CN112183136B - Method for directionally reading and tracking commercial label in real time, storage medium and equipment - Google Patents

Method for directionally reading and tracking commercial label in real time, storage medium and equipment Download PDF

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CN112183136B
CN112183136B CN202010969779.3A CN202010969779A CN112183136B CN 112183136 B CN112183136 B CN 112183136B CN 202010969779 A CN202010969779 A CN 202010969779A CN 112183136 B CN112183136 B CN 112183136B
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王鸽
丁菡
王一展
赵衰
惠维
赵鲲
蒋志平
王志
赵季中
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Xian Jiaotong University
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06K—GRAPHICAL DATA READING; PRESENTATION OF DATA; RECORD CARRIERS; HANDLING RECORD CARRIERS
    • G06K7/00—Methods or arrangements for sensing record carriers, e.g. for reading patterns
    • G06K7/10—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation
    • G06K7/10009—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves
    • G06K7/10198—Methods or arrangements for sensing record carriers, e.g. for reading patterns by electromagnetic radiation, e.g. optical sensing; by corpuscular radiation sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves setting parameters for the interrogator, e.g. programming parameters and operating modes

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Abstract

The invention discloses a method for directionally reading and tracking a commercial label in real time, a storage medium and equipment, wherein a main-auxiliary distributed antenna array is adopted, a main transmitter and an auxiliary transmitter of the distributed antenna array alternately transmit synchronous signals, the phase offset between a transmitting antenna and a receiving antenna is measured, and each auxiliary transmitter is compensated with an initial phase to be synchronous with the main transmitter; performing quick search, inquiring a reference label closest to the target label, and acquiring response information of the reference label; and obtaining energy distribution and related setting information for supplying energy to the target tag at different transmission settings, and combining a simulated annealing algorithm and a particle filter to dynamically select transmission parameters to excite the tag of the target area and track the movement of the target tag in real time to finish the directional reading and real-time tracking of the commercial tag at the target position. The invention greatly reduces the cost of directionally reading and tracking the target label and has wide application prospect.

Description

Method for directionally reading and tracking commercial label in real time, storage medium and equipment
Technical Field
The invention belongs to the technical field of sensing of the Internet of things, and particularly relates to a method for directionally reading and tracking a commercial label in real time, a storage medium and equipment.
Background
Radio Frequency Identification (RFID) technology is a wireless communication technology that identifies a specific object by radio signals and reads and writes related data, thereby achieving the purpose of object identification and data exchange. The RFID system has the characteristics of long service life, good safety and the like, and is widely applied to the fields of logistics, warehousing and the like.
In current passive RFID systems, orienting to improve the read rate of the tags is a challenging problem. The existing selective reading method has poor applicability mainly due to the following reasons:
(1) a typical selective read method is to set certain bit strings as a mask and allow tags with the same bit string in the ID number to respond. This approach requires that the ID information of all target tags be assumed to be known, which is not possible in many practical applications and that tags cannot be selected within a specific target area.
(2) The method of querying unknown tags requires modification of the hardware and communication protocol of the tags, and is difficult to implement on commercial RFID tags.
(3) Using RFID location algorithms to locate tags within a target area is not feasible because running RFID location algorithms in complex environments introduces large errors and has high latency that does not facilitate high read rates.
Disclosure of Invention
The technical problem to be solved by the present invention is to provide a method, a storage medium, and a device for directionally reading and tracking tags in real time for commercial use, which significantly improve the reading rate of tags around a target location, track the movement of the tags in real time, and are suitable for storage, logistics, and other situations.
The invention adopts the following technical scheme:
a commercial label directional reading and real-time tracking method comprises the following steps:
s1, adopting a master-slave distributed antenna array, wherein the master transmitter and the slave transmitter of the distributed antenna array alternately transmit synchronous signals, measuring the phase offset between the transmitting antenna and the receiving antenna, and compensating an initial phase for each slave transmitter to synchronize with the master transmitter;
s2, quickly searching, inquiring the reference label closest to the target label, and acquiring the response information E of the reference label0；
S3, response information E of reference label using step S20And obtaining energy distribution and setting information related to energy supply for the target tag at different transmission settings, combining a simulated annealing algorithm and a particle filter to dynamically select transmission parameters to excite the tag of the target area and track the movement of the target tag in real time, and finishing the directional reading and real-time tracking of the commercial tag at the target position.
Specifically, in step S1, before transmitting the beamforming signal, the frequency and phase synchronization antenna is compensated; adopting a prior equal distribution scheme, enabling the main transmitter and the auxiliary transmitter to alternately transmit synchronous signals, and obtaining the phase offset between the transmitting antenna and the receiving antenna according to the difference delta theta (t) between the main transmitter and the auxiliary transmitter
Figure BDA0002683682260000021
And frequency offset
Figure BDA0002683682260000022
Thereafter, each slave transmitter is compensated for an initial phase to synchronize with the master transmitter.
Further, the received signal on the master and slave antennas is PM(t) when the synchronization signal is transmitted from the transmitter alone, the received signal is Ps(t), Δ θ (t) is:
Figure BDA0002683682260000023
wherein,
Figure BDA0002683682260000024
for the phase captured from the host transmitter side to the host receiver side,
Figure BDA0002683682260000025
for capturing from the master transmitter side to the slave receiver sideThe phase of (a) is determined,
Figure BDA0002683682260000031
for the phase captured from the slave transmitter side to the master receiver side,
Figure BDA0002683682260000032
t is the time for the phase captured from the slave transmitter end to the slave receiver end.
Specifically, in step S2, a selective reading mechanism designed in a commercial EPC C1G2 protocol is adopted, a SELECT command is sent to SELECT a reference tag, reading of the reference tag is achieved by setting parameters in a Query command, then a reader SELECTs a plurality of transmission parameters, response information of the reference tag under different parameter settings is obtained, a master transmitter signal is kept unchanged, an initial phase of each slave transmitter signal is changed within [0,2 pi ] with δ as a step length, energy replied by the tag is evaluated by using an evaluation function f, values of the evaluation functions under all transmission settings are recorded, and response information E of the reference tag is formed0 A 1 is mixing E0As an initial setting of the simulated annealing algorithm in step S3.
Further, the response information E of the reference tag0The method specifically comprises the following steps:
E0＝[f(1)，f(2)，...，f(2π/δ)]
specifically, in step S3, a simulated annealing algorithm is used for approximating the given evaluation function EnAccording to an evaluation function EnObtain a list of appropriate transmission parameters for target tag tracking, andnordering from high to low, a transmission parameter list theta is obtainednTraversing the list Θ by changing the send parameters one by onenUsing the same transmission parameter theta in the same counting cyclen(k) Before starting the next inventory cycle, the system will En(Θn(k) ) and En(Θn(k +1)) are compared; switching to the next transmission parameter indeed according to the probability function P; refresh E based on the latest response of the reference tag before starting a new inventory cyclen(Θn(k) If E) is equal tonIf the element in (1) is not updated, the attenuation coefficient alpha is equal to EnK decreases with time; if under the current transmission parameter setting, the function E is evaluatednIs equal to 0, continues to transmit with a maximum EnUntil movement is detected.
Further, the function E is evaluatednComprises the following steps:
Figure BDA0002683682260000041
where N is the number of iterations, μ is the weight coefficient, NtAnd NuRespectively the number of target tags and non-target tags, beta is a constant, alpha is the attenuation coefficient over time k, k is time,
Figure BDA0002683682260000042
as a transmission parameter, TrAre reference labels.
Further, a particle filter is introduced, if the function E is to be evaluatednConsidering the probability density of the transmission setting, it is necessary to estimate the probability density under motion or environmental change, define the update function E of the transfer function wn，EnAll values in (1) are updated to En+1Starting from sorting and traversing until a mobility event is detected, wherein the function E is evaluatednDepending on the estimation of the number of target tags, in static scenarios, a classification method based on EPC is employed, increasing N if the received EPC belongs to a non-target taguOtherwise the tag is marked as the target tag and N is increasedtA value of (d); in a dynamic scene, the similarity between the amplitude curves of the reference label and the current label is calculated by adopting a dynamic time warping method, the amplitude of each label is recorded, and the distance M (u, upsilon) between the reference label and the current label is obtained.
Another aspect of the invention is a computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform any of the methods described.
Another technical solution of the present invention is a computing device, including:
one or more processors, memory, and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for performing any of the methods.
Compared with the prior art, the invention has at least the following beneficial effects:
according to the method for directionally reading and tracking the commercial label in real time, label ID information does not need to be assumed, hardware or a protocol on the commercial label does not need to be changed, and therefore the method is compatible with the existing RFID system, can be matched with various types of commercial passive labels for use, can selectively read the label at a target position, and can improve the reading rate of the target label by more than 3 times compared with the latest USRP Gen2 reader.
Furthermore, a phase offset of the transmitter can be compensated through antenna synchronization, and the signals transmitted subsequently can meet the design requirements.
Further, by calculating Δ θ (t), the phase offsets of the master and slave transmitters can be obtained, which can be synchronized with the master by compensating the slave for the phase offset.
Furthermore, by using a SELECT command and a Query command in a commercial EPC C1G2 protocol, communication can be accurately performed with a reference tag closest to a target tag, which is beneficial to directionally acquiring response information of the reference tag.
Further, the response message contains the amplitude of the reply signal from the reference tag at different transmission settings, which will serve as the initial setting for the simulated annealing algorithm in step S3.
Further, the transmission parameter setting which is most suitable for tracking the target label can be obtained by adopting a simulated annealing algorithm.
Further, the evaluation function reflects a list of suitable transmission parameters for target tag tracking. And optimizing by a simulated annealing algorithm to obtain the transmission parameter setting which is most suitable for tracking the target label.
Further, the particle filter is introduced to estimate the moving track of the target label in real time.
In conclusion, the method and the device do not need to know the ID of the target tag and modify the protocol and hardware, are compatible with the conventional commercial RFID system, greatly reduce the cost of directionally reading and tracking the target tag, and have wide application prospect.
The technical solution of the present invention is further described in detail by the accompanying drawings and embodiments.
Drawings
FIG. 1 is a flow chart of the system of the present invention;
FIG. 2 is a flow chart of a first type second generation protocol of EPC;
FIG. 3 is a graph of dynamic time warping results for different classes of labels, where (a) is the amplitude of the reference label and the target label, and (b) is the amplitude of the reference label and the non-target label;
FIG. 4 is a diagram of a system hardware deployment;
FIG. 5 is a flow chart of the method of the present invention.
Detailed Description
The invention provides a commercial label directional reading and real-time tracking method, a storage medium and equipment, which can obtain energy distribution and setting information related to energy supply for a target label at different transmission settings by capturing response information of a reference label stuck on a shelf or a mobile container, excite the label at a target position by adopting a radio frequency beam forming technology, and dynamically select proper transmission parameters by combining a simulated annealing algorithm and a particle filter so as to track the movement of the target label in real time. The method is different from the previous method for selectively reading the ID information of the known target tag, and the RFID tag does not need to be modified in any protocol or hardware, so that the reading rate of the tags around the target position is improved in the actual environment of large-scale deployment of commercial RFID tags, and the movement of the tags is tracked in real time; compared with the existing method, the method greatly reduces the deployment cost and has wider application.
Referring to fig. 5, a method for directional reading and real-time tracking of a commercial tag according to the present invention includes the following steps:
s1, synchronizing the distributed transmitting antennas;
the master transmitter and the slave transmitters of the distributed antenna array alternately transmit synchronization signals, and the phase offset between the transmitting antenna and the receiving antenna is measured, and each slave transmitter is compensated with an initial phase to synchronize with the master transmitter.
With a master-slave distributed antenna array, frequency and phase compensation is required to synchronize the antennas before re-transmitting the beamformed signals. And adopting an a priori same distribution scheme to enable the master transmitter and the slave transmitter to alternately transmit synchronous signals, and measuring the phase offset between the transmitting antenna and the receiving antenna. Each slave transmitter is compensated for an initial phase to synchronize with the master transmitter.
The master transmitter transmitting the synchronisation signal separately in a 'sync' message, the received signal P on the master and slave antennasM(t) is expressed as:
Figure BDA0002683682260000071
wherein H represents a channel parameter matrix between the master transmitter and the slave transmitter,
Figure BDA0002683682260000072
representing the transmitting end T of the slave main transmitterMReceiving end R to master or slave transmitterxThe phase of acquisition is represented by:
Figure BDA0002683682260000073
wherein,
Figure BDA0002683682260000074
is the transmit phase of the primary transmitter,
Figure BDA0002683682260000075
is the receive phase of the master or slave transmitter,
Figure BDA0002683682260000076
is the transmission frequency of the main transmitter and,
Figure BDA0002683682260000077
is the receive frequency of the master or slave transmitter.
When the synchronization signal is transmitted separately from the transmitter, the received signal is denoted as Ps(t)。
Calculating the difference Δ θ (t) between the two, we can obtain:
Figure BDA0002683682260000078
obtaining a phase offset
Figure BDA0002683682260000079
And frequency offset
Figure BDA00026836822600000710
The slave transmitter is then compensated for an initial phase to synchronize with the master transmitter.
S2, carrying out quick search, inquiring the reference label closest to the target label, and acquiring the response information of the reference label;
referring to fig. 2, a selective reading mechanism designed in the current commercial EPC C1G2 protocol is adopted to send an appropriate SELECT command and Query command to read a reference tag; and then the reader selects a plurality of transmission parameters to obtain the response information of the reference tag under different parameter settings.
The SELECT command and Query command can be reduced to tuples S and Q, as follows:
S(b,p,l,m),Q(s,q) (4)
the SELECT command aims at selecting a subset of tags with a sub-string of bits starting from the p-th bit and ending at the (p + l-1) -th bit in the b-th memory area and equal to m, and in tuple Q, the element Sel is set to true to SELECT a tag that meets the requirements set forth in the SELECT command so that it can respond in the current inventory round.
The reference label of the target position is effectively accessed by setting the EPC of the reference label as Mask m.
To collect information about the reference tag (called a snapshot), the reader selects a number of transmission parameters and gets a reply for the reference tag under different parameter settings.
The master transmitter signal is first kept constant and the initial phase of each slave transmitter signal is modified in steps of delta within the range of 0,2 pi). δ is set to 0.1 π.
I.e. the main transmitter constantly sends a signal PM(t) sending a signal P from the transmitterS(t) its initial phase is θ'TSAnd dynamically setting as follows:
Figure BDA0002683682260000081
where i represents the index of the inventory loop, i ∈ [1,2, 3., 2 π/δ ·]，
Figure BDA0002683682260000082
Is the initial phase of the signal from the transmitter. It is synchronized to the main transmitter by adding a phase and frequency offset Δ θ (t).
To evaluate the energy of the reference tag reply when using one transmit parameter set, an evaluation function f is defined as follows:
Figure BDA0002683682260000083
wherein A (-) denotes when the transmission parameter is equal to
Figure BDA0002683682260000084
Temporal slave reference tag TrThe amplitude of the received signal; the higher the energy received from the reader, the greater the amplitude of the tag signal.
At all placesRecording from reference tag T under output settingsrThe amplitude of the return, i.e.:
E0＝[f(1)，f(2)，...，f(2π/δ)] (7)
wherein E is0I.e. a snapshot of the reference tag, and E0As an initial setting of the Simulated Annealing (SA) algorithm in step S3.
And S3, obtaining energy distribution at different transmission settings and setting information related to energy supply for the target label by using the response information of the reference label, dynamically selecting proper transmission parameters to excite the label of the target area by combining a simulated annealing algorithm and a particle filter, and tracking the movement of the target label in real time.
Appropriate transmission parameters are dynamically selected in combination with the simulated annealing algorithm and the particle filter to track the movement of the target tag in real time, and once the reader detects possible movement or environmental changes, the reader updates the evaluation function and restarts the simulated annealing algorithm. And simultaneously comparing the similarity of the motion tracks between the reference label and the target label through a dynamic time warping algorithm, and distinguishing the target label from the whole label population.
When the target tag is movable, the reader needs to dynamically adjust the transmission parameters to track the target tag. Even if the tag is static, moving objects around the tag can cause the selected parameter settings to be less than ideal. To find the appropriate transmission settings, a simulated annealing algorithm is used, which is a probabilistic technique for approximating a given evaluation function EnThe global optimum value of (c).
Will evaluate the function EnIs defined as:
Figure BDA0002683682260000091
where N is the number of iterations and μ is a weight coefficient, which is set to 1.1, N, according to the experimenttAnd NuThe number of target tags and non-target tags, respectively.
In application, there is Nu＞＞NtUsing the parameter beta, let beta. NtAnd NuSimilarly. Default values are mu-1.1, beta-Nu/Nt. α is an attenuation coefficient with time k, and is set to 0.9 by experiment. When the transmission parameter is set to
Figure BDA0002683682260000092
Function EnAn evaluation of the system performance is given. As previously described, EnIs set as the snapshot E obtained in step S20。
According to an evaluation function EnObtain a list of appropriate transmission parameters for target tag tracking, andnordering from high to low, a transmission parameter list theta is obtainedn：
Θn＝arg(d(En)) (9)
Where d (-) represents the descending sort function. List ΘnThe order of (1) shows the priority of the transmission parameters.
The list Θ is then traversed by changing the transmission parameters one by onenUsing the same transmission parameter theta in the same counting cyclen(k) Before starting the next inventory cycle, the system will En(Θn(k) ) and En(Θn(K +1)) were compared.
Depending on whether the value of the probability function P does switch to the next transmission parameter:
Figure BDA0002683682260000101
where Γ represents the simulated temperature in the annealing algorithm, and Δ Γ is the change temperature after the switch, defined as:
ΔΓ＝En(Θn(K+1))-En(Θn(k)) (11)
the temperature Γ is reduced by multiplying by a cooling parameter η (i.e., Γ η · Γ), and the process is repeated until Γ is equal to 0 or less than a threshold.
Before starting a new inventory loop, the system will respond with the latest response of the tag (e.g., A (T)r，i)，NtAnd Nu) Refresh En(Θn(k) ) of the measured values. If E isnIf the element in (1) is not updated, the attenuation coefficient alpha will be EnThe elements in (a) decrease over time k. If under the current transmission parameter setting, the function E is evaluatednIs equal to 0, will continue to transmit with the maximum EnUntil movement is detected.
Evaluating function E if target tag is moving continuously or if moving object exists in current working areanThe recorded value in (a) will tend to be inaccurate. For example, if an obstacle obstructs the primary propagation path between the target tag and the reader, or the target tag moves to another location with the reference tag, previous annealing algorithms may result in loss of tracking of the target tag. The effect of mobility needs to be considered.
Experiments show that when the moving state of the label is determined, the phase information of the label is more reliable than the amplitude information.
Recording the phase of the reference tag when a snapshot of the reference tag is captured in step S2
Figure BDA0002683682260000111
In step S3, the corresponding phase is compared to the value in Φ, and if there is no movement, the phase will remain stable, otherwise the phase will fluctuate. And comparing the phase change with a threshold value determined according to experiments, and if the change is larger than the threshold value, considering that the target label is in a moving state.
The current system can determine when the target tag begins to move, but still does not know the movement trajectory of the tag. To solve this problem, a particle filter is introduced. If the function E is to be evaluatednConsidering the probability density of the transmission setting, the probability density under motion (or environmental change) needs to be estimated. To update the function EnDefining a transfer function w:
wn+1(i)＝C·[wn(i-1),wn(i),wn(i+1)]T (12)
where C represents a coefficient matrix, and means transition probability from the last state to the next state, and the values in C are set to 1/3.
The evaluation function E is then updatednIt is then compared with a transfer function wn+1Multiplication, i.e.:
En+1(i)＝wn+1(i)·En(i) (13)
at this time, EnWill update to En+1The sequencing and traversal will start until a mobility event is detected.
In step S3, the function E is evaluatednRelying on an accurate estimate of the number of target tags. Two cases are considered here:
(1) in a static scenario (e.g., warehouse shelf), the system has no knowledge of the EPC of the targeted tag (the tag of the newly incoming package on the shelf), but already knows the EPCs of the non-targeted tags (the tags of all packages on other shelves) in the environment.
(2) In a dynamic scenario (e.g., shopping cart), the system does not know the EPC information of the target and non-target tags, but the target tag moves with the reference tag.
In the first case, a classification method based on EPC is employed: increasing N if the received EPC belongs to a non-target taguA value of (d); otherwise, mark the label as the target label and increase NtThe value of (c).
In the second case, a trajectory-based classification method is used: because the physical distances are very close, the target label always has an amplitude track similar to that of the reference label;
referring to fig. 3, the similarity between the amplitude curves of the reference tag and the current tag is calculated by using a Dynamic Time Warping (DTW) method, and fig. 3 illustrates the amplitude values of the reference tag, the target tag, and the non-target tag after dynamic time warping. Wherein fig. 3(a) indicates that the reference tag and the target tag have similar amplitude distributions, and fig. 3(b) indicates that the reference tag and the non-target tag have different amplitude distributions.
The difference between the amplitudes is first calculated using the following formula:
ξ(u，υ)＝amp(Tr,u)-amp(Tc,υ) (14)
wherein, amp (T)xY) represents a tag TxAmplitude of the y-th response, TcRepresenting the current label.
The amplitude of each tag is recorded and the distance between the reference tag and the current tag is further calculated by the following formula:
M(u，υ)＝ξ(u，υ)+min(M(u-1,υ-1),M(u-1,υ),M(u,υ-1)) (15)
where M (u, upsilon) is a distance function.
The distance M in each inventory cycle is then calculated for all received tags and reference tags, and only tags whose distance is less than an experimentally selected threshold are considered target tags.
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. The components of the embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1, the present invention is divided into three major modules, namely an antenna synchronization module, a fast search module and a motion tracking module.
1. An antenna synchronization module:
the present invention employs a master-slave distributed antenna array, which requires frequency and phase compensation to synchronize the antennas before transmitting the beamforming signal. And adopting a prior equal distribution scheme to enable the master machine and the slave machine to alternately send synchronous signals and measure the phase offset between the transmitting antenna and the receiving antenna. Each slave is compensated for an initial phase to synchronize with the master transmitter.
2. A fast search module:
(1) communicating with the reference tag: the selective reading mechanism designed in the current commercial EPC C C1G2 protocol is adopted. An appropriate SELECT command is sent to SELECT a reference tag, and then efficient reading of the reference tag is achieved by setting parameters in the Query command.
(2) Selecting transmission parameters and collecting response information of the reference tag: keeping the master signal unchanged, continuously changing the initial phase of the slave signal, and evaluating the energy recovered by the tag by using an evaluation function. The value of the evaluation function at all transmission settings is recorded, constituting a snapshot E0 of the reference tag.
3. A motion tracking module: this module contains three sub-modules, see fig. 1 right side.
(1) And optimizing the evaluation function by using a simulated annealing algorithm to obtain a proper transmission parameter.
(2) And judging whether the target label is in a moving state according to whether the phase change of the label exceeds a threshold value. And then introducing a particle filter to estimate the moving track of the target label in real time.
(3) And calculating the similarity between the amplitude curves of the reference label and the current label by adopting a Dynamic Time Warping (DTW) algorithm, so that the target label can be distinguished from the whole label population.
Referring to fig. 4, the hardware deployment of the present invention is shown in fig. 4: the present invention is deployed on a USRP X310 software defined radio test bed with two SBX daughter boards as RFID readers. The reader adopts a Multiple Input Multiple Output (MIMO) model, and each daughter board supports full-duplex communication. The antenna employs four unidirectional antennas VERT900 with a gain of 3 dBi.
To demonstrate the improvement in the read rate of the target tag of this invention, it was compared to the recently developed USRP Gen2 reader. And comparing the reading rates of the target tag and the target tag by testing in three different scenes. The read rate is defined as the number of replies received from the target tag per second. According to experiments, the average reading rates of the Gen2 reader in the three scenes are 10.51/s, 5.74/s and 8.09/s respectively, and the average reading rates of the Gen2 reader in the same scene are 2.08/s, 1.44/s and 2.14/s respectively. Compared with the USRP Gen2 reader, the reading rate of the invention to the target label can be improved by more than 3 times.
In summary, according to the method, the storage medium, and the device for directionally reading and tracking the commercial tag in real time, the response information of the reference tag closest to the target tag is utilized to obtain the energy distribution at different transmission settings and the setting information for supplying energy to the target tag, the target tag is excited by using the rf beamforming technology, and the appropriate transmission parameters are dynamically selected by combining the simulated annealing algorithm and the particle filter, so that the target tag is read and tracked in real time.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The above-mentioned contents are only for illustrating the technical idea of the present invention, and the protection scope of the present invention is not limited thereby, and any modification made on the basis of the technical idea of the present invention falls within the protection scope of the claims of the present invention.

Claims (8)

1. A commercial label directional reading and real-time tracking method is characterized by comprising the following steps:
s1, adopting a master-slave distributed antenna array, wherein the master transmitter and the slave transmitter of the distributed antenna array alternately transmit synchronous signals, measuring the phase offset between the transmitting antenna and the receiving antenna, and compensating an initial phase for each slave transmitter to synchronize with the master transmitter;
s2, carrying out fast search, inquiring a reference label closest to a target label, adopting a selective reading mechanism designed in a commercial EPC C1G2 protocol, sending a SELECT command to SELECT the reference label, reading the reference label by setting parameters in a Query command, selecting a plurality of transmission parameters by a reader, obtaining response information of the reference label under different parameter settings, keeping a main transmitter signal unchanged, changing the initial phase of each slave transmitter signal within [0,2 pi ] by taking delta as a step length, evaluating the energy replied by the label by using an evaluation function f, and recording the energy replied by the label under all the transmission parametersEvaluating the value of the function, constituting the response information E of the reference tag0A 1 is mixing E0As an initial setting of the simulated annealing algorithm in step S3;
s3, response information E of reference label using step S20Obtaining energy distribution and related setting information for supplying energy to the target tag when different transmission parameters are obtained, dynamically selecting the transmission parameters to excite the tag of the target area and track the movement of the target tag in real time by combining a simulated annealing algorithm and a particle filter, and finishing the directional reading and real-time tracking of the commercial tag at the target position;
the method specifically comprises the following steps: using simulated annealing algorithm for approximating a given evaluation function EnAccording to an evaluation function EnObtain a list of appropriate transmission parameters for target tag tracking, andnordering from high to low, a transmission parameter list theta is obtainednTraversing the list Θ by changing the send parameters one by onenUsing the same transmission parameter theta in the same counting cyclen(k) Before starting the next inventory cycle, the system will En(Θn(k) ) and En(Θn(k +1)) are compared; switching to the next transmission parameter indeed according to the probability function P; refresh E based on the latest response of the reference tag before starting a new inventory cyclen(Θn(k) If E) is equal tonIf the element in (1) is not updated, the attenuation coefficient alpha is equal to EnK decreases with time; if under the current transmission parameter setting, the function E is evaluatednIs equal to 0, continues to transmit with a maximum EnUntil movement is detected.
2. The method of claim 1, wherein in step S1, before transmitting the beam-forming signal, the frequency and phase synchronization antenna is compensated; the method comprises the steps that a priori same distribution scheme is adopted, a main transmitter and a secondary transmitter are enabled to alternately send synchronous signals, and phase shift between a transmitting antenna and a receiving antenna is obtained according to difference delta theta (t) of the main transmitter and the secondary transmitter
Figure FDA0003224613760000021
And frequency offset
Figure FDA0003224613760000022
Thereafter, each slave transmitter is compensated for an initial phase to synchronize with the master transmitter.
3. The method of claim 2, wherein the received signal on the master and slave antennas is PM(t) when the synchronization signal is transmitted from the transmitter alone, the received signal is Ps(t), Δ θ (t) is:
Figure FDA0003224613760000023
wherein,
Figure FDA0003224613760000024
for the phase acquisition from the main transmitter side to the main receiver side,
Figure FDA0003224613760000025
for the phase acquisition from the master transmitter side to the slave receiver side,
Figure FDA0003224613760000026
for the phase acquisition from the transmitter side to the main receiver side,
Figure FDA0003224613760000027
t is the time for the phase from the transmitter side to the acquisition from the receiver side.
4. The method according to claim 1, wherein in step S2, the response information E of the reference label0The method specifically comprises the following steps:
E0＝[f(1)，f(2)，...，f(2π/δ)]。
5. the method according to claim 1, wherein in step S3, the function E is evaluatednComprises the following steps:
Figure FDA0003224613760000028
where N is the number of iterations, μ is the weight coefficient, NtAnd NuRespectively the number of target tags and non-target tags, beta is a constant, alpha is the attenuation coefficient over time k, k is time,
Figure FDA0003224613760000029
as a transmission parameter, TrAre reference labels.
6. The method of claim 5, wherein a particle filter is introduced if the evaluation function E is to be evaluatednConsidering the probability density of the transmission parameters, it is necessary to estimate the probability density under motion or environmental changes, define the update function E of the transfer function wn，EnAll values in (1) are updated to En+1Starting from sorting and traversing until a mobility event is detected, wherein the function E is evaluatednDepending on the estimation of the number of target tags, in static scenarios, a classification method based on EPC is employed, increasing N if the received EPC belongs to a non-target taguOtherwise the tag is marked as the target tag and N is increasedtA value of (d); in a dynamic scene, the similarity between the amplitude curves of the reference label and the current label is calculated by adopting a dynamic time warping method, the amplitude of each label is recorded, and the distance M (u, upsilon) between the reference label and the current label is obtained.
7. A computer readable storage medium storing one or more programs, the one or more programs comprising instructions, which when executed by a computing device, cause the computing device to perform any of the methods of claims 1-6.
8. A computing device, comprising:
one or more processors, memory, and one or more programs stored in the memory and configured to be executed by the one or more processors, the one or more programs including instructions for performing any of the methods of claims 1-6.
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