Radio frequency identification reading terminal and radio frequency identification reading success prompting method

Abstract

The invention relates to the technical field of data processing, and discloses a radio frequency identification reading terminal and a radio frequency identification reading success prompting method. The method comprises the following steps: receiving a tag backscattering signal through a phased-array antenna, resolving a three-dimensional space coordinate of the tag backscattering signal, and binding a tag ID with the coordinate; and the central control module generates a control instruction accordingly, and drives the laser indication module to accurately project the visible light spots to the positions of the corresponding physical labels, so that visual confirmation of ''what you see is what you get'' is realized. The system integrates the inertial measurement unit to perform motion compensation, supports multi-color light to distinguish target attributes, and significantly improves the checking efficiency, accuracy and operation experience.

Description

Technical Field

[0001] This invention belongs to the field of data processing technology, specifically relating to an RFID reading terminal and a method for indicating successful RFID reading. Background Technology

[0002] Radio Frequency Identification (RFID) technology, as a core component of the Internet of Things (IoT) sensing layer, has been widely applied in retail, logistics, warehousing, and asset management. Its basic principle is to achieve contactless identification and data interaction of target objects through wireless radio frequency communication between a reader and passive or active electronic tags. In practical deployments, RFID systems typically consist of readers, antennas, tags, and a back-end processing platform, with the reader responsible for initiating queries, receiving responses, and parsing data. As application scenarios evolve towards higher density and higher concurrency, a single reading operation often involves the simultaneous response of multiple neighboring tags, placing higher demands on the system's identification accuracy and human-machine interaction efficiency.

[0003] The successful RFID read notification mechanism is a crucial element in ensuring operational accuracy. Existing terminals generally use a single audio signal (such as a "beep") or a global status light as a common feedback method for successful reads, designed to confirm the connectivity of the communication link. However, in scenarios with densely packed multiple tags—such as supermarket shelf inventory or warehouse pallet batch scanning—this mechanism cannot establish a correspondence between the read result and the physical spatial location. While operators may know that "a tag has been read," it is difficult to determine which specific tag triggered the notification, especially when the tags look similar or are closely arranged, easily leading to misjudgments or missed detections.

[0004] Existing technologies have significant shortcomings in tag-level prompts: traditional prompt signals lack spatial directionality and cannot distinguish tag responses from different directions or distances; communication between the terminal and the tag is only one-way or simple response-based, failing to utilize spatial features (such as signal strength gradients, phase differences, or multi-antenna beamforming information) acquired during short-range interactions to construct a location mapping model. This forces operators to manually verify the tag ID list displayed on the screen against the physical location, which is not only inefficient but also significantly increases the error rate under high-intensity work environments. Therefore, there is an urgent need for an intelligent prompting method that can accurately associate successful read events with the physical tag location to eliminate multi-tag confusion and improve the reliability and smoothness of human-machine collaboration. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for indicating successful RFID reading, applied to an RFID reading terminal. The method includes the following steps: The RFID reading terminal's RFID module transmits an RFID query signal and receives a backscattered signal returned from a certain RFID tag, carrying the unique identification code of that RFID tag; The tag spatial positioning module of the radio frequency identification (RFID) reading terminal performs spatial information calculation synchronously based on the backscattered signals received by each antenna element of the phased array antenna unit of the RFID module, so as to determine the precise spatial coordinates of the RFID tag relative to the terminal in a preset three-dimensional coordinate system. The central control processing module of the radio frequency identification reading terminal associates and binds the acquired unique identification code with the calculated precise spatial coordinates to generate a tag-location data pair containing identity information and location information. Based on the precise spatial coordinates, the central control processing module calculates the control command that drives the target indication module of the radio frequency identification reading terminal to perform precise pointing. The central control processing module outputs the control command to the target indication module, driving the target indication module to generate a sensory indication signal with clear spatial directionality, and accurately projects or guides the sensory indication signal to the physical location of the RFID tag, thereby forming a momentary mark that can be perceived by the operator on the physical entity of the RFID tag or its adjacent area.

[0006] In one embodiment of the present invention, the radio frequency identification module includes a radio frequency transceiver chip and a planar phased array antenna unit composed of M rows and N columns of antenna elements, where M and N are integers greater than 1. When the tag spatial positioning module acquires the backscattered signal, it specifically acquires in parallel the complex amplitude values ​​of the backscattered signals received by each of the M multiplied by N antenna elements, wherein the complex amplitude values ​​include signal strength information and phase information.

[0007] Furthermore, the tag spatial positioning module determines the precise spatial coordinates of the RFID tag, specifically including: By comparing the phase difference of the backscattered signals received by different antenna elements in the phased array antenna unit, and using a multiple signal classification algorithm or a rotation-invariant subspace estimation algorithm, the angle of arrival of the backscattered signal is calculated. The angle of arrival includes the azimuth angle and the elevation angle. By analyzing the received signal strength indication value of the backscattered signal and combining it with a preset radio frequency signal spatial propagation attenuation model, the straight-line distance between the RFID tag and the RFID reader terminal can be estimated; or, by analyzing the phase change of the backscattered signal within a continuous query period, phase ranging calculation can be performed to obtain the straight-line distance. The coordinate transformation unit within the tag spatial positioning module converts the position information in the spherical coordinate system formed by the azimuth angle, pitch angle, and straight-line distance into Cartesian coordinates in the preset three-dimensional coordinate system, i.e., the precise spatial coordinates, through a preset coordinate transformation matrix.

[0008] In one embodiment of the present invention, the target indication module is a laser pointing module, which includes a laser diode light source and a dual-axis microelectromechanical system (MEMS) mirror. The sensory indication signal is a laser beam, and the instantaneous mark formed on the physical entity is a visible light spot. The central control processing module calculates control commands, specifically, based on the precise spatial coordinates, it reverse-calculates the first and second driving voltages required to drive the dual-axis MEMS mirror to deflect around the first and second axes to the target angle, respectively. After receiving the control commands, the target indication module applies the first and second driving voltages to the dual-axis MEMS mirror, causing its mirror surface to deflect precisely. Simultaneously, the central control processing module triggers the laser diode light source to emit light for a preset time duration, the preset time duration ranging from 100 milliseconds to 500 milliseconds. The laser beam emitted by the laser diode light source is reflected by the deflected dual-axis MEMS mirror and precisely guided to the physical location of the RFID tag.

[0009] Furthermore, the laser diode light source is a multi-color light source, internally integrating a light-emitting unit capable of emitting at least two different colors of light. The central control processing module internally stores a pre-set item list database, which records the unique identification code of the tag corresponding to the item to be inventoried or searched. The method also includes: Upon receiving the unique identification code, the central control processing module immediately performs a search and matching operation in the pre-set item list database. If a match is successful, it indicates that the RFID tag is a valid target. Then, the central control processing module controls the multicolor light source to emit a beam of light of the first color, which is green. If a match fails, indicating that the RFID tag is a non-target or unplanned item, the central control processing module controls the multi-color light source to emit a beam of a second color, which is red.

[0010] In one embodiment of the present invention, the tag spatial positioning module also integrates an inertial measurement unit, which includes a three-axis accelerometer and a three-axis gyroscope. When the RFID reader performs a reading operation, the inertial measurement unit outputs inertial data in real time characterizing the terminal's attitude and motion state. The central control processing module receives the inertial data and uses a Kalman filter algorithm to fuse the inertial data with the original spatial coordinates calculated by the tag spatial positioning module. This dynamically compensates for and corrects coordinate measurement errors caused by operator hand tremors or movement, thereby outputting more stable and accurate spatial coordinates after motion compensation.

[0011] Furthermore, the method also includes: The central control processing module has an internal read tag cache, which temporarily stores the unique identification codes of tags that have been successfully read and indicated in the current inventory session. Upon receiving a new unique identification code, the central control processing module first queries the read tag cache. If the unique identification code already exists in the cache, it is determined to be a duplicate read, and subsequent spatial positioning and target indication actions are not performed to avoid repeated interference with already inventoried targets and to save terminal power consumption.

[0012] In one embodiment of the present invention, within a single reading cycle, the RFID module simultaneously receives backscattered signals from several different RFID tags. The central control processing module processes these multiple signals in parallel, generating multiple tag-location data pairs. Subsequently, the central control processing module sorts the tag-location data pairs according to the received signal strength indication value of each signal from high to low, and controls the target indication module to project light spots onto the physical locations of the 111 RFID tags one by one and quickly in this order. Each projection is spaced at a preset time window, the value of which ranges from 50 milliseconds to 150 milliseconds.

[0013] To implement the above method, the present invention also provides a radio frequency identification (RFID) reader terminal, which includes: The radio frequency identification module is equipped with a radio frequency transceiver chip and a phased array antenna unit, which is used to transmit radio frequency query signals and receive backscattered signals carrying the unique identification code of the tag; The tag spatial positioning module is electrically connected to the phased array antenna unit of the radio frequency identification module, and is used to synchronously calculate the precise spatial coordinates of the radio frequency identification tag in a preset three-dimensional coordinate system based on the backscattered signals received by each antenna element. The target indication module is used to generate and project a sensory indication signal with clear spatial directionality when a control command is received. The central control processing module, as the control core of the terminal, establishes data and control bus connections with the radio frequency identification module, the tag spatial positioning module, and the target indication module, respectively. It is used to obtain the unique identification code and the precise spatial coordinates, associate and bind the two data, and generate and send the control command to the target indication module based on the precise spatial coordinates, so as to drive it to accurately guide the sensory indication signal to the physical location of the radio frequency identification tag.

[0014] In one embodiment of the present invention, the phased array antenna element is a microstrip patch antenna array with an operating frequency of 860 MHz to 960 MHz. The tag spatial positioning module is an independent digital signal processor, which has embedded algorithms for performing angle of arrival calculation, distance estimation, and coordinate transformation.

[0015] Furthermore, the target indication module is fixedly installed at the front end of the housing of the RFID reader terminal, and its beam emission axis is parallel to or at a preset small angle to the center normal direction of the phased array antenna element. The target indication module includes: A laser diode light source with a center wavelength of 532 nanometers and an output optical power of 5 milliwatts; A dual-axis microelectromechanical system reflector is installed in front of the optical path of the laser diode light source. Its mirror size is not less than 3 mm by 3 mm, and its resonant frequency is higher than 1000 Hz. It can respond to the driving voltage signal output by the central control processing module to achieve high-speed and precise deflection control of the reflected beam in two dimensions: azimuth and pitch.

[0016] In one embodiment of the present invention, the central control processing module is an embedded system-on-a-chip (SoC). Besides integrating a central processing unit core, it also integrates non-volatile flash memory for storing a pre-set item list database and a read tag cache, as well as dynamic random access memory for temporarily storing computational data. The terminal also includes a human-machine interface unit, which includes a physical trigger switch and an LCD screen. The operator initiates the reading and instruction process by pressing the physical trigger switch, and the unique identifier of the read tag and its status information in the pre-set item list are displayed in real time on the LCD screen.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Achieves precise binding between read confirmation and physical entity: By calculating the three-dimensional spatial coordinates of the tag in real time and projecting a directional cursor, this invention transforms the abstract digital read success event into a visual confirmation signal that directly acts on the physical tag entity, completely solving the core pain points of ambiguous feedback information and inability to locate specific read targets in the prior art.

[0018] 2. Significantly improved inventory efficiency and accuracy: Operators no longer need to repeatedly switch their gaze between the terminal screen and the actual items on the shelves for manual verification, realizing a "what you see is what you get" inventory mode, greatly shortening the single item confirmation time, and fundamentally eliminating errors and omissions caused by manual verification, resulting in a substantial improvement in inventory efficiency and data accuracy.

[0019] 3. Provides rich and configurable multi-dimensional information feedback: By adopting multi-color light sources, this invention can not only indicate "which" tag has been read, but also provide real-time feedback on the business attributes of the tag, such as "whether it is in the inventory list" or "whether it is an abnormal item", upgrading simple success prompts to on-site visualization of complex business logic, thereby enhancing the practicality and intelligence level of the terminal.

[0020] 4. By integrating an inertial measurement unit for motion compensation, the positioning accuracy and stability in dynamic operating environments are improved, enabling the invention to meet the needs of operators in actual working scenarios such as walking and moving, and ensuring the reliability of the indication.

[0021] 5. The system architecture is complete, tightly integrating radio frequency identification, spatial positioning, target indication and central control into one, forming an end-to-end closed-loop solution with high engineering feasibility and a good user experience. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall technical solution architecture of an RFID reading terminal and an RFID reading success notification method proposed in this invention; Figure 2 This is a schematic diagram of the core principle framework for solving the three-dimensional coordinates of the tag based on phased array antenna and spatial positioning algorithm in this invention; Figure 3 This is a flowchart illustrating the logical process of generating and sorting tag-location data pairs in a multi-tag scenario using an RFID reader terminal in this invention. Figure 4 This is a control logic and beam guiding principle framework diagram of the target indication module in this invention, which generates directional sensory signals based on precise spatial coordinates. Figure 5 This is a schematic diagram of the spatial coordinate correction interaction relationship in this invention, which integrates inertial measurement unit data to achieve dynamic motion compensation; Figure 6 This is a business logic framework diagram of the central control processing module in this invention, which performs tag identification code matching, cache management, and multi-color indication feedback. Detailed Implementation

[0023] Please refer to Figures 1 to 6This invention provides a radio frequency identification (RFID) reader terminal and a method for indicating successful RFID reading. It aims to solve the technical problems of existing terminals only providing global, non-directional sound or vibration feedback in scenarios with dense multi-tag reading. This prevents operators from matching successfully read electronic tags with their corresponding physical entities, leading to low inventory efficiency, heavy manual verification burden, and high error rates. To achieve this goal, this invention integrates a phased array antenna, a spatial positioning algorithm, a target indication module, and a central control processing module to construct a closed-loop RFID system with spatial perception and directional feedback capabilities.

[0024] The method for indicating successful RFID reading includes the following steps: First, the RFID module transmits an RFID query signal and receives a backscattered signal from an RFID tag, which carries the unique identification code of that RFID tag. Secondly, the tag spatial positioning module performs spatial information calculations simultaneously based on the backscattered signals received by each antenna element in the phased array antenna unit of the RFID module, so as to determine the precise spatial coordinates of the RFID tag relative to the terminal in the preset three-dimensional coordinate system. Subsequently, the central control processing module associates and binds the acquired unique identification code with the calculated precise spatial coordinates to generate a tag-location data pair containing identity and location information; then, based on the precise spatial coordinates, the central control processing module calculates the control command to drive the target indication module to point precisely. Finally, the central control processing module outputs the control command to the target indication module, which drives it to generate a sensory indication signal with clear spatial directionality, and accurately projects or directs the sensory indication signal to the physical location of the RFID tag, thereby forming a momentary mark that can be perceived by the operator on the physical entity of the tag or its adjacent area.

[0025] In the above method, the radio frequency identification (RFID) module includes an RFID transceiver chip and a planar phased array antenna unit composed of M rows and N columns of antenna elements, where M and N are both integers greater than 1. When acquiring backscattered signals, the tag spatial positioning module simultaneously collects the complex amplitude values ​​of the backscattered signals received by each of the M multiplied by N antenna elements. These complex amplitude values ​​simultaneously contain signal strength and phase information. Each antenna element is equipped with an independent low-noise amplifier, mixer, and analog-to-digital converter channel to ensure that all channels are strictly synchronized in time, with a sampling frequency of not less than 100 MHz to meet the requirements of subsequent high-precision phase difference calculations. The complex amplitude values ​​are stored in a 16-bit fixed-point format in a high-speed cache within the tag spatial positioning module for subsequent algorithm calls.

[0026] The specific process by which the tag spatial positioning module determines the precise spatial coordinates of the RFID tag is as follows: First, by comparing the phase difference between the backscattered signals received by different antenna elements in the phased array antenna unit, a phase difference matrix is ​​constructed. Then, this phase difference matrix is ​​input into a multi-signal classification algorithm model to perform eigenvalue decomposition, separating the signal subspace and the noise subspace. Subsequently, based on the orthogonality between the steering vector and the noise subspace, the spatial spectrum peak is searched to calculate the angle of arrival of the backscattered signal, which includes the azimuth angle. With pitch angle azimuth The value range is -90 degrees to +90 degrees, pitch angle The value ranges from -45 degrees to +45 degrees, with an angular resolution better than 0.5 degrees.

[0027] Distance estimation employs two parallel mechanisms: First, by analyzing the received signal strength indication value of the backscattered signal and combining it with the preset radio frequency signal spatial propagation attenuation model, which is a weighted combination of the free space path loss model and the multipath fading correction term, the straight-line distance r between the radio frequency identification tag and the terminal is estimated. Secondly, by analyzing the phase change of the backscattered signal over two consecutive query periods. Using the formula ; Perform phase ranging calculation, where At the speed of light, To continuously query the frequency step between signals, a value of 200 kHz is used. The two distance estimation results are weighted and averaged to obtain the final distance value. The weights are dynamically adjusted based on the signal-to-noise ratio (SNR). When the SNR is higher than 20 dB, the phase ranging result has a weight of 70%; otherwise, the received signal strength indication (RSI) estimation result has a weight of 60%. Subsequently, the coordinate transformation unit transforms the data into spherical coordinates (…). , , The coordinates are transformed into (x, y, z) Cartesian coordinates through a preset coordinate transformation matrix. The origin of this coordinate system is located at the geometric center of the phased array antenna element. The x-axis points in front of the terminal, the y-axis points to the right, and the z-axis points upward. The unit is millimeters, and the coordinate accuracy is better than 10 millimeters.

[0028] The central control processing module associates and binds the unique identifier with the precise spatial coordinates to generate a tag-location data pair. This data pair is stored in the form of a structure, containing the following fields: unique tag identifier (16 bytes), spatial coordinates x (4-byte floating-point), y (4-byte floating-point), z (4-byte floating-point), received signal strength indicator value (2-byte integer), and timestamp (8 bytes). This structure is pushed into a first-in-first-out queue for subsequent sorting and scheduling.

[0029] The target indication module is a laser pointing module, which includes a laser diode light source and a dual-axis microelectromechanical system (MEMS) mirror. The sensory indication signal is a visible laser beam, which forms an instantaneous mark on the physical entity as a circular spot with a diameter of no more than 5 mm. The central control processing module calculates the first driving voltage required to drive the dual-axis MEMS mirror based on the precise spatial coordinates (x, y, z). Second driving voltage The solution process is based on a pre-calibrated beam deflection mapping function, which is obtained by fitting a large amount of measured data using the least squares method. The expression is: ; in , , , , , , , These are calibration coefficients, stored in the non-volatile memory of the central control processing module. After the calculation is complete, the central control processing module generates a... and The control command packet is sent to the drive circuit of the target indication module via a high-speed serial bus. The drive circuit converts the digital command into an analog voltage signal, which is applied to the electrostatic drive electrode of the dual-axis microelectromechanical system (MEMS) mirror. Simultaneously, the central control processing module triggers the laser diode light source to emit light for 300 milliseconds, a duration sufficient for stable human visual perception while avoiding visual interference or power waste due to prolonged illumination. After being deflected by the mirror, the laser beam is precisely projected onto the label's location along the calculated direction.

[0030] The laser diode light source is a multi-color light source, integrating a green light-emitting unit and a red light-emitting unit, with center wavelengths of 532 nm and 650 nm, respectively. The central control processing module internally stores a pre-set item list database, organized in key-value pairs. The key is a unique tag identifier, and the value is an item status identifier. Upon receiving a unique identifier, the central control processing module immediately performs a hash lookup in the database. If a match is found, it is determined to be a valid target, and the green light-emitting unit is activated; if no match is found, it is determined to be a non-target item, and the red light-emitting unit is activated. The color switching response time is less than 5 milliseconds, ensuring stable color status during a single indication.

[0031] The tag spatial positioning module also integrates an inertial measurement unit (IMU), which includes a three-axis accelerometer and a three-axis gyroscope with a sampling frequency of 200 Hz. During the reading operation, the IMU continuously outputs the terminal's own linear acceleration and angular velocity data. The central control processing module receives this inertial data and constructs an extended Kalman filter model. The model's state vector contains the tag's spatial coordinates and their first derivatives, while the observation vector is the pose increment after fusing the original spatial coordinates with the inertial data. The filter performs a prediction and update step every 10 milliseconds to dynamically compensate for coordinate drift caused by operator hand tremors or movements. The compensated coordinates are used as the final accurate spatial coordinates for indication control, significantly improving indication stability in dynamic environments.

[0032] The central control processing module has an internal tag cache, which uses a circular buffer structure with a maximum capacity of 1000 tag unique identifiers. Upon receiving a new unique identifier, the central control processing module first iterates through this cache. If the identifier already exists, the subsequent spatial positioning and indication process is skipped, and the data packet is discarded directly. If it does not exist, the identifier is written to the end of the cache, and the complete processing flow is executed. This mechanism effectively prevents duplicate indications for the same tag, reduces system load, and extends battery life.

[0033] Within a single read cycle, the RFID module may simultaneously receive backscattered signals from multiple different RFID tags. The central control processing module analyzes these multiple signals in parallel, generating multiple tag-location data pairs. These data pairs are then sorted in descending order based on the received signal strength indication values. After sorting, the central control processing module sequentially schedules the target indication module to project a light spot onto each tag, with each projection spaced 100 milliseconds apart. This time window ensures that the human eye can clearly distinguish the indication actions at different locations, avoiding visual confusion. The entire multi-tag indication sequence is completed within 2 seconds, suitable for rapid inventory operations.

[0034] The hardware configuration of the RFID reader terminal is as follows: The RFID module is equipped with an RFID transceiver chip and a phased array antenna unit. The phased array antenna unit is a microstrip patch antenna array, operating at frequencies from 860 MHz to 960 MHz, with an element spacing of half a wavelength (160 mm), and an array size of 4 x 4, totaling 16 elements. The tag spatial positioning module is an independent digital signal processor with a main frequency of 500 MHz, internally containing dedicated algorithms for angle of arrival calculation, distance estimation, and coordinate transformation, supporting real-time processing of 16 parallel signal streams. The target indication module is fixedly installed at the front end of the terminal housing, with its beam emission axis parallel to the center normal direction of the phased array antenna unit, with a deviation angle of less than 0.1 degrees. The laser diode light source outputs 5 milliwatts of optical power, meeting the human eye safety level II standard. The dual-axis microelectromechanical system reflector has a mirror surface size of 3 mm x 3 mm, a resonant frequency of 1.2 kHz, a maximum deflection angle of ±10 degrees, and an angle control accuracy of 0.1 degrees.

[0035] The central control processing module is an embedded system-on-a-chip (SoC) integrating a quad-core ARM Cortex-A53 processor, 512 megabytes of dynamic random access memory (DRAM), and 8 gigabytes of non-volatile flash memory. The human-machine interface unit includes a physical trigger switch and a 3.5-inch LCD screen. When the operator presses the trigger switch, the terminal initiates a complete reading and indication process. The unique tag identifier, matching status (in / out of list), spatial coordinates, and indicator color information are displayed on the screen in real time at a refresh rate of 5 frames per second. The entire terminal is powered by a rechargeable lithium-ion battery, providing up to 8 hours of continuous operation on a full charge.

[0036] In summary, this embodiment deeply integrates RFID, high-precision spatial positioning, dynamic motion compensation, multi-color directional indication, and intelligent cache management to construct an end-to-end RFID reading system with physical space awareness capabilities. In multi-tag-dense scenarios, this system can automatically, accurately, and intuitively map successfully read digital events to corresponding physical entities, completely eliminating manual verification and significantly improving the efficiency and accuracy of inventory operations. Simultaneously, color coding provides business semantic feedback, enhancing the system's intelligence and practicality.

Claims

1. A method for indicating successful radio frequency identification (RFID) reading, characterized in that, include: The RFID reading terminal's RFID module transmits an RFID query signal and receives a backscattered signal returned from a certain RFID tag, carrying the unique identification code of that RFID tag; The tag spatial positioning module of the radio frequency identification (RFID) reading terminal performs spatial information calculation synchronously based on the backscattered signals received by each antenna element of the phased array antenna unit of the RFID module, so as to determine the precise spatial coordinates of the RFID tag relative to the terminal in a preset three-dimensional coordinate system. The central control processing module of the radio frequency identification reading terminal will associate and bind the acquired unique identification code with the calculated precise spatial coordinates to generate a tag-location data pair containing identity information and location information. Based on the precise spatial coordinates, the central control processing module calculates the control command that drives the target indication module of the radio frequency identification reading terminal to perform precise pointing. The central control processing module outputs the control command to the target indication module, driving the target indication module to generate a sensory indication signal with clear spatial directionality, and accurately projects or guides the sensory indication signal to the physical location of the RFID tag, thereby forming a momentary mark that can be perceived by the operator on the physical entity of the RFID tag or its adjacent area.

2. The method for indicating successful RFID reading according to claim 1, characterized in that, The radio frequency identification module includes a radio frequency transceiver chip and a planar phased array antenna unit composed of M rows and N columns of antenna elements, where M and N are integers greater than one; the tag spatial positioning module acquires in parallel the complex amplitude values ​​of the backscattered signals received by each of the M multiplied by N antenna elements, and the complex amplitude values ​​include signal strength information and phase information.

3. The method for indicating successful RFID reading according to claim 2, characterized in that, The tag spatial positioning module determines the precise spatial coordinates of the RFID tag, including: By comparing the phase difference of the backscattered signals received by different antenna elements in the phased array antenna unit, and using a multiple signal classification algorithm or a rotation-invariant subspace estimation algorithm, the angle of arrival of the backscattered signal is calculated. The angle of arrival includes the azimuth angle and the elevation angle. By analyzing the received signal strength indication value of the backscattered signal and combining it with a preset radio frequency signal spatial propagation attenuation model, the straight-line distance between the RFID tag and the RFID reader terminal can be estimated; or, by analyzing the phase change of the backscattered signal within a continuous query period, phase ranging calculation can be performed to obtain the straight-line distance. The position information in the spherical coordinate system formed by the azimuth angle, elevation angle and straight-line distance is converted into Cartesian coordinates in the preset three-dimensional coordinate system, i.e., the precise spatial coordinates, through a preset coordinate transformation matrix.

4. The method for indicating successful RFID reading according to claim 3, characterized in that, The target indication module is a laser pointing module, which includes a laser diode light source and a dual-axis microelectromechanical system (MEMS) mirror. The sensory indication signal is a laser beam, and the instantaneous mark is a visible light spot. The central control processing module calculates, based on the precise spatial coordinates, the first and second driving voltages required to drive the dual-axis MEMS mirror to deflect around the first and second axes to the target angle, respectively. After receiving the control command, the target indication module applies the first and second driving voltages to the dual-axis MEMS mirror, causing its surface to deflect precisely. Simultaneously, the central control processing module triggers the laser diode light source to emit light for a preset time, the preset time ranging from 100 milliseconds to 500 milliseconds. The laser beam, reflected by the deflected dual-axis MEMS mirror, is precisely guided to the physical location of the RFID tag.

5. The method for indicating successful RFID reading according to claim 4, characterized in that, The laser diode light source is a multi-color light source, which integrates light-emitting units capable of emitting at least two different colors of light; the central control processing module internally stores a pre-set item list database, which records the unique identification code of the tag corresponding to the item to be inventoried or searched; the method further includes: After receiving the unique identification code, the central control processing module performs a search and matching in the preset item list database. If the match is successful, the multicolor light source is controlled to emit a beam of light of the first color, which is green. If the matching fails, the multicolor light source is controlled to emit a beam of a second color, which is red.

6. The method for indicating successful RFID reading according to claim 5, characterized in that, The tag spatial positioning module also integrates an inertial measurement unit, which includes a three-axis accelerometer and a three-axis gyroscope. When the RFID reader performs a reading operation, the inertial measurement unit outputs inertial data in real time, representing the terminal's own attitude and motion state. The central control processing module receives the inertial data and uses a Kalman filter algorithm to fuse the inertial data with the original spatial coordinates calculated by the tag spatial positioning module. This dynamically compensates for and corrects coordinate measurement errors caused by operator hand tremors or movements, thereby outputting more stable and accurate spatial coordinates after motion compensation.

7. The method for indicating successful RFID reading according to claim 6, characterized in that, The central control processing module has a read tag cache area, which is used to temporarily store the unique identification code of the tag that has been successfully read and indicated in the current inventory session. After receiving a new unique identification code, the central control processing module first queries the read tag cache area. If the unique identification code already exists in the cache area, it is determined to be a duplicate read, and the subsequent spatial positioning and target indication actions are not performed.

8. The method for indicating successful RFID reading according to claim 7, characterized in that, Within a single reading cycle, the RFID module simultaneously receives backscattered signals from a plurality of different RFID tags; the central control processing module processes these plurality of signals in parallel to generate a plurality of tag-location data pairs; subsequently, the central control processing module sorts the tag-location data pairs according to the order of the received signal strength indication values ​​of each signal from high to low, and controls the target indication module to project light spots onto the physical locations of the 111 RFID tags one by one and quickly in this order, with each projection interval being a preset time window, the value of which ranges from 50 milliseconds to 150 milliseconds.

9. The method for indicating successful RFID reading according to claim 8, characterized in that, The phased array antenna unit is a microstrip patch antenna array with an operating frequency of 860 MHz to 960 MHz; the tag spatial positioning module is an independent digital signal processor with embedded algorithms for performing angle of arrival calculation, distance estimation, and coordinate transformation.

10. The method for indicating successful RFID reading according to claim 9, characterized in that, The target indication module is fixedly installed at the front end of the housing of the radio frequency identification reading terminal. Its beam emission axis is parallel to or at a preset small angle to the center normal direction of the phased array antenna unit. The center wavelength of the laser diode light source is 532 nanometers and the output optical power is 5 milliwatts. The mirror size of the dual-axis microelectromechanical system reflector is not less than 3 mm by 3 mm and its resonant frequency is higher than 1000 Hz.

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