RFID warehouse logistics label reading method and system

Abstract

The invention relates to the technical field of Internet of Things warehousing automation, and particularly discloses an RFID warehousing logistics label reading method and system. The method comprises the following steps: directionally activating a classification label deployed at the 1.5-2m height of a warehouse partition entrance through a 5-10-degree narrow-beam 18-25dBm radio frequency signal, and analyzing goods large-class data by adopting a bit-by-bit extension protocol comprising an initial discrimination code with a binary numerical value of 11; goods shelf coordinate data are obtained based on a dynamic time slot allocation algorithm that capacity expansion is carried out if the conflict time slot proportion exceeds 50% and capacity shrinkage is carried out if no conflict is carried out for five consecutive rounds through a first-level label of which the width is 1.5-3 m of a goods shelf laminate covered by a 60-90-degree wide-beam 26-30 dBm radio frequency signal; and scanning a second-level label at the height of 0.5-1.5 m of the cargo unit through a 20-30-degree medium wave beam 23-25 dBm radio frequency signal, and alternately calling a dynamic time slot and a bit-by-bit extension protocol according to an energy sudden change threshold value from-50 dBm to-45 dBm to read cargo batch data.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of Internet of Things and warehouse automation, and particularly relates to an RFID warehouse logistics label reading method and system. BACKGROUND

[0002] With the rapid development of intelligent warehousing and logistics automation technology, ultra-high frequency RFID systems are widely used in cargo tracking, inventory management, and equipment scheduling scenarios. However, the metal shelves, liquid cargo, and other special physical conditions in the warehouse environment significantly interfere with radio frequency signal propagation, leading to frequent problems of label misreading, missing reading, and reading delay. In addition, the dynamic changes in label distribution during the movement of forklifts make it difficult for traditional static reading schemes to adapt to complex scenarios.

[0003] Existing technologies generally use omnidirectional antennas and fixed time slot allocation protocols to achieve label identification, but there are significant defects. The omnidirectional antenna has a wide coverage range, which easily activates non-target area labels at the same time, causing multipath effects and signal superposition interference. The fixed time slot protocol cannot dynamically adjust resource allocation according to the fluctuation of label density, and the conflict rate increases significantly in high-density areas, while the time slot utilization rate is low in low-density areas. In addition, the existing conflict resolution mechanism relies on random retransmission, which increases the reading time and is not stable enough, making it difficult to meet the real-time and reliability requirements of industrial-grade warehouses. SUMMARY

[0004] The present application overcomes the shortcomings of the prior art and provides an RFID warehouse logistics label reading method and system.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows: an RFID warehouse logistics label reading method, comprising the following steps:

[0006] S1, activating a classification label by transmitting a first radio frequency signal of 18-25 dBm through a 5-10° narrow beam, detecting the response of the classification label, and if there is a conflict, executing a bit-by-bit expansion protocol to screen a unique classification label and read the stored cargo category data, otherwise directly reading the cargo category data;

[0007] S2, activating a first level label by transmitting a second radio frequency signal of 26-30 dBm through a 60-90° wide beam, detecting the response, and if there is a conflict, executing a dynamic time slot allocation algorithm to adjust the time slot parameters and read the stored shelf coordinate data, otherwise directly reading the shelf coordinate data;

[0008] S3, activating a second level label by transmitting a third radio frequency signal of 23-25 dBm through a 20-30° medium beam, detecting the response, and if there is a conflict, alternately calling a dynamic time slot allocation algorithm and a bit-by-bit expansion protocol to analyze the conflict and read the stored cargo batch data, otherwise directly reading the cargo batch data;

[0009] S4, encapsulating the goods category data, shelf coordinate data and goods batch data to generate a data packet.

[0010] Further, the bit-by-bit expansion protocol comprises:

[0011] An initial 1-bit binary discrimination code is generated and broadcast, only allowing tags to respond whose unique identifier low 16 bits match the first M bits completely; if a conflict is detected, the bit number is expanded and broadcast repeatedly until a unique tag is screened out.

[0012] Further, the dynamic time slot allocation algorithm comprises:

[0013] The number of time slots is initialized to 16, and if the time slot occupancy ratio of the first level tags exceeds 50% when there is a conflict, the number of time slots is increased; if there is no conflict for 5 consecutive rounds, the number of time slots is reduced.

[0014] Further, the alternate calling protocol is configured to:

[0015] The dynamic time slot allocation algorithm is first performed on the second level tags;

[0016] When the number of unresolved tags is ≤3, the bit-by-bit expansion protocol is executed;

[0017] Wherein the switching basis is that the signal energy mutation amplitude in the time slot exceeds the range of -50dBm to -45dBm.

[0018] Further, it also includes hierarchical sleep control:

[0019] After step S1, a sleep instruction is transmitted to the classification tags through a narrow beam;

[0020] After step S2, a sleep instruction is transmitted to the first level tags through a wide beam;

[0021] After step S3, a sleep instruction is transmitted to the second level tags through a medium beam.

[0022] Further, it also includes hierarchical wake-up control:

[0023] Before step S1, the classification tags are activated by a 125kHz 0.5A / m magnetic field;

[0024] Before step S2, the first level tags are activated by a 125kHz 0.6A / m magnetic field;

[0025] Before step S3, the second level tags are activated by a 125kHz 0.6A / m magnetic field.

[0026] Further, the data encapsulation includes marking the classification label data with version number 01, the first level label data with version number 02, the second level label data with version number 03, adding a time stamp and UWB coordinates, and encapsulating by CRC-16 check code.

[0027] The application further provides another technical scheme: an RFID warehouse logistics label reading system for implementing the above method, comprising:

[0028] The multi-beam antenna module comprises a narrow-beam antenna, a wide-beam antenna and a middle-beam antenna.

[0029] The data management module is connected to the warehouse management system through an Ethernet interface.

[0030] The hierarchical control module is connected to the multi-beam antenna module through a coaxial radio frequency cable.

[0031] The conflict resolution module receives the backscattering signals of the multi-beam antenna module and is connected to the data management module through a data bus.

[0032] The positioning and environment perception module is connected to the hierarchical control module and the data management module through a CAN bus.

[0033] Further, the hierarchical control module comprises:

[0034] The radio frequency activation execution unit is configured to drive the narrow-beam antenna to emit 18-25 dBm radio frequency signals to activate the classification label, the wide-beam antenna to emit 26-30 dBm radio frequency signals to activate the first level label, and the middle-beam antenna to emit 23-25 dBm radio frequency signals to activate the second level label.

[0035] The hibernation management unit is configured to generate a hibernation instruction containing a level identification code 01 / 02 / 03 and control the corresponding antenna to emit.

[0036] The low-frequency wake-up coordination unit is configured to trigger a 125 kHz low-frequency wake-up magnetic field in stages.

[0037] Further, the conflict resolution module comprises:

[0038] The bit-by-bit expansion protocol engine is configured to process the classification label conflict.

[0039] The dynamic time slot allocation engine is configured to process the first level label conflict.

[0040] The hybrid protocol arbiter is configured to process the second level label conflict.

[0041] The application solves the defects in the background art and has the following beneficial effects:

[0042] The application adopts 5-10° narrow-beam antenna to directively emit 18-25dBm radio frequency signals to activate the classification tags at the height of 1.5-2m of the warehouse sub-area entrance, and combines the initial identification code containing the binary value 11 to expand the protocol bit by bit to parse the cargo category data; at the same time, through the 60-90° wide-beam antenna, the first level tag covering the 1.5-3m width of the shelf layer plate, the dynamic time slot allocation algorithm is applied to obtain the shelf coordinate data when the conflict time slot ratio is more than 50%, and the capacity is expanded or reduced for 5 consecutive conflict-free times; and the 20-30° medium-beam antenna scans the second level tag at the height of 0.5-1.5m of the cargo unit, and the dynamic time slot allocation algorithm and the bit-by-bit expansion protocol are alternately called according to the-50dBm to-45dBm energy mutation threshold to read the cargo batch data. This multi-beam directional activation and hierarchical conflict resolution mechanism limits the radio frequency coverage range to a specific area, reducing signal interference caused by multi-path reflection of metal shelves and absorption of liquid goods; at the same time, for low-density classification tags, a bit-by-bit expansion fast screening is adopted, for medium-density first level tags, a dynamic time slot resource elastic adjustment is adopted, and for high-density second level tags, a mixed protocol is adopted to adapt to dynamic changes, which optimizes the conflict resolution efficiency, significantly compresses the reading time, reduces the misreading rate and the missing reading rate, and especially maintains stability in high interference scenes where the reflection coefficient of the metal environment is greater than 0.8 or the liquid dielectric constant is greater than 70. Compared with the existing omnidirectional antenna and fixed time slot protocol technology, the non-target tags are easily activated to cause multi-path superposition interference, and the conflict rate increases and the time slot utilization rate is low due to the inability to dynamically optimize according to the label density fluctuation, the progress effect of the application is to realize stable and efficient reading in complex warehouse environment, improve the automation level and real-time of inventory management, and support the dynamic scheduling demand in the forklift moving process.

[0043] The application implements the dynamic time slot allocation algorithm to initialize the time slot number as 16 and adjust the time slot parameters according to the rules that the capacity is expanded when the conflict time slot ratio is more than 50%, and the capacity is reduced for 5 consecutive conflict-free times, and at the same time, the hierarchical sleep control is combined to emit the sleep instruction containing the hierarchical identification code 00 to the classification tag by the narrow-beam, emit the sleep instruction containing the hierarchical identification code 01 to the first level tag by the wide-beam, and emit the sleep instruction containing the hierarchical identification code 10 to the second level tag by the medium-beam. The dynamic time slot allocation algorithm adaptively allocates time slot resources by real-time monitoring of the conflict rate, improving the time slot utilization rate; the sleep control uses the sleep signal attenuated by 6dB to emit by the directional beam, ensures that the UHF radio frequency module is turned off to retain only the 125kHz low frequency circuit after the label hierarchical attribute and position are matched, directly reduces the standby current and reduces the power consumption of the inactive label, realizes the minimization of time slot idle waste and the reduction of system power consumption. Compared with the existing fixed time slot protocol technology, the resource is rigid, the conflict rate increases in high-density areas, the time slot is wasted in low-density areas, and the label continues to consume power due to the lack of sleep mechanism, the progress effect of the application is to optimize resource allocation and energy consumption control, prolong the battery life of the equipment and reduce the maintenance frequency, support long-time unmanned operation of industrial-grade warehouses.

[0044] The multi-beam directional activation and the efficient reading mechanism of the hierarchical conflict resolution protocol, the dynamic time slot allocation algorithm and the resource optimization mechanism of the hierarchical sleep control. Analysis shows that the efficient reading protocol compresses the overall operation time by cooperating with the conflict resolution algorithm through narrow beam, wide beam and medium beam coverage, and the resource optimization mechanism triggers the sleep control immediately after the reading is completed to avoid unnecessary activation; at the same time, the dynamic time slot reduces the protocol processing delay and seamlessly connects with the sleep control. Through the efficient reading to shorten the operation period, the low power consumption characteristics of the sleep control are cooperated to realize the balance of the reading throughput improvement and the overall reduction of system energy consumption in the forklift moving process, for example, the power consumption is stable in the metal high reflection area, and the sustainable automated operation in complex environment is supported. BRIEF DESCRIPTION OF DRAWINGS

[0045] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0046] Figure 1 It is a flowchart of an RFID warehouse logistics label reading method;

[0047] Figure 2 It is a flowchart of the bit-by-bit expansion protocol;

[0048] Figure 3 It is a flowchart of a dynamic time slot allocation algorithm;

[0049] Figure 4 It is an architecture diagram of an RFID warehouse logistics label reading system. DETAILED DESCRIPTION

[0050] The technical solutions in the embodiments of the present application will be described clearly and completely in the embodiments of the present application combined with the drawings. Obviously, the described embodiments are only some of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0051] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, but the present application can also be implemented in other ways different from those described herein, therefore, the scope of protection of the present application is not limited by the specific embodiments disclosed below.

[0052] In the description of the present application, it needs to be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the scope of protection of the present application. In addition, the terms "first", "second" and the like are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined with "first", "second" and the like can be explicitly or implicitly included one or more. In the description of the present application, unless otherwise specified, the meaning of "a plurality of" is two or more.

[0053] In the description of the present application, it needs to be understood that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood through specific circumstances.

[0054] In the following embodiment, the classification label stores the goods category data, is deployed at the entrance of the warehouse partition, and has low density (1-3); the first level label stores the shelf coordinate data, is deployed at the shelf layer plate, and has medium density (10-30); the second level label stores the goods batch data, is attached to the goods unit, and has high dynamic density (1-50); the general label refers to the general attributes of all classification labels, first level labels and second level labels.

[0055] Exemplary method:

[0056] As shown in Figure 1 An RFID warehouse logistics label reading method, comprising the following steps:

[0057] S1, activate the classification label by transmitting 18-25dBm first radio frequency signal through 5-10° narrow beam, detect the classification label response, if there is a conflict, execute bit-by-bit expansion protocol to screen unique classification label and read stored goods category data, otherwise directly read goods category data;

[0058] S2. Activate the first-level tag by transmitting a 26-30dBm second radio frequency signal through a 60-90° wide beam, detect the response, and if there is a conflict, execute the dynamic time slot allocation algorithm to adjust the time slot parameters and read the stored shelf coordinate data; otherwise, directly read the shelf coordinate data.

[0059] S3. Activate the second-level tag by transmitting a 23-25dBm third radio frequency signal through a 20-30° mid-wave beam, detect the response, and if there is a conflict, alternately call the dynamic time slot allocation algorithm and the bit-by-bit extension protocol to resolve the conflict and read the stored cargo batch data; otherwise, directly read the cargo batch data.

[0060] S4. Generate a data package by encapsulating the major category data of goods obtained in S1, the shelf coordinate data obtained in S2, and the batch data of goods obtained in S3.

[0061] Furthermore, such as Figure 2 The bitwise extension protocol shown includes:

[0062] Generate an initial 1-bit binary identifier and broadcast it;

[0063] Only tag responses that completely match the binary identification code with the first M bits of the tag's unique identifier (N bits) are allowed, where N = 16 and M expands bit by bit starting from 1.

[0064] If a collision is detected, the binary identification code is expanded bit by bit and broadcast repeatedly until a unique tag is found.

[0065] A bit-by-bit expansion protocol is adopted to address classification tag conflicts because the classification tag deployment density is extremely low, with only 1 to 3 tags typically existing in each warehouse partition. In this case, an initial binary identification code of 1 bit is generated and broadcast, allowing only tags whose first M bits of the lower 16 bits of the tag's unique identifier are completely matched to respond. If a conflict is detected, the number of bits in the identification code is expanded bit by bit. This protocol can converge quickly through precise bit-level filtering, avoiding the resource waste caused by the initialization of the dynamic time slot framework. In directional coverage scenarios with a 3-10° narrow beam antenna and a transmit power of 20-25dBm, its resolution efficiency is significantly better than the group scheduling mechanism.

[0066] Furthermore, such as Figure 3 The dynamic time slot allocation algorithm shown includes:

[0067] Define the initial number of time slots as 2 raised to the power of Q, where Q is 4;

[0068] If the detected conflicting time slot ratio exceeds 50%, the Q value is incremented to increase the number of time slots;

[0069] If no conflict is detected for 5 consecutive rounds, the Q value is decreased to reduce time slot allocation overhead.

[0070] For the first level tag conflict, a dynamic time slot allocation algorithm is adopted, which is based on the medium-scale conflict characteristics of shelf location tags, i.e. 10-30 tags are usually deployed on a single shelf. The algorithm initializes a time slot framework (preset Q=4 corresponding to 16 time slots), and when the conflict time slot ratio exceeds 50%, the Q value is increased to expand the capacity, and when there is no conflict for 5 rounds, the Q value is decreased to optimize the resources. Through real-time monitoring of the conflict detection mechanism of the energy mutation amplitude of-50dBm to-45dBm, combined with the wide-area coverage of the 60-90° wide-beam antenna 26-30dBm transmission power, the goal of flexible adaptation to tag density fluctuations is achieved, which not only avoids the multi-round traversal overhead of the bit-by-bit protocol, but also overcomes the resource rigidification defect of the fixed time slot.

[0071] Further, the alternately calling dynamic time slot allocation algorithm and bit-by-bit expansion protocol to parse the conflict tags is configured to preferentially execute the dynamic time slot allocation algorithm if there is a conflict, and if the conflict is not completely parsed, the bit-by-bit expansion protocol is called again to handle the remaining conflict tags.

[0072] The second level tag conflict adopts the alternately calling strategy of dynamic time slot allocation algorithm and bit-by-bit expansion protocol, which is due to the high dynamic conflict characteristics of the goods unit tag, i.e. the tag number fluctuates between 1 to 50 and the signal stability is poor due to the interference of metal shelf reflection and liquid absorption. First, the dynamic time slot framework is used to quickly reduce the conflict base, and then the bit-by-bit screening is started for the residual conflict tags under the precise pointing of the 28-32° medium-beam antenna 23-25dBm transmission power. This hybrid strategy synchronously solves the group scheduling efficiency of ordinary tags and the immediate response demand of high-priority tags, and finally realizes the balance between stability and efficiency in complex environments.

[0073] Further, a directional beam transmission sleep instruction of the same type as the activation signal is used, which is transmitted after completing the current level tag reading:

[0074] The sleep instruction is transmitted to the warehouse partition through a narrow-beam antenna, and the target is a classification tag;

[0075] The sleep instruction is transmitted to the target shelf through a wide-beam antenna, and the target is a first level tag;

[0076] The sleep instruction is transmitted to the goods unit through a medium-beam antenna, and the target is a second level tag.

[0077] The sleep instruction uses 902-928MHz frequency band in-band radio frequency signal to embed the sleep command, including 2-bit binary level identification code (01 classification tag / 02 first level tag / 03 second level tag) and regional location code bound with activation signal coordinates; the sleep signal transmission power is attenuated by 6dB compared with the activation signal, which ensures that the coverage range of narrow-beam 3-10°, wide-beam 60-90°, and medium-beam 20-35° accurately matches the main lobe radiation pattern, and the sidelobe radiation suppression is greater than 15dB to prevent signal overflow to non-target tags.

[0078] Further, only when the tag pre-burned level attribute is consistent with the instruction level identification code (classification tag attribute 01 / first level tag 02 / second level tag 03), and the spatial position is within the active signal coordinate ±0.5m equipment displacement tolerance range, and there is no response in the current reading period, the deep sleep operation is performed: the UHF radio frequency module accounting for 85% of the total system power consumption is turned off, only the 125kHz low frequency wake-up circuit is reserved, and the standby current is reduced.

[0079] Specifically, the directional beam multiplexing utilizes narrow beam 3-10° to match the deployment height (1.5-2m) of the top of the classification tag metal beam, wide beam 60-90° to cover the horizontal distribution (width 1.5-3m) of the first level tag shelf board, and medium beam 20-35° to adapt to the vertical space (height 0.5-1.5m) of the second level tag goods stack, to realize the consistency of the physical layer coverage of the sleep signal and the active signal; power attenuation suppresses sidelobe radiation in narrow beam sleep; level and position dual authentication significantly reduces the metal environment false sleep rate through logical identification matching and coordinate verification.

[0080] Based on the 20dB attenuation characteristics of the warehouse metal shelf steel plate to the 902-928MHz radio frequency signal and the skin effect of the copper shelf beam, a 125kHz low frequency wake-up signal is used and the magnetic field strength is maintained ≥0.5A / m, so that the magnetic force line penetrates the steel plate to activate the tag attached to the back of the shelf. The hierarchical wake-up process includes:

[0081] Before the narrow beam 5-10° antenna transmits 18-25dBm first radio frequency signal, the 125kHz 0.5A / m magnetic field is used to directionally activate the classification tag at the top of the partition entrance beam, with an action distance ≤0.5m;

[0082] After the classification tag reading is completed, before the wide beam 60-90° antenna transmits 26-30dBm second radio frequency signal, 125kHz 0.6A / m magnetic field is used to activate the target first level tag, with an action distance ≤2m;

[0083] After the fork is positioned to the target height, before the medium beam 20-30° antenna transmits 23-25dBm third radio frequency signal, the 125kHz 0.6A / m magnetic field is used to penetrate the liquid container to activate the second level tag, with an action distance ≤1m.

[0084] The wake-up signal magnetic field strength is physically symmetrical with the 0.5A / m sleep pulse in the sleep mechanism, and the level action distance difference matches the beam coverage range; the backscattering receiving strength threshold is set to 70-75dBm, which is 20dB higher than the baseline of-50dBm to-45dBm in conflict detection in sleep to distinguish the wake-up response signal.

[0085] Further, to solve the problem of tag reading delay caused by the lack of priority differentiation in conventional conflict resolution protocols, an adaptive priority processing mechanism is adopted. By identifying the first two bits of the tag's unique identifier, a preset binary value 11 is used to identify high-priority identifiers. The identifier selection is based on the 2-bit minimum encoding efficiency and the low-cost modifiability of the tag ID header reserved management field. During the conflict resolution process, exclusive resources are dynamically allocated.

[0086] For classification tags, a bit-by-bit expansion protocol priority screening mechanism is adopted. When generating the initial 1-bit binary discrimination code, the high-priority bit pattern 11 is forced to be included. Only classification tags that match this pattern and have the first M bits of the low 16 bits of the unique identifier exactly match are allowed to respond. If the conflict persists, the number of bits is expanded, but the high-priority bit filtering is maintained to speed up the convergence.

[0087] For the first level of tags, a 10% exclusive time slot pool is pre-allocated within the dynamic time slot allocation algorithm framework. When a high-priority tag is detected, an idle exclusive time slot is immediately assigned and the Q value adjustment process is frozen until the response is complete, avoiding distortion of the conflict rate statistics and interfering with the algorithm stability.

[0088] For the second level of tags, the bit-by-bit expansion protocol and dynamic time slot allocation algorithm are alternately called. The exclusive time slot allocation is activated in the dynamic time slot stage, and the high-priority bit forced matching is embedded in the bit-by-bit expansion stage. At the same time, the conflict detection threshold of -50dBm to -45dBm energy mutation amplitude is used to exclude exclusive time slot interference to maintain the adaptability of Q value.

[0089] Through the above priority processing mechanism, the time-consuming of high-priority tags in classification level resolution is shortened, the response delay of exclusive time slots in shelf level is reduced, and the priority interruption rate is reduced under the mixed protocol of goods level. The whole process is compatible with the directional power constraints of narrow beam, wide beam and medium beam.

[0090] Further, in the complex warehouse environment of -65dBm to -60dBm environmental noise floor caused by metal shelf reflection and -15dB signal fading caused by liquid absorption, conflict detection is achieved by monitoring the energy mutation amplitude of backscattering signals, and the core threshold is set to -50dBm to -45dBm to suppress the interference of forklift motor start-stop and ensure the capture of weak signal conflicts.

[0091] For classification tags in narrow beam directional activation scenarios, the multipath reflection at the top of the metal beam increases the conflict signal attenuation slope. The threshold is dynamically increased to -48dBm to adapt to the local signal-to-noise ratio deterioration. Combined with the 1-3 low-density characteristics of classification tags, the single conflict detection time is compressed.

[0092] For the first level of tag wide beam wide area coverage, real-time monitoring of conflict time slot energy mutation and correlation dynamic time slot allocation algorithm Q value adjustment rule, through-50dBm to-45dBm baseline threshold to maintain the medium scale conflict statistics reliability of shelf layer label, avoid the resonance of metal frame caused by ±3dB fluctuation misjudgment.

[0093] For the second level of tag in the middle beam dynamic power scanning, liquid goods absorption effect makes the conflict signal energy dispersion degree expand, introduce adaptive threshold calibration algorithm: when the fork height is greater than 2m, the threshold is relaxed to-47dBm to compensate the path loss, when the liquid container is detected, it is tightened to-43dBm to filter absorption noise, and the misjudgment rate is reduced by synchronously cooperating with the alternative conflict analysis protocol.

[0094] Further, after completing the narrow beam directional reading classification tag goods category data, wide beam wide area acquisition of first level tag shelf coordinate data, and middle beam dynamic scanning of second level tag goods batch data, the packaging process is based on the characteristics of the packet loss rate caused by the multipath interference of the metal environment, including:

[0095] The hierarchical data is packaged using the JSON-LD semantic framework, version number 01 (classification tag goods category), 02 (first level tag shelf coordinate), and 03 (second level tag goods batch) respectively corresponding to the symmetric encoding of the hibernation mechanism level identification code 01 / 02 / 03, the data field is attached with time stamp and forklift UWB positioning coordinates, and CRC-16 check code (polynomial 0x8005) is used to cover all data blocks, and the check strength can correct 3-bit continuous error caused by metal reflection;

[0096] The baseline time limit is set to 180ms (classification tag conflict analysis 15ms, first level tag Q value adjustment 20ms, and second level tag mixed analysis 120ms), when the shelf reflection coefficient is greater than 0.8 (high interference metal area), it is relaxed to 200ms, and the liquid container dense area (dielectric constant greater than 70) is tightened to 170ms;

[0097] The timeout event triggers an abnormal log record, the log includes the number of conflict tags, Q value state, fork height and environmental reflection coefficient, which is mapped to the shelf coordinate through the warehouse management system API, and the high interference area is automatically labeled and the retry priority is improved (10ms retry interval), and the area is frozen to prevent mis-hibernation of unread tags.

[0098] Exemplary system:

[0099] As Figure 4As shown, an RFID warehouse logistics label reading system includes a hierarchical control module, a multi-beam antenna module, a conflict resolution module, a positioning and environment perception module, and a data management module. The hierarchical control module is connected to the multi-beam antenna module through a coaxial radio frequency cable. The conflict resolution module receives backscattering signals from the multi-beam antenna module and outputs them to the data management module. The positioning and environment perception module transmits spatial and environmental parameters to the hierarchical control module and the data management module through a CAN bus. The data management module is finally connected to a warehouse management system through an Ethernet interface.

[0100] The hierarchical control module includes a radio frequency activation execution unit, a sleep management unit, and a low-frequency wake-up coordination unit.

[0101] The radio frequency activation execution unit is configured to drive the narrow-beam antenna to emit a first radio frequency signal of 18-25 dBm to activate a classification label storing large category data of goods, drive the wide-beam antenna to emit a second radio frequency signal of 26-30 dBm to activate a first level label storing coordinate data of shelves, and drive the medium-beam antenna to emit a third radio frequency signal of 23-25 dBm to activate a second level label storing batch data of goods.

[0102] The sleep management unit is used to realize hierarchical sleep control and is configured to generate a sleep instruction containing a 2-bit binary level identification code 01 classification label / 02 first level label / 03 second level label, control the narrow-beam antenna to emit the sleep instruction to a warehouse partition at a power of 18 dBm, control the wide-beam antenna to emit the sleep instruction to a target shelf at a power of 22 dBm, control the medium-beam antenna to emit the sleep instruction to a goods unit at a power of 20 dBm, and attenuate all sleep signals by 6 dB compared to the activation signals to match the coverage of the main lobe of the directional beam.

[0103] The low-frequency wake-up coordination unit is configured to trigger a 125 kHz low-frequency wake-up magnetic field in stages, generate a magnetic field strength of 0.5 A / m in the narrow-beam area to activate the classification label within a distance of ≤0.5 m, generate a magnetic field strength of 0.6 A / m in the wide-beam area to activate the first level label within a distance of ≤2 m, and generate a magnetic field strength of 0.6 A / m in the medium-beam area to activate the second level label within a distance of ≤1 m. The magnetic field strength parameters and the sleep mechanism 0.5 A / m sleep pulse form a physical layer symmetry.

[0104] The radio frequency activation execution unit sends a level identification code 00 trigger signal to the sleep management unit after completing the classification label reading, and the sleep management unit generates a classification label sleep instruction accordingly. The low-frequency wake-up coordination unit receives a timing synchronization request from the activation execution unit and triggers a 0.6 A / m wake-up magnetic field 200 ms before the wide-beam antenna emits the second radio frequency signal of 26-30 dBm.

[0105] The conflict resolution module includes a bit-by-bit expansion protocol engine, a dynamic time slot allocation engine, and a hybrid protocol arbitrator.

[0106] The bit-by-bit extension protocol engine is configured to generate an initial 1-bit binary discriminator compulsively including a high priority bit 11, and only allow the classification tag response that the identifier low 16-bit first M-bit is completely matched to respond, and extend bit by bit until the unique tag is screened.

[0107] The dynamic time slot allocation engine is configured to initialize Q=4 corresponding to a 16-time slot framework, increment the Q value when the conflict time slot occupancy ratio exceeds 50%, and decrease the Q value when there is no conflict for 5 rounds, and pre-allocate a 10% exclusive time slot pool for high priority tags to respond immediately.

[0108] The hybrid protocol arbitrator is configured to alternately call the dynamic time slot allocation and the bit-by-bit extension protocol, and dynamically switch the strategy according to the energy mutation threshold of -50dBm to -45dBm, and tighten the threshold to -43dBm to filter absorption noise when the dielectric constant of the liquid container is greater than 70.

[0109] The hybrid protocol arbitrator dynamically calls the output time slot framework of the dynamic time slot allocation engine to process the second level tag conflict, and switches to the bit-by-bit extension protocol engine to perform bit screening when the number of residual conflict tags is less than or equal to 3; the bit-by-bit extension protocol engine detects a high priority tag (the first two bits of the identifier are 11) and requests exclusive time slot resources from the dynamic time slot allocation engine.

[0110] The positioning and environment perception module includes a UWB positioning unit, a fork height sensing unit, and an electromagnetic environment analysis unit.

[0111] The UWB positioning unit is configured to obtain real-time forklift coordinate data and trigger narrow-beam antenna activation classification tags.

[0112] The fork height sensing unit is configured to drive the middle-beam antenna to compensate for path loss.

[0113] The electromagnetic environment analysis unit is configured to detect a metal shelf greater than 0.8 reflection coefficient and a liquid cargo greater than 70 dielectric constant, and output calibration parameters to the conflict resolution module and the data management module: when the reflection coefficient is greater than 0.8, the conflict detection threshold is increased to -48dBm and the timeout threshold is extended to 200ms, and when the dielectric constant is greater than 70, the conflict detection threshold is tightened to -43dBm and the timeout threshold is compressed to 170ms.

[0114] The UWB positioning unit shares real-time forklift coordinates to the electromagnetic environment analysis unit, and when it is detected that the shelf reflection coefficient is greater than 0.8, the electromagnetic environment analysis unit sends a metal interference flag to the height sensing unit, triggering the middle-beam antenna power to be raised to an upper limit of 25dBm.

[0115] The data management module comprises a hierarchical data packaging unit, an exception control unit and an adaptive transmission unit.

[0116] The hierarchical data packaging unit is configured to package the classification label goods category data marked version number 01, the first level label goods shelf coordinate data marked version number 02 and the second level label goods batch data marked version number 03 into a structured data packet in the JSON-LD format, and attach a timestamp, UWB coordinates and a CRC-16 check code (polynomial 0x8005). The check code can correct 3-bit metal reflection errors.

[0117] The exception control unit is configured to record the number of conflict labels, the dynamic time slot Q value state, the fork height and the environmental parameters when the operation time exceeds the 180 ms baseline, map the parameters to the shelf coordinates through the warehouse management system API and trigger a priority retry, and freeze the high reflection area hibernation instruction to prevent mis-hibernation of unread labels.

[0118] The adaptive transmission unit is configured to transmit data to the warehouse management system through a 100 Mbps Ethernet interface, and enable a TCP retransmission protocol to ensure data integrity when the packet loss rate exceeds 5%.

[0119] The exception control unit monitors the timeout event (greater than 180 ms) of the hierarchical data packaging unit, freezes the hibernation instruction forwarding function of the adaptive transmission unit when triggering a retry, and requests the hierarchical data packaging unit to regenerate a CRC-16 check packet when the packet loss rate of the adaptive transmission unit is greater than 5%.

[0120] In a specific embodiment, the hierarchical control module is integrated in a forklift main control cabinet, and is connected to a multi-beam antenna module through an on-board coaxial radio frequency cable.

[0121] The narrow-beam antenna is fixed to the top bracket of the forklift at an elevation angle of 5-10° and is aligned with the metal crossbeam (height 1.5-2 m) at the entrance of the warehouse partition;

[0122] The wide-beam antenna is installed on both sides of the forklift mast at a horizontal 0° inclination angle, and the beam center axis is parallel to the shelf plate plane;

[0123] The medium-beam antenna is connected to the fork lifting device through a pitch mechanism and vertically scans the stacking height of goods (0.5-1.5 m).

[0124] The conflict resolution module is embedded in the on-board industrial computer, the input port receives the backscattering signal cable of the multi-beam antenna module, and the output port is directly connected to the data management module; the entity configuration of the positioning and environmental perception module is as follows:

[0125] The UWB positioning unit antenna is arranged at the center point of the forklift top cover;

[0126] Fork height sensor embedded in lift column hydraulic system;

[0127] Environment perception probe (reflection coefficient / dielectric constant detector) installed at fork tip.

[0128] Data management module deployed in vehicle-mounted communication box, interconnected through the following physical links:

[0129] CAN bus connects sensor interface of positioning and environment perception module;

[0130] Ethernet interface connects industrial switch of warehouse management system.

[0131] The exemplary system collects spatial coordinates and electromagnetic parameters through the positioning and environment perception module, drives the hierarchical control module to execute hierarchical tag activation and dormancy; the directional radiation characteristics of the multi-beam antenna module constrain the classified tag response to a 5-10° narrow beam area, the first level tag is distributed in a 60-90° wide beam coverage, and the second level tag is controlled in a 20-30° medium beam scanning; the conflict resolution module calls differentiated protocols according to the tag type, specifically, the low-density conflict of classified tags uses the bit-by-bit expansion protocol to resolve within 15ms, the medium-density conflict of the first level tag realizes Q value elastic adjustment through a dynamic time slot allocation algorithm, and the high dynamic conflict of the second level tag is handled by a mixed arbiter alternating protocol; finally, the data management module encapsulates hierarchical data packets and implements environment self-adaptive fault tolerance, and the timeout threshold of the metal high reflection area is relaxed to 200ms to trigger dormancy freezing.

[0132] The above is based on the ideal embodiment of the present application, through the above description, relevant personnel can make various changes and modifications without deviating from the scope of the technical idea of the present application. The technical scope of the present application is not limited to the contents of the specification, and must be determined according to the scope of the claims.

Claims

1. An RFID warehouse logistics tag reading method, characterized by, Comprising the following steps: S1, activating the classification tag by transmitting 18-25dBm first radio frequency signal through 5-10° narrow beam, detecting the classification tag response, if there is a conflict, then execute the bit-by-bit expansion protocol to screen the unique classification tag and read the stored goods category data, otherwise directly read the goods category data; S2, activating the first level tag by transmitting 26-30dBm second radio frequency signal through 60-90° wide beam, detecting the response, if there is a conflict, then execute the dynamic time slot allocation algorithm to adjust the time slot parameters and read the stored shelf coordinate data, otherwise directly read the shelf coordinate data; S3, activating the second level tag by transmitting 23-25dBm third radio frequency signal through 20-30° middle beam, detecting the response, if there is a conflict, then alternately call the dynamic time slot allocation algorithm and the bit-by-bit expansion protocol to analyze the conflict and read the stored goods batch data, otherwise directly read the goods batch data; S4, packaging the goods category data, shelf coordinate data and goods batch data to generate a data packet.

2. The method of claim 1, wherein, The bit-by-bit expansion protocol comprises: Generating an initial 1-bit binary discrimination code and broadcasting, only allowing the tag response of the classification tag whose unique identifier low 16-bit first M-bit to be completely matched; if a conflict is detected, then repeatedly broadcast the bit-by-bit expansion bit until the unique tag is screened out.

3. The method of claim 1, wherein, The dynamic time slot allocation algorithm comprises: Initializing the time slot number to 16, if the first level tag conflict time slot proportion exceeds 50%, then increase the time slot number; if there is no conflict for 5 consecutive rounds, then reduce the time slot number.

4. The method of claim 1, wherein, The alternately calling protocol is configured to: Firstly execute the dynamic time slot allocation algorithm on the second level tag; When the number of unresolved tags is ≤3, execute the bit-by-bit expansion protocol; Wherein the switching basis is that the signal energy mutation amplitude in the time slot exceeds the range of-50dBm to-45dBm.

5. The method of claim 1, wherein, Further comprising hierarchical sleep control: After step S1, transmitting sleep instructions to the classification tag through narrow beam; After step S2, transmitting sleep instructions to the first level tag through wide beam; After step S3, transmitting sleep instructions to the second level tag through middle beam.

6. The method of claim 5, wherein, Further comprising hierarchical wake-up control: Before step S1, activating the classification tag through 125kHz 0.5A / m magnetic field; Before step S2, activating the first level tag through 125kHz 0.6A / m magnetic field; Before step S3, activating the second level tag through 125kHz 0.6A / m magnetic field.

7. The method of claim 1, wherein, The data packaging comprises marking the classification tag data with version number 01, the first level tag data with version number 02, the second level tag data with version number 03, and attaching time stamp and UWB coordinates, and packaging through CRC-16 check code.

8. An RFID warehouse logistics tag reading system for implementing the method of any one of claims 1-7, characterized by Comprising: A multi-beam antenna module comprising a narrow beam antenna, a wide beam antenna and a middle beam antenna; A data management module connected to the warehouse management system through an Ethernet interface; A hierarchical control module connected to the multi-beam antenna module through a coaxial radio frequency cable; A conflict resolution module receiving the backscattering signal of the multi-beam antenna module and connected to the data management module through a data bus; A positioning and environment perception module connected to the hierarchical control module and the data management module through a CAN bus.

9. The system of claim 8, wherein, The hierarchical control module comprises: The radio frequency activation execution unit is configured to drive the narrow-beam antenna to emit a first radio frequency signal of 18-25 dBm to activate the classification tag, drive the wide-beam antenna to emit a second radio frequency signal of 26-30 dBm to activate the first hierarchical tag, and drive the middle-beam antenna to emit a third radio frequency signal of 23-25 dBm to activate the second hierarchical tag. The hibernation management unit is configured to generate a hibernation instruction and control the corresponding antenna to emit. The low-frequency wake-up coordination unit is configured to trigger a 125 kHz low-frequency wake-up magnetic field in stages.

10. The system of claim 9, wherein, The conflict resolution module comprises: A bit-by-bit extension protocol engine configured to process classification tag conflicts. A dynamic time slot allocation engine configured to process first hierarchical tag conflicts. A hybrid protocol arbitrator configured to process second hierarchical tag conflicts.

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