KR101104137B1 - Method of detecting the most suitable attachment place of rfid tag - Google Patents

Abstract

Disclosed is a method for detecting an optimal attachment position of an RFID tag. According to an aspect of the present invention, there is provided a method for detecting an optimum position of an RFID tag, a method of attaching a test tag, testing whether the tag is recognized under a conveyor RFID recognition process environment, and repeating the test while changing an environment variable. Calculating the average recognition rate by which the RFID reader recognizes the tag and selecting an optimal attachment position using the recognition success rate and the average recognition rate, wherein the recognition success rate and the average recognition rate are attached to the product case. It is characterized in that it is calculated for all test tags. Accordingly, it is possible to detect an optimal attachment position that ensures a stable and uniform recognition rate of the tag regardless of the tag attachment environment and the attachment substance.

Conveyor, RFID Tag

Description

Optimal attachment position detection method of RFID tag {METHOD OF DETECTING THE MOST SUITABLE ATTACHMENT PLACE OF RFID TAG}

The present invention relates to a method for detecting an attachment position of an RFID tag, and more particularly, to a method for detecting an optimal attachment position of an RFID tag attached to a moving product in a conveyor portal structure.

RFID (Radio Frequency Identification) is a technology that provides a foundation for recognizing, tracking, and controlling things by using radio radio frequencies. It captures and moves information of things through RFID readers and tags without requiring human intervention. It is a short-range wireless communication technology that can be delivered to the system.

The research direction related to the introduction of RFID technology has been focused on stabilization and low cost of RFID tags, RFID readers, antennas and software systems constituting RFID systems.

However, the reading rate of data stored in the tag and the possibility of error, such as the change of RFID recognition rate according to the attachment material or the attachment environment, which is the limitation of RFID technology itself, and the lack of research on the development of guidelines for the application of optimal RFID at the time of introduction. It is an obstacle to the practical introduction of this RFID system technology.

In particular, technical problems related to guaranteeing a stable and uniform recognition rate of a tag according to an attachment environment or an attachment material are obstacles to the introduction of RFID system technology.

As a way to solve this problem, it is common to solve the problem by trial & error at the time of site introduction. In particular, by studying a method of attaching an RFID tag, there is an example to solve the problem of the recognition rate as described above.

Examples are Sam's Club's EPC RFID Tagging Requirements developed by Sam's Club in the US and Conveyor Portal Test Method by EPCglobal.

The guidelines of Sam's Club in the United States suggest the location of RFID tags in single packaging units for real products such as food, vegetables, and fruits sold by Sam's Club. The technical paper presented by EPCglobal describes a lab test method for pre-testing RFID applications on conveyors.

However, Sam's Club's technical document suggests the position of RFID tag attachment for a specific product, but the tag attachment unit is a single packaging unit, and it is difficult to apply to an outer packaging box product that is a mobile product unit on a conveyor where RFID is mainly introduced. There are disadvantages. In addition, rather than suggesting the exact RFID tag attachment position by experiment, it only suggests the optimal attachment position by experience value.

In addition, EPCglobal's 'Conveyor Portal Test Method' is a test method to determine the possibility of RFID introduction only in the experimental environment. There is a limit to testing. In addition, since data is analyzed using only a simple recognition rate (= recognition count / test count), there is a disadvantage in that data distortion, which may occur depending on an environment, cannot be considered.

It is an object of the present invention to provide a method for detecting an optimal RFID tag attachment position on the surface of a product case moving on a conveyor.

The object of the present invention is not limited to the above-mentioned object, and other objects that are not mentioned will be clearly understood by those skilled in the art from the following description.

RFID tag optimal attachment position detection method according to an aspect of the present invention for achieving the above object is a conveyor including a test tag attachment step, a conveyor for moving the product case with the RFID tag, the product case with the test tag attached Testing whether the tag is recognized under an RFID recognition process environment, calculating a recognition success rate of the tag by repeating the test a predetermined number of times while changing an environment variable affecting the recognition rate of the tag, and the RFID reader Calculating an average recognition rate of the reader by calculating the average number of times of recognition and selecting an optimal attachment position on the surface of the product case using the recognition success rate and the average recognition rate, wherein the recognition success rate and the average recognition rate are attached to the product case. It is calculated for all test tags.

The method for detecting a tag optimal attachment position further includes selecting a test tag by using a tag performance measurement step of measuring a recognition distance of the tag and a measurement result.

The test tag is a tag having an average recognition distance as a result of tag performance measurement.

The surface of the product case is characterized in that the blocking in the form of a matrix so that a plurality of test tags are attached.

The test tag is attached to the front, side and top of the product case, respectively.

The tag is characterized in that the EPC code (Electronics Product Code) is encoded.

The tag is attached in the form of a crisscross in two directions, horizontally and vertically.

The serial code may be mapped to a position where a test tag is attached on the surface of the product case.

The environmental variable may include a conveyor speed, an output size of a reader, a test tag, an RFID reader, or an antenna angle of the reader.

The recognition success rate is a ratio of the number of times the RFID reader recognizes the test tag and the number of tests.

Specific details of other embodiments are included in the detailed description and the drawings.

By using the RFID tag optimal attachment position detection method according to the present invention, it is possible to detect the optimal attachment position to ensure a stable and uniform recognition rate of the tag irrespective of the attachment environment and the attachment material.

In addition, it is possible to detect the site-centered RFID tag optimal attachment position reflecting the various characteristics of the site environment and the applied product.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be embodied in various different forms, and only the present embodiments make the disclosure of the present invention complete, and those of ordinary skill in the art to which the present invention belongs. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims.

1 is a flowchart illustrating a method of detecting an RFID tag optimal attachment position according to an exemplary embodiment of the present invention, and FIG. 2 is a flowchart illustrating a process of selecting a test tag according to the present invention.

1 to 2, in order to perform a test for detecting an optimal position of an RFID tag to be attached to a case of a product, an RFID tag to be used for the test must first be selected (S101). In general, various information such as a product name, a manufacturer's logo, and a box barcode are printed on the box surface of a product to be shipped. In the case of actually attaching an RFID tag, it is common to attach the tag in consideration of such a review item.

However, if you want to test which part of the surface of the product case the tag is the best recognition rate as in the present invention, in order to perform a more precise test (front side, side side) of the product case Test by attaching the number of test tags on the upper side.

On the other hand, the size of the case of the product to which the test tag is attached is preferably set to the case size of the product actually distributed. The tagging unit is also based on the distribution unit of the actual product distributed on the conveyor. For the products under test, the packaging unit is the distribution unit.

According to the technical standard proposed by the lab test method of EPCglobal, RFID tags are attached to the top, bottom, left, right, front and rear of the outer packaging surface of the product, but in the present invention, the test tag is applied to the front, side, and top surfaces. Attach. When selecting an RFID tag, considering the size and performance of the product case, the RFID tag is selected and issued.

When the RFID tag to be selected is selected, a test tag is selected, which tests the performance of the plurality of tags first (S103) and selects a test tag from these (S105).

Generally, even the tag of the same model produced by the same manufacturer, the recognition distance may be different for each tag. Therefore, before performing the test according to the present invention, it is preferable to select only tags having similar recognition distances on average and select them as test tags. This is also necessary to improve the reliability of the test. Test the recognition distance of the tag to be tested first, and then select only the tag with the average recognition distance and use it as the test tag.

When the test tag is selected, the test tag is attached to the case surface of the product (S110). Test tags are attached to the front, side, and top of the case surface of the test product. The product case surface is blocked in a matrix form (e.g., 3x4, 3x3 matrix) so that a plurality of the test tags are attached, and a test tag is attached to each of the blocks.

However, in order to analyze data after the test is performed, the test tag is pre-encoded with the EPC code. EPC (Electronics Product Code) is an electronic product code, meaning as an identification code of RFID. The concept includes a network standard for utilizing RFID technology based on the Internet. The RFID tag stores only minimal information such as a product identification code (EPC code), and detailed product related information can be searched and used through the Internet.

EPC standards include an EPC code system, an object naming service (ONS) that indicates the location of the computer where the details are stored, an EPC IS (EPX Information System) that stores the details, and RFID tag readout information to be filtered or forwarded to the required location. The state consists of middleware and the like.

The EPC code may be encoded in the test tag, and at the same time, the code may be outputted to a label of a tag to facilitate identification. Meanwhile, the product case surface and serial number are pre-mapped in software. The serial number is a unique identification number assigned to an individual product of the same item, which is usually assigned by the manufacturer of the product, which can be assigned code to approximately 260 million companies in 28-bit capacity.

When the test tag is attached to the surface of the product case, it is tested whether the tag is recognized (S120). The test is performed under a conveyor RFID recognition process environment that includes an RFID reader and a conveyor for moving the product case and can be tested using a conveyor portal.

Before performing the test through the conveyor portal, it is necessary to analyze in advance whether there is no RF shadow area for the RFID zone (510, see FIG. 5) through which the test tagged product passes. It uses a single dipole antenna to inspect the section within 1m of the portal and measures up to 2 minutes to ensure reliability.

The conveyor RFID recognition process environment includes various environmental variables. The environment variable may be considered a conveyor speed, the output size of the reader, the RFID tag, the RFID reader, the antenna angle of the reader.

The speed at which the product case moves can be adjusted according to the conveyor speed, so the tag recognition rate can be measured according to the conveyor speed. For example, while changing the speed of the conveyor in three steps of 60m / min, 120m / min, 180m / min, the recognition rate of each tag attachment position is measured. In addition, the reader's output size is divided into three levels of output: minimum, middle, and maximum. RFID tags are also tested using at least two tags. RFID readers are also tested using at least two readers. The antenna angle of the reader is divided into two stages of 0 ° and 30 ° to test.

The above-described environment variable is just an example, and the test may be performed in consideration of various environment variables in addition to the illustrated environment variables. When interpreting the data using only the recognition rate (= recognition count / test count) of the tag, it is necessary to change the environment variable to various conditions in order to consider the data distortion that may occur depending on the environment. In other words, it is possible to grasp the environmental conditions for the maximum recognition rate while changing the above-described environmental variables in order to detect the optimal RFID operation method in the field.

In particular, if the humidity or the temperature is high among the external factors affecting the recognition rate of the RFID tag, the recognition rate of the RFID tag may be remarkably lowered, and the recognition rate of the tag is reduced when an electric device is located near the conveyor portal. . That is, the recognition rate of the RFID tag may be distorted by environmental variables such as external electrical influence, temperature, and humidity generated at the test point.

When the repeated test is completed by changing all set environment variables, the recognition success rate is calculated using the measured data (S140), and the average recognition rate is calculated (S150). Recognition success rate and average recognition rate is an analysis index for analyzing the data of the test results according to the present invention, it is to select the optimal attachment position using these two analysis indexes. Scheme of the analysis index will be described later with reference to FIG.

Recognition success rate is the primary index indicating the recognition performance according to the attachment position of the RFID tag, and is used as the first filtering basis when trying to detect the optimum RFID tagging position.

Recognition success rate indicates that when the test is performed x times with the set test environment, recognition of the test tag is divided into success and failure for each test execution, and the increase and decrease of the recognition success rate is displayed according to the success or failure. The perceived rate.

Typically, in a process using an RFID tag, the RFID reader needs to recognize the tag one or more times. Even if the same RFID tag is recognized a plurality of times, it is interpreted as redundant data and filtered, and only the first recognized information is used.

For example, when a case of a tagged product passes through the conveyor portal once, the reader may recognize the same tag once or multiple times, so that the tag may be recognized more than once even when passing through the conveyor portal once. It is. As such, the recognition success rate determines the recognition rate only by True or False whether the reader recognizes the tag or not even when the product case passes through the conveyor portal once. That is, when passing through the conveyor portal once, it is determined that the case of five times and the case of the first recognition as the same recognition rate.

However, if the recognition success rate is determined through the recognition rate test, the following problems may occur. For example, on the surface of the product case blocked in the form of a predetermined matrix (eg, 3 × 4, 3 × 3), the recognition rate of the test tag attached to the attachment position 10 and the attachment position 11 is equal to 70%. Assume

The recognition success rate is the same as that the tags 10 and 11 were recognized 7 times through 10 repeated tests, but the tag 10 was recognized 30 times each time through the conveyor portal, and the tag 11 was 1 In the case of recognition, if the optimum attachment position is determined only by the recognition success rate, the position 10 and the position 11 have the same reliability in the optimal attachment position.

Therefore, if the concept of average recognition rate is used through the number of times recognized by the reader when passing through the conveyor portal once, it is possible to improve the reliability of the test in the detection test of the optimum attachment position.

Using the calculated success recognition rate and the average recognition rate, data is analyzed (S160), and an optimal attachment position is selected (S170).

3A to 3B illustrate an example in which a test tag is attached to a product case surface according to an RFID tag optimal attachment position detecting method according to an embodiment of the present invention. The tag may be attached in a crosswise shape in the horizontal and vertical directions to analyze the performance deviation according to the tag antenna.

The tagging method illustrated in FIGS. 3A to 3B is only an example, and may be attached to four parts of the top, bottom, side, and top of the product case including the bottom of the product case, or may be attached to six sides. .

4 is a block diagram illustrating code mapping of a test tag according to the present invention.

EPC codes are very complex with 96 bits in length. Therefore, the tagging position where the tag is attached to the surface of the product case is set as the serial number, and the set serial number is mapped to the EPC code by software. Referring to FIG. 4, the actual EPC code value of serial number 31 has a complex value of 96 bits, and the EPC code is recognized by the reader, but it is mapped by software 31 as recognized.

FIG. 5A illustrates a front view of a test performing apparatus for detecting an RFID optimal attachment position according to an embodiment, and FIG. 5B illustrates a cross-sectional view of the test performing apparatus illustrated in FIG. 5A.

5A to 5B, the test case-attached product case is moved to the conveyor portal mechanism 500 through the conveyor 505. RFID reader antennas 501, 502, 503, 504 that recognize the tag are attached to the conveyor portal mechanism 500. The antenna uses circular polarization and uses an antenna having a gain of up to 6 dB. Conveyor portal refers to the identification and sorting of goods on the conveyor felt and is a tool mainly used for sorting and marking products.

On the other hand, the conveyor 505 is a belt-type conveyor, it is composed of a straight run (straight run conveyor) and the circular portion (Continuous loop conveyor) connecting the straight portion. The straight portion has a size of 1000 × 8000 × 800mm (W × L × H), and the belt width is 1000mm. The belt width of the circular portion is a belt type conveyor having a diameter of 1000 mm, an inner diameter of 1400 mm, and an angle of 90 degrees.

The conveyor portal is configured such that the minimum size of the product passing through the conveyor is 100 x 100 x 150 mm and the maximum size is 736 x 762 x 1219 mm.

The speed of the conveyor is 190.5 m / min (+/- 5% tolerance). Before performing the test, the field is measured by using a dipole antenna at a predetermined test point in the RFID Zone to verify that there is no shadow area. It is desirable to proceed with the test.

 Table 1 shows the location of the test point at each point C1, C2, ..., C8, B1, ..., B4, T1, ..., T4 shown in FIG. 5B, and Table 2 shows the conveyor portal at that point. This is the result of measuring the field of.

point Description X [cm] Y [cm] Z [cm] C1



Centerline


-122 0 38 C2 -91 0 38 C3 -61 0 38 C4 -30 0 38 C5 30 0 38 C6 61 0 38 C7 91 0 38 C8 122 0 38 B1
Bottom
-30 -37 5 B2 30 -37 5 B3 -30 37 5 B4 30 37 5 T1

Top -30 -31 71 T2 30 -31 71 T3 -30 31 71 T4 30 37 71

point Raw power
Measurement (dBm) Frequency
(MHz) Antenna
Gain (dB) (-) Cable and connector
loss (dB) (+) Field Strength (dBm) C1 -4.28 912.05 1.63 1.41 -4.50 C2 -1.67 912.55 1.63 1.40 -1.90 C3 1.40 910.90 1.64 1.40 1.16 C4 5.25 911.05 1.64 1.40 5.01 C5 5.03 911.35 1.64 1.40 4.79 C6 1.90 911.00 1.64 1.40 1.66 C7 -2.14 911.50 1.63 1.40 -2.37 C8 -4.07 911.06 1.64 1.40 -4.31 B1 6.87 911.05 1.64 1.39 6.62 B2 6.97 911.65 1.63 1.41 6.75 B3 2.48 912.40 1.63 1.40 2.25 B4 5.88 910.90 1.64 1.40 5.64 T1 5.52 911.65 1.63 1.41 5.30 T2 3.15 910.90 1.64 1.40 2.91 T3 3.87 912.50 1.63 1.40 3.64 T4 3.18 911.95 1.63 1.41 2.96

In Table 2, Field Strength = Raw Power Measurement-Antenna Gain + Cable and connector loss + Attenuator.

Referring to Tables 1 to 2 above, as a result of confirming the recognition of the test tags at the C1 and C8 positions having the smallest field size, the tags were recognized, and it was determined that there was no shadow area in the conveyor portal.

In addition, since RFID is affected by temperature or humidity, it is necessary to verify the reliability of the experimental data by measuring temperature and humidity before performing the test. In the case of environmental conditions according to one embodiment, the temperature is maintained within 10 ℃ ~ 45 ℃, the humidity is carried out while maintaining within 20% to 95%.

6 is a graph illustrating a process of detecting an RFID tag optimal attachment position using a recognition success rate and an average recognition rate according to an RFID tag optimal attachment position detection method according to an embodiment of the present invention.

Referring to FIG. 6, the X coordinate represents an attachment position of the tag, the coordinate Y coordinate represents an average recognition rate, and the right Y coordinate represents a recognition success rate. The vertical bar graph shows the average number of recognition for each attachment position according to the results of 20 repeated tests. Since the average recognition rate is high when the tag is attached in the environment suitable for recognition, when the recognition success recognition rate and the average recognition rate are considered at the same time, the recognition success rate is 100% and the tag attachment position with the high average recognition rate is used for the final tag attachment. It can be judged as a suitable position.

Therefore, according to FIG. 6, in the environment where the output of the reader is 30 dBm and the conveyor speed is 600 f / min, the optimum tag attachment position is 100%, and the average recognition rate is also very high, with an average value of 6 or more. Positions 14 and 15 can be determined as ideal tagging positions.

If the test is repeated while changing the environment variable of the test, it is possible to determine the influence of the environment variable on the tag attachment position and the pattern of recognition rate change according to the tag attachment position. That is, through the data analysis of the recognition success rate and the average recognition rate, it is possible to finally detect the optimum position for the tag attachment position in the conveyor RFID recognition process environment that the user intends to use.

7 is a graph illustrating a process of detecting an RFID tag optimal attachment position in consideration of an average recognition rate according to an RFID tag optimal attachment position detection method according to an embodiment of the present invention.

Referring to FIG. 7, the output of the conveyor portal reader and the conveyor speed are repeated 20 times based on the recognition rate measured while passing through the conveyor portal on the surface of the product case having 50 tagged candidate paper under the same conditions as in FIG. 6. Results The average recognition rate is measured. Among them, positions 6, 31, 32, 33, 34, 35, 35, 38, and 40 can be selected as the optimal attachment position by showing the average recognition rate of 3.5 times or more for each attachment position. However, in the 15th, 47th and 48th times, the repetition average recognition rate was low because many cases were not recognized among 20 repetition tests.

In addition, the tag candidates located on the upper left side of the upper surface of the test case with the test tag showed a higher average recognition rate than the side and front, and on the contrary, the upper right side had a low average recognition rate.

Those skilled in the art will appreciate that the present invention can be embodied in other specific forms without changing the technical spirit or essential features of the present invention. For example, a program for realizing the RFID tag optimal attachment position detecting method of the present invention may be implemented in various forms such as a recording medium in which a program is recorded. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the scope of the following claims rather than the detailed description, and all changes or modifications derived from the meaning and scope of the claims and the equivalent concept are included in the scope of the present invention. Should be interpreted.

1 is a flowchart illustrating a method of detecting an RFID tag optimal attachment position according to an embodiment of the present invention.

2 is a flowchart illustrating a process of selecting a test tag according to the present invention.

3A to 3B illustrate an example in which a test tag is attached to a product case surface according to an RFID tag optimal attachment position detecting method according to an embodiment of the present invention.

4 is a block diagram showing code mapping of a test tag according to the present invention;

5A illustrates a front view of a test execution device for detecting an RFID optimal attachment position according to an embodiment.

FIG. 5B is a cross-sectional view of the apparatus for performing test shown in FIG. 5A. FIG.

6 is a graph illustrating a process of detecting an RFID tag optimal attachment position using a recognition success rate and an average recognition rate according to an RFID tag optimal attachment position detection method according to an embodiment of the present invention.

7 is a graph illustrating a process of detecting an RFID tag optimal attachment position in consideration of the average recognition rate according to the RFID tag optimal attachment position detection method according to an embodiment of the present invention.

`` Explanation of symbols for main parts of drawings ''

310: front of the product case 320: side of the product case

330: upper surface of the product case 505: conveyor

501,502,503,504: RFID reader antenna

510: RFID Zone

Claims (10)

Attaching a test tag; Testing whether the tag is recognized under a conveyor RFID recognition process environment including an RFID reader and a conveyor for moving the product case to the product case to which the test tag is attached; Calculating the recognition success rate of the tag by repeating the test a predetermined number of times while changing an environment variable affecting the recognition rate of the tag; Calculating an average recognition rate of the reader by calculating an average number of times the RFID reader recognizes the tag; And Selecting the optimal attachment position of the surface of the product case using the recognition success rate and the average recognition rate, The recognition success rate is, The ratio of the number of times the tag is successfully recognized while the product case passes through the conveyor a plurality of times, The average recognition rate is, An average of the number of times the tag was recognized by the product case once through the conveyor, The recognition success rate and average recognition rate are calculated for all test tags attached to the product case, The selection step, Among the tags having the highest recognition success rate, the attachment position of the test tag having the highest average recognition rate is selected as the optimum attachment position, The tag is, The method of detecting an optimal attachment position of an RFID tag, characterized in that attached to the surface of the product case in the form of a cross in the horizontal, vertical direction. The method of claim 1, A tag performance measurement step of measuring a recognition distance of the tag; And Selecting a tag for test using the measurement result Optimal attachment position detection method of the RFID tag further comprising. The method of claim 2, wherein selecting the test tag comprises: A method for detecting an optimal attachment position of an RFID tag in which only a tag having an average recognition distance is selected as a result of tag performance measurement. The method of claim 1, The surface of the product case is blocked in the form of a matrix so that a plurality of test tags attached to the RFID tag detection method of optimal attachment position. The method of claim 1, wherein the attaching the test tag is Optimal attachment position detection method of the RFID tag to attach the test tag to the front, side, top of the product case, respectively. The method of claim 1, wherein the tag is A method for detecting an optimal attachment position of an RFID tag, characterized in that an EPC code (Electronics Product Code) is encoded. delete The method of claim 1, And a serial code is mapped to a position where the test tag is attached on the surface of the product case. The method of claim 1, wherein the environment variable And a speed of the conveyor, an output size of the reader, an antenna angle of the test tag, the RFID reader, or the RFID reader. The method of claim 1, wherein the recognition success rate And a ratio of the number of times the RFID reader recognizes the test tag and the number of tests.

Images