Measuring system

Abstract

To provide a measuring system that is able to measure a displacement with a simple configuration.SOLUTION: A measuring system includes: an RFID tag; a conductive portion that is conductive and disposed apart from the RFID tag; a non-conductive portion that is non-conductive and disposed to be interposed between the RFID tag and the conductive portion; an antenna that is disposed apart from the RFID tag and capable of receiving a radio wave transmitted from the RFID tag; a radio wave intensity measurement unit that measures a received radio wave intensity, which is an intensity of a radio wave received by the antenna; and a distance measurement unit that measures a distance between the RFID tag and the conductive portion by referring to relation information indicating a relation between a distance between the RFID tag and conductive portions and the received radio wave intensity, based on the measured received radio wave intensity.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to measurement systems. [Background technology]

[0002] A conventional system is known that includes a wireless tag attached to a facility, a reader that reads the signal from the wireless tag, and a system that identifies the location of the wireless tag based on the read signal. The wireless tag is an IC tag used for RFID (Radio Frequency Identification), and is also called an RFID tag.

[0003] For example, Patent Document 1 discloses a monitoring system for monitoring structural components, which includes a sensor for performing mechanical monitoring of the structural components, one or more power supply tags for supplying the power necessary for stable operation of the sensor, and a data acquisition tag for wirelessly communicating the sensor detection data. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-64346 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the monitoring system described in Patent Document 1 requires two types of wireless tags: a power supply tag for supplying power and an acquisition tag for wirelessly communicating inspection data, which results in a complex system configuration and increases costs.

[0006] An object of the present disclosure is to provide a measurement system capable of performing displacement measurement with a simple configuration. [Means for solving the problem]

[0007] In order to achieve the above object, the measurement system in the present disclosure includes: RFID tags and a conductive portion that is conductive and is spaced apart from the RFID tag; a non-conductive portion that is non-conductive and is disposed between the RFID tag and the conductive portion; an antenna that is disposed at a distance from the RFID tag and is capable of receiving radio waves transmitted from the RFID tag; a radio wave intensity measuring unit that measures the intensity of radio waves received by the antenna; a distance measurement unit that measures the distance between the RFID tag conductive parts based on the measured received radio wave intensity and referring to relationship information that indicates the relationship between the RFID tag-to-RFID tag conductive part distance, which is the distance between the RFID tag and the conductive part, and the received radio wave intensity; Equipped with. [Effects of the Invention]

[0008] According to the present disclosure, displacement measurement can be performed with a simple configuration. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a configuration diagram showing a general configuration of a measurement system according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a functional block diagram illustrating functions of the measurement system according to the embodiment of the present disclosure. [Figure 3] FIG. 3 is a diagram showing the positional relationship between the RFID tag and the antenna, etc. [Figure 4] FIG. 4 is a curve graph showing the relationship between the RSSI attenuation and the distance between the conductive parts of the RFID tags. [Figure 5] FIG. 5 is a curve graph showing the relationship between the amount of RSSI attenuation and the distance between the conductive parts of the RFID tags under each of the four conditions. [Figure 6] FIG. 6 is a curve graph showing the relationship between the amount of attenuation of RSSI and the distance between the conductive parts of the RFID tags when they are offset by a predetermined distance. [Figure 7A] FIG. 7A is a plan view of measurement system 200 according to the embodiment of the present disclosure. [Figure 7B] FIG. 7B is a front view of measurement system 200 according to the embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Fig. 1 is a configuration diagram showing a general configuration of a measurement system according to an embodiment of the present disclosure. Fig. 2 is a functional block diagram showing functions of the measurement system according to an embodiment of the present disclosure. Fig. 3 is a diagram showing the positional relationship between an RFID tag, an antenna, etc.

[0011] As shown in Figures 1, 2 and 3, the measurement system 100 in this embodiment includes an RFID tag 1, a conductive part 2, a non-conductive part 3, an antenna 4, a reader / writer 5 and a personal computer 6 (PC).

[0012] The RFID tag 1 has a loop antenna section (not shown) that transmits and receives signals without contact with the antenna 4, a memory section (not shown) that stores tag information, a control section (not shown) that controls the operation of the RFID tag 1, and a capacity hat section (not shown) that accumulates the energy of the carrier wave transmitted from the antenna 4 and received by the loop antenna section as a driving power source for the RFID tag 1.

[0013] The conductive part 2 is a conductive member and is arranged at a distance from the RFID tag 1. The conductive part 2 is, for example, a flat metal plate. In the following description, the distance between the RFID tag 1 and the conductive part 2 is referred to as the "RFID tag-conductive part distance" and is represented by the RFID tag-conductive part distance D (see FIG. 3).

[0014] The non-conductive portion 3 is a non-conductive member, and is disposed so as to be interposed between the RFID tag 1 and the conductive portion 2. In other words, the RFID tag 1, the conductive portion 2, and the non-conductive portion 3 are disposed so as to overlap each other, thereby constituting a laminated portion 7.

[0015] The antenna 4 transmits and receives signals to and from a loop antenna portion (not shown) of the RFID tag 1 in a non-contact manner.

[0016] The reader / writer 5 reads / writes data from / to the RFID tag 1 via the antenna 4. In the following description, the distance between the RFID tag 1 and the antenna 4 is referred to as the "antenna distance" and is represented by the antenna distance S (see FIG. 3).

[0017] The control device 10 is provided in the PC 6. The control device 10 includes a control unit 20 and a storage unit .

[0018] (Storage unit 26) The memory unit 26 is a storage device such as a ROM (Read Only Memory) that stores the BIOS (Basic Input Output System) of the computer that realizes the control device 10, a RAM (Random Access Memory) that serves as the working area of ​​the control device 10, an HDD (Hard Disk Drive) or an SSD (Solid State Drive) that stores the OS (Operating System), application programs, various information referenced when the application programs are executed, and various maps.

[0019] The storage unit 26 stores a table TL that indicates the relationship between the received radio wave intensity (also called electric field intensity), which is the intensity of the radio wave received by the antenna 4, and the distance D between the conductive parts of the RFID tags.

[0020] (control unit 20) The control unit 20 is a processor such as a CPU (Central Processing Unit) or GPU (Graphics Processing Unit) of the control device 10, and functions as an acquisition unit 21, a radio wave intensity measurement unit 22, a distance measurement unit 23, a load measurement unit 24, and a calibration unit 25 by executing programs stored in the memory unit 26.

[0021] 2 shows an example in which the control device 10 is configured as a single device. However, the control device 10 may be realized by, for example, multiple processors, memories, and other computational resources. In this case, each unit constituting the control unit 20 is realized by at least one of multiple different processors executing a program.

[0022] When the antenna 4 receives the radio wave transmitted from the RFID tag 1, the acquisition unit 21 acquires the voltage induced by the antenna 4.

[0023] The radio wave intensity measurement unit 22 measures the received radio wave intensity (dB) of the antenna 4 based on the acquired voltage and antenna coefficient. The antenna coefficient is stored in the storage unit 26. In the following description, the received radio wave intensity is referred to as RSSI (Received Signal Strength Indicator).

[0024] Based on the measured RSSI (received radio wave intensity), the distance measurement unit 23 measures the distance D between the RFID tag conductive parts by referring to relationship information indicating the relationship between the RSSI and the distance D between the RFID tag conductive parts. Details of the relationship information will be described later.

[0025] In free space and when the object being measured does not absorb or reflect radio waves, as the distance D between the RFID tag and conductive parts becomes smaller, the electric field strength becomes 0 on the surface of the conductive part 2 (e.g., metal), and the RSSI attenuates. This makes it possible to measure the RSSI and estimate the distance D between the RFID tag and conductive parts based on the measured RSSI. In other words, it becomes possible to measure the displacement of the RFID tag 1 relative to the conductive part 2.

[0026] The measured displacement of the RFID tag 1 relative to the conductive part 2 is also the amount of deformation of the elastic member 3a (described later). Therefore, it is possible to measure the load acting on the elastic member 3a based on the amount of deformation of the elastic member 3a (measured displacement of the RFID tag 1), the length of the elastic member 3a when no load is applied (natural length of the elastic member 3a), and the elastic modulus of the elastic member 3a.

[0027] (Measurement System 200) The above describes the measurement system 100 that can measure the displacement of the RFID tag 1 relative to the conductive part 2. Next, we will explain the measurement system 200 used for load measurement. In the following description, the case where a load is applied between the RFID tag 1 and the conductive part 2 is referred to as "under load," and the case where no load is applied between the RFID tag 1 and the conductive part 2 is referred to as "under no load."

[0028] (Elastic member 3a) The non-conductive part 3 in the measurement system 200 has an elastic member 3a that elastically deforms when a load is applied. The elastic member 3a is, for example, a rubber member. In this embodiment, the elastic member 3a is provided integrally with the non-conductive part 3. The storage unit 26 stores the elastic coefficient of the elastic member 3a.

[0029] (Proofreading Section 25) The calibration unit 25 calculates the amount of RSSI attenuation by subtracting the no-load RSSI (calibrated value) measured under no load from the loaded RSSI (measured value) measured under load. Using the calibrated value makes it possible to reduce measurement errors caused by fluctuations in RSSI due to the installation position of the antenna 4 and the antenna output P.

[0030] Next, the relationship between the RSSI attenuation (dB) and the distance D (mm) between the conductive parts of the RFID tag will be described with reference to Fig. 4. Fig. 4 is a curve graph showing the relationship between the RSSI attenuation and the distance D between the conductive parts of the RFID tag. The horizontal axis of Fig. 4 shows the measured distance D between the conductive parts of the RFID tag, and the vertical axis shows the RSSI attenuation. As shown in Fig. 4, the RSSI changes depending on the distance D between the conductive parts of the RFID tag. Fig. 4 shows the amount of change in RSSI due to the distance D between the conductive parts of the RFID tag, ΔRSSI.

[0031] Figure 5 is a graph showing the relationship between the RSSI attenuation (dBm) and the distance (mm) between the RFID tag and the conductive part under four conditions. The four conditions are: a combination of antenna output P1 (mW) and antenna distance S1 (mm), a combination of antenna output P1 and antenna distance S2, a combination of antenna output P2 and antenna distance S1, and a combination of antenna output P2 and antenna distance S2. As can be seen from Figure 5, when the antenna output P is changed, the position of the black circle on the graph rises or falls. On the other hand, the change in RSSI due to the distance D between the RFID tag and the conductive part (see Figure 4) does not change significantly with the antenna output P. Therefore, by offsetting the graph up or down using RSSI at a distance (a predetermined distance) that eliminates mutual influence between the RFID tag 1 and the conductive part 2 (e.g., metal), it is possible to reduce the effect of the magnitude of the antenna output P. Here, the predetermined distance is the amount of deformation of the elastic member 3 a disposed between the RFID tag 1 and the conductive part 2.

[0032] FIG. 6 is a curve graph showing the relationship between the RSSI attenuation (dBm) and the distance (mm) between the conductive parts of the RFID tags when offset by a predetermined distance. From FIG. 6, it can be seen that the gradients of the curve graphs are almost the same. In this embodiment, a table TL created based on the gradient is used as relationship information showing the relationship between the distance D between the conductive parts of the RFID tags and the received radio wave intensity. As described above, the table TL is stored in the storage unit 26. Note that a mathematical formula created based on the gradient may also be used as the relationship information.

[0033] (Specific example of measurement system 200) The measurement system 100 according to the present embodiment has been described above. Next, a specific example of a measurement system according to the present disclosure will be described with reference to FIGS. 7A and 7B. Note that, to distinguish from the above-described measurement system 100, the specific example of the measurement system will be described as measurement system 200 for convenience. FIG. 7A is a plan view of measurement system 200 according to the embodiment of the present disclosure. FIG. 7B is a front view of measurement system 200 according to the embodiment of the present disclosure. Note that FIG. 7B shows a load F to be measured, and reaction forces R1 and R2 against the load F.

[0034] The measurement system 200 includes a beam 8 and a base 9 in addition to the RFID tag 1, conductive part 2, non-conductive part 3, antenna 4, reader / writer 5, and personal computer 6 (PC) that the measurement system 100 includes.

[0035] (Beam 8) The beam 8 is a double-supported beam. One end of the beam 8 is supported by a rotating fulcrum. The laminated section 7 is a one-end support section that supports one end of the beam 8. When measuring the measurement object, a reaction force R1 is applied to the laminated section 7 (one-end support section). Figure 7B shows the distance a between the position of the laminated section 7 (one-end support section) and the position where the load F is applied. The other end of the beam 8 is supported by a rotating and moving fulcrum. The rotating and moving fulcrum is a other-end support section that supports the other end of the beam 8.

[0036] (9 units) A base 9 is placed at the other end of the beam 8. The measurement object is placed on the base 9. When measuring the measurement object, a reaction force R2 is applied to the support part at the other end. Figure 7B shows the distance b between the position of the support part at the other end and the position where the load F is applied.

[0037] The reaction force R1 can be calculated from the following equation (1). R1=b*F / (a+b) (1) Furthermore, F can be calculated from the following formula (2). F=(a+b)*R1 / b (2) Here, the reaction force R1 corresponds to the load applied to the elastic member 3a. Therefore, as described above, the load measuring unit 24 measures the load (corresponding to the reaction force R1) acting on the elastic member 3a based on the deformation amount of the elastic member 3a (measured displacement of the RFID tag 1), the length of the elastic member 3a when no load is applied (natural length of the elastic member 3a), and the elastic coefficient of the elastic member 3a. Furthermore, the load measuring unit 24 can measure the load F from the measured load (reaction force R1) acting on the elastic member 3a using equation (2). Specifically, the load (reaction force R1) acting on the elastic member 3a can be calculated from the following equations (3) and (4). R1=E*ε*A (3) ε=ΔL / L (4) Here, E is the elastic modulus, ε is the strain, A is the cross-sectional area of ​​the elastic member 3a, L is the natural length of the elastic member 3a, and ΔL is the deformation amount of the elastic member 3a.

[0038] The measurement system 100 in the above embodiment comprises an RFID tag 1, a conductive portion 2 that is conductive and is arranged at a distance from the RFID tag 1, a non-conductive portion 3 that is non-conductive and is arranged so as to be interposed between the RFID tag 1 and the conductive portion 2, an antenna 4 that is arranged at a distance from the RFID tag 1 and is capable of receiving radio waves transmitted from the RFID tag, a radio wave intensity measuring unit 22 that measures the received radio wave intensity, which is the intensity of the radio waves received by the antenna 4, and a distance measuring unit 23 that measures the RFID tag-conductive portion distance D, which is the distance between the RFID tag and the conductive portion, based on the measured received radio wave intensity and by referring to relationship information that indicates the relationship between the received radio wave intensity and the RFID tag-conductive portion distance D.

[0039] With the above configuration, the distance D between the conductive parts of the RFID tags can be measured using the RFID tag 1, the conductive part 2, the non-conductive part 3, the antenna 4, and the radio wave intensity measurement unit 22 and distance measurement unit 23 possessed by the control device 10, making it possible to measure the displacement of the RFID tag with a simple configuration.

[0040] Furthermore, in the measurement system 200 of the above embodiment, the non-conductive portion 3 has an elastic member 3a that elastically deforms when a load is applied between the RFID tag 1 and the conductive portion 2, and the difference between the distance D between the RFID tag conductive portions measured when a load is applied and the distance D between the RFID tag conductive portions measured when there is no load is taken as the deformation amount of the elastic member 3a, and the measurement system 200 further includes a load measurement unit 24 that measures the load based on the deformation amount, the length of the elastic member 3a when there is no load, and the elastic coefficient of the elastic member 3a.

[0041] With the above configuration, the load can be measured by measuring the difference between the distance D between the conductive parts of the RFID tags when under load and the distance D between the conductive parts of the RFID tags when no load is applied, making it possible to measure the load with a simple configuration.

[0042] Furthermore, in the measurement system 200 according to the above embodiment, a stacking unit 7 on which the RFID tag 1 and the like are stacked is disposed on one end side of a beam 8, and a stage 9 on which the measurement object is placed is disposed on the other end side of the beam 8. This allows the RFID tag 1 and the measurement object to be sufficiently separated from each other, thereby reducing the mutual influence between the RFID tag 1 and the measurement object, and therefore makes it possible to accurately measure the load of the measurement object, such as metal or water, which has conductivity.

[0043] In the measurement system 100 in the above embodiment, the elastic member 3a is provided integrally with the non-conductive portion 3, but the present disclosure is not limited to this, and for example, the elastic member 3a may be provided separately from the non-conductive portion 3.

[0044] Furthermore, in the measurement system 100 in the above embodiment, the RFID tag 1 is placed on the upper side (antenna 4 side) of the laminated portion 7, and the conductive portion 2 is placed on the lower side (opposite the antenna 4) of the laminated portion 7, but the present disclosure is not limited to this, and for example, the conductive portion 2 may be placed on the upper side of the laminated portion 7, and the RFID tag 1 may be placed on the lower side of the laminated portion 7.

[0045] Furthermore, the above-described embodiments are merely examples of specific embodiments for carrying out the present disclosure, and the technical scope of the present disclosure should not be interpreted as being limited by these embodiments. In other words, the present disclosure can be carried out in various forms without departing from its gist or main features. [Industrial Applicability]

[0046] The present disclosure is suitably used in a measuring instrument having a measurement system that is required to measure displacement with a simple configuration. [Explanation of symbols]

[0047] 1. RFID tag 2 Conductive part 3 Non-conductive parts 4 Antennas 5 Reader / Writer 6 PC 7 Lamination section 8 beams 9 units 10 Control device 20 Control Unit 21 Acquisition Department 22 Radio wave intensity measurement unit 23 Distance measurement unit 24 Load measurement section 25 Proofreading Department 26 Memory section 100 Measurement System 200 Measurement System

Claims

1. an RFID tag; a conductive portion having conductivity and disposed at a distance from the RFID tag; a non-conductive portion that is non-conductive and is disposed between the RFID tag and the conductive portion; an antenna that is disposed at a distance from the RFID tag and is capable of receiving radio waves transmitted from the RFID tag; a radio wave intensity measuring unit that measures the intensity of radio waves received by the antenna; a distance measurement unit that measures the distance between the RFID tag conductive parts based on the measured received radio wave intensity, by referring to relationship information that indicates the relationship between the RFID tag-to-RFID tag conductive part distance, which is the distance between the RFID tag and the conductive part, and the received radio wave intensity; Equipped with Measurement system.

2. the non-conductive portion has an elastic member that elastically deforms when a load is applied between the RFID tag and the conductive portion, a load measuring unit that measures the load based on the deformation amount of the elastic member, the length of the elastic member when no load is applied, and the elastic coefficient of the elastic member, and that determines the difference between the distance between the conductive parts of the RFID tags measured when the load is applied and the distance between the conductive parts of the RFID tags measured when no load is applied, as the deformation amount of the elastic member, The measurement system of claim 1 .

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