which the tag was first discovered, stored in the timestamp field, may be a power level ID.

[0009] The method, in the step of estimating the location of each tag of interest using the identified antenna and the minimum power level that identified each tag of interest, may include the step of identifying the height level of the storage system in which each tag is located. The step of identifying the height level of the storage system in which each tag is located may include the step of applying a power level offset that offsets the antenna power level to a lower height level with respect to each height level of the storage system. The power level offset may be applied to the logic power level of each antenna. The method, in the step of estimating the location of each tag of interest using the identified antenna and the minimum power level that identified each tag of interest, may include the step of identifying the horizontal position of each tag of interest at the height level of the storage system in which the tag is located. The horizontal position of each tag of interest may be identified as a distance from the antenna having the minimum power level that identified the tag, and at a distance corresponding to the range of the antenna at the minimum power level.

[0010] The first antenna and the at least one further antenna may be located on or within the storage system. The storage system may have a height level, and at least a portion of the height level may have at least two overlapping antennas, each containing overlapping coils. Each of the at least two overlapping antennas, each containing overlapping coils, may have a first loop having a first current and a second loop having a second current rotating in the opposite direction to the first current. The overlapping coils may be arranged to overlap so that the loops are aligned along the axis, thereby generating a continuous reading zone along the axis. The continuous reading zone may correspond to a section of the storage system.

[0011] In another embodiment, a system is provided for locating RFID-tagged articles located within a storage system containing a plurality of RFID-tagged articles. The system comprises a plurality of antenna coils associated with one or more height levels of the storage system, an antenna controller that powers the antenna coils at power levels corresponding to received power level signals, and a processor that communicates with the antenna controller. The processor outputs a plurality of power level signals to the antenna controller to selectively activate each of the antenna coils at a plurality of different power levels, receives response signals from each of the antenna coils corresponding to each power level, identifies each RFID tag found in each received response signal, identifies the antenna coil with the lowest power level that identified each RFID tag of interest, and estimates the location of each RFID-tagged article of interest using the identified antenna coil and the lowest power level that identified each RFID tag of interest.

[0012] The descriptions made herein should be understood to relate to certain non-limiting embodiments and are not intended to be descriptions of the entire invention. Where there are promises that are deemed to apply to all non-limiting embodiments, the applicant / patentee reserves the right to later delete them from this specification and shall not rely on these descriptions for the acceptance or subsequent grant of a patent in any country. [Brief explanation of the drawing]

[0013] These and other embodiments and features will become apparent to those skilled in the art by considering the following description relating to certain non-limiting embodiments in conjunction with the accompanying drawings.

[0014] A detailed description of exemplary (non-limiting) embodiments will be better understood by considering them in conjunction with the accompanying drawings.

[0015] [Figure 1] This is a schematic diagram of a non-limiting embodiment of an RFID system.

[0016] [Figure 2A] It is a schematic representation of the magnetic field coupling between an RFID antenna and an RFID tag.

[0017] [Figure 2B] It is a perspective view of a storage system having a plurality of shelves and RFID antennas distributed throughout.

[0018] [Figure 3] It is a diagram showing an exemplary non - limiting embodiment of a cabinet in which the RFID system of FIG. 1 can be used to identify the position of an item with an RFID tag inside the cabinet.

[0019] [Figure 4] It is a schematic diagram of a prior - art antenna configuration.

[0020] [Figure 5] It is a flowchart of a non - limiting embodiment of a method for identifying the position of an item in a storage system.

[0021] [Figure 6] It is a schematic diagram of a multi - level antenna arrangement for discovering tags.

[0022] In the drawings, like reference numerals indicate like parts.

[0023] The drawings are not necessarily to scale and may be illustrated by phantom lines, perspective views, and fragmentary views. In certain instances, details not necessary for an understanding of the non - limiting embodiments, or details that would make it difficult to perceive other details, may be omitted.

Embodiments for Carrying Out the Invention

[0024] Next, various non-limiting embodiments of methods and systems for locating articles within a storage system will be described in detail. Other non-limiting embodiments, modifications, and equivalents will be apparent to those skilled in the art in view of the non-limiting embodiments disclosed herein, and these variations should be considered to fall within the scope of the appended claims.

[0025] Furthermore, it will be recognized by those skilled in the art that certain structural and operational details of the non-limiting embodiments (one or more) described below may be modified or omitted entirely (i.e., are not essential). In other examples, well-known methods, procedures, and components are not described in detail.

[0026] System Overview

[0027] Figure 1 is a schematic diagram of a non-limiting embodiment of an RFID reader system 100 for locating items within a section of a storage system. The RFID reader system 100 has an array of antenna coils 102 that communicate with an RFID reader 104. The RFID reader 104 comprises an antenna controller 106 that selectively supplies power to each antenna coil 108 at multiple different power levels, and a processor 110. The processor 110 receives multiple response signals from the array of antenna coils 102. The response signals are generated in response to one or more query signals from the RFID reader 104. In some non-limiting embodiments, the controller and processor may be located in a single shared processing unit.

[0028] In addition to the antenna controller 106 and processor 110, the RFID reader 104 may include various modules 120 that support the operation of the RFID reader 104. These modules may include one or more of the following: memory 112 (e.g., volatile memory, non-volatile memory, and / or other storage), a communication interface 114 that supports communication between the RFID reader 104 and other devices (e.g., in the form of a network interface controller or other interface hardware), and a user interface 116. The modules 120 of the RFID reader 104 cooperate with each other by exchanging data via the bus 118.

[0029] The user interface 116 may include, for example, a display means such as a screen and / or touchscreen, along with a keyboard and / or other buttons / levers. The communication interface 114 can communicate with or support communication between the RFID reader 104 and a user device (not shown). The user device may include a computer, laptop, handheld device, tablet, smartphone, etc. The user device may include software for receiving and displaying information received from the RFID reader 104 via an end-user application in the form of application software, such as a mobile "app", website, and / or web application, which receives and displays tag location data identified by the RFID reader 104.

[0030] Figure 2A shows the operation of an RFID reader 104 communicating with an antenna coil 208. The antenna coil 208 induces a magnetic field 210 around the coil, as illustrated by the dashed line. The magnetic field 210 defines a reading zone around the coil in which an RFID tag can be detected. The magnetic field can be coupled with the tag antenna of an RFID tag 308 located within the magnetic field either above or below the antenna coil 208. In an exemplary, non-limiting embodiment, the antenna coil 208 is positioned on the shelf floor, within the shelf, or in relation to the shelf floor, so that the shelf is considered to lie in the XY plane shown in Figure 2A. Thus, the RFID tag may be positioned above the shelf floor (+Z direction) or below the shelf floor (-Z direction), i.e., on a lower shelf, within the generated magnetic field.

[0031] Figure 2B shows a storage system 200 having multiple levels in the form of shelves 202A to 202D. The articles 220 contained within the storage system 200 have RFID tags 308 that can be read by one or more antenna coils 208. The shelves 202A to 202D can take other forms, such as racks, drawers, trays, compartments, etc. For clarity, only one antenna coil per shelf is illustrated, but this is merely illustrative. Therefore, more or fewer (including zero) antenna coils may be provided on each shelf. In some non-limiting embodiments, each shelf has multiple antenna coils to enable precise location of articles. Each coil can induce a magnetic field, which provides a reading zone 212 where tags can be detected by the antennas.

[0032] The storage system may be a cabinet or a refrigerator. Another embodiment of the storage system 300, shown in Figure 3, is a trolley or cabinet 300 in which the items to be stored are plasma boxes or blood bags 306 to which electronic tags in the form of RFID tags 308 are attached. Each blood bag 306 is placed on a cabinet level (e.g., in a drawer or on a shelf 314). Each tagged item is also placed within a section 310 of the cabinet 300. Each section 310 is in the form of a container, such as a tray 312. In this non-limiting embodiment, each shelf 314 contains a plurality of containers 312. As shown, the exemplary cabinet 300 includes a plurality of levels in the form of shelves 314 (arranged vertically so as to be labeled by the Y axis), and each shelf 314 contains a plurality of trays 312. In the exemplary non-limiting embodiment, the trays 312 are arranged in a row along the width of the cabinet 300 (arranged horizontally so as to be labeled by the X axis).

[0033] Each tray 312 has an elongated shape. It holds multiple RFID-tagged blood bags 306 stacked longitudinally across the tray 312, spanning the depth of the cabinet 300 (labeled by the Z-axis). Each blood bag 306 has an RFID tag 308 with a tag antenna. In the illustrated example, the blood bags 306 are stacked in the Z direction. The tag antenna of the RFID tag 308 is substantially in the XY plane. In alternative, non-limiting embodiments, the trays may be arranged and / or stacked in a variety of alternative configurations. For example, each shelf may include two parallel columns of trays.

[0034] Antenna placement

[0035] Figure 4 is a schematic diagram of a prior art antenna configuration 400. In this example, two antenna coils 402 are arranged for four trays 404, such that each antenna coil 402 is associated with two of the trays 404. In this configuration, if the first antenna coil 406 provides a signal to the reader indicating the presence of an RFID tag, the RFID tag may be placed in one of the first two trays 408, 410 associated with the first antenna coil 406. Similarly, if the second antenna coil 412 provides a signal to the reader indicating the presence of an RFID tag, the RFID tag may be placed in one of the two trays 414, 416 associated with the second antenna coil 412. Therefore, in this antenna configuration 400, it is impossible to precisely place an RFID tag in one of the four trays.

[0036] Another drawback of the configuration in Figure 4 is that the maximum power generated by each coil is limited by electromagnetic compatibility (EMC) regulations that specify limits on electromagnetic radiation at a certain distance from electronic equipment. One solution is to configure two antenna coils 402, such that the current flowing through one coil flows in opposite directions to the current flowing through the other, thereby generating magnetic fields that cancel each other out in the far field. However, if both coils are operating simultaneously and the far field magnetic field becomes net zero, it becomes impossible to distinguish which of the four trays 404 the tagged item is in.

[0037] In some non-limiting embodiments, each level of the storage system (e.g., each shelf 202A-202D of the storage system 200 in Figure 2) has overlapping antenna coils such that each item 220 having an RFID tag placed therein is powered by one or more coils and / or can be seen by coils at multiple levels. When in use, the antenna coil has a first loop having a first current and a second loop having a second current with a rotational direction opposite to that of the first current. Other antenna coils overlap the antenna coil so that the loops are aligned along an axis. This makes it possible to generate a continuous reading zone along that axis.

[0038] By using such an antenna arrangement, multiple reading zones can be formed. In some non-limiting embodiments, the reading zones are aligned with sections of the storage system. This allows for narrowing down the likely locations where tags of interest are present. Furthermore, such antenna arrangements can be used to reduce external emissions so that the storage system meets EMC requirements.

[0039] Method Overview

[0040] Figure 5 is a flowchart of a non-limiting embodiment of a method 500 for locating an item associated with a detectable tag in a storage system. The method includes steps 520 of performing antenna power level calibration and 540 of performing a scan to identify a detectable tag by each antenna at different power levels. The method further includes steps 560 of analyzing the scan to identify each tag found by each antenna at multiple power levels and step 580 of using the analysis to locate the item. In a further step (not shown), the located location is displayed on the user interface 116 of the RFID reader 104 and / or provided to the end user via the reader's communication interface 114 (for example, on a user device such as a laptop running an end-user application). Each step is described in more detail below.

[0041] Antenna power level calibration

[0042] In typical operation, the antenna coil provides the largest possible reading range. This means it operates at the maximum power level to maximize reception of RFID tags and determine their presence. However, this approach does not reveal the location of the tag or its associated items. The range of the antenna coil can be reduced by decreasing the power supplied to it. This can be achieved by converting a digital power level signal, such as from processor 110, into an analog voltage (typically not necessarily between 0 and 12-15V) that powers the antenna coil. The effective range of the antenna coil changes proportionally to its power level. Therefore, for each antenna coil, antenna power level calibration can be performed to determine how the power level correlates with distance.

[0043] For example, in a shelf antenna, different antenna coils may have different shapes. This means that the actual range of each coil is likely to be different. To compare the detection distance between different antenna coils, calibration measures the power required to read tags at several distances and sets a calibration value for each antenna coil. Calibration needs to be performed only once for each unique model of the storage system. Then, the calibration value for each antenna coil can be saved and reused for each model.

[0044] First, many logical power level stages are identified. A tag reader may have a large number of discrete power levels, for example, 256 or more. While it is possible to use such a large number of power levels to achieve high resolution, this is generally not practical, at least considering the time required to perform calibration and subsequent measurements. Therefore, in some non-limiting embodiments, 2 to 32 power levels, e.g., 2 to 16 power levels, are used. For most applications, it has been found that using 2 to 8 power levels, depending on the size and nature of the antenna and / or storage system, provides a sufficiently useful resolution for the tag distance from each antenna.

[0045] To perform calibration, calibration tags are placed in a storage system. In some non-limiting embodiments, the calibration tags can be placed individually and manually. In other non-limiting embodiments, the calibration tags are (a) attached at a predetermined distance from each other, and (b) attached to a movable calibration member that can be moved together. The movable calibration member is preferably made of a non-metallic material such as cardboard or plastic that does not interfere with the antenna field. In some non-limiting embodiments, the movable calibration member consists of a flat surface such as corrugated cardboard or a plastic sheet. The calibration tags are arranged in a linear or two-dimensional array. In some situations, it may be advantageous for the calibration member to have a shape that extends significantly in each dimension so that the calibration tags can be arranged three-dimensionally.

[0046] Once the calibration tags are placed as desired within the memory system, each antenna coil scans for the calibration tags at multiple different power levels. The relationship between the power level and the discovered calibration tags can be used to determine the effective range of each antenna coil at each power level.

[0047] An example of the calibration process is as follows: 1) Begin the calibration tags at the level of the storage system, for example, the bottom shelf of the cabinet. 2) For each antenna coil, start at the lowest power level and gradually increase the power until one or more tags are found, recording the power level at which each calibration tag is found. 3) Move the calibration tag to the highest possible position at that level, for example, just below the top shelf of a storage cabinet with shelves. 4) Repeat the power level scan from step 2 and record it as the second power level. 5) Move the calibration tag to a different level of the storage system, for example, to a shelf above and / or below the previous level. 6) Repeat the power level scan from step 2 and record it as a third power level. 7) Repeat the above steps for each level of the storage system.

[0048] With this example in mind, it can be seen that the calibration member may be configured in a suitable shape with sufficient calibration tags in appropriate positions, thus eliminating the need for steps 3 and 4.

[0049] Once this measurement phase is complete, three measurements are obtained of the minimum power level required to find the calibration tags at the nearest, intermediate, and furthest distances. The raw measurements are converted into a set of logical power level settings to be used for a given number of power levels. The logical power levels may differ from the actual power levels of each antenna. Thus, they can be mapped to account for the different sensitivities of each antenna. Thus, the logical power levels can correspond to distances using known antenna input power. In some non-limiting embodiments, the final power level step is the maximum power, so all remaining calibration tags at any distance within the maximum range are found. In some non-limiting embodiments, the furthest distance is within the same shelf to which the antenna is associated. In other non-limiting embodiments, the furthest distance is in shelves above and / or below the shelf to which the antenna is associated.

[0050] Each antenna coil may have a different physical power level for each logical power level. Therefore, the calibration process helps ensure that discovery information for the same tag on different antenna coils can be compared to the power levels input to each antenna coil that approximate the range of antenna coils.

[0051] For example, antenna coil A might require 100 power settings to detect a tag at a distance of 10 cm. In contrast, antenna coil B might only require 60 power settings to detect the same distance. Calibration values ​​can be used to compensate for this difference. Each logical power level corresponds to approximately the same distance from the antenna coil.

[0052] In some non-limiting embodiments, the calibration process includes the step of calibrating the RFID reader power level of the shelf to which the antenna coil is associated, i.e., the step of relating the power level to a predefined distance from the antenna coil in the same shelf. In some non-limiting embodiments, the calibration process further includes the step of calibrating the RFID reader power level not only for the shelf to which the antenna coil is associated, but also for the shelves below and / or above the shelf to which the antenna coil is associated.

[0053] Scanning items / tags

[0054] In standard (prior art) operations where the presence of a tag needs to be determined, each tag is discovered only once by the first antenna it is found on. It is then muted for the remainder of the scan of other antennas. The reader continues scanning. Even if a known tag is recognized multiple times as part of this process, the tag discovery message—the information generated by the RFID reader when it first receives a response from a previously unknown tag as part of the scanning process—is generated only for the first response received. In this type of non-specific location scanning, the tag discovery message is generated immediately each time it is first discovered, and the non-specific location information typically consists of only a single antenna number.

[0055] In contrast, in the non-limiting embodiments described herein, namely in the case of specific location scanning, each tag may be found by multiple antennas. A tag discovery message may or may not be generated for any of these actual discoveries. In some non-limiting embodiments, a tag discovery message is generated by the RFID reader 104 after the scanning of all antennas is completed at the end of the analysis phase and refers to a specific location, such as "shelf 4 left side". The tag discovery message for a specific location may be the only tag discovery message generated and provided by the RFID reader 104, or it may be added to a non-specific tag discovery message related to the actual antenna readings.

[0056] In some non-limiting embodiments, the item / tag scan searches for tags at multiple different power levels using each antenna coil. The minimum power level of each antenna for finding a tag is recorded. The tag reader performs a complete scan of each antenna coil, so all tags are re-checked multiple times on as many antenna coils as power can be supplied.

[0057] For each discovery, the antenna coil name and the minimum power level required to find the tag are recorded. By the time the scan is complete, each tag will have a list of discoveries on different antennas and at different power levels. This tag discovery data is stored for subsequent analysis to determine the location of the tag and, consequently, the location of the associated item.

[0058] Scanning can be performed in many ways. Power level scanning when deeply stacked and power level scanning when shallowly stacked are recognized as two useful variants, which are described below.

[0059] In some applications, tags are deeply stacked, meaning multiple tags are closely stacked. A common example of deeply stacked tags is document tracking, where each document has a tag. In such situations, a slower but more reliable method is used. To use this method, tags are first set to a low-power mode, such as a quarter-power mode where only a quarter of the tags are activated at a time.

[0060] The following is an example of a process for scanning deeply stacked tags to find the appropriate tag. 1) Set the antenna coil to the lowest power level. 2) Scan all visible tags at this power level. 3) Next, set a high power level. 4) Repeat scanning all tags at this power level. 5) Repeat steps 3 and 4 until the maximum power level is reached (until all power levels have been scanned).

[0061] In other applications, tags may be stacked shallowly. This means that two or more tags will not be stacked too close together. For example, consider products in boxes with tags attached. Even in a wooden crate filled with tagged products, the tags are spaced apart because the size of the product boxes maintains spacing between them. Two tags attached to two boxes may be adjacent to each other (for example, if the tags are facing each other), but they will not be stacked any deeper than this.

[0062] In situations like this, a faster method can be used. To use this method, set all tags to normal power mode. This makes the scanning process four times faster than using quarter-power mode, as explained in the deeply stacked situation.

[0063] This method utilizes the tag memory of the tag itself. In this non-limiting embodiment, the tag has temporary RAM (TRAM) used to store tag settings and information. For example, a PJM chip has tag memory that can be used as a timestamp and / or to mute or unmute the tag.

[0064] In the case of the "C-series PJM chip," which is considered a suitable chip for use in RFID tags, the timestamp memory is a 16-bit TRAM field. When the tag receives its first command after power-up, the tag reader's timestamp field is stored in the chip memory. When a command is received in the future, this stored value is returned in the timestamp field of the tag's response.

[0065] The following is an example of a process that utilizes the memory of such tags and scans for suitable tags among shallowly stacked tags that have memory in the form of a timestamp field. 1) Set the power level to the lowest setting and set the command's timestamp field to the power level ID (for example, 1 initially). 2) Send a single command that includes this timestamp field. 3) Next, set a higher power level, increment the power level ID, and set the timestamp field to the new power level ID. 4) Send a command that includes this timestamp field once. 5) Repeat steps 3 and 4 for each power level except the final power level. 6) For the final power level, perform a full tag identification scan to read the power level ID set in the timestamp field of each tag.

[0066] Once the final scan is performed and all tags have been matched, the response for each tag will include a timestamp. The timestamp field for each tag contains the power level ID from when that tag first entered the range, so the returned timestamp defines the lowest power level at which each tag was found.

[0067] location analysis

[0068] Once the tag reader has finished scanning all the antenna coils, each tag will have discovery data from the antenna coil at different power levels. This tag discovery data can be used to pinpoint the location of each tag within the storage system.

[0069] For example, Figure 6 shows a tag 602 attached to an item on shelf 620. Above shelf 620 is a higher shelf 622. As shown, tag 602 can be identified by both the lower shelf antenna 604 and the upper shelf antenna 606. In the illustrated example, because tag 602 is closer to the lower antenna 604, it is identified by a lower electric field strength (604') from the lower antenna 604 than the higher electric field strength (606') required for the upper antenna 606.

[0070] A known relationship exists between the physical structure of the storage system and the antenna coil. This relationship can be used to understand the meaning of multiple discovery information for tags. The layout of the antenna coil defines a hierarchy with the following characteristics: 1) Shelf. All antenna coils are located on the same horizontal plane. 2) Horizontal position. A group of antennas that supply power only to tags located in a level section (such as a shelf) of the storage system (only specific antenna designs provide this function).

[0071] For each shelf level, a power level offset can be defined so that the results are biased towards lower shelves. The power level offset may be an offset applied to the logical power level of the antenna. This is because, if the antenna coil is located on, within, on, or near the floor of the shelf, the magnetic field will combine with tags above (i.e., inside the shelf) and below (i.e., in the lower shelf) the antenna coil, so tags found at similar logical power levels at two different shelf height levels are more likely to be on the lower shelf.

[0072] For example, on the bottom shelf, the antenna can have a power level offset of zero. The next shelf has an offset (e.g., 2), the shelf above that has a larger offset (e.g., 4), and so on (for example, the offset increases in steps of 2 for each shelf). For each tag discovery, a power level offset can be added to the logical power level. So, for example, if a tag is discovered on the bottom shelf at a logical power level of 1, the tag remains at 1, but on the next shelf it will be 3. Using this example, if a tag is between two shelves and discovered by antennas on both shelves at the same logical power level (no offset), the offset will cause the antenna associated with the lower shelf to discover a tag at a power level two steps lower than the antenna associated with the upper shelf. Therefore, that location is identified as the lower shelf (i.e., lower power). Please understand that the offset numbers provided are merely examples. In practice, different offsets are used depending on various factors such as the number of logical power levels, the spacing between shelves, and antenna sensitivity. For this reason, the offset numbers are likely to differ and have more variability.

[0073] For example, referring to the non-limiting embodiment in Figure 2B, if there are four shelves, each having an antenna coil (or an antenna coil arrangement consisting of multiple coils) associated with the floor of each shelf, coil 1 detects a tag located on the first shelf 202D (which is the bottom shelf, so there are no tags below it). Coil 2 detects a tag located on the second shelf 202C and a tag located on the first shelf 202D below it, since the distance above coil 2 and within the second shelf is approximately the same as the distance below coil 2 and within the first shelf. Coil 3 detects a tag located on the third shelf 202B and a tag located on the second shelf 202C. In this exemplary non-limiting embodiment, if both coil 4 and coil 3 detect the same tag, the processor 110 of the RFID reader 104 is configured to determine that the tag is located on the third shelf 202B (i.e., biased towards the lower shelf). This is because the reading zones 212 formed by the magnetic fields of coils 3 and 4 overlap within the third shelf. The overlap reading zone 214, shown in Figure 2B, is located below the fourth shelf 202A and above and inside the third shelf 202B.

[0074] In alternative, non-limiting embodiments where the antenna coil arrangement differs, different height-level biases may be applied. For example, if the antenna coils are positioned on the roof of the shelf and / or if an overlapping reading zone is generated on the higher of two shelves, the RFID reader's processor may be configured to determine that the location of the tag identified by the two antenna coils is on the higher of the two adjacent shelves. Similarly, the principles described herein are also applicable to other configurations of containers, e.g., single-shelf containers having horizontally adjacent sections (e.g., two or more drawers adjacent to each other). It will be understood that the antenna configurations related to various sections operate such that an antenna arrangement associated with one section detects tags in two or more sections (or an antenna arrangement associated with one or more sections detects tags in two or more sections).

[0075] If horizontal positioning is not used, the definition of each shelf height level defines the set of antenna coils at that shelf height level. If horizontal positioning is used, each position at each shelf height level defines the set of antenna coils at that position.

[0076] For each tag, all detection antennas are checked. Even if the horizontal position needs to be determined, the first step is to identify the shelf height level at which the tag is located.

[0077] To determine the vertical position of a tag, we first assume that the tag is located at one of several discrete storage system height levels (e.g., a shelf). A power level offset is applied to the discovered power level of each tag to correct for the vertical relationship between the discrete storage system height levels. The tag's height position is determined to be at the discrete storage system height level with the minimum logical power level, including the correction for the power level offset.

[0078] If the horizontal position is also to be determined, a second inspection is performed using only the tag's location information at the determined discrete storage system height level. Since all antenna coils are on the same horizontal plane, power level offsets do not apply to determining the horizontal position at that level. Therefore, the minimum logical power level from the antenna coils determines the horizontal position along the shelf. If the tag has close or equal power levels at two locations, the tag is determined to be located midway between the two groups of antenna coils. For example, in a shelf with four horizontal antenna groups, there are three additional locations due to the midpoint between two groups.

[0079] Once the tag location is identified, the tag location identified by the RFID reader 104's processor 110 is displayed via the user interface 116 and / or transmitted to the end-user application via the communication interface 114. The specific location may also be described by the layout name, for example, "shelf 6," or "shelf 2, location 4" if a horizontal position is included.

[0080] advantage

[0081] The system described herein locates the position of tagged items (at an appropriately selected resolution) and provides this information to the user to assist in the rapid and accurate location and identification of tagged items. Advantageously, the locating function works in storage systems with open shelves. The method is efficient and can be implemented with a negligible performance penalty compared to existing systems. The system is scalable to locate any number of tagged items within a storage system.

[0082] Taking a blood supply service freezer as an example, traditionally, staff had to manually search for specific blood bags at a temperature of -40°C. This was not only unpleasant for staff but also prone to human error and the risk of damaging bags if handled carelessly. Using the system described herein, staff can first inquire about the location of the required blood bag and know where it is (i.e., its location on the shelf and its position within the shelf). As a result, a great deal of time and discomfort can be saved, potential damage can be avoided, and the possibility of human error can be reduced.

[0083] In another example, using a blood shelf management system, tagged blood bags are stored in trays over one meter long. The trays are removable and slide onto shelves in a multi-tier storage system. Conventional RFID systems could only roughly locate the tagged blood bags, for example, that they were located in one of the zones on the left, right, or center of the shelf. The system described herein provides a high-resolution method that can precisely locate one or more blood bags of interest.

[0084] It should be noted that some more appropriate non-limiting embodiments have been outlined above. It will be apparent to those skilled in the art that modifications to the disclosed non-limiting embodiments can be made without departing from their spirit and scope. Thus, the described non-limiting embodiments should be considered merely illustrative of some of the more prominent features and uses. Other beneficial results can be achieved by applying the non-limiting embodiments in different ways or by modifying them in ways known to those skilled in the art. This includes mixing and matching features. Since elements and / or functions between various non-limiting embodiments (one or more) are expressly constrained herein, those skilled in the art will understand from this disclosure that features, elements and / or functions of one non-limiting embodiment may be incorporated into another non-limiting embodiment as appropriate, unless otherwise stated above. While this specification describes specific arrangements and methods, its intent and concepts can be suitably applied to other arrangements and uses.

[0085] In the subsequent claims and prior description, unless otherwise required by contextual, explicit wording or necessary implied meaning, the word “comprise” or variations such as “comprises” or “comprising” are used in a comprehensive sense, that is, to identify the presence of the described features, but not to exclude the presence or addition of further features in various non-limiting embodiments.

Claims

1. A method for locating the positions of multiple tagged articles in a storage system having multiple height levels, The first step involves scanning the tag at multiple power levels using a first antenna, The first antenna identifies each tag of interest found at each of the multiple power levels and records the first tag discovery data. The steps include scanning tags at multiple power levels using at least one additional antenna, The steps include: using each of the additional antennas to identify each tag of interest found at each of the multiple power levels and recording further tag discovery data; The process includes the step of analyzing the first tag discovery data and the further tag discovery data, and determining the location of each tag of interest by applying a height level bias that favors lower shelves, The first antenna is associated with a first height level of the storage system, The at least one additional antenna is associated with each of the additional height levels of the storage system, A method characterized in that the location of each tag of interest determined includes the height level of the article.

2. The step of scanning tags at multiple power levels using the first antenna includes the step of activating the antenna coil of the first antenna at each of the multiple power levels. The method according to claim 1, characterized in that the step of identifying each tag of interest found at each of the plurality of power levels using the first antenna includes the step of receiving response signals from at least some of the tags of interest at each of the plurality of power levels.

3. The method according to 1 or 2, characterized in that the electric field strength radiated from each of the aforementioned antennas changes by a predetermined amount according to each power level.

4. The method according to any one of claims 1 to 3, characterized in that the power level is a logical power level corresponding to the actual power level required for a predetermined antenna range.

5. The method according to any one of 1 to 4, further comprising the step of calibrating the antenna power level in the storage system.

6. The step of calibrating the antenna power level in the storage system is: The steps include placing multiple calibration tags in the storage system, The steps include scanning calibration tags at multiple different power levels using the aforementioned antennas, The steps include: identifying the minimum power level at which each antenna discovers each calibration tag; The method according to 5, further comprising the step of setting one or more calibration values ​​for each antenna from a specified minimum power level.

7. The method according to 6, characterized in that the step of calibrating the antenna power level in the storage system is repeated with the calibration tags positioned at multiple different levels in the storage system.

8. The method according to any one of 5 to 7, wherein the step of calibrating the antenna power levels in the storage system is characterized by compensating for differences in antenna coils such that each logical power level of each antenna corresponds to substantially the same antenna coil range.

9. The method according to any one of 1 to 8, further comprising the step of setting the tag to a low-power mode that reduces the number of activated tags in the storage system before scanning the tag.

10. The aforementioned tag includes memory, The method according to any one of 1 to 9, further comprising the step of storing a value representing the power level that was first detected in the tag.

11. The aforementioned memory is a timestamp field, The method according to the present invention, characterized in that the value representing the power level at which the tag was first discovered, stored in the timestamp field, is a power level ID.

12. The step of analyzing the first tag discovery data and the further tag discovery data and determining the location of each tag of interest includes the step of applying a power level offset that offsets the antenna power level to a lower height level with respect to each height level of the storage system, The method according to claim 1, characterized in that the power level offset increases as the height level increases.

13. The method according to 12, characterized in that the power level offset is applied to the logic power level of each of the antennas.

14. The method according to any one of 11 to 13, wherein the step of estimating the location of each tag of interest using the identified antenna and the minimum power level that identified each tag of interest includes the step of determining the horizontal position of each tag of interest at the height level of the storage system in which the tag is identified.

15. The method according to 14, characterized in that the horizontal position of each tag of interest is determined to be a position at a distance from the antenna having the minimum power level that identified the tag, and the distance corresponds to the range of the antenna at the minimum power level.

16. The method according to any one of 1 to 15, characterized in that the first antenna and the at least one further antenna are located on or inside the storage system.

17. The aforementioned storage system has a height level, The method according to 16, characterized in that at least a portion of the height level has at least two overlapping antennas including overlapping coils.

18. The method according to 17, characterized in that each of the at least two overlapping antennas including the overlapping coils has a first loop having a first current and a second loop having a second current rotating in the opposite direction to the first current.

19. The method according to 18, characterized in that the overlapping coils are arranged to overlap such that the loops are aligned along the axis, thereby generating a continuous reading zone along the axis.

20. The method according to 19, characterized in that the continuous reading zone corresponds to a section of the storage system.

21. A system for locating RFID-tagged articles located within a storage system having multiple height levels, which includes multiple RFID-tagged articles, A plurality of antenna coils associated with each of one or more height levels of the storage system, An antenna controller that supplies power to the antenna coil at a power level corresponding to the received power level signal, The system includes a processor that communicates with the aforementioned antenna controller, The aforementioned processor, Multiple power level signals are output to the antenna controller in order to selectively activate each of the antenna coils at multiple different power levels. A response signal corresponding to each power level is received from each of the aforementioned antenna coils. Identify each RFID tag found within each received response signal, and record the tag discovery data. The location of each RFID tag is determined by analyzing the aforementioned tag discovery data and applying a height level bias that favors lower shelves. A system characterized in that the determined position of each RFID tag includes the height level of the item.

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