CN110794363A - Positioning system and positioning method of RFID (radio frequency identification) tag - Google Patents
Positioning system and positioning method of RFID (radio frequency identification) tag Download PDFInfo
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- CN110794363A CN110794363A CN201810873920.2A CN201810873920A CN110794363A CN 110794363 A CN110794363 A CN 110794363A CN 201810873920 A CN201810873920 A CN 201810873920A CN 110794363 A CN110794363 A CN 110794363A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S5/00—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations
- G01S5/02—Position-fixing by co-ordinating two or more direction or position line determinations; Position-fixing by co-ordinating two or more distance determinations using radio waves
- G01S5/0284—Relative positioning
- G01S5/0289—Relative positioning of multiple transceivers, e.g. in ad hoc networks
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Abstract
The invention discloses a positioning system and a positioning method of an RFID label, which are characterized by comprising the following steps: the RFID reader sends a radiation beam with a fixed emission angle and data information, and detects the RSSI of the tags in the area range; the 2D galvanometer system reflects the radiation beam, and the servo control system is connected with the 2D galvanometer system to control the angle of the rotary galvanometer and indirectly control the radiation direction of the radiation beam; the tag receives a radiation signal sent by the reader and generates RSSI (received signal strength indicator); according to the position adjustment of the galvanometer to the radiation wave beam, in a unit time period, the reader acquires the reading times of the tag to be detected and tag information, the reading times represent the intensity of RSSI, and the information is uploaded to a PC (personal computer) terminal; and finally, screening out at least three groups of optimal data information by the PC terminal, solving the weight of the optimal data information, and calculating the position coordinates of each label by combining a positioning algorithm. The invention does not use a distance measurement mode for positioning, greatly improves the accuracy of label positioning, has low cost and easy construction, and can be applied to a dense label distribution environment.
Description
Technical Field
The invention relates to the technical field of label identification, in particular to an RFID label positioning system and method applied to the fields of logistics, warehouse management, intelligent identification and the like.
Background
Due to the fact that the target product needs to be positioned in the fields of commodity production and sale, cargo management and distribution, intelligent identification and the like, the positioning system is more and more popular. The current common positioning is wireless local area network positioning, Bluetooth positioning, GPS positioning and the like. With the improvement of the requirement on the positioning precision of products and the increase of the number of products, the traditional positioning technology can not meet the requirement, and a low-cost and high-precision positioning system is urgently needed.
Radio Frequency Identification (RFID) is a wireless communication technology that can identify a specific target and read and write related data by Radio signals without establishing mechanical or optical contact between an Identification system and the specific target. The radio signal is used to transmit data from the tag attached to the article by means of an electromagnetic field modulated at a radio frequency to automatically identify and track the article. Some tags can obtain energy from the electromagnetic field emitted by the identifier during identification, and do not need a battery; there are also tags that have their own power source and can actively emit radio waves (electromagnetic fields tuned to radio frequencies). The tag contains electronically stored information that can be identified within a few meters. Unlike bar codes, radio frequency tags need not be in the line of sight of the identifier, but can be embedded within the tracked object. In the system, a positioning algorithm is the key of an RFID positioning technology, and the current RFID positioning technology comprises a positioning algorithm of a ranging technology and an algorithm of a non-ranging technology. The positioning algorithms Of the ranging technique include Time Of Arrival location (TOA), Time difference Of Arrival location (TDOA), Angle-Of-Arrival location (AOA), and Signal Strength location (RSSI); the location algorithm based on the non-ranging comprises a DV-HOP location algorithm, an APIT location algorithm and a convex planning algorithm.
The existing positioning method comprises a two-dimensional positioning method and a triangular centroid positioning method, the two methods have large errors, the label cannot be accurately positioned, and the method is not suitable for being used in an environment with dense labels. In the more advanced RFID positioning technology, a plurality of read-write heads are arranged in a tag area to acquire the RSSI (received signal strength indicator) strength of a tag to be positioned and a reference tag, so that the RSSI strength of a plurality of groups of tags to be positioned and reference tags is obtained, and the positioning information of the tag to be positioned is calculated according to the obtained data and a two-dimensional positioning algorithm. Although this method is feasible, it is inconvenient and expensive to lay and construct. There is also a positioning method developed based on a phased array antenna reader, which adjusts the direction of a beam through the change of the phase of electromagnetic waves to achieve the scanning positioning of the label direction, and the disadvantage is that the phased array antenna is too expensive in cost and is not easy to realize.
Disclosure of Invention
In order to solve the defects of the prior art, the invention mainly aims to provide an RFID positioning system and an RFID positioning method, which aim to realize the accurate positioning and identification of multiple tags without ranging, and are easy to realize, low in cost, convenient to integrate and convenient to apply.
In order to achieve the purpose, the technical scheme provided by the invention is as follows: a positioning system and a positioning method of an RFID tag are characterized by comprising an RFID reader, the RFID tag, a 2D galvanometer system, a servo control system and a PC (personal computer) end; the positioning method of the positioning system of the RFID label comprises the following steps:
s1: the RFID reader sends a radio frequency signal with constant power and a fixed beam angle;
s2: the 2D galvanometer system reflects a radiation beam emitted by the RFID reader;
s4: the RFID tag receives a signal sent by an RFID reader, generates RSSI (received signal strength indicator), and detects the RSSI strength of the RFID tag in an area range;
s3: the servo control system rotates the angle of the galvanometer in the 2D galvanometer system, controls the radiation direction of the radiation beam reflected by the galvanometer and uploads the information of the rotating angle to the PC terminal;
s5: the RFID reader uploads the received RFID label information to a PC (personal computer) end connected with the RFID reader;
s6: and the PC terminal processes the received data information, screens at least three optimal coordinate points (namely at least three groups of data) from the multiple groups of data, refers to the RSSI (received signal strength indicator) strength of the label, and calculates to obtain the position information of the label by combining with a weighted re-evaluation value of a positioning algorithm.
Further, the RFID reader is a radio frequency signal sending and receiving device.
Furthermore, the 2D galvanometer system is used to reflect the radiation beam, adjust the scanning direction of the beam to complete the scanning of the two-dimensional surface, and form the surface coordinates of the detection area to determine the position coordinates of the tag.
Furthermore, the servo control system is used for fixing the 2D galvanometer system, generating rotating angles in different directions, assisting the 2D galvanometer system to realize directional reflection of radiation beams and realizing scanning on a target area surface.
Furthermore, the tag contains data information, and is used for receiving the RSSI of the reader in the system, making feedback of the corresponding RSSI strength and realizing the authentication and positioning of the reader.
Furthermore, the PC is connected with the reader and used for receiving the label information fed back by the reader, and the position coordinates are analyzed and calculated through a weighting algorithm of the system.
Further, the RFID reader transmits radio frequency signals at constant power, and the beam angle of the radio frequency signals is kept consistent.
Further, the beam angle of the reflected wave passing through the 2D galvanometer system remains unchanged.
Furthermore, the servo motor system is connected with the PC end, and information can be uploaded to the PC end every time a unit variable quantity is generated.
Further, the coordinates of the detection area surface are obtained by calculating position information of each coordinate point based on the beam angle θ, the vertical distance H from the galvanometer to the area surface, and the deflection angle α of the galvanometer, and coordinating the detection area.
Furthermore, the reading times have a certain linear relation with the RSSI intensity in the effective area of the radiation wave spot.
The invention provides a positioning system and a positioning method of an RFID label, and the implementation mode is as follows: in the detection area range, the RFID reader sends out radiation beams, the deflection direction of the 2D galvanometer system is controlled through the servo control system, radiation wave spots are projected to the surface of the detection area, the detection area is coordinated, and the RSSI signal intensity of the label is detected. The reader and the servo control system transmit the detection information and the control information back to the PC end, the PC end screens out at least 3 groups of optimal data (the data can be increased into more groups according to the precision requirement), and the positioning information of the label is calculated by combining a positioning algorithm and a weight algorithm.
The RFID label positioning system has the advantages that the system is more convenient to integrate due to the adoption of a mode of reflecting by the vibrating mirror, the manufacturing cost is much lower than that of the traditional RFID label positioning system, the RFID label positioning system is easy to build, the positioning precision of the label is improved by the method, and the RFID label positioning system can be widely applied to application scenes with more labels.
Drawings
FIG. 1 is a schematic diagram of the operation of a dual-mirror system in accordance with the present invention.
FIG. 2 is a schematic diagram of a weight location method according to the present invention.
FIG. 3 is a schematic diagram of the RFID tag locating system of the present invention.
Detailed Description
A positioning system and a positioning method of an RFID tag are provided, wherein the positioning system of the RFID tag mainly comprises: the system comprises a PC terminal, an RFID reader, a galvanometer, a servo control system and an RFID label. The RFID reader and the servo control system are respectively connected with the PC end, so that data communication can be realized; the RFID reader is used for generating a radiation beam and reading tag information; the galvanometer is fixed on the servo control system, can realize angle deflection and is used for reflecting a radiation beam generated by an RFID reader and realizing scanning and detection of a label area; the PC terminal is used as a data processing center of the system to calculate the position information of the label.
The RFID reader sends radio frequency signals with constant power and a fixed beam angle, the RSSI of the tags in the area range is detected, the servo control system controls the rotation angle of the 2D galvanometer system, and the propagation direction of the radiation beam is controlled to scan the plane where the tags to be positioned are located. Since the closer the tag is to the center of the spot, the stronger the RSSI received, the more times the reader scans the tag. Within a certain range, the reading times and the RSSI strength have a good linear relation, so that the RSSI strength can be reflected according to the number of times that a reader scans a label.
In the system, an RFID reader, a servo control system and a 2D galvanometer system are integrated and connected with a PC end so as to be convenient to use and fix. The RFID reader and the servo control system transmit data information back to the PC end connected with the RFID reader and the servo control system in real time for processing.
In the present system, the device is mounted in a fixed location and the reader transmits data information at a constant power to ensure that the beam angle and intensity of the transmitted beam are substantially constant.
When the system is installed, firstly, the stepping and scanning modes of the servo control system are preset, and secondly, the detection area is completely scanned, so that the area is coordinated for subsequent positioning and use.
In the positioning process, the tag to be positioned receives the signal of the reader, and when the tag is closer to the center of the beam, the RSSI signal strength received by the tag is stronger, so that the number of times detected by the reader is more. The reader uploads the times of reading the label at each position point to the PC terminal, and the PC terminal screens at least three groups of position points with the maximum times of reading the same label. And then the PC end realizes the accurate positioning of the label by combining a positioning algorithm. By the method, the corresponding reading times of the labels to be detected are collected, and the positioning information of the labels to be detected is obtained.
When the method is adopted, in order to distinguish the position information of the labels to be detected, each label contains different label information, the collected data are grouped after the system detects correspondingly each time, and the data of each label are processed in a small group mode.
The key operating principles and algorithms employed in the present invention are described below.
FIG. 1 is a schematic diagram of the operation of a dual-mirror system in accordance with the present invention. The RFID reader sends out radiation waves, the vibrating mirror 1 and the vibrating mirror 2 in the 2D vibrating mirror system sequentially reflect the radiation waves, and the reflected waves 1 vertically hit the surface of an area to be detected; the servo control system rotates the galvanometer 1 and the galvanometer 2 to enable radiation wave spots reflected by the galvanometer 1 and the galvanometer 2 to traverse the whole label area and scan the whole label area; rotation of the mirror system causes the reflected beam (e.g., reflected wave 2) to be angularly offset from the verticalOffset from the X axis by an angle of
. Then according to
、
And the height H of the galvanometer from the area surface can be used for calculating the value of each central coordinate point of the radiation wave spot, so that a coordinate graph of the detection area can be drawn in the system. The calculation formula is as follows.
FIG. 2 is a schematic diagram of a weight location method applied in the present invention,
in order to radiate a central coordinate point of the wave spot, after the antenna detects the tag information in the wave beam range, at least three position points with strongest signals are selected through the detection of the RSSI (received signal strength indicator) intensity of the tag, and the optimal positioning point of the tag can be obtained by weighting the coordinate points corresponding to the position points in combination with the intensity of the signals. The formula is as follows.
SiThe RSSI intensity of the position point label is S is the sum of the RSSI intensity of each position point label, and M is the number of the selected position points.Is the beam center coordinate point of the corresponding position point.
In the system, the RSSI intensity detection of the tag is implemented by using frequent reading times to show the distance between the tag and a radiation center because the RSSI intensity is influenced by a propagation medium. Since passive tags use backscatter communications, this means that tags near the center of radiation will gain more energy than those far from the center of radiation and therefore have a higher probability of reading more frequently, and the number of readings has a good linear relationship to RSSI strength over the effective range of the radiation spot. Here, we record the number of reads as N, then the weighting factor can be expressed as.
The position coordinates can be expressed as.
Fig. 3 is a schematic diagram of the RFID tag positioning system of the present invention, and the main working process is as follows: the PC end can control the reader and the servo control system to execute detection operation. In the detection area range, the RFID reader generates radiation beams, the servo control system adjusts the galvanometer to reflect the radiation beams to the surface where the label is located, and the detection of the detection area coordinate and the RSSI signal intensity of the label are completed. Then, the reader uploads the label information and the reading times to the PC terminal; and the servo control system uploads the data such as the stepping and deflection angles of the galvanometer to the PC terminal. The PC end screens out at least 3 groups of optimal data (more groups of data can be added according to the precision requirement), and the accurate position information of the label can be obtained through calculation by combining a positioning algorithm and a weight algorithm, so that the label is positioned.
The above embodiments are provided only for illustrating the present invention and not for limiting the present invention, and those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and therefore all equivalent technical solutions should also fall within the scope of the present invention.
Claims (10)
1. A positioning system and a positioning method of an RFID tag are characterized by comprising an RFID reader, a 2D galvanometer system, the RFID tag and a PC end, wherein the PC end is connected with the FID reader and the 2D galvanometer system; the positioning method comprises the following steps:
s1: the RFID reader sends a radio frequency signal with constant power and a fixed beam angle, and detects the RSSI of the tag in the area range;
s2: the 2D galvanometer system reflects a radiation beam sent by the RFID reader;
s3: the servo control system rotates the galvanometer angle in the 2D galvanometer system, controls the radiation direction of radiation beams and uploads the rotating angle information to the PC terminal;
s4: the RFID tag receives a signal sent by an RFID reader, generates RSSI (received signal strength indicator), and detects the RSSI strength of the RFID tag in an area range;
s5: the RFID reader uploads the received label information to a PC (personal computer) end connected with the RFID reader;
s6: and processing the received data information by the PC, screening at least three optimal coordinate points (namely at least three groups of data) from the multiple groups of data by the system, referring to the RSSI (received signal strength indicator) strength of the label, weighting and re-evaluating by combining a positioning algorithm, and calculating to obtain the position information of the label.
2. The positioning system and the positioning method of the RFID tag according to claim 1, wherein: the RFID reader is a radio frequency signal sending and receiving machine; the RFID reader sends radio frequency signals with constant power, and the beam angle width of the radio frequency signals is kept consistent.
3. The positioning system and the positioning method of the RFID tag according to claim 1, wherein: the 2D galvanometer system can be composed of two galvanometers and is used for reflecting radiation beams, adjusting the scanning direction of the beams to complete scanning of a two-dimensional surface and determining position coordinates.
4. The positioning system and the positioning method of the RFID tag of claim 1, wherein the servo control system is used to fix the 2D galvanometer system, to generate rotation angles with different directions, to assist the 2D galvanometer system to realize directional reflection of the radiation beam, and to realize coordinate scanning on the target area.
5. The positioning system and the positioning method of the RFID tag according to claim 1, wherein: the RFID tag contains data information, is used for receiving the RSSI of the reader in the system, and feeds back the corresponding RSSI strength to realize the positioning of the reader; the RSSI strength of the REID tag is expressed in terms of the number of times the tag reads in calculating the location coordinates.
6. The positioning system and the positioning method of the RFID tag according to claim 1, wherein: and the PC is connected with the reader and used for receiving the label information fed back by the reader and analyzing and solving the position coordinates through a weight algorithm of the system.
7. The system and method for locating an RFID tag according to claim 1, wherein: the servo motor system is connected with the PC end, and information can be uploaded to the PC end every time a unit variable quantity is generated.
8. The positioning system and the positioning method of the RFID tag according to claim 1, wherein: the at least three groups of data are used under the condition of low precision requirement, and when the precision requirement is higher, the calculation of the multiple groups of data can be carried out according to the actual condition, so that more accurate positioning is realized.
9. The RFID tag positioning system and method as claimed in claims 3-4, wherein: the scanning surface can realize the coordinate transformation according to the parameters such as the angle generated by the galvanometer, the distance of the central point of the wave beam, the width of the wave beam and the like controlled by the servo control system.
10. The positioning system and the positioning method of the RFID tag according to claim 6, wherein: the reading times have a certain linear relation with the RSSI intensity in the effective area of the radiation wave spot.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111985587A (en) * | 2020-08-06 | 2020-11-24 | 运易通科技有限公司 | Automatic matching method for container and truck |
| CN112055409A (en) * | 2020-08-04 | 2020-12-08 | 暨南大学 | RFID indoor positioning method based on power control |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112055409A (en) * | 2020-08-04 | 2020-12-08 | 暨南大学 | RFID indoor positioning method based on power control |
| CN111985587A (en) * | 2020-08-06 | 2020-11-24 | 运易通科技有限公司 | Automatic matching method for container and truck |
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Application publication date: 20200214 |